REST Handler Documentation

Not Included in official Wikka version

See also:
Development: RESTHandler
This is the documentation page for the REST handler.


Short description
Turn your wiki into a web service provider, by extracting selected bits of a page and serving them as XML data.

Parameters are passed in the URL suffix, formatted as rest/tag/attribute/value/rank, where:

tagstringoptional *The name of an XHTML tag (e.g. 'p', 'div', etc.)
attributestringoptional *The name of an XHTML attribute (e.g. 'class', 'id', etc.)
valuestringoptional *The value of the XHTML attribute. If present, attribute has to be present too (see examples below)
rankintegeroptionalnoneThe sequence number of the targeted tag in the page

Use the default value of the parameters you do not want to filter on (see examples below.)

Long description
All wikkawiki pages are structured documents, the structure being provided by XHTML tags. With the REST handler, specified chunks of a page can be extracted and provided as XML data. This helps turning any wiki into a web service provider and enables other applications or data consumers to access and process portions of a page.
This handler is a partial implementation (offering only a read-only mode, i.e. only the 'GET' method is supported) of the REST style of implementing web services.
All wiki page elements (paragraphs, images, hyperlinks, etc.) are called "resources" in REST parlance. The resource(s) to be selected by the handler are specified by the parameters passed in the URL (see previous paragraph and the examples below.) Note that only resources located inside the page content itself, but not the header and footer, are accessible (in technical terms, inside the '<div class="page">')
The output of this handler is a text file containing valid XHMTL, with an XML preamble and the HTTP 'Content-Type' set to text/xml. It is thus valid XML data and can be processed by any XML parser. Note that the output of this handler can be viewed inside a web browser (e.g. for debugging purposes), but that most of the time it is expected to be consumed by a program, not viewed directly.


Error handling
Any error will be reported both in the HTTP 'Status-Code' header and in the body of the XML reply, formatted as in this example (the message string can be localized):
  <Message>Illegal parameter(s) value</Message>
  <Resource>GET */*/*/8</Resource>


tagattributevaluerankURL suffixComments
p/pSelects all the paragraphs (<p> tag) in the page
pclass/p/classSelects all the paragraphs in the page having a 'class' attribute, whatever its value. This will select <p class='title'> but not <p id='examples'>
pclasscode/p/class/codeSelects all the paragraphs in the page having a 'class' attribute equal to 'code'
pclasscode3/p/class/code/3Selects the third paragraph in the page which has a 'class' attribute equal to 'code'
p**3/p/*/*/3Selects the third paragraph in the page, whatever its attributes
pid*3/p/id/*/3Selects the third paragraph in the page having a 'id' attribute, whatever its value
***3/*/*/*/3Not allowed
p*code/p/*/codeNot allowed
**code/*/*/codeNot allowed

As an example, the following URL:*/*/2

yields the following result:
<?xml version="1.0" encoding="utf-8" ?>
<wikkapage><div class="center">
<h2> Welcome to Wikka Wiki </h2>

To-do, bugs and limitations


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