JQM is able to load payloads from jar files (in case your code is actually inside a war, it is possible to simply rename the file), which gives a clear guidance as to how the code should be packaged. However, there are also other elements that JQM needs to run the code.
For example, when a client requests the payload to run, it must be able to refer to the code unambiguously, therefore JQM must know an “application name” corresponding to the code. This name, with other data, is to be put inside an XML file that will be imported by JQM - it’s a deployment descriptor, akin to a web.xml or an ejb-jar.xml. A code can only run if its XML has been imported (or the corresponding values manually entered though the web administration console, or manually written inside the database, which by the way is a fully unsupported way to do it).
Should some terms prove to be obscure, please refer to the Glossary.
4.5.1. Libraries handling¶
JQM itself is hidden from the payloads - payloads cannot see any of its internal classes and resources. So JQM itself does not provide anything to payloads in terms of libraries (with the exception of libraries explicitly added to the ext directory, see below).
But there are two ways, each with two variants, to make sure that required libraries are present at runtime.
All the four variants are exclusive. Only one library source it used at the same time.
188.8.131.52. Maven POM¶
A jar created with Maven always contains the pom.xml hidden inside META-INF. JQM will extract it, read it and download the dependencies, putting them on the payload’s class path.
It is also possible to put a pom.xml file in the same directory as the jar, in which case it will have priority over the one inside the jar.
JQM uses the Maven 3 engine internally, so the pom resolution should be exactly similar to one done with the command line. It includes using your settings.xml. There a few Parameters that can tweak that behaviour.
Conclusion: in that case, no packaging to do.
using this means the pom is fully resolvable from the engine server (repository access, etc). This includes every parent pom used.
184.108.40.206. lib directory¶
If using Maven is not an option (not the build system, no access to a Nexus/Maven central, etc), it is possible to simply put a directory named “lib” in the same directory as the jar file.
POM files are ignored if a lib directory is present. An empty lib directory is valid (allows to ignore a pom).
The lib directory may also be situated at the root of the jar file (lower priority than external lib directory).
Conclusion: in that case, libraries must be packaged.
4.5.3. Creating a JobDef¶
The full XSD is given inside the lib directory of the JQM distribution.
An XML can contain as many Job Definitions as needed. Moreover, a single jar file can contain as many payloads as needed, therefore there can be multiple job definitions with the same referenced jar file.
The general XML structure is this:
<jqm> <jar> <path>jqm-test-fibo/jqm-test-fibo.jar</path> <jobdefinitions> <jobDefinition> ... </jobDefinition> ... other job definitions ... </jobdefinitions> </jar> <jar>... as many jars as needed ...</jar> </jqm>
220.127.116.11. Jar attributes¶
|path||the path to the jar. It must be relative to the “repo” attribute of the nodes. (default is installdir/jobs)|
New in version 1.1.6: There used to be a field named “filePath” that was redundant. It is no longer used and should not be specified in new xmls. For existing files, the field is simply ignored so there is no need to modify the files.
18.104.22.168. JobDef attributes¶
All JobDefinition attributes are mandatory, yet the tag fields (keyword, module, ...) can be empty.
All attributes are case sensitive.
|name||the name that will be used everywhere else to designate the payload. (can be seen as the primary key).|
|description||a short description that can be reused inside GUIs|
|canBeRestarted||some payloads should never be almlowed to restarted after a crash|
|javaClassName||the fully qualified name of the main class of the payload (this is how JQM can launch a payload even without any jar manifest)|
|application||An open classification. Not used by the engine, only offered to ease querying and GUI creation.|
|highlander||if true, there can only be one running instance at the same time (and queued instances are consolidated)|
It is also possible to define parameters, as key/value pairs. Note that it is also possible to give parameters inside the Job Request (i.e. at runtime). If a parameter specified inside the request has the same name as one from the JobDef, the runtime value wins.
There is an optional parameter named “queue” in which it is possible ot specify the name of the queue to use for all instances created from this job definition. If not specified (the default), JQM will use the default queue.
22.214.171.124. XML example¶
Other examples are inside the jobs/xml directory of the JQM distribution.
This shows a single jar containing two payloads.
<jqm> <jar> <path>jqm-test-fibo/jqm-test-fibo.jar</path> <jobdefinitions> <jobDefinition> <name>Fibo</name> <description>Test based on the Fibonachi suite</description> <canBeRestarted>true</canBeRestarted> <javaClassName>com.enioka.jqm.tests.App</javaClassName> <application>CrmBatchs</application> <module>Consolidation</module> <keyword1>nightly</keyword1> <keyword2>buggy</keyword2> <keyword3></keyword3> <highlander>false</highlander> <parameters> <parameter> <key>p1</key> <value>1</value> </parameter> <parameter> <key>p2</key> <value>2</value> </parameter> </parameters> </jobDefinition> <jobDefinition> <name>Fibo2</name> <description>Test to check the xml implementation</description> <canBeRestarted>true</canBeRestarted> <javaClassName>com.enioka.jqm.tests.App</javaClassName> <application>ApplicationTest</application> <module>TestModule</module> <keyword1></keyword1> <keyword2></keyword2> <keyword3></keyword3> <highlander>false</highlander> <parameters> <parameter> <key>p1</key> <value>1</value> </parameter> <parameter> <key>p2</key> <value>2</value> </parameter> </parameters> </jobDefinition> </jobdefinitions> </jar> </jqm>
The XML can be imported through the command line.
java -jar jqm.jar -importjobdef /path/to/xml.file
Please note that if your JQM deployment has multiple engines, it is not necessary to import the file on each node - only once is enough (all nodes share the same configuration). However, the jar file must obviously still be present on the nodes that will run it.
Also, jmq.ps1 or jqm.sh scripts have an “allxml” option that will reimport all xml found under JQM_ROOT/jobs and subdirectories.