SISCweb programs can generate HTTP responses of a variety of data types -- HTML/XML/XHTML represented in SXML notation, images --, or they can forward requests to standard JSPs/Servlet components. Procedures to generate HTTP errors are also available. Other response types can be easily plugged on top of a basic set of response procedures.
The procedures that produce HTTP responses are in the form
send-*/*, with the first pattern indicating
the type of response, and the latter determining whether or not to
save the execution state, and whether or not to clear previously
saved states.
All the procedures accept an optional association list of HTTP
response headers as the first, optional argument. The association
list is in the form ((name value)
...). This can be used to override the default
Content-Type, to set caching options, etc.
SISCweb provides a number of modules with an uniform API to produce HTML, XHTML and XML markup. Their procedures accept documents in SXML syntax, and in the case of HTML and XHTML, a few extra elements and attributes are used to assist with continuation-based programming (see the section called “Extended HTML markup”.)
Requires:
(import siscweb/html)
Requires:
(import siscweb/xhtml)
Located in:
siscweb-sxml.jar
The XHTML and HTML modules serialize SXML differently, with the former producing pure XML, and the latter producing markup tweaked to display properly in known browsers. When producing XHTML for common user agents, it is advisable to keep the HTML Compatibility Guidelines in mind.
Also, while the XHTML module implements the complete SXML
specification, the HTML module is more limited in that only
understands DTD declarations,
*VERBATIM* and
*COMMENT* elements besides the basic
element+attribute syntax. Also, while the XHTML module
considers the *TOP* element functional,
the HTML module silently ignores it.
procedure:
(send-html/suspend [header-alist] (lambda (k-url) <sxml>)) => request
procedure:(send-xhtml/suspend [header-alist] (lambda (k-url) <sxml>)) => request
procedure:
(send-html/forward [header-alist] (lambda (k-url) <sxml>)) => request
procedure:(send-xhtml/forward [header-alist] (lambda (k-url) <sxml>)) => request
Requires:
(import siscweb/xml)
Located in:
siscweb-sxml.jar
This module provides functions to send XML responses with the
same features as those in the HTML and XHTML modules. This
enables clients to conduct a stateful conversation with the
server. The same features available through the extended
(X)HTML can be reproduced in any XML element by using the
store/forward! procedure described in
the section called “Forwarding Requests”.
SISCweb's send-[html/xhtml/xml]/*
procedures accept a slightly extended version of the SXML
syntax.
Numbers in attributes and text nodes are automatically
converted to strings using pretty-print.
The element *VERBATIM* can be used to produce non-escaped text.
attribute:
`(a (@ (bindings ,binding-alist [(anchor name)]...) ...)
attribute:`(form (@ (bindings ,binding-alist) [(anchor name)] ...) ...)
attribute:`(iframe (@ (bindings ,binding-alist) [(anchor name)] ...) ...)
attribute:`(img (@ (bindings ,binding-alist) ...) ...)
attribute:`(link (@ (bindings ,binding-alist) ...) ...)
attribute:`(object (@ (bindings ,binding-alist) [(anchor name)] ...) ...)
attribute:`(script (@ (bindings ,binding-alist) ...) ...)This syntax is only usable from the
*/suspendand*/forwardprocedures. It will produce a link that, when followed, will bind the given bindings to the request object returned by these two functions. Thebinding-alistis in the format specified in Chapter 6, Request Bindings.The optional
anchorattribute allowed by some of the elements is made part of the generated URL.
attribute:
`(a (@ (href-p ,proc) [(bindings ,binding-alist)] [(anchor ,name)] ...) ...)
attribute:`(form (@ (action-p ,proc) [(bindings ,binding-alist)] [(anchor ,name)] ...) ...)
attribute:`(iframe (@ (src-p ,proc) [(bindings ,binding-alist)] [(anchor ,name)] ...) ...)
attribute:`(img (@ (src-p ,proc) [(bindings ,binding-alist)] ...))
attribute:`(link (@ (href-p ,proc) [(bindings ,binding-alist)] ...))
attribute:`(object (@ (data-p ,proc) [(bindings ,binding-alist)] [(anchor ,name) ...) ...)
attribute:`(script (@ (src-p ,proc) [(bindings ,binding-alist)] ...) ...)
attribute:
`(a (@ (href-c ,c-url) [(bindings ,binding-alist)] ...) ...)
attribute:`(form (@ (action-c ,c-url) [(bindings ,binding-alist)] ...) ...)
attribute:`(iframe (@ (src-c ,c-url) [(bindings ,binding-alist)] ...))
attribute:`(img (@ (src-c ,c-url) [(bindings ,binding-alist)] ...))
attribute:`(link (@ (href-c ,c-url) [(bindings ,binding-alist)] ...))
attribute:`(object (@ (data-c ,c-url) [(bindings ,binding-alist)] ...) ...)
attribute:`(script (@ (src-c ,c-url) [(bindings ,binding-alist)] ...) ...)
attribute:
`(a (@ (href-e ,url) ...) ...)
attribute:`(form (@ (action-e ,url) ...) ...)
attribute:`(iframe (@ (src-e ,url) ...))
attribute:`(img (@ (src-e ,url) ...))
attribute:`(link (@ (href-e ,url) ...))
attribute:`(object (@ (data-e ,url) ...) ...)
attribute:`(script (@ (src-e ,url) ...) ...)
attribute:
`(object (@ (type "graphviz") (layout ,layout) (format ,format) ...) (graph (@ (id ,id) ...))The
layoutandformatattributes are analogous to the omonymous parameters to thesend-graphviz/*functions (see the section called “Graphviz Procedures”.) However, the value offormatdetermines how the content is included:
gif, jpg, png: The graph is embedded as animgtag, and a corresponding image map is generated. Links associated to nodes, edges and records will be mapped appropriately. Just as for other document elements, the@href[-[p|c|e]]and@bindingsattributes are available, and behave as described in the section called “Extended HTML markup”.ps, svg, etc.: The graph is embedded as anobjecttag. The appropriate mime type is automatically set, and needs not be specified explicitely.In both cases, any attribute specified for the
objecttag will be applied toward the generatedobjectorimgtag.
(send-html/suspend
(lambda (k-url)
`(html
(head
(title "Embedded Graphviz")
(body
(h3 "Embedded Graphviz")
(object (@ (type "graphviz")
(layout dot) (format png))
(graph (@ (id "G"))
(node (@ (id "c") (label "scissors") (href "http://www.google.com/search?q=scissors")))
(node (@ (id "p") (label "paper") (href "http://www.google.com/search?q=paper")))
(node (@ (id "s") (label "stone") (href "http://www.google.com/search?q=stone")))
(edge (@ (from "c") (to "p") (label "cut") (href-p ,cut)))
(edge (@ (from "p") (to "s") (label "wraps") (href-c "/")))
(edge (@ (from "s") (to "c") (label "breaks") (href-e ,k-url))))))))))
Requires:
(import siscweb/text)
Located in:
siscweb.jar
This module provides functions to send plain text responses.
procedure:
(send-text/suspend [header-alist] (lambda (k-url) <text>)) => request
procedure:(send-text/forward [header-alist] (lambda (k-url) <text>)) => request
procedure:(send-text/back [header-alist] <text>) => does not return
procedure:(send-text/finish [header-alist] <text>) => does not return
Requires:
(import siscweb/forward)
Located in:
siscweb.jar
See the section called “Extracting Bindings from Java” for details on how to access bindings from Java.
procedure:
(send-forward/suspend context-url [bindings]) => requestForwards the current request and suspends. The
context-urlis relative to the context in which the SISCweb application is running. The optionalbindingsparameter is either a <bindings> object or an a-list as specified in Chapter 6, Request Bindings. The continuation URL will be set in thesiscweb.kURLrequest attribute.
procedure:
(forward/store! proc [bindings]) => k-url
procedure:(forward/store! c-url [bindings]) => k-urlwill see them as bindings in its request.In the second form
forward/store!stores a closure that forwards the request to the given context-relativec-url, including any specified bindings, if any.This function is especially useful when passing bindings through the
send-forward/*functions, as it allows to embed links to closures in JSPs and the such, and can thus be used to implement the same style of page navigation afforded by the tags@*-c+@bindingsand@*-c+@bindingsin the extended (X)HTML described in the section called “Extended HTML markup” Notably missing is the equivalent of the plain@bindings.
Requires:
(import siscweb/image)
Located in:
siscweb.jar
This module provides procedures to send images from
java.awt.image.RenderedImage or files.
procedure:
(send-image/finish [header-alist] format java.awt.image.RenderedImage) => does not return
Requires:
(import siscweb/graphviz)
Located in:
siscweb-sxml.jar
This module provides procedures to send graphs in various formats as generated by Graphviz (http://www.graphviz.org). Most of the functions accept a markup representation of DOT, the GraphViz language, in the form of DotML (see the section called “DotML”.)
The GraphViz programs (dot, neato, etc.) should be installed
somewhere in the system path. This is usually the case in
UNIX. Alternatively, it is possible to set the absolute paths to
the GraphViz programs by using the
graphiz/put-layout-command! function.
Graphs can be generated either using the
send-graphviz/* functions, or by embedding
the @type="graphviz" attribute
in the (X)HTML object tag (see the section called “Extended HTML markup”.)
Both send-graphviz/* procedures accept
the same three parameters:
layout: This is a string specifying
which Graphviz layout engine to use. The current choices are
dot, neato, twopi, circo, and fdp.
format: This is a string specifying
the output format. The most useful choices currently are
gif, jpg, 'png, 'ps, and 'svg.
<dotml>: This is an sxml
representation of the DotML language. See the section called “DotML”.
The send-graphviz/* procedures accept a
graph description expressed in DotML. DotML was created by
Martin Loetzsch, and an exhaustive description rich with
excellent examples is at http://www.martin-loetzsch.de/DOTML.
SISCweb does not use code from the DotML project, but it implements the same markup syntax in sxml form. There are a few differences between SISCweb's implementation and the original:
graph,
sub-graph, cluster
and node elements must always specify
an id attribute.
id attribute values at the moment
are limited to strings of alphanumeric characters and
underscore.
record elements must
specify an id attribute, but nested
record and node
elements do not have to.
Requires:
(import siscweb/error)
Located in:
siscweb.jar
HTTP error responses can be generated using two functions, which differ in how the affect the continuation table. Neither function returns. The error codes should abide to the RFC2616 specifications.