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{{Mark|Introduced with Version 9.0:}}
contents entry for job:services
All functions in this module are assigned to the <code><nowiki>http://basex.org/modules/jobs</nowiki></code> namespace, which is statically bound to the {{Code|jobs}} prefix. Errors will be bound to the same prefix.
=Services= Jobs can additionally be registered as persistent services. An additional {{Code|service}} option has been added to the options list of {{Function|Jobs|jobs:eval}} and {{Function|Jobs|jobs:invoke}}: <pre class="brush:xquery">(: register job, which will be run every day at 1 am :)jobs:eval('db:drop("tmp")', (), map { 'id':'cleanup', 'start':'01:00:00', 'interval':'P1D', 'service': true() }), (: list registered services :)jobs:services(),(: result: <job base-uri="..." id="cleanup" interval="P1D" start="01:00:00">db:drop("tmp")</job> :) (: unregister job :)jobs:stop('cleanup', map { 'service': true() })</pre> '''Some more notes:''' * All registered jobs will be scheduled for evaluation when the BaseX server or BaseX HTTP server is started.* If a job service is outdated (e.g. because a supplied end time has been exceeded), it will be removed from the jobs file at startup time.* Job services can be updated: If a new job is registered, and if there is already a job with the same id, the old entry will be replaced.* The job definitions are stored in a {{Code|jobs.xml}} file in the database directory. It can also be edited manually. =Basic Functions=
==jobs:current==
|-
| '''Summary'''
|Returns the ids of all jobs that are currently registered. The list includes scheduled, queued, running, stopped, and completed finished jobs with cached results.
|-
| '''Examples'''
|-
| '''Examples'''
|* <code>jobs:list-details()</code> returns information on the currently running job and possibly others:
<pre class="brush:xml">
<job id="job1" type="XQuery" state="running" user="admin" duration="PT0.001S">
</pre>
|}
==jobs:finished==
|}
==jobs:stopservices==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:stopservices|$id as xs:string|empty-sequenceelement(job)*}}
|-
| '''Summary'''
|Triggers the cancelation of Returns a job with the specified {{Code|$id}}, drops the cached result list of a query, or cancels a scheduled job. Unknown ids are ignored. All jobs are gracefully stopped; it is up to the process to decide when it is safe to shut down.|-| '''Examples'''| <code>jobs:list()[. != jobs:current()] ! jobs:stop(.)</code> stops and discards all jobs except for the current one.|} ==jobs:wait== {| width='100%'|-| width='120' | '''Signatures'''|{{Func|jobs:wait|$id that have been persistently registered as xs:string[[#Services|empty-sequence()}}|-| '''Summary'''|Waits for the completion of a job with the specified {{Code|$id}}:* The function will terminate immediately if the job id is unknown. This is the case if a future job has not been queued yet, or if the id has already been discarded after job evaluation.* If the function is called with the id of a queued job, or repeatedly executed job, it may stall and never terminateServices]].
|-
| '''Errors'''
|{{Error|selfservices|#Errors}} The current job is addressedRegistered services cannot be parsed.<br/>
|}
=Asynchronous Execution=
Asynchronous query execution is recommendable if a client does not, or cannot, wait until a request is fully processed. This is e. g. the case with web browsers, which will usually cancel a request after a specific timeout. In such cases, you can use asynchronous execution to trigger another server-side process, which will start the time-consuming process, and fetch the result later on as soon as it is available.
|-
| '''Summary'''
|Schedules the evaluation of the supplied {{Code|$query}} and returns a query id. The query will be queued, and the result will optionally be cached. Queries can be updating. Variables and context items can be declared via {{Code|$bindings}} (see [[XQuery Module#xquery:eval|xquery:eval]] for more details). The following {{Code|$options}} parameter contains scheduling optionscan be supplied:
* {{Code|cache}}: indicates if the query result will be cached or ignored (default: <code>false</code>):
** The result will be cached in main-memory until it is fetched via [[#jobs:result|jobs:result]], or until {{Option|CACHETIMEOUT}} is exceeded.
* {{Code|base-uri}}: sets the [https://www.w3.org/TR/xquery-31/#dt-static-base-uri base-uri property] for the query. This URI will be used when resolving relative URIs, such as with {{Code|fn:doc}}.
* {{Code|id}}: sets a custom job id. The id must not start with the standard <code>job</code> prefix, and it can only be assigned if no job with the same name exists.
* {{Code|service}}: additionally registers the job as [[#Services|service]].
|-
| '''Errors'''
==jobs:invoke==
{| width='100%'
|-
| '''Summary'''
|Schedules the evaluation of the XQuery expression located at {{Code|$uri}} and returns a query id. The semantics and remaining arguments are identical to For further details, see [[#jobs:eval|jobs:eval]].
|-
| '''Errors'''
|-
| '''Examples'''
|* Runs an Run XQuery expression that may perform some cleanups:
<pre class='brush:xquery'>
jobs:invoke("cleanup.xq", (), ())
</pre>
Please note that queries of this kind can cause deadlocks. For example, if both the original query and the query to be executed asynchronously perform updates on the same database, the second query would only be run after the first one has been executed, and the first query will wait forever. This is why you should avoid this pattern in practice and resort to [[XQuery Module#xquery:fork-join|xquery:fork-join]] if you want to do things in parallel.
|}
==jobs:stop==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:stop|$id as xs:string|empty-sequence()}}
|-
| '''Summary'''
|Triggers the cancelation of a job with the specified {{Code|$id}}, drops the cached result of a query, or cancels a scheduled job. Unknown ids are ignored. All jobs are gracefully stopped; it is up to the process to decide when it is safe to shut down. The following {{Code|$options}} can be supplied:
* {{Code|service}}: additionally removes the job from the [[#Services|job services]] list.
|-
| '''Examples'''
| <code>jobs:list()[. != jobs:current()] ! jobs:stop(.)</code> stops and discards all jobs except for the current one.
|}
==jobs:wait==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:wait|$id as xs:string|empty-sequence()}}
|-
| '''Summary'''
|Waits for the completion of a job with the specified {{Code|$id}}:
* The function will terminate immediately if the job id is unknown. This is the case if a future job has not been queued yet, or if the id has already been discarded after job evaluation.
* If the function is called with the id of a queued job, or repeatedly executed job, it may stall and never terminate.
|-
| '''Errors'''
|{{Error|self|#Errors}} The current job is addressed.<br/>
|}
|{{Code|self}}
| The current job cannot be addressed.
|-
|{{Code|service}}
| Registered services cannot be parsed, added or removed.
|-
|{{Code|unknown}}
;Version 9.0
* Added: {{Function|Jobs|jobs:invoke}}, [[#jobs:invokeServices|jobs:invokeServices]]
;Version 8.6
