Execute a Talend job into Petals and passing it a context as a parameter described in the service's WSDL interface..
The job is exposed as a service into Petals. When this service is called, the parameter is passed to the job, which is then executed.
{tip}
Unlike the native way of passing options, exporting a context as a parameter is one of the recommended ways to pass information to a job from Petals ESB.
{tip}
The input message provides the value of of the context which is exposed as a parameter in the service's interface.
Only the job's result is expected in the response.
h1. Creating and exporting the job
The job to be executed performs the following actions:
# The job is passed the value of the context variable.
# The job connects to a database.
# It retrieves the content of a table.
# It serializes part of the extracted data as a CSV file on the disk.
This job has one context variable, which indicates the location of the CSV file.
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{info}
In the scope of this use case, it is assumed there is a database *formationtalend* on the localhost, having a table named *customers*.
The schema of the *customers* table includes two columns named *CustomerName* and *CustomerAddress*, both being of type varchar(255).
{info}
h2. Creating the job
The job export is detailled in the use case "A Simple Talend Job".
There is no difference.
h2. Exporting the job
Select the job and right-click it. Select *Export to Petals ESB*.
Update the target destination.
Let the job be exposed as a singleton.
Click *Edit the exposed contexts*.
A dialog shows up. Export the _outputLocation_ context as a *Parameter*.
You should have the following dialog:
!SimpleJobExportContext1.jpg!
Click the *Export mode* column, and select *Parameter* in the combo box. Click *OK*.
The link label should be updated and indicate the number of exported contexts.
!SimpleJobExportContext2.jpg!
Click *Finish*.
h1. Deploying and testing in Petals
h2. Looking at the generated WSDL
In the created Petals service assembly, the most interesting thing to look at is the WSDL.
Indeed, the WSDL will determine the way the exported service will be called.
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The input message's description expects a value for the exported context.
{code:lang=xml}
<xs:element name="executeJob" type="tns:executeJob" />
<xs:complexType name="executeJob">
<xs:sequence>
<xs:element minOccurs="0" name="contexts" type="tns:talendContexts" />
<xs:element minOccurs="0" name="in-attachments" type="tns:inAttachments" />
<xs:element maxOccurs="unbounded" minOccurs="0" name="in-data-bean" type="tns:inRow" />
<xs:element maxOccurs="unbounded" minOccurs="0" name="talend-option" type="xs:string" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="talendContexts">
<xs:sequence>
<xs:element name="outputLocation" type="xs:string" minOccurs="0"
default="C:/Documents and Settings/vzurczak/Bureau/output.csv" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="inAttachments">
<xs:sequence>
</xs:sequence>
</xs:complexType>
<xs:complexType name="inRow">
<xs:sequence>
</xs:sequence>
</xs:complexType>
{code}
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As you can see, the context name, type and default value have been exported in the generated WSDL.
In any case, the default value is more useful to document the service than for the execution.
{note}
Obviously, the file path example to illustrate a context may not be the best one (for portability reasons).
Anyway, it serves its purpose, which is being an example of interactions between Petals ESB and a Talend job.
{note}
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And the output message only includes the job's result.
{code:lang=xml}
<xs:element name="executeJobResponse" type="tns:executeJobResponse" />
<xs:complexType name="executeJobResponse">
<xs:sequence>
<xs:element minOccurs="0" name="talend-job-output" type="tns:talendJobOutput" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="talendJobOutput">
<xs:sequence>
<xs:element maxOccurs="unbounded" minOccurs="0" name="executionResult" nillable="true" type="ns1:stringArray" />
<xs:element minOccurs="0" name="outAttachment" type="tns:outAttachments" />
<xs:element maxOccurs="unbounded" minOccurs="0" name="outDataBean" nillable="true" type="tns:outRow" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="outAttachments">
<xs:sequence>
</xs:sequence>
</xs:complexType>
<xs:complexType name="outRow">
<xs:sequence>
</xs:sequence>
</xs:complexType>
{code}
h2. Deploying and testing this new service
To test this service, you can use a tool like SoapUI.
This way, you can see what the XML messages look like.
The first thing to do is to create a service-unit for the Petals-BC-SOAP component, that exposes (consumes) our _Talend job as a service_ outside the bus.
This step is not described here. You can take a look at the Petals-BC-SOAP documentation and the Petals Studio documentation.
Just make sure the SOAP configuration uses the InOut MEP.
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Now, your input message (in SoapUI) should look like this:
{code:lang=xml}
<soapenv:Envelope
xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:tal="http://petals.ow2.org/talend/">
<soapenv:Header/>
<soapenv:Body>
<tal:executeJob>
<!--Optional:-->
<tal:contexts>
<!--Optional:-->
<tal:outputLocation>C:/Documents and Settings/vzurczak/Bureau/output.csv</tal:outputLocation>
</tal:contexts>
<!--Optional:-->
<tal:in-attachments/>
<!--Zero or more repetitions:-->
<tal:in-data-bean/>
<!--Zero or more repetitions:-->
<tal:talend-option>?</tal:talend-option>
</tal:executeJob>
</soapenv:Body>
</soapenv:Envelope>
{code}
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By default, SoapUI (as well as any generated Java client) puts the default value as the initial value.
However, the interest is that it can be changed.
{tip}
Exposing a context as a parameter allows anyone to specify a context value.
While using the native Talend parameters requires the user to know both how jobs work and how this job was designed.
{tip}
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The returned message, when everything works, is:
{code:lang=xml}
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
<soapenv:Body>
<tns:executeJobResponse
xmlns:tns="http://petals.ow2.org/talend/"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<tns:talend-job-output>
<tns:executionResult>
<jaxb:item xmlns:jaxb="http://jaxb.dev.java.net/array">0</jaxb:item>
</tns:executionResult>
<tns:outAttachment/>
</tns:talend-job-output>
</tns:executeJobResponse>
</soapenv:Body>
</soapenv:Envelope>
{code}
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If the job execution fails, the 0 is replaced by another integer, e.g. 1.
One failure reason can be, as an example, that the database is not started.
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Another way to check the job's successful completion, is to check the existence of the output file.
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