Introduction
Besides the specification, here is an informal
introduction to this module. See also the samples page for
more elaborate samples. This module defines a single function,
http:send-request() (with several arities for the sake of ease of use.) The
function takes a description of the request in parameter, and returns a representation of
the response.
The request is represented by an http:request element, giving the URI, the
HTTP method, the headers and the body content (for POST and PUT methods.) The response is
returned as a sequence of one or more items. The first one is an http:response
element with quite the same structure as an http:request, but without the
content itself. The content is returned as the second item (or several items in case of a
multipart response) as a string, a document node or a binary item, depending on the
Content-Type returned by the server. Here is a simple example of call in
XQuery, which sends a text content by POST:
http:send-request( <http:request href="..." method="post"> <http:body content-type="text/plain"> Hello, world! </http:body> </http:request> )
The response element can look like the following:
<http:response status="200" message="Ok"> <http:header name="Content-Type" value="text/html"/> <http:header name="Server" value="Apache ..."/> ... <http:body content-type="text/html"/> </http:response>
It is important to understand that the result of the function, in the example of the
above call, is a sequence of 2 items: the http:response element, and a
document node representing the HTML document. Here is an example of query that illustrate
that fact; it checks the status of the response within the http:response
element, then use the title element in the HTML document:
<!-- The request element to get Google page. --> <xsl:variable name="req" as="element()"> <http:request href="http://www.google.com/" method="get"/> </xsl:variable> <!-- The response sequence (http:response + HTML doc.) --> <xsl:variable name="resp" select="http:send-request($req)"/> <!-- If status code is not 200, throw an error. --> <xsl:if test="$resp[1]/xs:integer(@status) ne 200"> <xsl:sequence select="error((), 'Status is not 200.')"/> </xsl:if> <!-- Use the title element in the HTML document. --> <xsl:value-of select="$resp[2]/h:html/h:head/h:title"/>
You can find other examples on the samples page.
