Pictures and a little more text

marketplace/scribblings/background.scrbl

@@ -66,14 +66,20 @@ Programs can handle exceptions to @emph{contain} partial failure:
 Partial failures interact with shared, mutable state in unpredictable
 ways, especially in larger programs that combine stateful subprograms.
 
-Programmers often ignore issues of security and trust between
+@note{For a good overview of PL-based approaches to security and
-subprograms within a larger program. Most programming languages
+trust, see Mark S. Miller's
-entirely lack any means of securely isolating subprograms from each
+"@hyperlink["http://www.erights.org/talks/thesis/markm-thesis.pdf"]{Robust
-other, leading to predictable failures. Even memory-safe languages
+composition: Towards a unified approach to access control and
-such as Racket, Java and .NET only offer weak techniques for securely
+concurrency control}" and Jonathan A. Rees's
-composing mutually suspicious subprograms. Techniques such as avoiding
+"@hyperlink["http://dspace.mit.edu/bitstream/handle/1721.1/5944/AIM-1564.pdf"]{A
-@emph{ambient authority} and using @emph{object capabilities} to
+Security Kernel Based on the Lambda-Calculus}".} Programmers often
-compose subprograms
+ignore issues of security and trust between subprograms within a
+larger program. Most programming languages entirely lack any means of
+securely isolating subprograms from each other, leading to predictable
+failures. Even memory-safe languages such as Racket, Java and .NET
+only offer weak techniques for securely composing mutually suspicious
+subprograms. Techniques such as avoiding @emph{ambient authority} and
+using @emph{object capabilities} to compose subprograms
 
 TODO ^
 
@@ -81,22 +87,29 @@ TODO ^
 
 Programs which engage in I/O are very obviously part of a network:
 
-@racketblock[(define username (read-line))
+@racketblock[(define (greet-user)
-	     (printf "Hello, ~a!\n" username)]
+	       (define username (read-line))
+	       (define greeting (format "Hello, ~a!\n" username))
+	       (display greeting)
+	       (newline))
+	     (greet-user)]
 
-But look closely! There is a difference here between the kind of communication 
+Here, the network has two components: the program, and the user at the
+terminal.
 
-This program is more obviously composed of a number of moving pieces:
+But look closely! There is a difference here between the kind of
+communication between this program and its @emph{peer} and the
+communication @emph{internal} to the program itself. Portions of the
+program relay information from the outside world, translating it to
+and from an internal representation as they go, while other portions
+perform computations on the relayed information.
 
-@interaction[(let ((b (box 3)))
+@vm-figure[(vm (vm-label "Operating System")
-               (set-box! b (+ (unbox b) 4))
+	       (network-label "")
-               (unbox b))]
+	       (process "User")
-
+	       (process-space)
-@interaction[(define (add-three-to b)
+	       (vm (vm-label "Program")
-               (set-box! b (+ (unbox b) 3)))
+		   (network-label "")
-             (define (add-four-to b)
+		   (process "Read line")
-               (set-box! b (+ (unbox b) 4)))
+		   (process "Format greeting")
-             (define my-box (box 0))
+		   (process "Print greeting")))]
-             (add-three-to my-box)
-             (add-four-to my-box)
-	     (unbox my-box)]

marketplace/scribblings/concepts.scrbl

@@ -4,16 +4,15 @@
 
 @title{Concepts}
 
-We integrate ideas from both distributed systems
+Marketplace integrates ideas from both distributed systems and
-and virtualized operating system designs to obtain a novel
+virtualized operating system designs to obtain an architecture of
-architecture of nested virtual machines. Each nested layer is equipped with
+nested @emph{virtual machines}. Each nested layer is equipped with its
-its own publish/subscribe network that also propagates information
+own publish/subscribe network that also propagates @emph{presence}
-about the (dis)appearance of services.
+information about the (dis)appearance of services.
 
-The result suggests a @emph{
+The result suggests a @emph{marketplace} metaphor, where communicating
-marketplace} metaphor, where communicating programs exist in a
+programs exist in a noisy, crowded, even chaotic context, rather than
-noisy, crowded, even chaotic context, rather than in a quiet place
+in a quiet place systematically going through their inboxes.
-systematically going through their inboxes.
 
 @section{What is a process, what are event handlers?}
 

marketplace/scribblings/prelude.inc

@@ -2,6 +2,10 @@
 (require scribble/racket
 	 scribble/eval
 	 scriblib/footnote
+
+	 slideshow/pict
+	 "vm-pictures.rkt"
+
 	 (for-syntax racket)
 	 (for-label typed/racket/base))
 
@@ -17,3 +21,6 @@
 	   desc ...)]
       [(_ t d desc ...)
        #`(defthing #:kind "type" t d desc ...)])))
+
+(define (vm-figure p)
+  (centered (to-element (render (scale p 1.2) #:target 'pict))))

marketplace/scribblings/vm-pictures.rkt

@@ -0,0 +1,113 @@
+#lang racket/base
+
+(require (only-in racket/math pi))
+(require slideshow/pict)
+(require file/convertible)
+
+(provide (all-defined-out))
+
+(define default-process-height 98)
+
+(define default-font (make-parameter 'roman))
+
+(define final-border (make-parameter 1))
+
+(define process-angle (make-parameter 90))
+(define process-width (make-parameter 24))
+(define process-corner (make-parameter 6))
+(define process-height (make-parameter default-process-height))
+(define process-gap (make-parameter 6))
+(define process-fill-color (make-parameter "white"))
+
+(define PROCESS-SHADED (list #xdd #xdd #xdd))
+
+(define leg-offset (make-parameter 4))
+(define leg-width (make-parameter 2))
+(define leg-spot-width (make-parameter 4))
+
+(define (default-leg-height)
+  (/ (network-height) 2))
+
+(define (meta-leg-height)
+  (+ (default-leg-height) (vm-height) (network-height)))
+
+(define network-height (make-parameter 12))
+(define vm-height (make-parameter 27))
+(define process-label-size (make-parameter 12))
+(define network-label-size (make-parameter 9))
+(define vm-label-size (make-parameter 12))
+(define ellipsis-size (make-parameter 24))
+
+(define (process label)
+  (cb-superimpose
+   (colorize (filled-rounded-rectangle (process-width) (process-height) (process-corner))
+	     (process-fill-color))
+   (rounded-rectangle (process-width) (process-height) (process-corner))
+   (vc-append (text label (default-font) (process-label-size) (d2r (process-angle)))
+	      (blank (/ (- (process-width) (process-label-size)) 2)))))
+
+(define (process-group . ps)
+  (apply hb-append (process-gap) ps))
+
+(define (process-space [n 1])
+  (blank (+ (* (- n 1) (/ (process-width) 2))
+	    (- (/ (process-width) 2) (* 2 (process-gap)))) (process-height)))
+
+(define (vm-label str)
+  (text str (default-font) (vm-label-size) (d2r 0)))
+
+(define (network-label str)
+  (text str (default-font) (network-label-size) (d2r 0)))
+
+(define (vm label net-label . ps)
+  (define ps-pict (apply process-group ps))
+  (define label-width (max (pict-width label) (pict-width net-label)))
+  (define width (max (+ label-width (* 2 (max (vm-label-size) (network-label-size))))
+		     (pict-width ps-pict)))
+  (vl-append ps-pict
+	     (cb-superimpose (colorize (filled-rectangle width (network-height))
+				       (process-fill-color))
+			     (rectangle width (network-height))
+			     net-label)
+	     (cc-superimpose (colorize (filled-rectangle width (vm-height))
+				       (process-fill-color))
+			     (rectangle width (vm-height))
+			     label)))
+
+(define (process-ellipsis)
+  (cc-superimpose (text ". . ." (default-font) (ellipsis-size) 0)
+		  (blank 0 (process-height))))
+
+(define (d2r d)
+  (* pi (/ d 180.0)))
+
+(define (leg p offset height)
+  (define x (+ (/ (pict-width p) 2) (* offset (leg-offset))))
+  (define y (pict-height p))
+  (define leg-pict (vc-append (vline (leg-width) (- height (/ (leg-spot-width) 2)))
+			      (disk (leg-spot-width) #:draw-border? #f)))
+  (pin-over p (- x (/ (pict-width leg-pict) 2)) y leg-pict))
+
+(define (relay-legs p)
+  (leg (leg p 1 (default-leg-height)) -1 (meta-leg-height)))
+
+(define (local-leg p)
+  (leg p 0 (default-leg-height)))
+
+(define (render p #:target [target (string->symbol (or (getenv "VM_PICTURES_TARGET") "eps"))])
+  (define final-pict (cc-superimpose (blank (+ (pict-width p) (* 2 (final-border)))
+					    (+ (pict-height p) (* 2 (final-border))))
+				     (panorama p)))
+  (case target
+    [(pict)
+     final-pict]
+    [(screen)
+     ;; FFS. This connects to the display even if you don't use it.
+     ;; (local-require racket/gui/base)
+     ;; (show-pict final-pict 800 600)
+     (log-error "You need to uncomment a couple of lines in vm-pictures.rkt")
+     (void)]
+    [(png)
+     (display (convert final-pict 'png-bytes))]
+    [(eps)
+     (display (convert final-pict 'eps-bytes))]))