Difference between revisions of "Client Module"

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Revision as of 20:13, 25 May 2012

This XQuery Module contains functions to access remote BaseX server instances from XQuery. With this module, you can on the one hand execute database commands and on the other hand evaluate queries, the results of which are returned as XDM sequences.

Conventions

All functions are assigned to the http://basex.org/modules/client namespace, which is statically bound to the client prefix.
Errors are assigned to the http://basex.org/errors namespace, which is statically bound to the bxerr prefix.

Functions

client:connect

Signatures client:connect($host as xs:string, $port as xs:integer, $user as xs:string, $password as xs:string) as xs:anyURI
Summary This function establishes a connection to a remote BaseX server, creates a new client session, and returns a session id. The parameter $host is the name of the database server, $port specifies the server port, and $user and $password represent the login data.
Errors BXCL0001 is raised if an error occurs while creating the session (possible reasons: server not available, access denied).

client:execute

Signatures client:execute($id as xs:anyURI, $command as xs:string) as xs:string
Summary This function executes a database command and returns the result as string. The parameter $id contains the session id returned by client:connect(). The $command represents the database command string, which will be executed by the server.
Examples The following query creates a new database TEST on a remote BaseX server:
let $c := client:connect('basex.server.org', 8080, 'admin', 'admin')
return client:execute($c, 'create database TEST')

client:query

Signatures client:query($id as xs:anyURI, $query as xs:string) as item()*
Summary This function evaluates a query and returns the result as sequence. The parameter $id contains the session id returned by client:connect(), and $query represents the query string, which will be evaluated by the server.
Examples The following query performs a query on a first server, the results of which are passed on to a second server:
let $c1 := client:connect('server1.basex.org', 8080, 'jack', 'C0S19tt2X')
let $c2 := client:connect('server2.basex.org', 8080, 'john', '465wFHe26')
return
  for $c in client:query($c1, '1 to 10')
  return client:query($c1, $c || '* 2')

client:close

Signatures client:close($id as xs:anyURI) as empty-sequence()
Summary This function closes a client session. $id specifies the session id.

Errors

Code Description
BXCL0001 An error occurred while creating a new session (possible reasons: server not available, access denied).
BXCL0002 The specified session is unknown, or has already been closed.
BXCL0003 An I/O error occurred while transferring data from or to the server.
BXCL0004 An error occurred while executing a command.
BXCL0005 An error occurred while evaluating a query. Will only be raised if the XQuery error cannot be extracted from the returned error string.

Changelog

The module was introduced with Version 7.2.2.