Difference between revisions of "HTTP Client Module"

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</html>
 
</html>
 
</pre>
 
</pre>
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=Errors=
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{| class="wikitable" width="100%"
 +
! width="5%"|Code
 +
! width="95%"|Description
 +
|-
 +
|<code>FOHC0001</code>
 +
|An HTTP error occurred.
 +
|-
 +
|<code>FOHC0002</code>
 +
Error parsing the entity content as XML or HTML.
 +
|-
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|<code>FOHC0003</code>
 +
With a multipart response, the override-media-type must be either a multipart media type or application/octet-stream.
 +
|-
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|<code>FOHC0004</code>
 +
The src attribute on the body element is mutually exclusive with all other attribute (except the media-type).
 +
|-
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|<code>FOHC0005</code>
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The request element is not valid.
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|-
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|<code>FOHC0006</code>
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A timeout occurred waiting for the response.
 +
|}
  
 
[[Category:XQuery]]
 
[[Category:XQuery]]

Revision as of 01:32, 26 May 2012

This XQuery Module contains a single function to send HTTP requests and handle HTTP responses. The function send-request is based on the EXPath HTTP Client Module:

Conventions

All functions in this module are assigned to the http://expath.org/ns/http-client namespace, which is statically bound to the http prefix.
All errors are assigned to the http://expath.org/ns/error namespace, which is statically bound to the exerr prefix.

Functions

http:send-request

Signatures http:send-request($request as element(http:request)?, $href as xs:string?, $bodies as item()*) as item()+
http:send-request($request as element(http:request)) as item()+
http:send-request($request as element(http:request)?, $href as xs:string?) as item()+
Summary Sends an HTTP request and interprets the corresponding response. $request contains the parameters of the HTTP request such as HTTP method and headers. In addition to this it can also contain the URI to which the request will be sent and the body of the HTTP method. If the URI is not given with the parameter $href, its value in $request is used instead. The structure of http:request element follows the EXPath specification.
Notes The attribute auth-method of $request is not considered in our implementation because we are handling only basic authentication.

Examples

Status Only

Simple GET request. As the attribute status-only is set to true, only the response element is returned.

Query:

http:send-request(<http:request method='get' status-only='true'/>, 'http://basex.org')

Result:

<http:response status="200" message="OK">
  <http:header name="Date" value="Mon, 14 Mar 2011 20:55:53 GMT"/>
  <http:header name="Content-Length" value="12671"/>
  <http:header name="Expires" value="Mon, 14 Mar 2011 20:57:23 GMT"/>
  <http:header name="Set-Cookie" value="fe_typo_user=d10c9552f9a784d1a73f8b6ebdf5ce63; path=/"/>
  <http:header name="Connection" value="close"/>
  <http:header name="Content-Type" value="text/html; charset=utf-8"/>
  <http:header name="Server" value="Apache/2.2.16"/>
  <http:header name="X-Powered-By" value="PHP/5.3.5"/>
  <http:header name="Cache-Control" value="max-age=90"/>
  <http:body media-type="text/html; charset=utf-8"/>
</http:response>

Google Homepage

Retrieve Google search home page. TagSoup must be referenced in the class path in order to parse html.

Query:

http:send-request(<http:request method='get' href='http://www.google.com'/>)

Result:

<http:response status="200" message="OK">
  <http:header name="Date" value="Mon, 14 Mar 2011 22:03:25 GMT"/>
  <http:header name="Transfer-Encoding" value="chunked"/>
  <http:header name="Expires" value="-1"/>
  <http:header name="X-XSS-Protection" value="1; mode=block"/>
  <http:header name="Set-Cookie" value="...; expires=Tue, 13-Sep-2011 22:03:25 GMT; path=/; domain=.google.ch; HttpOnly"/>
  <http:header name="Content-Type" value="text/html; charset=ISO-8859-1"/>
  <http:header name="Server" value="gws"/>
  <http:header name="Cache-Control" value="private, max-age=0"/>
  <http:body media-type="text/html; charset=ISO-8859-1"/>
</http:response>
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <meta http-equiv="content-type" content="text/html; charset=ISO-8859-1"/>
    <title>Google</title>
    <script>window.google={kEI:"rZB-
    ... 
    </script>
    </center>
  </body>
</html>

SVG Data

Content-type ending with +xml, e.g. image/svg+xml.

Query:

http:send-request(<http:request method='get'/>, 'http://upload.wikimedia.org/wikipedia/commons/6/6b/Bitmap_VS_SVG.svg')

Result:

<http:response status="200" message="OK">
  <http:header name="ETag" value="W/"11b6d-4ba15ed4""/>
  <http:header name="Age" value="9260"/>
  <http:header name="Date" value="Mon, 14 Mar 2011 19:17:10 GMT"/>
  <http:header name="Content-Length" value="72557"/>
  <http:header name="Last-Modified" value="Wed, 17 Mar 2010 22:59:32 GMT"/>
  <http:header name="Content-Type" value="image/svg+xml"/>
  <http:header name="X-Cache-Lookup" value="MISS from knsq22.knams.wikimedia.org:80"/>
  <http:header name="Connection" value="keep-alive"/>
  <http:header name="Server" value="Sun-Java-System-Web-Server/7.0"/>
  <http:header name="X-Cache" value="MISS from knsq22.knams.wikimedia.org"/>
  <http:body media-type="image/svg+xml"/>
</http:response>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" width="1063" height="638">
  <defs>
    <linearGradient id="lg0">
      <stop stop-color="#3333ff" offset="0"/>
      <stop stop-color="#3f3fff" stop-opacity="0" offset="1"/>
    </linearGradient>
    ...
</svg>

POST Request

POST request to the BaseX REST Service, specifying a username and password.

Query:

let $request :=
  <http:request href='http://localhost:8984/rest'
    method='post' username='admin' password='admin' send-authorization='true'>
    <http:body media-type='application/xml'>
    <query xmlns="http://basex.org/rest">
      <text><![CDATA[
        <html>{
          for $i in 1 to 3
          return <div>Section {$i }</div>
        }</html>
      ]]></text>
    </query>
    </http:body>
  </http:request>
return http:send-request($request)

Result:

<http:response xmlns:http="http://expath.org/ns/http-client" status="200" message="OK">
  <http:header name="Content-Length" value="135"/>
  <http:header name="Content-Type" value="application/xml"/>
  <http:header name="Server" value="Jetty(6.1.26)"/>
  <http:body media-type="application/xml"/>
</http:response>
<html>
  <div>Section 1</div>
  <div>Section 2</div>
  <div>Section 3</div>
</html>

Errors

Code Description
FOHC0001 An HTTP error occurred.
FOHC0002

Error parsing the entity content as XML or HTML.

FOHC0003

With a multipart response, the override-media-type must be either a multipart media type or application/octet-stream.

FOHC0004

The src attribute on the body element is mutually exclusive with all other attribute (except the media-type).

FOHC0005

The request element is not valid.

FOHC0006

A timeout occurred waiting for the response.