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Asynchronous query execution is recommendable if a client does not{| width='100%'|-| width='120' | '''Signatures'''|{{Func|jobs:list-details||element(job)*}}<br/>{{Func|jobs:list-details|$id as xs:string|element(job)*}}|-| '''Summary'''|Returns information on all jobs that are currently registered, or cannot, wait until on a request job with the specified {{Code|$id}} (or an empty sequence if this job is fully processednot found). This is eThe list includes scheduled, queued, running jobs, and cached jobs. gA string representation of the job, or its URI, will be returned as value. The returned elements have additional attributes:* <code>id</code>: job id* <code>type</code>: type of the case with web browsersjob (command, query, REST, RESTXQ, which will usually cancel a request after a specific timeoutetc. In such cases)* <code>state</code>: current state of the job: <code>scheduled</code>, <code>queued</code>, you can use asynchronous execution to trigger another server-side process<code>running</code>, which will start <code>cached</code>* <code>user</code>: user who started the job* <code>duration</code>: evaluation time-consuming process, and fetch (included if a job is running or if the result later was cached)* <code>start</code>: next start of job (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 as soon as it is availablethe currently running job and possibly others:<syntaxhighlight lang="xml"><job id="job1" type="XQuery" state="running" user="admin" duration="PT0.001S"> XQUERY jobs:list-details()</job></syntaxhighlight>|}
no edit summary
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.
=FunctionsServices=
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. =Executing Jobs= There are cases in which a client does not, or cannot, wait until a request is fully processed. The client may be a browser, which sends an HTTP request to the server in order to start another time-consuming query 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., as soon as the [[Transaction Management#Concurrency Control|Concurrency Control]] allows it) 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:currenteval==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:currenteval|$query as xs:anyAtomicItem|xs:string}}<br />{{Func|jobs:eval|$query as xs:anyAtomicItem, $bindings as map(*)?|xs:string}}<br />{{Func|jobs:eval|$query as xs:anyAtomicItem, $bindings as map(*)?, $options as map(*)?|xs:string}}<br />
|-
| '''Summary'''
|Returns Schedules the evaluation of the supplied {{Code|$query}} ({{Code|xs:string}}, or of type {{Code|xs:anyURI}}, pointing to a resource), and returns a query id . The query will be queued, and the result will optionally be cached. Queries can be updating. Variables and the context value can be declared via {{Code|$bindings}} (see [[XQuery Module#xquery:eval|xquery:eval]] for more details). The following {{Code|$options}} can 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 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 the specified number is greater than the elapsed minutes of the current hour, the query will be executed one 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 jobwith 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]]:<syntaxhighlight lang="xquery">jobs:eval("1+3", (), map { 'cache': true() })</syntaxhighlight>* A happy birthday mail will be sent at the given date:<syntaxhighlight lang="xquery">jobs:eval("import module namespace mail='mail'; mail:send('Happy birthday!')", (), map { 'start': '2018-09-01T06:00:00' })}}</syntaxhighlight>* 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:<syntaxhighlight lang="xquery">declare %rest:POST("{$query}") %rest:path('/start-scheduling') function local:start($query) { jobs:eval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' })};declare %rest:path('/stop-scheduling/{$id}') function local:stop($id) { jobs:stop($id)};</syntaxhighlight>* 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:<syntaxhighlight lang="xquery">jobs:eval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' })</syntaxhighlight>* 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 in a file, will be evaluated every 5 seconds:<syntaxhighlight lang="xquery">jobs:eval( static-base-uri(), map { }, map { 'start': 'PT5S' })</syntaxhighlight>
|}
==jobs:listresult== {{Mark|Updated with Version 9.7:}} Return empty sequence if no result is cached.
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:list|result|$id as xs:string|item()*}}
|-
| '''Summary'''
|Returns the ids cached result of all jobs that are currently registereda job with the specified job {{Code|$id}}:* If the original job has raised an error, the cached error will be raised instead.* Results can only be retrieved once. The list includes scheduledAfter retrieval, queuedthe cached result will be dropped.* If the result has already been retrieved, running jobsor if it has not been cached, and cached jobsan empty sequence is returned.
|-
| '''Examples'''
|
* The following [[RESTXQ]] function will either return the result of a previously started job or raise an error:<codesyntaxhighlight lang="xquery">declare %rest:path('/result/{$id}') function local:result($id) { jobs:listresult($id)};</codesyntaxhighlight> returns * The following query demonstrates how the results of an executed query can be returned within the same job id as [[#jobsquery (see below why you should avoid this pattern in practice):current|jobs:current]] if no other job is registered.* <codesyntaxhighlight lang="xquery">let $query := jobs:listeval('(1 to 10000000)[. != 1]', map { }, map { 'cache': true() })return ( jobs:currentwait($query)] ! , jobs:stopresult(.$query))</codesyntaxhighlight> stops Queries of this kind can cause deadlocks! If the original query and invalidates all asynchronous queries the new query perform updates on the same database, the second query will only be run after the first one has been executed, and results except the first query will wait for the current onesecond query forever. You should resort to [[XQuery Module#xquery:fork-join|xquery:fork-join]] if you want to have full control on parallel query execution.
|}
==jobs:list-detailsstop==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:list-details||element(job)*}}<br/>{{Func|jobs:list-detailsstop|$id as xs:string|elementempty-sequence(job)*}}
|-
| '''Summary'''
|Returns information on all jobs that are currently registered. The list includes scheduledTriggers the cancelation of a job with the specified {{Code|$id}}, queued, running jobs, and drops the cached jobs. A string representation result of the a query, or cancels a scheduled job will be returned in . Unknown ids are ignored. All jobs are gracefully stopped; it is up to the text nodeprocess to decide when it is safe to shut down. The returned elements have additional attributesfollowing {{Code|$options}} can be supplied:* <code>id</code>{{Code|service}}: additionally removes the job id* <code>type</code>: type of from the [[#Services|job (command, query, REST, RESTXQ, etcservices]] list.)* <code>state</code>: current state of the job (scheduled, queued, running, or cached)* <code>user</code>: the user who started the job* <code>duration</code>: evaluation time (for running and cached jobs)* <code>start</code>: dateTime string with next start (for jobs that will be executed repeatedly)
|-
| '''Examples'''
|* <code>jobs:list-details()</code> returns information on the currently running job and possibly others:<pre class[. !="brushjobs:xml"><job id="job1" type="XQuery" state="running" user="admin" duration="PT0.001S"> XQUERY current()] ! jobs:list-detailsstop(.)</job></precode>stops and discards all jobs except for the current one.
|}
==jobs:finishedwait==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:finishedwait|$id as xs:string|xs:booleanempty-sequence()}}
|-
| '''Summary'''
|Indicates if Waits for the evaluation completion of an already running a job with the specified {{Code|$id}} has finished. As the ids of finished jobs will usually be discarded, unless caching is enabled, the :* The function will also return <code>true</code> for unknown jobs.* <code>false</code> indicates that terminate immediately if the job id is scheduled, queued, or currently runningunknown.* <code>true</code> will be returned This is the case if the a future job has either finishednot been queued yet, or if the id has already been discarded after job evaluation.* If the function is unknown (because called with the ids id of all finished jobs will not be cached)a queued job, or repeatedly executed job, it may stall and never terminate.|-| '''Errors'''|{{Error|self|#Errors}} The current job is addressed.<br/>
|}
=Listing Jobs= ==jobs:stopcurrent==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:stopcurrent||$id as xs:string|empty-sequence()}}
|-
| '''Summary'''
|Triggeres Returns the cancelation id of a job with the specified {{Code|$id}}, drops the cached result of a query, or cancels a scheduled current 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:waitlist==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:waitlist||$id as xs:string|empty-sequence()*}}
|-
| '''Summary'''
|Waits for Returns the completion ids of a job with the specified {{Code|$id}}all jobs that are currently registered. If the function is called with the id of a The list includes scheduled, queued job, or repeatedly executed jobrunning, stopped, it may stall and never terminatefinished jobs with cached results.
|-
| '''ErrorsExamples'''|<code>jobs:list()</code> returns the same job id as {{ErrorFunction|selfJobs|#Errorsjobs:current}} if the current no other job is addressedregistered.<br/>
|}
=Asynchronous Execution=jobs:list-details==
==jobs:evalbindings==
{{Mark|Updated Introduced with Version 810.60}}: <code>id</code> option added.
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:evalbindings|$query id as xs:string|xs:string}}<br />{{Func|jobs:eval|$query as xs:string, $bindings as map(*)?|xs:string}}<br />{{Func|jobs:eval|$query as xs:string, $bindings as map(*)?, $options as map(xs:string, xs:string)|xs:string}}<br />
|-
| '''Summary'''
|Schedules Returns the evaluation variable bindings of an existing job with the supplied specified {{Code|$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|$bindings}} (see [[XQuery Module#xquery:eval|xquery:eval]] for more details). The {{Code|$options}} parameter contains scheduling options:* {{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 or dateTime can be specified no variables have been bound 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 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)job, <code>12:00:00Z</code> (noon, UTC). If the time lies in the past, the query will be executed the next day.** If a dateTime an empty map 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 pastreturned.* {{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}}==jobs: 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.finished==* {{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.width='100%'
|-
| width='120'| 'Errors''Signatures'''|{{ErrorFunc|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:finished|$idas xs:string|#Errorsxs:boolean}} The specified id is invalid or has already been assigned.
|-
| '''ExamplesSummary'''|* Cache query result. The returned id can be used to pick up Indicates if the result evaluation of an already running job with [[#jobs:result|jobs:result]]:<pre class='brush:xquery'>jobs:eval("1+3", (), map the specified { 'cache': true() })</pre>* A happy birthday mail will be sent at the given date:<pre class="brush:xquery">jobs:eval("import module namespace mail='mail'; mail:send('Happy birthday!')", (), map { 'start': '2018-09-01T06:00:00' })Code|$id}}</pre>* The following [[RESTXQ]] functions can be called to execute a query at 2 am every dayhas finished. An id As the ids of finished jobs will usually be returned by the first functiondiscarded, unless caching is enabled, which can be used to stop the scheduler via the second function:will also return <pre class='brush:xquery'code>declare %rest:POST("{$query}") %rest:path('true</start-scheduling') function local:start($query) { code> for unknown jobs:eval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' })};declare %rest:path('/stop-scheduling/{$id}') function local:stop($id) { jobs:stop($id)};.* <code>false</precode>* Query execution indicates that the job id is scheduled for every second, and for 10 seconds in totalqueued, or currently running. As the query itself will take 1.5 seconds, it will only be executed every second time:* <pre class="brush:xquery"code>jobs:eval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' })true</precode>* The following expressionwill be returned if the job has either finished, or if stored as a file, calls and evaluates itself every 5 seconds:<pre class="brush:xquery">the id is unknown (because the ids of all finished jobs:eval( file:read-text(static-base-uri(will not be cached)), map { }, map { 'start': 'PT5S' })</pre>.
|}
==jobs:resultservices==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:resultservices|$id as xs:string|itemelement(job)*}}
|-
| '''Summary'''
|Returns the cached result a list of a job with the specified job {{Codeall jobs that have been persistently registered as [[#Services|$id}}:* Results can only be retrieved once. After retrieval, the cached result will be dropped.* If the original job has raised an error, the cached error will be raised insteadServices]].
|-
| '''Errors'''
|{{Error|runningservices|#Errors}} the job is still running.<br/>{{Error|unknown|#Errors}} the supplied id is unknown: The id is unknown, or the result has already been retrievedRegistered services cannot be parsed.<br/>|-| '''Examples'''|* The following [[RESTXQ]] function will either return the result of a previously started job or raise an error:<pre class='brush:xquery'>declare %rest:path('/result/{$id}') function local:result($id) { jobs:result($id)};</pre>* The following query demonstrates how the results of an asynchronously executed query can be returned within the same query:<pre class='brush:xquery'>let $query := jobs:eval('(1 to 10000000)[. = 1]', map{}, map{ 'cache': true() })return ( jobs:wait($query), jobs:result($query))</pre>Please note that this query can easily cause a deadlock if the asynchronously executed query will be queued. In practice. In practice, you should avoid this pattern and resort to [[XQuery Module#xquery:fork-join|xquery:fork-join]] if you want to do things in parallel.
|}
|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.
|}
=Changelog=
;Version 10.0
* Added: {{Function|Jobs|jobs:bindings}}
;Version 9.7
* Updated: {{Function|Jobs|jobs:result}}: return empty sequence if no result is cached.
;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.
