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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= A job can be registered as ''service'' by supplying the {{Code|service}} option to {{Function|Jobs|jobs:eval}}: <syntaxhighlight lang="xquery">(: register job as service; 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() })</syntaxhighlight> '''Some more notes:''' * All job services will be scheduled for evaluation when the BaseX server or BaseX HTTP server is started.* If a job service is outdated (e.g. because a supplied end time has been exceeded), it will be removed from the jobs file at startup time.* The job definitions are stored in a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 jobs, stopped, and finished jobs with cached jobsresults.
|-
| '''Examples'''
|* <code>jobs:list()</code> returns the same job id as [[#jobs:current{{Function|Jobs|jobs:current]] }} if no other job is registered.* <code>jobs:list()[. != jobs:current()] ! jobs:stop(.)</code> stops and invalidates all asynchronous queries and results except for the current one.
|}
|-
| '''Summary'''
|Returns information on all jobs that are currently registered, or on a job with the specified {{Code|$id}} (or an empty sequence if this job is not found). The list includes scheduled, queued, running jobs, and cached jobs. A string representation of the job , or its URI, will be returned in the text nodeas value. The returned elements have additional attributes:
* <code>id</code>: job id
* <code>type</code>: type of the job (command, query, REST, RESTXQ, etc.)
* <code>state</code>: current state of the job (: <code>scheduled</code>, <code>queued</code>, <code>running</code>, or <code>cached)</code>* <code>user</code>: the user who started the job* <code>duration</code>: evaluation time (for included if a job is running and or if the result was cached jobs)* <code>start</code>: dateTime string with next start of job (for jobs that included if a job will be executed repeatedly)* <code>time</code>: time when job was registered
|-
| '''Examples'''
|* <code>jobs:list-details()</code> returns information on the currently running job and possibly others:<pre classsyntaxhighlight lang="brush:xml">
<job id="job1" type="XQuery" state="running" user="admin" duration="PT0.001S">
XQUERY jobs:list-details()
</job>
</presyntaxhighlight>
|}
|}
==jobs:stopservices==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:stopservices|$id as xs:string|empty-sequenceelement(job)*}}
|-
| '''Summary'''
|Triggeres the cancelation of Returns a job with the specified {{Code|$id}}, drops the cached result list of a query, or cancels a scheduled job. Unknown ids are ignored. All jobs are gracefully stopped; it is up to the process to decide when it is safe to shut down.|} ==jobs:wait== {| width='100%'|-| width='120' | '''Signatures'''|{{Func|all jobs:wait|$id that have been persistently registered as xs:string|empty-sequence()}}[[#Services|-| '''Summary'''|Waits for the completion of a job with the specified {{Code|$id}}. If the function is called with the id of a queued job, or repeatedly executed job, it may stall and never terminateServices]].
|-
| '''Errors'''
|{{Error|selfservices|#Errors}} if the current job is addressedRegistered services cannot be parsed.<br/>
|}
=Asynchronous Execution=
Asynchronous query execution is recommendable if There are cases in which a client does not, or cannot, wait until a request is fully processed. This is e. g. the case with web browsersThe client may be a browser, which will usually cancel a sends an HTTP request after a specific timeout. In such cases, you can use asynchronous execution to trigger another the server-side process, which will in order to start the another time-consuming processquery job. The functions in this section allow you to register a new query job from a running query. Jobs can be executed immediately (i.e., and fetch the result later on as soon as the [[Transaction Management#Concurrency Control|Concurrency Control]] allows it is available) or scheduled for repeated execution. Each registered job gets a job id, and the id can be used to retrieve a query result, stop a job, or wait for its termination.
==jobs:eval==
{{Mark|Updated with Version 89.65}}: <code>id</code> option Integers addedas valid start and end times.
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:eval|$query as xs:stringanyAtomicItem|xs:string}}<br />{{Func|jobs:eval|$query as xs:stringanyAtomicItem, $bindings as map(*)?|xs:string}}<br />{{Func|jobs:eval|$query as xs:stringanyAtomicItem, $bindings as map(*)?, $options as map(xs:string, xs:string*)?|xs:string}}<br />
|-
| '''Summary'''
|Schedules the evaluation of the supplied {{Code|$query}} and returns a query id. The query will be queued, and the result will optionally be cached. Queries can be updating. Variables The query can be a URI or a string, and 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.
** If the query raises an error, it will be cached and returned instead.
* {{Code|start}}: a dayTimeDuration, time , dateTime or dateTime integer can be specified to delay the execution of the query:
** If a dayTimeDuration is specified, the query will be queued after the specified duration has passed. Examples for valid values are: <code>P1D</code> (1 day), <code>PT5M</code> (5 minutes), <code>PT0.1S</code> (100 ms). An error will be raised if a negative value is specified.
** If a dateTime is specified, the query will be executed at this date. Examples for valid values are: <code>2018-12-31T23:59:59</code> (New Year's Eve 2018, close to midnight). An error will be raised if the specified time lies in the past.
** If a time is specified, the query will be executed at this time of the day. Examples for valid times are: <code>02:00:00</code> (2am local time), <code>12:00:00Z</code> (noon, UTC). If the time lies in the past, the query will be executed the next day.
** An integer will be interpreted as minutes. If a dateTime is the specifiednumber exceeds the minutes of the current hour, the query will be executed at this date. Examples for valid values are: <code>2018-12-31T23:59:59</code> (New Year's Eve 2018, close to midnight). An error will be raised if the specified time lies in the pastone hour later.
* {{Code|interval}}: a dayTimeDuration string can be specified to execute the query periodically. An error is raised if the specified interval is less than one second (<code>PT1S</code>). If the next scheduled call is due, and if a query with the same id is still running, it will be skipped.
* {{Code|end}}: scheduling can be stopped after a given time or duration. The string format is the same as for {{Code|start}}. An error is raised if the resulting end time is smaller than the start time.
* {{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]]. Registered services must have no variable bindings.
* {{Code|log}}: writes the specified string to the [[Logging|database logs]]. Two log entries are stored, one at the beginning and another one after the execution of the job.
|-
| '''Errors'''
|{{Error|overflow|#Errors}} Query execution is rejected, because too many jobs are queued or being executed. {{Option|CACHETIMEOUT}} can be decreased if the default setting is too restrictive.<br/>{{Error|range|#Errors}} A specified time or duration is out of range.<br/>{{Error|id|#Errors}} The specified id is invalid or has already been assigned.<br/>{{Error|options|#Errors}} The specified options are conflicting.
|-
| '''Examples'''
|
* Cache query result. The returned id can be used to pick up the result with [[#jobs:result|jobs:result]]:
<pre classsyntaxhighlight lang='brush:"xquery'">
jobs:eval("1+3", (), map { 'cache': true() })
</presyntaxhighlight>
* A happy birthday mail will be sent at the given date:
<pre classsyntaxhighlight lang="brush:xquery">
jobs:eval("import module namespace mail='mail'; mail:send('Happy birthday!')",
(), map { 'start': '2018-09-01T06:00:00' })}}
</presyntaxhighlight>
* The following [[RESTXQ]] functions can be called to execute a query at 2 am every day. An id will be returned by the first function, which can be used to stop the scheduler via the second function:
<pre classsyntaxhighlight lang='brush:"xquery'">
declare %rest:POST("{$query}") %rest:path('/start-scheduling') function local:start($query) {
jobs:eval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' })
jobs:stop($id)
};
</presyntaxhighlight>
* Query execution is scheduled for every second, and for 10 seconds in total. As the query itself will take 1.5 seconds, it will only be executed every second time:
<pre classsyntaxhighlight lang="brush:xquery">
jobs:eval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' })
</presyntaxhighlight>* The query in the specified file will be evaluated once:<syntaxhighlight lang="xquery">jobs:eval(xs:anyURI('cleanup.xq'))</syntaxhighlight>* The following expression, if stored as in a file, calls and evaluates itself will be evaluated every 5 seconds:<pre classsyntaxhighlight lang="brush:xquery">
jobs:eval(
file:read-text(static-base-uri()),
map { },
map { 'start': 'PT5S' }
)
</presyntaxhighlight>
|}
|
* The following [[RESTXQ]] function will either return the result of a previously started job or raise an error:
<pre classsyntaxhighlight lang='brush:"xquery'">
declare %rest:path('/result/{$id}') function local:result($id) {
jobs:result($id)
};
</presyntaxhighlight>* The following query demonstrates how the results of an asynchronously executed query can be returned within the same query(see below why you should avoid this pattern in practice):<pre classsyntaxhighlight lang='brush:"xquery'">let $query := jobs:eval('(1 to 10000000)[. = 1]', map{}, map{ 'cache': true() })
return (
jobs:wait($query),
jobs:result($query)
)
</presyntaxhighlight>Please note that queries Queries of this kind can cause deadlocks. For example, if both ! If the original query and the new query to be executed asynchronously perform updates on the same database, the second query would will only be run after the first one has been executed, and the first query will wait for the second query forever. This is why you You should avoid this pattern in practice and resort to [[XQuery Module#xquery:fork-join|xquery:fork-join]] if you want to do things in have full control on parallelquery execution.|} ==jobs:stop== {| width='100%'|-| width='120' | '''Signatures'''|{{Func|jobs:stop|$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/>
|}
|Description
|-
|{{Code|unknownoptions}}| The supplied query id is unknown or not available anymorespecified options are conflicting.
|-
|{{Code|runningid}}| A query The specified id is still runninginvalid or has already been assigned.
|-
|{{Code|overflow}}
| A specified time or duration is out of range.
|-
|{{Code|idrunning}}| The specified A query is invalid or has already been assignedstill running.
|-
|{{Code|self}}
| The current job cannot be addressed.
|-
|{{Code|service}}
| Registered services cannot be parsed, added or removed.
|-
|{{Code|unknown}}
| The supplied query id is unknown or not available anymore.
|}
=Changelog=
 
;Version 9.5
* Updated: {{Function|Jobs|jobs:eval}}: integers added as valid start and end times.
 
;Version 9.4
* Updated: {{Function|Jobs|jobs:eval}}: option added for writing log entries.
* Updated: {{Function|Jobs|jobs:list-details}}: interval added.
 
;Version 9.2
* Deleted: jobs:invoke (merged with {{Function|Jobs|jobs:eval}})
 
;Version 9.1
* Updated: {{Function|Jobs|jobs:list-details}}: registration time added.
 
;Version 9.0
* Added: {{Function|Jobs|jobs:invoke}}, [[#Services|Services]]
;Version 8.6
 * Updated: [[#jobs:eval{{Function|Jobs|jobs:eval]]}}: <code>id</code> option added.
The module was introduced with Version 8.5.
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