Changes

{{Announce|Updated with Version 10:}} Renamed from ''Jobs Module'' to ''Job Module''. The namespace URI has been updated as well. This [[Module Library|XQuery Module]] provides functions for organizing scheduled, queued, running and cached jobs. Jobs can be commands, queries, client , or HTTP requests.

All functions in this module are assigned to the <code><nowiki>http://basex.org/modules/jobsjob</nowiki></code> namespace, which is statically bound to the {{Code|jobsjob}} prefix. Errors will be bound to the same prefix.

Jobs A job can additionally be registered as persistent services. An additional ''service'' by supplying the {{Code|service}} option has been added to the options list of {{Function|Jobs|jobsjob:eval}} and {{Function|Jobs|jobs:invoke}}:

<pre classsyntaxhighlight lang="brush:xquery">(: register job, which as service; will be run every day at 1 am :)jobsjob:eval('db:drop("tmp")', (), map { 'id':'cleanup', 'start':'01:00:00', 'interval':'P1D', 'service': true() }),

jobsjob:services(),

jobsjob:stopremove('cleanup', map { 'service': true() })</presyntaxhighlight>

* All registered jobs job services will be scheduled for evaluation when the BaseX server or BaseX HTTP server is started.

=Basic FunctionsExecuting 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 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.

==jobsjob:currenteval==

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|{{Func|jobsjob:currenteval|$query as xs:anyAtomicType|xs:string}}<br />{{Func|job:eval|$query as xs:anyAtomicType, $bindings as map(*)?|xs:string}}<br />{{Func|job:eval|$query as xs:anyAtomicType, $bindings as map(*)?, $options as map(*)?|xs:string}}<br />|-valign="top"

|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 {{Function|XQuery|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}}):** The result will be cached in main-memory until it is fetched via {{Function||job: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 of 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 of 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 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.|- valign="top"| '''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.|- valign="top"| '''Examples'''|* Cache query result. The returned ID can be used to pick up the result with {{Function||job:result}}:<syntaxhighlight lang="xquery">job:eval("1+3", (), map { 'cache': true() })</syntaxhighlight>* A happy birthday mail will be sent at the current given date:<syntaxhighlight lang="xquery">job: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($query) { job:eval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' })};declare %rest:path('/stop-scheduling/{$id}') function local:stop($id) { job:remove($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">job:eval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' })</syntaxhighlight>* The query in the specified file will be evaluated once:<syntaxhighlight lang="xquery">job:eval(xs:anyURI('cleanup.xq'))</syntaxhighlight>* The following expression, if stored in a file, will be evaluated every 5 seconds:<syntaxhighlight lang="xquery">job:eval( static-base-uri(), map { }, map { 'start': 'PT5S' })</syntaxhighlight>

==jobsjob:listresult== {{Announce|Version 10:}} options argument added.

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|{{Func|jobsjob:listresult|$id as xs:string|item()*}}<br/>{{Func|job:result|$id as xs:string, $options as map(*)|item()*}}|-valign="top"

|Returns the ids cached result of all jobs that are currently registereda job with the specified job {{Code|$id}}:* If the original job has raised an error, the cached error will be raised instead. * The list includes scheduledcached result or error will be dropped after it has been retrieved.* If the result has not been cached or if it has been dropped, queued, running, stopped, and finished jobs with an empty sequence is returned.The following {{Code|$options}} can be supplied:* {{Code|keep}}: Keep the cached resultsresult or error after retrieval. |-valign="top"

| * The following [[RESTXQ]] function will either return the result of a previously started job or raise an error:<codesyntaxhighlight lang="xquery">jobsdeclare %rest:path('/result/{$id}') function local:listresult($id){ job:result($id)};</codesyntaxhighlight> returns * 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):<syntaxhighlight lang="xquery">let $query := job id as :eval('(1 to 10000000)[. = 1]', map { }, map { 'cache': true() })return ( job:wait($query), job:result($query))</syntaxhighlight>Queries of this kind can cause deadlocks! If the original query and the new query perform updates on the same database, the second query will only be run after the first one has been executed, and the first query will wait for the second query forever. You should resort to {{Function|JobsXQuery|jobsxquery:currentfork-join}} if no other job is registeredyou want to have full control on parallel query execution.

==jobsjob:list-detailsremove==

{{MarkAnnounce|Updated with Version 9.110:}} Renamed from {{Code|jobs:stop}} registration time added.

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|{{Func|jobsjob:list-detailsremove|$id as xs:string|elementempty-sequence(job)*}}<br/>{{Func|jobsjob:list-detailsremove|$id as xs:string, $options as map(*)?|elementempty-sequence(job)*}}|-valign="top"

|Returns information on all jobs that are currently registered, or on Triggers the cancelation of a job with the specified {{Code|$id}} (, cancels a scheduled job or an empty sequence if this job is not found)removes a cached result. Unknown IDs are ignored. The list includes scheduled, queued, running All jobs, and cached jobs. A string representation of are gracefully stopped; it is up to the job, or its URI, will be returned as valueprocess to decide when it is safe to shut down. The returned elements have additional attributesfollowing {{Code|$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: <code>scheduled</code>, <code>queued</code>, <code>running</code>, <code>cached</code>* <code>user</code>: user who started the job* <code>duration</code>: evaluation time (included if a job is running or if the result 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|-valign="top"

| * <code>jobsjob:list-details()[. != job:current()] ! job:remove(.)</code> returns information on stops and discards all jobs except for the currently running job and possibly others:current one.* <pre class="brushcode>job:xml"><remove(job id="job1" type="XQuery" state="running" user="admin" duration="PT0.001S"> XQUERY jobs:list-detailscurrent())</code> interrupts the current job></pre>.

==jobsjob:finishedwait==

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|{{Func|jobsjob:finishedwait|$id as xs:string|xs:booleanempty-sequence()}}|-valign="top"

|Indicates if Waits for the evaluation completion of an already running a job with the specified {{Code|$id}} has finished. As :* The function will terminate immediately if the ids of finished jobs will usually be discarded, unless caching job ID is enabled, the function will also return <code>true</code> for unknown jobs.* <code>false</code> indicates that This is the case if a future job id is scheduled, has not been queuedyet, or currently runningif the ID has already been discarded after job evaluation.* <code>true</code> will be returned if If the function is called with the ID of a queued job has either finished, or if the id repeatedly executed job, it may stall and never terminate.|- valign="top"| '''Errors'''|{{Error|self|#Errors}} The current job is unknown (because the ids of all finished jobs will not be cached)addressed.<br/>

=Listing Jobs=jobs ==job:servicescurrent==

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|{{Func|jobsjob:servicescurrent||element(job)*xs:string}}|-valign="top"

|Returns a list the ID of all jobs that have been persistently registered as [[#Services|Services]]the current job.|-| '''Errors'''|{{Error|services|#Errors}} Registered services cannot be parsed.<br/>

=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. ==jobsjob:evallist==

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|{{Func|jobsjob: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 />|-valign="top"

|Schedules Returns the evaluation IDs of the supplied {{Code|$query}} and returns a query idall jobs that are currently registered. The query will be queued, and the result will optionally be cached. Queries can be updating. Variables and context items can be declared via {{Code|$bindings}} (see [[XQuery Module#xquery:eval|xquery:eval]] for more details). The following {{Code|$options}} 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]]list includes scheduled, 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>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.** 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.* {{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 finished jobs with the same name exists.* {{Code|service}}: additionally registers the job as [[#Services|service]].|-| '''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 conflictingcached results.|-valign="top"

|* Cache query result. The returned id can be used to pick up the result with [[#jobs:result|jobs:result]]:<pre class='brush:xquery'code>jobsjob:eval("1+3", list(), map { 'cache': true() })</precode>* A happy birthday mail will be sent at returns the given date:<pre class="brush:xquery">jobs:eval("import module namespace mail='mail'; mail:send('Happy birthday!')", (), map same job ID as { '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 class='brush:xquery'>declare %rest:POST("{$query}") %rest:path('/start-scheduling') function local:start($query) { jobs:eval($query, (), map { 'start': '02Function||job:00:00', 'interval': 'P1D' current})};declare %rest:path('/stop-scheduling/{$id}') function local:stop($id) { jobs:stop($id)};</pre>* Query execution if no other job is scheduled for every second, and for 10 seconds in total. As the query itself will take 1registered.5 seconds, it will only be executed every second time:<pre class="brush:xquery">jobs:eval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' })</pre>* The following expression, if stored as a file, calls and evaluates itself every 5 seconds:<pre class="brush:xquery">jobs:eval( file:read-text(static-base-uri()), map { }, map { 'start': 'PT5S' })</pre>

==jobsjob:invokelist-details==

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|{{Func|jobsjob:invoke|$uri as xs:string|xs:string}}<br />{{Funclist-details|jobs:invoke|$uri as xs:string, $bindings as mapelement(job)*)?|xs:string}}<br />{{Func|jobsjob:invokelist-details|$uri id as xs:string, $bindings as map|element(*job)?, $options as map(*)?|xs:string}}<br />|-valign="top"

|Schedules Returns information on all jobs that are currently registered, or on a job with the evaluation of the XQuery expression located at specified {{Code|$uriid}} (or an empty sequence if this job is not found). The list includes scheduled, queued, running jobs, and returns cached jobs. A string representation of the job, or its URI, will be returned as a query value. The returned elements have additional attributes:* <code>id. For further details, see [[#jobs</code>:eval|jobsjob ID* <code>type</code>:eval]]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>, <code>cached</code>| '''Errors'''* <code>user</code>: user who started the job|{{Error|overflow|#Errors}} Query execution * <code>duration</code>: evaluation time (included if a job is rejected, because too many jobs are queued running or being executed. {{Option|CACHETIMEOUT}} can be decreased if the default setting is too restrictive.result was cached)* <code>start<br/code>{{Error|range|#Errors}} A specified time or duration is out : next start of range.job (included if a job will be executed repeatedly)* <br/code>{{Error|id|#Errors}} The specified id is invalid or has already been assigned.time<br/code>{{Error|options|#Errors}} The specified options are conflicting.: time when job was registered|-valign="top"

| Run XQuery expression that may perform some cleanups<code>job:list-details()</code> returns information on the currently running job and possibly others:<pre classsyntaxhighlight lang='brush:xquery'"xml">jobs:invoke(<job id="job1" type="XQuery" state="running" user="admin" duration="cleanupPT0.xq001S", > XQUERY job:list-details(), ())</prejob></syntaxhighlight>

==jobsjob:resultbindings== {{Announce|Introduced with Version 10.}}

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|{{Func|jobsjob:resultbindings|$id as xs:string|itemmap(*)*}}|-valign="top"

|Returns the cached result variable bindings of a an existing job with the specified job {{Code|$id}}:* Results can only be retrieved once. After retrieval, the cached result will be dropped.* If the original no variables have been bound to this job has raised an error, the cached error will be raised instead.|-| '''Errors'''|{{Error|running|#Errors}} the job is still running.<br/>{{Error|unknown|#Errors}} the supplied id is unknown: The id is unknown, or the result has already been retrieved.<br/>|-| '''Examples'''|* The following [[RESTXQ]] function will either return the result of a previously started job or raise an error:<pre class='brush:xquery'>declare %rest:path('/result/{$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 $query := jobs:eval('(1 to 10000000)[. = 1]', map{}, empty map{ 'cache': true() })return ( jobs:wait($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 parallelreturned.

==jobsjob:stopfinished==

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|{{Func|jobsjob:stopfinished|$id as xs:string|empty-sequence()xs:boolean}}|-valign="top"

|Triggers Indicates if the cancelation evaluation of a an already running job with the specified {{Code|$id}}, drops has finished. As the cached result IDs of a queryfinished jobs will usually be discarded, or cancels a scheduled job. Unknown ids are ignored. All jobs are gracefully stopped; it unless caching is up to enabled, the process to decide when it is safe to shut downfunction will also return <code>true</code> for unknown jobs. The following {{Code|$options}} can be supplied:* {{Code|service}}: additionally removes <code>false</code> indicates that the job from the [[#Services|job services]] listID is scheduled, queued, or currently running.|-| '''Examples'''| * <code>jobs:list()[. != jobs:current()] ! jobs:stop(.)true</code> stops and discards will be returned if the job has either finished, or if the ID is unknown (because the IDs of all finished jobs except for the current onewill not be cached).

==jobsjob:waitservices==

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|{{Func|jobsjob:waitservices|$id as xs:string|empty-sequenceelement(job)*}}|-valign="top"

|Waits for the completion Returns a list of a job with the specified {{Codeall jobs that have been persistently registered as [[#Services|$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]].|-valign="top"

|{{Error|selfservices|#Errors}} The current job is addressedRegistered services cannot be parsed.<br/>

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| The specified id ID is invalid or has already been assigned.|-valign="top"

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 * Updated: {{Function|Jobs|jobsjob:list-details}}: registration time added.

 * Added: {{Function|Jobs|jobsjob:invoke}}, [[#Services|Services]]

 * Updated: [[#jobs:eval{{Function||jobsjob:eval]]}}: <code>id</code> option added.