Fetch Module

This XQuery Module provides simple functions to fetch the content of resources identified by URIs. Resources can be stored locally or remotely and e.g. use the file:// or http:// scheme. If more control over HTTP requests is required, the HTTP Module can be used. With the HTML Module, retrieved HTML documents can be converted to XML.

Conventions

All functions in this module are assigned to the http://basex.org/modules/fetch namespace, which is statically bound to the fetch prefix.
All errors are assigned to the http://basex.org/errors namespace, which is statically bound to the bxerr prefix.

Functions

fetch:binary

Signatures	fetch:binary($uri as xs:string) as xs:base64Binary
Summary	Fetches the resource referred to by the given URI and returns it as streamable xs:base64Binary.
Errors	BXFE0001: the URI could not be resolved, or the resource could not be retrieved.
Examples	fetch:binary("http://images.trulia.com/blogimg/c/5/f/4/679932_1298401950553_o.jpg") returns the addressed image. stream:materialize(fetch:binary("http://en.wikipedia.org")) returns a materialized representation of the streamable result.

fetch:text

Signatures	fetch:text($uri as xs:string) as xs:string fetch:text($uri as xs:string, $encoding as xs:string) as xs:string fetch:text($uri as xs:string, $encoding as xs:string, $fallback as xs:boolean) as xs:string
Summary	Fetches the resource referred to by the given $uri and returns it as streamable xs:string: The UTF-8 default encoding can be overwritten with the optional $encoding argument. By default, invalid characters will be rejected. If $fallback is set to true, these characters will be replaced with the Unicode replacement character FFFD (�).
Errors	BXFE0001: the URI could not be resolved, or the resource could not be retrieved. BXFE0002: the specified encoding is not supported, or unknown.
Examples	fetch:text("http://en.wikipedia.org") returns a string representation of the English Wikipedia main HTML page. stream:materialize(fetch:text("http://en.wikipedia.org")) returns a materialized representation of the streamable result.

fetch:xml

Signatures	fetch:xml($uri as xs:string) as document-node() fetch:xml($uri as xs:string, $options as map(*)) as document-node()
Summary	Fetches the resource referred to by the given $uri and returns it as an XML document. In contrast to fn:doc, each function call returns a different document node. As a consequence, document instances created by this function will not be kept in memory until the end of query evaluation. The $options argument can be used to change the parsing behavior. Allowed options are all parsing and XML parsing options in lower case.
Errors	BXFE0001: the URI could not be resolved, or the resource could not be retrieved.
Examples	The following expression returns an XML representation of the English Wikipedia main HTML page and chops all whitespace nodes: fetch:xml("http://en.wikipedia.org", map { 'chop': true() })

fetch:content-type

Signatures	fetch:content-type($uri as xs:string) as xs:string
Summary	Returns the content-type (also called mime-type) of the resource specified by $uri: If a remote resource is addressed, the request header will be evaluated. If the addressed resource is locally stored, the content-type will be guessed based on the file extension.
Errors	BXFE0001: the URI could not be resolved, or the resource could not be retrieved.
Examples	fetch:content-type("http://docs.basex.org/skins/vector/images/wiki.png") returns image/png.

Errors

Code	Description
BXFE0001	The URI could not be resolved, or the resource could not be retrieved.
BXFE0002	The specified encoding is not supported, or unknown.

Changelog

Version 8.5

• Updated: fetch:text: $fallback argument added.

Version 8.0

• Added: fetch:xml

The module was introduced with Version 7.6.