Difference between revisions of "Session Module"

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=Conventions=
 
=Conventions=
  
{{Mark|Updated with Version 9.0}}:
+
* The module will be available if the {{Code|basex-api}} library is found in the classpath. This is the case if you use one of the complete distributions of BaseX (zip, exe, war).
 
+
* All functions and errors are assigned to the <code><nowiki>http://basex.org/modules/session</nowiki></code> namespace, which is statically bound to the {{Code|session}} prefix.
* The {{Code|basex-api}} package must be included in the classpath. This is always the case if you use one of the complete distributions (zip, exe, war) of BaseX.
+
* If any of the functions is called outside the servlet context, <code>[[XQuery Errors#BaseX Errors|basex:http]]</code> is raised.
* All functions and errors are assigned to the <code><nowiki>http://basex.org/modules/session</nowiki></code> namespace. The module must be imported in the query prolog:
+
* As sessions are side-effecting operations, all functions are flagged as ''non-deterministic''. As a result, some query optimizations will be suppressed.
<pre class="brush:xquery">
 
import module namespace session = "http://basex.org/modules/session";
 
...
 
</pre>
 
* If any of the functions is called outside the servlet context, the error {{Error|basex:http|XQuery Errors#BaseX Errors}} is raised.
 
* As sessions are side-effecting operations, all functions are flagged as ''non-deterministic''. As a result, the functions will not be reordered by the compiler.
 
  
 
=Functions=
 
=Functions=
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| '''Summary'''
 
| '''Summary'''
 
|Returns the session ID of a servlet request.
 
|Returns the session ID of a servlet request.
 +
|-
 +
| '''Errors'''
 +
|{{Error|not-found|#Errors}} No session is available for the current client.
 
|-
 
|-
 
| '''Examples'''
 
| '''Examples'''
 
|Running the server-side XQuery file {{Code|id.xq}} via <code><nowiki>http://localhost:8984/id.xq</nowiki></code>:
 
|Running the server-side XQuery file {{Code|id.xq}} via <code><nowiki>http://localhost:8984/id.xq</nowiki></code>:
<pre class="brush:xquery">
+
<syntaxhighlight lang="xquery">
 
import module namespace session = "http://basex.org/modules/session";
 
import module namespace session = "http://basex.org/modules/session";
 
'Session ID: ' || session:id()
 
'Session ID: ' || session:id()
</pre>
+
</syntaxhighlight>
 
|}
 
|}
  
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| '''Summary'''
 
| '''Summary'''
 
|Returns the creation time of a session.
 
|Returns the creation time of a session.
 +
|-
 +
| '''Errors'''
 +
|{{Error|not-found|#Errors}} No session is available for the current client.
 
|}
 
|}
  
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| '''Summary'''
 
| '''Summary'''
 
|Returns the last access time of a session.
 
|Returns the last access time of a session.
 +
|-
 +
| '''Errors'''
 +
|{{Error|not-found|#Errors}} No session is available for the current client.
 
|}
 
|}
  
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|-
 
|-
 
| '''Summary'''
 
| '''Summary'''
|Returns the names of all variables bound to the current session.
+
|Returns the names of all attributes bound to the current session.
 
|-
 
|-
 
| '''Examples'''
 
| '''Examples'''
 
|Running the server-side XQuery file {{Code|names.xq}} via <code><nowiki>http://localhost:8984/names.xq</nowiki></code>:
 
|Running the server-side XQuery file {{Code|names.xq}} via <code><nowiki>http://localhost:8984/names.xq</nowiki></code>:
<pre class="brush:xquery">
+
<syntaxhighlight lang="xquery">
 
import module namespace session = "http://basex.org/modules/session";
 
import module namespace session = "http://basex.org/modules/session";
 
session:names() ! element variable { . }
 
session:names() ! element variable { . }
</pre>
+
</syntaxhighlight>
 
|}
 
|}
  
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|-
 
|-
 
| '''Summary'''
 
| '''Summary'''
|Returns the value of <code>$name</code> bound to the current session. If the specified variable is unknown, an empty sequence or the optionally specified default value is returned instead.
+
|Returns the value of a session attribute with the specified <code>$name</code>. If the attribute is unknown, an empty sequence or the optionally specified {{Code|$default}} value will be returned instead.
|-
 
| '''Errors'''
 
|{{Error|get|#Errors}} the value of a session variable could not be retrieved.
 
 
|-
 
|-
 
| '''Examples'''
 
| '''Examples'''
 
|Running the server-side XQuery file {{Code|get.xq}} via <code><nowiki>http://localhost:8984/get.xq?key=user</nowiki></code>:
 
|Running the server-side XQuery file {{Code|get.xq}} via <code><nowiki>http://localhost:8984/get.xq?key=user</nowiki></code>:
<pre class="brush:xquery">
+
<syntaxhighlight lang="xquery">
 
import module namespace session = "http://basex.org/modules/session";
 
import module namespace session = "http://basex.org/modules/session";
 
'Value of ' || $key || ': ' || session:get($key)
 
'Value of ' || $key || ': ' || session:get($key)
</pre>
+
</syntaxhighlight>
 
|}
 
|}
  
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|-
 
|-
 
| '''Summary'''
 
| '''Summary'''
|Binds the specified name/value pair to a session.
+
|Binds the specified {{Code|$value}} to the session attribute with the specified {{Code|$name}}.
 
|-
 
|-
 
| '''Errors'''
 
| '''Errors'''
|{{Error|set|#Errors}} a function item was specified as value of a session variable.
+
|{{Error|set|#Errors}} The supplied value cannot be materialized.<br/>{{Error|not-found|#Errors}} No session is available for the current client.
 
|-
 
|-
 
| '''Examples'''
 
| '''Examples'''
 
|Running the server-side XQuery file {{Code|set.xq}} via <code><nowiki>http://localhost:8984/set.xq?key=user&value=john</nowiki></code>:
 
|Running the server-side XQuery file {{Code|set.xq}} via <code><nowiki>http://localhost:8984/set.xq?key=user&value=john</nowiki></code>:
<pre class="brush:xquery">
+
<syntaxhighlight lang="xquery">
 
import module namespace session = "http://basex.org/modules/session";
 
import module namespace session = "http://basex.org/modules/session";
 
session:set($key, $value), 'Variable was set.'
 
session:set($key, $value), 'Variable was set.'
</pre>
+
</syntaxhighlight>
 
|}
 
|}
  
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|-
 
|-
 
| '''Summary'''
 
| '''Summary'''
|Deletes a session value bound to <code>$name</code>.
+
|Deletes a session attribute with the specified <code>$name</code>.
 
|-
 
|-
 
| '''Examples'''
 
| '''Examples'''
 
|Running the server-side XQuery file {{Code|delete.xq}} via <code><nowiki>http://localhost:8984/delete.xq?key=user</nowiki></code>:
 
|Running the server-side XQuery file {{Code|delete.xq}} via <code><nowiki>http://localhost:8984/delete.xq?key=user</nowiki></code>:
<pre class="brush:xquery">
+
<syntaxhighlight lang="xquery">
 
import module namespace session = "http://basex.org/modules/session";
 
import module namespace session = "http://basex.org/modules/session";
 
session:delete($key), 'Variable was deleted.'
 
session:delete($key), 'Variable was deleted.'
</pre>
+
</syntaxhighlight>
 
|}
 
|}
  
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=Errors=
 
=Errors=
 
{{Mark|Updated with Version 9.0}}:
 
  
 
{| class="wikitable" width="100%"
 
{| class="wikitable" width="100%"
! width="110" |Code
+
! width="110"|Code
 
|Description
 
|Description
 
|-
 
|-
 
|{{Code|set}}
 
|{{Code|set}}
|Function items cannot be stored.
+
|The supplied value cannot be stored.
 
|-
 
|-
|{{Code|get}}
+
|{{Code|not-found}}
|The stored attribute is no XQuery value.
+
|No session is available for the current client.
 
|}
 
|}
  
 
=Changelog=
 
=Changelog=
 +
 +
;Version 9.4
 +
* Updated: Only create session if required.
 +
 +
;Version 9.3
 +
* Updated: [[#session:get|session:get]]: Values that have no XQuery type will be returned as strings.
  
 
;Version 9.0
 
;Version 9.0
 
 
* Updated: error codes updated; errors now use the module namespace
 
* Updated: error codes updated; errors now use the module namespace
  
 
;Version 8.0
 
;Version 8.0
 
 
* Updated: Allow sequences as session values.
 
* Updated: Allow sequences as session values.
  
 
This module was introduced with Version 7.5.
 
This module was introduced with Version 7.5.

Revision as of 11:50, 8 July 2020

This XQuery Module contains functions for accessing and modifying server-side session information. This module is mainly useful in the context of Web Applications.

Conventions

  • The module will be available if the basex-api library is found in the classpath. This is the case if you use one of the complete distributions of BaseX (zip, exe, war).
  • All functions and errors are assigned to the http://basex.org/modules/session namespace, which is statically bound to the session prefix.
  • If any of the functions is called outside the servlet context, basex:http is raised.
  • As sessions are side-effecting operations, all functions are flagged as non-deterministic. As a result, some query optimizations will be suppressed.

Functions

session:id

Signatures session:id() as xs:string
Summary Returns the session ID of a servlet request.
Errors not-found: No session is available for the current client.
Examples Running the server-side XQuery file id.xq via http://localhost:8984/id.xq:

<syntaxhighlight lang="xquery"> import module namespace session = "http://basex.org/modules/session"; 'Session ID: ' || session:id() </syntaxhighlight>

session:created

Signatures session:created() as xs:dateTime
Summary Returns the creation time of a session.
Errors not-found: No session is available for the current client.

session:accessed

Signatures session:accessed() as xs:dateTime
Summary Returns the last access time of a session.
Errors not-found: No session is available for the current client.

session:names

Signatures session:names() as xs:string*
Summary Returns the names of all attributes bound to the current session.
Examples Running the server-side XQuery file names.xq via http://localhost:8984/names.xq:

<syntaxhighlight lang="xquery"> import module namespace session = "http://basex.org/modules/session"; session:names() ! element variable { . } </syntaxhighlight>

session:get

Signatures session:get($name as xs:string) as item()*
session:get($name as xs:string, $default as item()*) as item()*
Summary Returns the value of a session attribute with the specified $name. If the attribute is unknown, an empty sequence or the optionally specified $default value will be returned instead.
Examples Running the server-side XQuery file get.xq via http://localhost:8984/get.xq?key=user:

<syntaxhighlight lang="xquery"> import module namespace session = "http://basex.org/modules/session"; 'Value of ' || $key || ': ' || session:get($key) </syntaxhighlight>

session:set

Signatures session:set($name as xs:string, $value as item()*) as empty-sequence()
Summary Binds the specified $value to the session attribute with the specified $name.
Errors set: The supplied value cannot be materialized.
not-found: No session is available for the current client.
Examples Running the server-side XQuery file set.xq via http://localhost:8984/set.xq?key=user&value=john:

<syntaxhighlight lang="xquery"> import module namespace session = "http://basex.org/modules/session"; session:set($key, $value), 'Variable was set.' </syntaxhighlight>

session:delete

Signatures session:delete($name as xs:string) as empty-sequence()
Summary Deletes a session attribute with the specified $name.
Examples Running the server-side XQuery file delete.xq via http://localhost:8984/delete.xq?key=user:

<syntaxhighlight lang="xquery"> import module namespace session = "http://basex.org/modules/session"; session:delete($key), 'Variable was deleted.' </syntaxhighlight>

session:close

Signatures session:close() as empty-sequence()
Summary Unregisters a session and all data associated with it.

Errors

Code Description
set The supplied value cannot be stored.
not-found No session is available for the current client.

Changelog

Version 9.4
  • Updated: Only create session if required.
Version 9.3
  • Updated: session:get: Values that have no XQuery type will be returned as strings.
Version 9.0
  • Updated: error codes updated; errors now use the module namespace
Version 8.0
  • Updated: Allow sequences as session values.

This module was introduced with Version 7.5.