remove out of date cont-responder docs
chris.double
parent
a452f95788
commit
9f5845d09e
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@ -193,7 +193,7 @@ M: promised-label set-label-color set-promised-label-color ;
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M: promised-label set-label-font set-promised-label-font ;
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M: promised-label set-label-font set-promised-label-font ;
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: fib ( n -- n )
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: fib ( n -- n )
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yield dup 2 < [ drop 1 ] [ dup 1 - fib swap 2 - fib + ] if ;
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1 sleep dup 2 < [ drop 1 ] [ dup 1 - fib swap 2 - fib + ] if ;
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: test-promise-ui ( -- )
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: test-promise-ui ( -- )
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<promise> dup <promised-label> gadget. [ 30 fib unparse swap fulfill ] cons spawn drop ;
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<promise> dup <promised-label> gadget. [ 15 fib unparse swap fulfill ] cons spawn drop ;
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@ -1,375 +0,0 @@
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cont-responder v0.3
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===================
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NOTE: This documentation is slightly out of date with respect to the
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current code but contains the basic idea.
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In a continuation based web application the current position within
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the web application is identified by a random URL. In this example the
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URL is generated as a string of random digits:
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: get-random-id ( -- id )
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#! Generate a random id to use for continuation URL's
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<% 16 [ random-digit % ] times %> ;
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Each URL is associated with a quotation or continuation. When that URL
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is accessed, that quotation is executed. The quotation will receive an
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alist on the top of the stack which holds any POST or query
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parameters. A global table is maintained that holds the association of
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quotations to id's.
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: continuation-table ( -- <namespace> )
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#! Return the global table of continuations
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"cont" get ;
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: reset-continuation-table ( -- )
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#! Create the initial global table
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<namespace> "cont" set ;
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: register-continuation ( quot -- id )
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#! Store a continuation in the table and associate it with
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#! a random id.
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continuation-table [ get-random-id dup [ set ] dip ] bind ;
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: get-registered-continuation ( id -- cont )
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#! Return the continuation associated with the given id.
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continuation-table [ get ] bind ;
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: resume-continuation ( value id -- )
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#! Call the continuation associated with the given id,
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#! with 'value' on the top of the stack.
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get-registered-continuation call ;
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When a an URL is accessed, the continuation for the specific URL is
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obtained and called. That continuation needs to exit back to the
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caller when it has some HTML that it needs to display. returning that
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HTML to the caller. To exit back to the caller it calls an 'exit
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continuation' that is stored in an "exit" variable:
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: exit-continuation ( -- exit )
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#! Get the current exit continuation
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"exit" get ;
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: call-exit-continuation ( value -- )
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#! Call the exit continuation, passing it the given value on the
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#! top of the stack.
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"exit" get call ;
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: with-exit-continuation ( quot -- )
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#! Call the quotation with the variable "exit" bound such that when
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#! the exit continuation is called, computation will resume from the
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#! end of this 'with-exit-continuation' call, with the value passed
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#! to the exit continuation on the top of the stack.
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[ "exit" set call call-exit-continuation ] callcc1 nip ;
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All this calling of continuations is hidden behind a single 'show'
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call. 'show' will take a quotation on the stack. That quotation should
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return an HTML string. 'show' will call it to generate the HTML and
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call the exit continuation with this string on the stack so it gets
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returned to the httpd responder. The quotation receives a 'url' on the
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top of the stack which is the 'id' of the continuation to resume when
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that URL is accessed.
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The HTML page that 'show' displays can contain links to
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'callbacks'. These are links to other quotations that when called
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will perform some action and return back to the calling page. To
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return back to the calling page 'show' must capture and store the
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current continuation before 'show' does anything so it can be later
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return to by the callback. The following words store the current
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continuation and retrieve it:
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: store-callback-cc ( -- )
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#! Store the current continuation in the variable 'callback-cc'
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#! so it can be returned to later by callbacks. Note that it
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#! recalls itself when the continuation is called to ensure that
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#! it resets it's value back to the most recent show call.
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[
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[ "callback-cc" set call ] callcc0 drop store-callback-cc
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] callcc0 ;
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To generate the string of HTML I use 'with-string-stream' which calls
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a quotation and all output inside that call gets appended to a string:
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: with-string-stream ( quot -- string )
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#! Call the quotation with standard output bound to a string output
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#! stream. Return the string on exit.
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<namespace> [
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"stdio" <string-output-stream> put call "stdio" get stream>str
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] bind ;
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: show ( quot -- alist )
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#! Call the quotation with the URL associated with the current
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#! continuation. Return the HTML string generated by that code
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#! to the exit continuation. When the URL is later referenced then
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#! computation will resume from this 'show' call with a alist on
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#! the stack containing any query or post parameters.
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store-callback-cc
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[
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register-continuation swap with-string-stream
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call-exit-continuation
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] callcc1
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nip ;
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An httpd get responder is used that takes the ID as an argument, retrieves
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the continuation associated with it and calls it. For the post
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responder the post data is converted into an alist and it is put on
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the top of the stack when calling the continuation.
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: cont-get-responder ( id -- )
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#! httpd responder that retrieves a continuation and calls it.
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[ f swap resume-continuation ] with-exit-continuation
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serving-html print drop ;
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: post-request>alist ( post-request -- alist )
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#! Return an alist containing name/value pairs from the
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#! post data.
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dup "&" swap str-contains [
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"(.+)&(.+)" groups [ "(.+)=(.+)" groups uncons car cons ] inject
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] [
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"(.+)=(.+)" groups uncons car cons unit
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] ifte ;
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: cont-post-responder ( id -- )
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#! httpd responder that retrieves a continuation for the given
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#! id and calls it with the POST data as an alist on the top
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#! of the stack.
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[
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read-post-request post-request>alist swap resume-continuation
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] with-exit-continuation
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serving-html print drop ;
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Some code to install the responder:
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: install-cont-responder ( -- )
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#! Install the cont-responder in the table of httpd responders
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"httpd-responders" get [
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<responder> [
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[ cont-get-responder ] "get" set
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[ cont-post-responder ] "post" set
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reset-continuation-table
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] extend "cont" set
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] bind ;
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Now to test it. Here's a function that displays some text on an HTML page:
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: display-page ( title -- )
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#! Display a page with some text to test the cont-responder.
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#! The page has a link to the 'next' continuation.
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[
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swap [
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"<a href='" write write "'>Next</a>" write
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] html-document
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] show drop ;
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Note that it contains an A HREF link to the URL that resumes the
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computation (The quotation passed to show has this URL passed to it by
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show).
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An example of a POST request is a page that requests input of a
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name. The following function calls show to display it and returns the
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result of the 'name' field by retrieving it from the alist. Notice how
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the 'action' of the post request is set to the URL passed in to the
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quotation passed to show. So the 'next' that happens here is not an A
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HREF but the action field of the POST.
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: display-get-name-page ( -- name )
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#! Display a page prompting for input of a name and return that name.
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[
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"Enter your name" [
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"<form method='post' action='" write write "'>" write
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"Name: <input type='text' name='name' size='20'>" write
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"<input type='submit' value='Ok'>" write
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"</form>" write
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] html-document
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] show
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"name" swap assoc ;
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A word that displays a sequence of these pages would be:
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: test-cont-responder ( alist - )
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#! Test the cont-responder responder by displaying a few pages in a row.
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drop
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"Page one" display-page
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"Hello " display-get-name-page cat2 display-page
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"Page three" display-page ;
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This displays the first page, then a page prompting for the
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name. "Hello " is concatenated to the result of the page and a third
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page is displayed. A fourth page is available as well.
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The following registers this word with the continuation system:
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: register-test-cont-responder ( -- id )
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#! Register the test-cont-responder word so that accessing the
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#! URL with the returned ID will call it.
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"httpd-responders" get [
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"cont" get [
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[ test-cont-responder ] register-continuation
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] bind
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] bind ;
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This returns an ID which can be used from the web server to resume
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it. Start the web server:
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8888 httpd
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Now access the URL with that id:
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http://localhost:8888/cont/1234567890
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(replace 1234567890 with the ID returned by register-continuation above)
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You'll see the first page and a link. Click the link and you'll see
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the second page requesting a name. Enter the name and press 'Ok'. A
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third page will display a message using that name. You can book mark,
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refresh, go back, enter a new name, etc as expected.
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You can do any form of computation inside the handlers. Here's an
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example of looping a set number of times:
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: test-cont-responder2 ( alist - )
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#! Test the cont-responder responder by displaying a few pages in a loop.
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[ "one" "two" "three" "four" ] [ display-page ] each
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"Done!" display-page ;
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: register-test-cont-responder2 ( -- id )
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#! Register the test-cont-responder2 word so that accessing the
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#! URL with the returned ID will call it.
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"httpd-responders" get [
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"cont" get [
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[ test-cont-responder2 ] register-continuation
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] bind
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] bind ;
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There is currently a limited ability to do 'callbacks'. You can
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register a quotation as an HTML A HREF anchor thar when accessed by
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the browser will run the quotation and then return to the most recent
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'show' call. This has the effect of allowing 'subroutine' calls as
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page links that can do anything (including display other pages and
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complicated action) and will return back to the originating page. The
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word to generate this link is:
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: quot-href ( text quot -- )
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#! Write to standard output an HTML HREF where the href,
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#! when referenced, will call the quotation and then return
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#! back to the most recent 'show' call (via the callback-cc).
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#! The text of the link will be the 'text' argument on the
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#! stack.
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"<a href='" write
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"callback-cc" get [ call ] cons append register-continuation write
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"'>" write
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write
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"</a>" write ;
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An example of use is a simple menu page that displays links to the
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words written previously:
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: test-cont-responder3 ( alist - )
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#! Test the quot-href word by displaying a menu of the current
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#! test words. Note that we drop the 'url' argument to the show
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#! quotation as we don't link to a 'next' page.
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drop
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[
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drop
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"Menu" [
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"<ol>" write
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"<li>" write
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"Test responder1" [ test-cont-responder ] quot-href
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"</li>" write
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"<li>" write
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"Test responder2" [ test-cont-responder2 ] quot-href
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"</li>" write
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"</ol>" write
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] html-document
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] show drop ;
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: register-test-cont-responder3 ( -- id )
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#! Register the test-cont-responder3 word so that accessing the
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#! URL with the returned ID will call it.
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"httpd-responders" get [
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"cont" get [
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[ test-cont-responder3 ] register-continuation
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] bind
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] bind ;
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You should now be able to click on the menu items, navigate through
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those pages and when the sequence of pages ends, return back to the
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original menu page.
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Note that this is just a proof of concept. In a real framework the
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continuations need to be expired after time. It would also enable
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generating links to other pages, etc rather than just a sequence of
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pages. I plan to flesh this out over the next few days and present
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some more useful examples. My main point was to see if it was possible
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to do this type of thing in Factor.
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The number of words required to get things going is amazingly small
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and it was very easy to develop this far.
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The code is contained in cont-responder.factor. Here are the steps to
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run all the examples starting with a default Factor 0.60 install:
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1) java -cp Factor.jar factor.FactorInterpreter
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-db:factor.db.FileStore:factor.db
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At the prompt enter:
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---8<---
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USE: httpd-responder
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default-responders
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exit
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---8<---
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2) java -cp Factor.jar factor.FactorInterpreter
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-db:factor.db.FileStore:factor.db
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-no-compile
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At the prompt enter:
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---8<---
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USE: httpd
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"cont-responder.factor" run-file
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USE: cont-responder
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init-cont-responder
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register-test-cont-responder .
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---8<---
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Make note of the number returned by the last line call this [1].
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---8<---
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register-test-cont-responder2 .
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---8<---
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Make note of the number returned by the last line call this [2].
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---8<---
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register-test-cont-responder3 .
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---8<---
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Make note of the number returned by the last line call this [3].
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---8<---
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8888 httpd
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---8<---
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For the first example go to http://localhost:8888/cont/[1]
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where you replace [1] with the number from [1] above. In my system
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it was:
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http://localhost:8888/cont/0406763029866672
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For the second example go to http://localhost:8888/cont/[2]
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where you replace [2] with the number from [2] above. In my system
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it was:
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http://localhost:8888/cont/6018237533813007
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For the menu example go to http://localhost:8888/cont/[3]
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where you replace [3] with the number from [3] above. In my system
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it was:
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http://localhost:8888/cont/3568874223456634
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||||||
3) You can use the inspector to look at the continuation table:
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|
||||||
|
|
||||||
http://localhost:8888/inspect/global'httpd-responders'cont'cont
|
|
||||||
Loading…
Reference in New Issue