Client Module

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 in this module are assigned to the http://basex.org/modules/client namespace, which is statically bound to the client prefix.
All 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.
Errors	BXCL0003 is raised if an I/O error occurs while transferring data from or to the server. BXCL0004 is raised if an error occurs while executing a command.
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.
Errors	BXCL0003 is raised if an I/O error occurs while transferring data from or to the server. BXCL0005 is raised if an error occurs while evaluating a query, and if the original error cannot be extracted from the returned error string.
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. At the end of query execution, open sessions will be automatically closed.
Errors	BXCL0003 is raised if an I/O error occurs while transferring data from or to the server.

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.