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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.
=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:currentstop('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services will be scheduled for evaluation when the BaseX server or BaseX HTTP server is started.* If a job service is outdated (e.g. because a supplied end time has been exceeded), it will be removed from the jobs file at startup time.* The job definitions are stored in a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=
{| width='100%'|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| width='120' | '''Signatures'''|{{Func|jobs:current||xs:string}}|-| '''Summary'''|Returns Concurrency Control]] allows it) or scheduled for repeated execution. Each registered job gets a job id, and the id of the current can be used to retrieve a query result, stop a job, or wait for its termination.|}
==jobs:listeval==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:listeval|$query as xs:anyAtomicItem|xs:string}}<br />{{Func|jobs:eval|$query as xs:anyAtomicItem, $bindings as map(*)?|xs:string}}<br />{{Func|jobs:eval|$query as xs:anyAtomicItem, $bindings as map(*)?, $options as map(*)?|xs:string}}<br />
|-
| '''Summary'''
|Returns Schedules the ids evaluation of all the supplied {{Code|$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 that :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 currently registered: <code>2018-12-31T23:59:59</code> (New Year's Eve 2018, close to midnight). The list includes 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 scheduledcall is due, queued, and if a query with the same id is still running, it will be skipped.* {{Code|end}}: scheduling can be stoppedafter 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 finished 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 with cached resultsare 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]]:<codesyntaxhighlight lang="xquery">jobs:listeval("1+3", (), map { 'cache': true() })</codesyntaxhighlight> returns * A happy birthday mail will be sent at the same job 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 as 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) {Function|Jobs| jobs:currenteval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' })};declare %rest:path('/stop-scheduling/{$id}') function local:stop($id) { jobs:stop($id)} if no other job ;</syntaxhighlight>* Query execution is registeredscheduled 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:list-detailsresult== {{Mark|Updated with Version 9.7:}} Return empty sequence if no result is cached.
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:list-details||element(job)*}}<br/>{{Func|jobs:list-detailsresult|$id as xs:string|elementitem(job)*}}
|-
| '''Summary'''
|Returns information on all jobs that are currently registered, or on the cached result of a job with the specified job {{Code|$id}} (or :* If the original job has raised an empty sequence if this job is not found). The list includes schedulederror, queued, running jobs, and the cached jobs. A string representation of the job, or its URI, error will be returned as valueraised instead. The returned elements have additional attributes:* <code>id</code>: job id* <code>type</code>: type of Results can only be retrieved once. After retrieval, the job (command, query, REST, RESTXQ, etccached result will be dropped.)* <code>state</code>: current state of If the job (scheduled, queued, runningresult has already been retrieved, or if it has not been 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), an empty sequence is returned.
|-
| '''Examples'''
| <code>jobs:list-details()</code> returns information on * The following [[RESTXQ]] function will either return the currently running result of a previously started job and possibly othersor raise an error:<pre classsyntaxhighlight lang="brush:xmlxquery"><job declare %rest:path('/result/{$id}') function local:result($id="job1" type="XQuery" state="running" user="admin" duration="PT0.001S">) { XQUERY jobs:list-detailsresult($id)};</jobsyntaxhighlight>* The following query demonstrates how the results of an executed query can be returned within the same query (see below why you should avoid this pattern in practice):</presyntaxhighlight lang="xquery">|} =let $query :=jobs:finishedeval('(1 to 10000000)[. == 1]', map { }, map {| width='100%cache': true() })|-return (| width='120' | '''Signatures''' jobs:wait($query),|{{Func| jobs:finished|result($id as xs:string|xs:boolean}}query)|-)| '''Summary'''</syntaxhighlight>|Indicates if Queries of this kind can cause deadlocks! If the original query and the evaluation of an already running job with new query perform updates on the specified {{Code|$id}} has finished. As same database, the ids of finished jobs second query will usually only be discarded, unless caching is enabledrun after the first one has been executed, and the function first query will also return <code>true</code> wait for unknown jobs.* <code>false</code> indicates that the job id is scheduled, queued, or currently runningsecond query forever.* <code>true</code> will be returned You should resort to [[XQuery Module#xquery:fork-join|xquery:fork-join]] if the job has either finished, or if the id is unknown (because the ids of all finished jobs will not be cached)you want to have full control on parallel query execution.
|}
|-
| '''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'''
|}
=ExecutionListing Jobs=
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.==jobs:current==
{| width='100%'|-| width='120' | '''Signatures'''|{{Func|jobs:evalcurrent||xs:string}}|-| '''Summary'''|Returns the id of the current job.|} ==jobs:list==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:evallist|$query as xs:string|xs:string}}<br />{{Func|jobs:eval|$query as xs:string, $bindings as map(*)?|xs:string}}<br />{{Func|jobs:eval|$query as xs:string, $bindings as map(*)?, $options as map(*)?|xs:string}}<br />
|-
| '''Summary'''
|Schedules Returns the evaluation ids of the supplied {{Code|$query}} and returns a query idall jobs that are currently registered. The query will be list includes scheduled, queued, running, stopped, and the result will optionally be finished jobs with cachedresults. 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 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>02jobs:00:00</code> list(2am local time), <code>12:00:00Z</code> (noon, UTC). If returns the time lies in the past, the query will be executed the next day.** 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.* same job id as {{CodeFunction|intervalJobs|jobs:current}}: a dayTimeDuration string can be specified to execute the query periodically. An error is raised if the specified interval no other job 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 skippedregistered.* {{Code|end}==jobs: scheduling can be stopped after a given time or duration. The string format is the same as for list-details== {{Code|start}}. An error is raised if the resulting end time is smaller than the start time.width='100%'|-| width='120' | '''Signatures'''* |{{CodeFunc|basejobs:list-uridetails||element(job)*}}: sets the [https:<br//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 >{{CodeFunc|fnjobs:doc}}.* {{Codelist-details|$idas xs:string|element(job)*}}: sets a custom job id. The id must not start with the standard <code>job</code> prefix, and it can only be assigned if no job with the same name exists.
|-
| '''ErrorsSummary'''|Returns information on all jobs that are currently registered, or on a job with the specified {{ErrorCode|overflow|#Errors$id}} Query execution (or an empty sequence if this job is rejectednot found). The list includes scheduled, because too many queued, running jobs are queued , and cached jobs. A string representation of the job, or being executedits URI, will be returned as value. {{Option|CACHETIMEOUT}} can be decreased if The returned elements have additional attributes:* <code>id</code>: job id* <code>type</code>: type of the default setting is too restrictivejob (command, query, REST, RESTXQ, etc.)* <code>state</code>: current state of the job: <code>scheduled</code>, <code>queued</code>, <code>running</code>, <code>cached<br/code>* <code>user</code>: user who started the job* <code>{{Error|range|#Errors}} A specified time or duration is out of range.<br/code>{{Error|id|#Errors}} The specified id : evaluation time (included if a job is invalid running or has already been assigned.if the result was cached)* <code>start</code>: next start of job (included if a job will be executed repeatedly)* <code>time<br/code>{{Error|options|#Errors}} The specified options are conflicting.: time when job was registered
|-
| '''Examples'''
|* Cache query result. The returned id can be used to pick up the result with [[#jobs:result|jobs:result]]:<pre class='brush:xquery'code>jobs:eval("1+3", list-details(), map { 'cache': true() })</precode>* A happy birthday mail will be sent at returns information on the given datecurrently running job and possibly others:<pre classsyntaxhighlight lang="brush:xqueryxml">jobs:eval(<job id="import module namespace mail='mail'; mail:send('Happy birthday!')job1", (), map { 'start': '2018-09-01T06:00:00' })}}</pre>* 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 classtype='brush:xquery'>declare %rest:POST("{$query}XQuery") %rest:path('/start-scheduling') function local:start($query) { jobs:eval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' })};declare %rest:path('/stop-scheduling/{$id}') function local:stop($id) { jobs:stop($id)};</pre>* 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 classstate="brush:xqueryrunning">jobs:eval(user="prof:sleep(1500)admin", (), map { 'interval': 'PT1S', 'end': 'PT10S' })</pre>* The following expression, if stored as a file, calls and evaluates itself every 5 seconds:<pre classduration="brush:xqueryPT0.001S"> XQUERY jobs:eval( file:read-text(static-baselist-uridetails()), map { }, map { 'start': 'PT5S' })</job></presyntaxhighlight>
|}
==jobs:invokebindings==
{{Mark|Introduced with Version 910.0:}}
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:invoke|$uri as xs:string|xs:string}}<br />{{Func|jobs:invokebindings|$uri as xs:string, $bindings id as map(*)?|xs:string}}<br />{{Func|jobs:invoke|$uri as xs:string, $bindings as map(*)?, $options as map(*)?|xs:string}}<br />
|-
| '''Summary'''
|Schedules Returns the evaluation variable bindings of an existing job with the XQuery expression located at specified {{Code|$uriid}} and returns a query id. The semantics and remaining arguments are identical If no variables have been bound to [[#this job, an empty map is returned.|} ==jobs:evalfinished== {|jobs:eval]].width='100%'
|-
| width='120' | '''ErrorsSignatures'''|{{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|$idas xs:string|#Errors}} The specified id is invalid or has already been assigned.<br/>{{Error|options|#Errorsxs:boolean}} The specified options are conflicting.
|-
| '''ExamplesSummary'''| Run XQuery expression that may perform some cleanups:Indicates if the evaluation of an already running job with the specified {{Code|$id}} has finished. As the ids of finished jobs will usually be discarded, unless caching is enabled, the function will also return <code>true<pre class='brush:xquery'/code>for unknown jobs:invoke("cleanup.xq"* <code>false</code> indicates that the job id is scheduled, ()queued, ())or currently running.* <code>true</precode>will be returned if the job has either finished, or if the id is unknown (because the ids of all finished jobs will not be cached).
|}
==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 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.
|}
| The current job cannot be addressed.
|-
|{{Code|unknownservice}}| The supplied query id is unknown Registered services cannot be parsed, added or not available anymoreremoved.
|}
=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}}, [[#jobs:invokeServices|jobs:invokeServices]]
;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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