106 lines
99 KiB
HTML
106 lines
99 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><title>3 Low-level interface</title><link rel="stylesheet" type="text/css" href="scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="racket.css" title="default"/><link rel="stylesheet" type="text/css" href="footnote.css" title="default"/><link rel="stylesheet" type="text/css" href="manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="manual-racket.css" title="default"/><script type="text/javascript" src="scribble-common.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="scribble-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">▼</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x">Marketplace:<span class="mywbr"> </span> Network-<wbr></wbr>Aware Programming</a></td></tr></table></div><div class="tocviewsublisttop" style="display: block;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="Concepts.html" class="tocviewlink" data-pltdoc="x">Concepts</a></td></tr><tr><td align="right">2 </td><td><a href="high-level-interface.html" class="tocviewlink" data-pltdoc="x">High-<wbr></wbr>level interface</a></td></tr><tr><td align="right">3 </td><td><a href="low-level-interface.html" class="tocviewselflink" data-pltdoc="x">Low-<wbr></wbr>level interface</a></td></tr><tr><td align="right">4 </td><td><a href="Drivers.html" class="tocviewlink" data-pltdoc="x">Drivers</a></td></tr><tr><td align="right">5 </td><td><a href="Management_and_Monitoring.html" class="tocviewlink" data-pltdoc="x">Management and Monitoring</a></td></tr><tr><td align="right">6 </td><td><a href="Examples.html" class="tocviewlink" data-pltdoc="x">Examples</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_1");">►</a></td><td>3 </td><td><a href="low-level-interface.html" class="tocviewselflink" data-pltdoc="x">Low-<wbr></wbr>level interface</a></td></tr></table><div class="tocviewsublistbottom" style="display: none;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">3.1 </td><td><a href="low-level-interface.html#%28part._handler-functions%29" class="tocviewlink" data-pltdoc="x">Handler Functions</a></td></tr><tr><td align="right">3.2 </td><td><a href="low-level-interface.html#%28part._.Messages__.Topics_and_.Roles%29" class="tocviewlink" data-pltdoc="x">Messages, Topics and Roles</a></td></tr><tr><td align="right">3.3 </td><td><a href="low-level-interface.html#%28part._endpoint-events%29" class="tocviewlink" data-pltdoc="x">Endpoint Events</a></td></tr><tr><td align="right">3.4 </td><td><a href="low-level-interface.html#%28part._.Actions%29" class="tocviewlink" data-pltdoc="x">Actions</a></td></tr></table></div></div></div><div class="tocsub"><div class="tocsubtitle">On this page:</div><table class="tocsublist" cellspacing="0"><tr><td><span class="tocsublinknumber">3.1<tt> </tt></span><a href="#%28part._handler-functions%29" class="tocsubseclink" data-pltdoc="x">Handler Functions</a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Handler%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Handler</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Trap.K%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Trap<span class="mywbr"> </span>K</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Interrupt.K%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Interrupt<span class="mywbr"> </span>K</span></span></a></td></tr><tr><td><span class="tocsublinknumber">3.2<tt> </tt></span><a href="#%28part._.Messages__.Topics_and_.Roles%29" class="tocsubseclink" data-pltdoc="x">Messages, Topics and Roles</a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Message%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Message</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Topic%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Topic</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._wild%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">wild</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._~3f%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._role%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">role</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Role%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Role</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Orientation%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Orientation</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Interest.Type%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Interest<span class="mywbr"> </span>Type</span></span></a></td></tr><tr><td><span class="tocsublinknumber">3.3<tt> </tt></span><a href="#%28part._endpoint-events%29" class="tocsubseclink" data-pltdoc="x">Endpoint Events</a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Endpoint.Event%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Endpoint<span class="mywbr"> </span>Event</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Presence.Event%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Presence<span class="mywbr"> </span>Event</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Absence.Event%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Absence<span class="mywbr"> </span>Event</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Message.Event%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Message<span class="mywbr"> </span>Event</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._presence-event%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">presence-<wbr></wbr>event</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._absence-event%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">absence-<wbr></wbr>event</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._message-event%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">message-<wbr></wbr>event</span></span></a></td></tr><tr><td><span class="tocsublinknumber">3.4<tt> </tt></span><a href="#%28part._.Actions%29" class="tocsubseclink" data-pltdoc="x">Actions</a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Action%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Action</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Pre.Action%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Pre<span class="mywbr"> </span>Action</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._at-meta-level%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">at-<wbr></wbr>meta-<wbr></wbr>level</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.At.Meta.Level%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">At<span class="mywbr"> </span>Meta<span class="mywbr"> </span>Level</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._yield%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">yield</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Yield%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Yield</span></span></a></td></tr><tr><td><span class="tocsublinknumber">3.4.1<tt> </tt></span><a href="#%28part._endpoints-and-messages%29" class="tocsubseclink" data-pltdoc="x">Endpoints and Messages</a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._add-endpoint%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">add-<wbr></wbr>endpoint</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Add.Endpoint%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Add<span class="mywbr"> </span>Endpoint</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._delete-endpoint%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">delete-<wbr></wbr>endpoint</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Delete.Endpoint%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Delete<span class="mywbr"> </span>Endpoint</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._send-message%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">send-<wbr></wbr>message</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Send.Message%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Send<span class="mywbr"> </span>Message</span></span></a></td></tr><tr><td><span class="tocsublinknumber">3.4.2<tt> </tt></span><a href="#%28part._.Process_.Management%29" class="tocsubseclink" data-pltdoc="x">Process Management</a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._spawn%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">spawn</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._process-spec%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">process-<wbr></wbr>spec</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Co.Transition%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Co<span class="mywbr"> </span>Transition</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Spawn%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Spawn</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Process.Spec%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Process<span class="mywbr"> </span>Spec</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._quit%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">quit</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Quit%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">Quit</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.P.I.D%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">PID</span></span></a></td></tr></table></div></div><div class="maincolumn"><div class="main"><div class="versionbox"><span class="version">6.0.0.1</span></div><div class="navsettop"><span class="navleft"> </span><span class="navright"> <a href="high-level-interface.html" title="backward to "2 High-level interface"" data-pltdoc="x">← prev</a> <a href="index.html" title="up to "Marketplace: Network-Aware Programming"" data-pltdoc="x">up</a> <a href="Drivers.html" title="forward to "4 Drivers"" data-pltdoc="x">next →</a></span> </div><h3>3<tt> </tt><a name="(part._low-level-interface)"></a><a name="(mod-path._marketplace)"></a>Low-level interface</h3><p><table cellspacing="0" class="defmodule"><tr><td align="left"><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/require.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._require%29%29" class="RktStxLink" data-pltdoc="x">require</a></span><span class="stt"> </span><a href="low-level-interface.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">marketplace</span></a><span class="RktPn">)</span></td><td align="right"><span class="RpackageSpec"><span class="Smaller"> package:</span> <span class="stt">marketplace</span></span></td></tr></table></p><p>At its heart, the interface between each <a href="Concepts.html#%28tech._proces%29" class="techoutside" data-pltdoc="x"><span class="techinside">process</span></a> and its
|
|
containing <a href="Concepts.html#%28tech._vm%29" class="techoutside" data-pltdoc="x"><span class="techinside">VM</span></a> is based on <a href="low-level-interface.html#%28tech._handler._function%29" class="techoutside" data-pltdoc="x"><span class="techinside">handler functions</span></a> exchanging
|
|
<a href="Concepts.html#%28tech._event%29" class="techoutside" data-pltdoc="x"><span class="techinside">event</span></a> and <a href="Concepts.html#%28tech._action%29" class="techoutside" data-pltdoc="x"><span class="techinside">action</span></a> structures with the VM. Both events and
|
|
actions are simple Racket structures.</p><p>This low-level interface between a VM and a process is analogous to
|
|
the <span style="font-style: italic">system call interface</span> of a Unix-like operating system. The
|
|
<a href="high-level-interface.html" data-pltdoc="x">High-level interface</a> corresponds to the <span style="font-style: italic">C library
|
|
interface</span> of a Unix-like operating system.</p><h4>3.1<tt> </tt><a name="(part._handler-functions)"></a>Handler Functions</h4><p>Each <a name="(tech._handler._function)"></a><span style="font-style: italic">handler function</span> is always associated with a particular
|
|
<a href="Concepts.html#%28tech._endpoint%29" class="techoutside" data-pltdoc="x"><span class="techinside">endpoint</span></a>, registered with the VM via
|
|
<span class="RktSym">endpoint</span>/<span class="RktSym">endpoint:</span>/<span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._add-endpoint%29%29" class="RktValLink" data-pltdoc="x">add-endpoint</a></span>. A handler
|
|
function for a given process with state type <span class="RktSym">State</span> has type:</p><blockquote class="SCodeFlow"><p><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Endpoint.Event%29%29" class="RktValLink" data-pltdoc="x">EndpointEvent</a></span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Transition%29%29" class="RktValLink" data-pltdoc="x">Transition</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span><span class="RktPn">)</span></p></blockquote><p>That is, given an <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Endpoint.Event%29%29" class="RktValLink" data-pltdoc="x">EndpointEvent</a></span> followed by the process’s
|
|
current state, the handler should reply with a <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Transition%29%29" class="RktValLink" data-pltdoc="x">Transition</a></span>
|
|
containing a new process state and a collection of <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Action%29%29" class="RktValLink" data-pltdoc="x">Action</a></span>s.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><table cellspacing="0" class="argcontract RForeground"><tr><td><a name="(def._((lib._marketplace/main..rkt)._.Handler))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Handler%29%29" class="RktValDef RktValLink" data-pltdoc="x">Handler</a></span></span></td><td><span class="hspace"> </span>:<span class="hspace"> </span></td><td><table cellspacing="0" class="RktBlk"><tr><td><span class="RktPn">(</span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.All%29%29" class="RktStxLink" data-pltdoc="x">All</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">State</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Trap.K%29%29" class="RktValLink" data-pltdoc="x">TrapK</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr></table></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><table cellspacing="0" class="argcontract RForeground"><tr><td><a name="(def._((lib._marketplace/main..rkt)._.Trap.K))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Trap.K%29%29" class="RktValDef RktValLink" data-pltdoc="x">TrapK</a></span></span></td><td><span class="hspace"> </span>:<span class="hspace"> </span></td><td><table cellspacing="0" class="RktBlk"><tr><td><span class="RktPn">(</span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.All%29%29" class="RktStxLink" data-pltdoc="x">All</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">State</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Endpoint.Event%29%29" class="RktValLink" data-pltdoc="x">EndpointEvent</a></span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Interrupt.K%29%29" class="RktValLink" data-pltdoc="x">InterruptK</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr></table></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><table cellspacing="0" class="argcontract RForeground"><tr><td><a name="(def._((lib._marketplace/main..rkt)._.Interrupt.K))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Interrupt.K%29%29" class="RktValDef RktValLink" data-pltdoc="x">InterruptK</a></span></span></td><td><span class="hspace"> </span>:<span class="hspace"> </span></td><td><table cellspacing="0" class="RktBlk"><tr><td><span class="RktPn">(</span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.All%29%29" class="RktStxLink" data-pltdoc="x">All</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">State</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">State</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Transition%29%29" class="RktValLink" data-pltdoc="x">Transition</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr></table></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Typed Racket types capturing various notions of handler function.</div></p><h4>3.2<tt> </tt><a name="(part._.Messages__.Topics_and_.Roles)"></a>Messages, Topics and Roles</h4><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Message))"></a><span title="Provided from: marketplace, marketplace/sugar-untyped, marketplace/sugar-typed"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Message%29%29" class="RktValDef RktValLink" data-pltdoc="x">Message</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types..rkt%29._.Any%29%29" class="RktStxLink" data-pltdoc="x">Any</a></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Topic))"></a><span title="Provided from: marketplace, marketplace/sugar-untyped, marketplace/sugar-typed"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Topic%29%29" class="RktValDef RktValLink" data-pltdoc="x">Topic</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types..rkt%29._.Any%29%29" class="RktStxLink" data-pltdoc="x">Any</a></span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">As previously mentioned, <a href="Concepts.html#%28tech._message%29" class="techoutside" data-pltdoc="x"><span class="techinside">messages</span></a> are ordinary Racket values,
|
|
and <a href="Concepts.html#%28tech._topic%29" class="techoutside" data-pltdoc="x"><span class="techinside">topics</span></a> are ordinary Racket values which may have embedded
|
|
wildcards.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._marketplace/main..rkt)._wild))"></a><span title="Provided from: marketplace, marketplace/sugar-untyped, marketplace/sugar-typed"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._wild%29%29" class="RktValDef RktValLink" data-pltdoc="x">wild</a></span></span><span class="RktPn"></span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Topic%29%29" class="RktValLink" data-pltdoc="x">Topic</a></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/sugar-untyped..rkt)._~3f))"></a><span title="Provided from: marketplace, marketplace/sugar-untyped, marketplace/sugar-typed"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">?</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Topic%29%29" class="RktValLink" data-pltdoc="x">Topic</a></span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Each time <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._~3f%29%29" class="RktValLink" data-pltdoc="x">?</a></span> (or <span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._wild%29%29" class="RktValLink" data-pltdoc="x">wild</a></span><span class="RktPn">)</span>) is used in an expression
|
|
context, it produces a fresh topic wildcard, suitable for use in a
|
|
topic pattern.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._marketplace/main..rkt)._role-interest-type))"></a><a name="(def._((lib._marketplace/main..rkt)._role-topic))"></a><a name="(def._((lib._marketplace/main..rkt)._role-orientation))"></a><a name="(def._((lib._marketplace/main..rkt)._role~3f))"></a><a name="(def._((lib._marketplace/main..rkt)._struct~3arole))"></a><a name="(def._((lib._marketplace/main..rkt)._role))"></a><span title="Provided from: marketplace, marketplace/sugar-untyped, marketplace/sugar-typed"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._role%29%29" class="RktValDef RktValLink" data-pltdoc="x">role</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">orientation</span><span class="stt"> </span><span class="RktSym">topic</span><span class="stt"> </span><span class="RktSym">interest-type</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">orientation</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Orientation%29%29" class="RktValLink" data-pltdoc="x">Orientation</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">topic</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Topic%29%29" class="RktValLink" data-pltdoc="x">Topic</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">interest-type</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Interest.Type%29%29" class="RktValLink" data-pltdoc="x">InterestType</a></span></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Role))"></a><span title="Provided from: marketplace, marketplace/sugar-untyped, marketplace/sugar-typed"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Role%29%29" class="RktValDef RktValLink" data-pltdoc="x">Role</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._role%29%29" class="RktValLink" data-pltdoc="x">role</a></span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Roles are almost always constructed by the
|
|
<span class="RktSym">endpoint</span>/<span class="RktSym">endpoint:</span> macros or by the VM
|
|
implementations themselves. User programs generally only need to
|
|
destructure <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._role%29%29" class="RktValLink" data-pltdoc="x">role</a></span> instances.</div></p><p>A <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._role%29%29" class="RktValLink" data-pltdoc="x">role</a></span> describes the conversational role of a peer as seen by
|
|
some process. For example, a subscriber to topic <span class="RktVal">'</span><span class="RktVal">foo</span> with
|
|
interest-type <span class="RktVal">'</span><span class="RktVal">participant</span> might receive a presence
|
|
notification carrying the role</p><blockquote class="SCodeFlow"><p><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._role%29%29" class="RktValLink" data-pltdoc="x">role</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">publisher</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">foo</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">participant</span><span class="RktPn">)</span></p></blockquote><p>Notice that the orientation of the role is the opposite of the
|
|
orientation of the endpoint.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Orientation))"></a><span title="Provided from: marketplace, marketplace/sugar-untyped, marketplace/sugar-typed"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Orientation%29%29" class="RktValDef RktValLink" data-pltdoc="x">Orientation</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.U%29%29" class="RktStxLink" data-pltdoc="x">U</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">publisher</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">subscriber</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Describes an endpoint’s orientation: will it be acting as a publisher
|
|
of messages, or as a subscriber to messages? Publishers (orientation
|
|
<span class="RktVal">'</span><span class="RktVal">publisher</span>) tend to use <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._send-message%29%29" class="RktValLink" data-pltdoc="x">send-message</a></span> and tend to
|
|
respond to feedback from subscribers; subscribers
|
|
(<span class="RktVal">'</span><span class="RktVal">subscriber</span>) tend to use <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._send-feedback%29%29" class="RktValLink" data-pltdoc="x">send-feedback</a></span> and respond
|
|
to messages from publishers.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Interest.Type))"></a><span title="Provided from: marketplace, marketplace/sugar-untyped, marketplace/sugar-typed"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Interest.Type%29%29" class="RktValDef RktValLink" data-pltdoc="x">InterestType</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.U%29%29" class="RktStxLink" data-pltdoc="x">U</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">participant</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">observer</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">everything</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Using interest-type <span class="RktVal">'</span><span class="RktVal">participant</span> in an endpoint’s role
|
|
indicates that the endpoint is intending to act as a genuine
|
|
participant in whatever protocol is associated with the endpoint and
|
|
its topic.</div></p><p>Using <span class="RktVal">'</span><span class="RktVal">observer</span> indicates that the endpoint is intended to
|
|
<span style="font-style: italic">monitor</span> other ongoing (participant) conversations instead.
|
|
Observer endpoints receive presence and absence notifications about
|
|
participant endpoints, but participant endpoints only receive
|
|
notifications about other participant endpoints, and not about
|
|
observer endpoints.</p><p>The <span class="RktVal">'</span><span class="RktVal">observer</span> interest-type is intended to make it easier to
|
|
monitor resource demand and supply. The monitoring endpoints/processes
|
|
can react to changing demand by creating or destroying resources to
|
|
match.</p><p>Finally, the <span class="RktVal">'</span><span class="RktVal">everything</span> interest-type receives notifications
|
|
about presence and absence of <span style="font-style: italic">all</span> the types of endpoint,
|
|
<span class="RktVal">'</span><span class="RktVal">participant</span>, <span class="RktVal">'</span><span class="RktVal">observer</span>, and <span class="RktVal">'</span><span class="RktVal">everything</span>.
|
|
Endpoints with interest-type <span class="RktVal">'</span><span class="RktVal">everything</span> are rare: they are
|
|
relevant for managing demand for <span style="font-style: italic">observers</span>, as well as in some
|
|
cases of cross-layer presence/absence propagation. Most programs (and
|
|
even most drivers) will not need to use the <span class="RktVal">'</span><span class="RktVal">everything</span>
|
|
interest-type.</p><h4>3.3<tt> </tt><a name="(part._endpoint-events)"></a>Endpoint Events</h4><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Endpoint.Event))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Endpoint.Event%29%29" class="RktValDef RktValLink" data-pltdoc="x">EndpointEvent</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.U%29%29" class="RktStxLink" data-pltdoc="x">U</a></span><span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Presence.Event%29%29" class="RktValLink" data-pltdoc="x">PresenceEvent</a></span><span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Absence.Event%29%29" class="RktValLink" data-pltdoc="x">AbsenceEvent</a></span><span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Message.Event%29%29" class="RktValLink" data-pltdoc="x">MessageEvent</a></span><span class="RktPn">)</span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Presence.Event))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Presence.Event%29%29" class="RktValDef RktValLink" data-pltdoc="x">PresenceEvent</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._presence-event%29%29" class="RktValLink" data-pltdoc="x">presence-event</a></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Absence.Event))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Absence.Event%29%29" class="RktValDef RktValLink" data-pltdoc="x">AbsenceEvent</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._absence-event%29%29" class="RktValLink" data-pltdoc="x">absence-event</a></span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Message.Event))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Message.Event%29%29" class="RktValDef RktValLink" data-pltdoc="x">MessageEvent</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._message-event%29%29" class="RktValLink" data-pltdoc="x">message-event</a></span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Endpoint events are passed to handler functions by VMs, conveying some
|
|
change in the world the process lives in. An endpoint event can signal
|
|
the arrival or departure of a conversational peer, or can deliver a
|
|
message that has been sent on a VM’s IPC facility.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._marketplace/main..rkt)._presence-event-role))"></a><a name="(def._((lib._marketplace/main..rkt)._presence-event~3f))"></a><a name="(def._((lib._marketplace/main..rkt)._struct~3apresence-event))"></a><a name="(def._((lib._marketplace/main..rkt)._presence-event))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._presence-event%29%29" class="RktValDef RktValLink" data-pltdoc="x">presence-event</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">role</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">role</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Role%29%29" class="RktValLink" data-pltdoc="x">Role</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Indicates the arrival of a new conversational partner: an endpoint
|
|
with a topic that intersects our own, with <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Orientation%29%29" class="RktValLink" data-pltdoc="x">Orientation</a></span>
|
|
opposite to our own.</div></p><p>The <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._presence-event-role%29%29" class="RktValLink" data-pltdoc="x">presence-event-role</a></span> describes the arriving peer, or more
|
|
precisely, describes the shared interest between ourselves and the new
|
|
peer. In particular, the <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._role-orientation%29%29" class="RktValLink" data-pltdoc="x">role-orientation</a></span> of the
|
|
<span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._presence-event-role%29%29" class="RktValLink" data-pltdoc="x">presence-event-role</a></span> is the orientation that the <span style="font-style: italic">peer</span>
|
|
supplied in its <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._add-endpoint%29%29" class="RktValLink" data-pltdoc="x">add-endpoint</a></span> structure.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._marketplace/main..rkt)._absence-event-reason))"></a><a name="(def._((lib._marketplace/main..rkt)._absence-event-role))"></a><a name="(def._((lib._marketplace/main..rkt)._absence-event~3f))"></a><a name="(def._((lib._marketplace/main..rkt)._struct~3aabsence-event))"></a><a name="(def._((lib._marketplace/main..rkt)._absence-event))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._absence-event%29%29" class="RktValDef RktValLink" data-pltdoc="x">absence-event</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">role</span><span class="stt"> </span><span class="RktSym">reason</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">role</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Role%29%29" class="RktValLink" data-pltdoc="x">Role</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">reason</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types..rkt%29._.Any%29%29" class="RktStxLink" data-pltdoc="x">Any</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Indicates the departure of an existing conversational partner, through
|
|
either an explicit <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._delete-endpoint%29%29" class="RktValLink" data-pltdoc="x">delete-endpoint</a></span> action or the implicit
|
|
deleting of all of a process’s endpoints when a process exits.</div></p><p>The <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._absence-event-role%29%29" class="RktValLink" data-pltdoc="x">absence-event-role</a></span> describes the departing peer,
|
|
analogously to <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._presence-event-role%29%29" class="RktValLink" data-pltdoc="x">presence-event-role</a></span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._marketplace/main..rkt)._message-event-message))"></a><a name="(def._((lib._marketplace/main..rkt)._message-event-role))"></a><a name="(def._((lib._marketplace/main..rkt)._message-event~3f))"></a><a name="(def._((lib._marketplace/main..rkt)._struct~3amessage-event))"></a><a name="(def._((lib._marketplace/main..rkt)._message-event))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._message-event%29%29" class="RktValDef RktValLink" data-pltdoc="x">message-event</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">role</span><span class="stt"> </span><span class="RktSym">message</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">role</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Role%29%29" class="RktValLink" data-pltdoc="x">Role</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">message</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Message%29%29" class="RktValLink" data-pltdoc="x">Message</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Indicates the arrival of a message matching the topic pattern in the
|
|
handler’s <a href="Concepts.html#%28tech._endpoint%29" class="techoutside" data-pltdoc="x"><span class="techinside">endpoint</span></a>.</div></p><h4>3.4<tt> </tt><a name="(part._.Actions)"></a>Actions</h4><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><table cellspacing="0" class="argcontract RForeground"><tr><td><a name="(def._((lib._marketplace/main..rkt)._.Action))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Action%29%29" class="RktValDef RktValLink" data-pltdoc="x">Action</a></span></span></td><td><span class="hspace"> </span>:<span class="hspace"> </span></td><td><table cellspacing="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.All%29%29" class="RktStxLink" data-pltdoc="x">All</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">State</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.U%29%29" class="RktStxLink" data-pltdoc="x">U</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Pre.Action%29%29" class="RktValLink" data-pltdoc="x">PreAction</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="high-level-interface.html#%28form._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._yield%29%29" class="RktStxLink" data-pltdoc="x">yield</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._at-meta-level%29%29" class="RktValLink" data-pltdoc="x">at-meta-level</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr></table></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><table cellspacing="0" class="argcontract RForeground"><tr><td><a name="(def._((lib._marketplace/main..rkt)._.Pre.Action))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Pre.Action%29%29" class="RktValDef RktValLink" data-pltdoc="x">PreAction</a></span></span></td><td><span class="hspace"> </span>:<span class="hspace"> </span></td><td><table cellspacing="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.All%29%29" class="RktStxLink" data-pltdoc="x">All</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">State</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.U%29%29" class="RktStxLink" data-pltdoc="x">U</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._add-endpoint%29%29" class="RktValLink" data-pltdoc="x">add-endpoint</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._delete-endpoint%29%29" class="RktValLink" data-pltdoc="x">delete-endpoint</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._send-message%29%29" class="RktValLink" data-pltdoc="x">send-message</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="high-level-interface.html#%28form._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._spawn%29%29" class="RktStxLink" data-pltdoc="x">spawn</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._quit%29%29" class="RktValLink" data-pltdoc="x">quit</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr></table></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Actions are requests from a process to its containing VM. If wrapped
|
|
in an <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._at-meta-level%29%29" class="RktValLink" data-pltdoc="x">at-meta-level</a></span> structure, the action is to apply to
|
|
<span style="font-style: italic">the VM’s own containing VM</span>; otherwise, the action applies to
|
|
the process’s containing VM.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._marketplace/main..rkt)._at-meta-level-preaction))"></a><a name="(def._((lib._marketplace/main..rkt)._at-meta-level~3f))"></a><a name="(def._((lib._marketplace/main..rkt)._struct~3aat-meta-level))"></a><a name="(def._((lib._marketplace/main..rkt)._at-meta-level))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._at-meta-level%29%29" class="RktValDef RktValLink" data-pltdoc="x">at-meta-level</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">preaction</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">preaction</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Pre.Action%29%29" class="RktValLink" data-pltdoc="x">PreAction</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.At.Meta.Level))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.At.Meta.Level%29%29" class="RktValDef RktValLink" data-pltdoc="x">AtMetaLevel</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.All%29%29" class="RktStxLink" data-pltdoc="x">All</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">State</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._at-meta-level%29%29" class="RktValLink" data-pltdoc="x">at-meta-level</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span><span class="RktPn">)</span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">An <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._at-meta-level%29%29" class="RktValLink" data-pltdoc="x">at-meta-level</a></span> structure wraps a plain action, and makes it
|
|
apply to the outer VM instead of the inner VM (the default).</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._marketplace/main..rkt)._yield-k))"></a><a name="(def._((lib._marketplace/main..rkt)._yield~3f))"></a><a name="(def._((lib._marketplace/main..rkt)._struct~3ayield))"></a><a name="(def._((lib._marketplace/main..rkt)._yield))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="high-level-interface.html#%28form._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._yield%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">yield</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">k</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">k</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Interrupt.K%29%29" class="RktValLink" data-pltdoc="x">InterruptK</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Yield))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Yield%29%29" class="RktValDef RktValLink" data-pltdoc="x">Yield</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.All%29%29" class="RktStxLink" data-pltdoc="x">All</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">State</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="high-level-interface.html#%28form._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._yield%29%29" class="RktStxLink" data-pltdoc="x">yield</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span><span class="RktPn">)</span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Because current VM implementations are cooperatively scheduled, it can
|
|
sometimes be necessary to explicitly yield the CPU to other processes
|
|
using a <span class="RktSym"><a href="high-level-interface.html#%28form._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._yield%29%29" class="RktStxLink" data-pltdoc="x">yield</a></span> action. When control returns to the yielding
|
|
process, the <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._yield-k%29%29" class="RktValLink" data-pltdoc="x">yield-k</a></span> is invoked.</div></p><h5>3.4.1<tt> </tt><a name="(part._endpoints-and-messages)"></a>Endpoints and Messages</h5><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._marketplace/main..rkt)._add-endpoint-handler))"></a><a name="(def._((lib._marketplace/main..rkt)._add-endpoint-role))"></a><a name="(def._((lib._marketplace/main..rkt)._add-endpoint-pre-eid))"></a><a name="(def._((lib._marketplace/main..rkt)._add-endpoint~3f))"></a><a name="(def._((lib._marketplace/main..rkt)._struct~3aadd-endpoint))"></a><a name="(def._((lib._marketplace/main..rkt)._add-endpoint))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._add-endpoint%29%29" class="RktValDef RktValLink" data-pltdoc="x">add-endpoint</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">pre-eid</span><span class="stt"> </span><span class="RktSym">role</span><span class="stt"> </span><span class="RktSym">handler</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">pre-eid</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types..rkt%29._.Any%29%29" class="RktStxLink" data-pltdoc="x">Any</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">role</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Role%29%29" class="RktValLink" data-pltdoc="x">Role</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">handler</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Handler%29%29" class="RktValLink" data-pltdoc="x">Handler</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Add.Endpoint))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Add.Endpoint%29%29" class="RktValDef RktValLink" data-pltdoc="x">AddEndpoint</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.All%29%29" class="RktStxLink" data-pltdoc="x">All</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">State</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._add-endpoint%29%29" class="RktValLink" data-pltdoc="x">add-endpoint</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span><span class="RktPn">)</span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Creates a new endpoint subscribing to the given <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Role%29%29" class="RktValLink" data-pltdoc="x">Role</a></span>. When
|
|
events pertaining to the given role occur, the <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Handler%29%29" class="RktValLink" data-pltdoc="x">Handler</a></span> is
|
|
invoked.<span class="NoteBox"><span class="NoteContent">If invoked <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._at-meta-level%29%29" class="RktValLink" data-pltdoc="x">at-meta-level</a></span>, subscribes to events
|
|
in the containing VM’s container.</span></span></div></p><p>The name of the new endpoint will be the <span class="RktSym">pre-eid</span>; it must be
|
|
unique within the current process, but otherwise can be any value at
|
|
all. If the endpoint’s name matches an existing endpoint, and the new
|
|
role is the same as the existing endpoint’s role, the handler function
|
|
is <span style="font-style: italic">replaced</span> in the existing endpoint.</p><p>To delete an endpoint, perform a <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._delete-endpoint%29%29" class="RktValLink" data-pltdoc="x">delete-endpoint</a></span> action built
|
|
with the name of the endpoint to delete.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._marketplace/main..rkt)._delete-endpoint-reason))"></a><a name="(def._((lib._marketplace/main..rkt)._delete-endpoint-pre-eid))"></a><a name="(def._((lib._marketplace/main..rkt)._delete-endpoint~3f))"></a><a name="(def._((lib._marketplace/main..rkt)._struct~3adelete-endpoint))"></a><a name="(def._((lib._marketplace/main..rkt)._delete-endpoint))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._delete-endpoint%29%29" class="RktValDef RktValLink" data-pltdoc="x">delete-endpoint</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">pre-eid</span><span class="stt"> </span><span class="RktSym">reason</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">pre-eid</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types..rkt%29._.Any%29%29" class="RktStxLink" data-pltdoc="x">Any</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">reason</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types..rkt%29._.Any%29%29" class="RktStxLink" data-pltdoc="x">Any</a></span></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Delete.Endpoint))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Delete.Endpoint%29%29" class="RktValDef RktValLink" data-pltdoc="x">DeleteEndpoint</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._delete-endpoint%29%29" class="RktValLink" data-pltdoc="x">delete-endpoint</a></span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Deletes an existing endpoint named <span class="RktSym">pre-eid</span>. The given
|
|
<span class="RktSym">reason</span> is passed along to peer endpoints as part of an
|
|
<span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._absence-event%29%29" class="RktValLink" data-pltdoc="x">absence-event</a></span>.</div></p><p>If no specific reason is needed, it is conventional to supply
|
|
<span class="RktVal">#f</span> as the <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._delete-endpoint-reason%29%29" class="RktValLink" data-pltdoc="x">delete-endpoint-reason</a></span>. See also the
|
|
convenience <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._delete-endpoint%29%29" class="RktValLink" data-pltdoc="x">delete-endpoint</a></span>
|
|
function from <span class="RktSym">marketplace/sugar-values</span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._marketplace/main..rkt)._send-message-orientation))"></a><a name="(def._((lib._marketplace/main..rkt)._send-message-body))"></a><a name="(def._((lib._marketplace/main..rkt)._send-message~3f))"></a><a name="(def._((lib._marketplace/main..rkt)._struct~3asend-message))"></a><a name="(def._((lib._marketplace/main..rkt)._send-message))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._send-message%29%29" class="RktValDef RktValLink" data-pltdoc="x">send-message</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">body</span><span class="stt"> </span><span class="RktSym">orientation</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">body</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Message%29%29" class="RktValLink" data-pltdoc="x">Message</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">orientation</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Orientation%29%29" class="RktValLink" data-pltdoc="x">Orientation</a></span></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Send.Message))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Send.Message%29%29" class="RktValDef RktValLink" data-pltdoc="x">SendMessage</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._send-message%29%29" class="RktValLink" data-pltdoc="x">send-message</a></span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Sends a message to peers.<span class="NoteBox"><span class="NoteContent">Or, if <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._at-meta-level%29%29" class="RktValLink" data-pltdoc="x">at-meta-level</a></span>, peers of
|
|
the containing VM.</span></span> The given <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Orientation%29%29" class="RktValLink" data-pltdoc="x">Orientation</a></span> should describe the
|
|
role the sender is playing when sending this message: usually, it will
|
|
be <span class="RktVal">'</span><span class="RktVal">publisher</span>, but when the message is <span style="font-style: italic">feedback</span> for
|
|
some publisher, it will be <span class="RktVal">'</span><span class="RktVal">subscriber</span>.
|
|
See also the <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._send-message%29%29" class="RktValLink" data-pltdoc="x">send-message</a></span> and
|
|
<span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._send-feedback%29%29" class="RktValLink" data-pltdoc="x">send-feedback</a></span> convenience functions from
|
|
<span class="RktSym">marketplace/sugar-values</span>.</div></p><h5>3.4.2<tt> </tt><a name="(part._.Process_.Management)"></a>Process Management</h5><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._marketplace/main..rkt)._spawn-debug-name))"></a><a name="(def._((lib._marketplace/main..rkt)._spawn-k))"></a><a name="(def._((lib._marketplace/main..rkt)._spawn-spec))"></a><a name="(def._((lib._marketplace/main..rkt)._spawn~3f))"></a><a name="(def._((lib._marketplace/main..rkt)._struct~3aspawn))"></a><a name="(def._((lib._marketplace/main..rkt)._spawn))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="high-level-interface.html#%28form._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._spawn%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">spawn</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">spec</span><span class="stt"> </span><span class="RktSym">k</span><span class="stt"> </span><span class="RktSym">debug-name</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">spec</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._process-spec%29%29" class="RktValLink" data-pltdoc="x">process-spec</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">k</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types..rkt%29._.Option%29%29" class="RktStxLink" data-pltdoc="x">Option</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.P.I.D%29%29" class="RktValLink" data-pltdoc="x">PID</a></span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Interrupt.K%29%29" class="RktValLink" data-pltdoc="x">InterruptK</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">debug-name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types..rkt%29._.Any%29%29" class="RktStxLink" data-pltdoc="x">Any</a></span></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._marketplace/main..rkt)._process-spec-boot))"></a><a name="(def._((lib._marketplace/main..rkt)._process-spec~3f))"></a><a name="(def._((lib._marketplace/main..rkt)._struct~3aprocess-spec))"></a><a name="(def._((lib._marketplace/main..rkt)._process-spec))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._process-spec%29%29" class="RktValDef RktValLink" data-pltdoc="x">process-spec</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">boot</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">boot</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.P.I.D%29%29" class="RktValLink" data-pltdoc="x">PID</a></span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Co.Transition%29%29" class="RktValLink" data-pltdoc="x">CoTransition</a></span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><table cellspacing="0" class="argcontract RForeground"><tr><td><a name="(def._((lib._marketplace/main..rkt)._.Co.Transition))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Co.Transition%29%29" class="RktValDef RktValLink" data-pltdoc="x">CoTransition</a></span></span></td><td><span class="hspace"> </span>:<span class="hspace"> </span></td><td><table cellspacing="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.All%29%29" class="RktStxLink" data-pltdoc="x">All</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">Result</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.All%29%29" class="RktStxLink" data-pltdoc="x">All</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">State</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Transition%29%29" class="RktValLink" data-pltdoc="x">Transition</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym">Result</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym">Result</span><span class="RktPn">)</span></td></tr></table></td></tr></table></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Spawn))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Spawn%29%29" class="RktValDef RktValLink" data-pltdoc="x">Spawn</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types-extra..rkt%29._.All%29%29" class="RktStxLink" data-pltdoc="x">All</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">State</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="high-level-interface.html#%28form._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._spawn%29%29" class="RktStxLink" data-pltdoc="x">spawn</a></span><span class="hspace"> </span><span class="RktSym">State</span><span class="RktPn">)</span><span class="RktPn">)</span></p></blockquote></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Process.Spec))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Process.Spec%29%29" class="RktValDef RktValLink" data-pltdoc="x">ProcessSpec</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._process-spec%29%29" class="RktValLink" data-pltdoc="x">process-spec</a></span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">A <span class="RktSym"><a href="high-level-interface.html#%28form._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._spawn%29%29" class="RktStxLink" data-pltdoc="x">spawn</a></span> requests the creation of a sibling process<span class="NoteBox"><span class="NoteContent">If
|
|
wrapped in an <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._at-meta-level%29%29" class="RktValLink" data-pltdoc="x">at-meta-level</a></span>, the new process will instead be
|
|
a sibling of the creating process’s VM.</span></span>. The <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._spawn-k%29%29" class="RktValLink" data-pltdoc="x">spawn-k</a></span> runs in
|
|
the context of the <span style="font-style: italic">creating</span> process, communicating to it the
|
|
PID of the new process.</div></p><p>The <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._spawn-spec%29%29" class="RktValLink" data-pltdoc="x">spawn-spec</a></span> describes the new process to be created. Its
|
|
<span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._process-spec-boot%29%29" class="RktValLink" data-pltdoc="x">process-spec-boot</a></span> field is a function taking the PID of the
|
|
new process and returning a "cotransition". Cotransitions use a
|
|
second-order encoding of existential types to guarantee that the VM
|
|
remains oblivious to the specific process state type of the new
|
|
process. The downside of this approach is its syntactic and type
|
|
complexity: see <span class="RktSym"><a href="high-level-interface.html#%28form._%28%28lib._marketplace%2Fsugar-typed..rkt%29._spawn~3a%29%29" class="RktStxLink" data-pltdoc="x">spawn:</a></span> for an easier-to-use, higher-level
|
|
approach.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._marketplace/main..rkt)._quit-reason))"></a><a name="(def._((lib._marketplace/main..rkt)._quit-pid))"></a><a name="(def._((lib._marketplace/main..rkt)._quit~3f))"></a><a name="(def._((lib._marketplace/main..rkt)._struct~3aquit))"></a><a name="(def._((lib._marketplace/main..rkt)._quit))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._quit%29%29" class="RktValDef RktValLink" data-pltdoc="x">quit</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">pid</span><span class="stt"> </span><span class="RktSym">reason</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">#:prefab</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">pid</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types..rkt%29._.Option%29%29" class="RktStxLink" data-pltdoc="x">Option</a></span><span class="hspace"> </span><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.P.I.D%29%29" class="RktValLink" data-pltdoc="x">PID</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">reason</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types..rkt%29._.Any%29%29" class="RktStxLink" data-pltdoc="x">Any</a></span></td></tr></table></td></tr><tr><td><table cellspacing="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.Quit))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.Quit%29%29" class="RktValDef RktValLink" data-pltdoc="x">Quit</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-values..rkt%29._quit%29%29" class="RktValLink" data-pltdoc="x">quit</a></span></p></blockquote></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Kills a sibling process.<span class="NoteBox"><span class="NoteContent">Or, if <span class="RktSym"><a href="high-level-interface.html#%28def._%28%28lib._marketplace%2Fsugar-untyped..rkt%29._at-meta-level%29%29" class="RktValLink" data-pltdoc="x">at-meta-level</a></span>, a sibling
|
|
process of the containing VM.</span></span> If <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._quit-pid%29%29" class="RktValLink" data-pltdoc="x">quit-pid</a></span> is <span class="RktVal">#f</span>,
|
|
kills the current process; otherwise, kills the process with the given
|
|
PID. The <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._quit-reason%29%29" class="RktValLink" data-pltdoc="x">quit-reason</a></span> is passed on to peers of
|
|
currently-active endpoints in the process to be killed, as part of a
|
|
<span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._absence-event%29%29" class="RktValLink" data-pltdoc="x">absence-event</a></span>, just as if each active endpoint were deleted
|
|
manually before the process exited.</div></p><p>If no specific reason is needed, it is conventional to supply
|
|
<span class="RktVal">#f</span> as the <span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._quit-reason%29%29" class="RktValLink" data-pltdoc="x">quit-reason</a></span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>type</p></div></div><p class="RForeground"><a name="(def._((lib._marketplace/main..rkt)._.P.I.D))"></a><span title="Provided from: marketplace"><span class="RktSym"><a href="low-level-interface.html#%28def._%28%28lib._marketplace%2Fmain..rkt%29._.P.I.D%29%29" class="RktValDef RktValLink" data-pltdoc="x">PID</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/ts-reference/type-ref.html#%28form._%28%28lib._typed-racket%2Fbase-env%2Fbase-types..rkt%29._.Number%29%29" class="RktStxLink" data-pltdoc="x">Number</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">In the current VM implementations, process IDs are simply numbers.
|
|
PIDs are scoped to and allocated by each individual VM instance.</div></p><div class="navsetbottom"><span class="navleft"> </span><span class="navright"> <a href="high-level-interface.html" title="backward to "2 High-level interface"" data-pltdoc="x">← prev</a> <a href="index.html" title="up to "Marketplace: Network-Aware Programming"" data-pltdoc="x">up</a> <a href="Drivers.html" title="forward to "4 Drivers"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html> |