d61eb53686
Started as fixing misindented definitions, then more indentations, then a bunch of similar things (square brackets, huge spaces at end-of-lines, etc).
55 lines
1.9 KiB
Racket
55 lines
1.9 KiB
Racket
#lang scribble/doc
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@(require "web-server.rkt")
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@title[#:tag "namespace"]{Servlet Namespaces}
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@(require (for-label web-server/configuration/namespace))
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@defmodule[web-server/configuration/namespace]{
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This module provides a function to help create the
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@racket[make-servlet-namespace] procedure needed by the @racket[make] function
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of @racketmodname[web-server/dispatchers/dispatch-servlets].
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@defthing[make-servlet-namespace/c contract?]{
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Equivalent to
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@racketblock[
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(->* ()
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(#:additional-specs (listof module-path?))
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namespace?)
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]
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}
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@defproc[(make-make-servlet-namespace (#:to-be-copied-module-specs to-be-copied-module-specs (listof module-path?)))
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make-servlet-namespace/c]{
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This function creates a function that when called will construct a new
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@racket[namespace] that has all the modules from
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@racket[to-be-copied-module-specs] and @racket[additional-specs], as
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well as @racket[racket] and @racket[mred], provided they are already
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attached to the @racket[(current-namespace)] of the call-site.
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Example:
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@racketblock[
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(make-make-servlet-namespace
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#:to-be-copied-module-specs `((lib "database.rkt" "my-module")))
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]
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}
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}
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@section{Why this is useful}
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A different namespace is needed for each servlet, so that if servlet A
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and servlet B both use a stateful module C, they will be isolated from
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one another. We see the @web-server as an operating system for servlets,
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so we inherit the isolation requirement on operating systems.
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However, there are some modules which must be shared. If they were not,
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then structures cannot be passed from the @web-server to the servlets,
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because Racket's structures are generative.
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Since, on occasion, a user will actually wanted servlets A and B to
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interact through module C. A custom @racket[make-servlet-namespace] can
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be created, through this procedure, that attaches module C to all
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servlet namespaces. Through other means (see @secref["dispatchers"])
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different sets of servlets can share different sets of modules.
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