Empty string returned when fetching properties stored in WSO2 ESB?

Once I encountered this scenario where I have set of properties stored in registry and I wanted to fetch them in my ESB mediation sequence.

I had set of properties stored in /_system/config/myConfig. So I used get-property function as follows in my mediation sequence to read the value of stored properties,

get-property('registry','conf:/myConfig@myProperty1')

Problem

The problem was, get-property function was keep returning empty value.

Then I debugged org.apache.synapse.GetPropertyFunction.java to find out the issue and it turned out that registry stored in the synapse context was null.

Fix

The reason for the registry to be not loaded into the context was, I have missed following in my synapse definition,

<registry provider="org.wso2.carbon.mediation.registry.WSO2Registry">

<parameter name="cachableDuration">15000</parameter>

</registry>

When browsed to the soruce view of WSO2 ESB, I noticed that above entry is not present in the configuration and I prevents registry being loaded into the synapse context. After adding the above to the synapse definition everything started working as expected.

Avoiding "Provider net.sf.saxon.TransformerFactoryImpl not found" error in Axis2

Scenario

When I'm trying to access the WSDL's of  web services deployed in a Axis2 SOAP engine the following error is occurring,

javax.xml.transform.TransformerFactoryConfigurationError: Provider net.sf.saxon.TransformerFactoryImpl not found
    at javax.xml.transform.TransformerFactory.newInstance(Unknown Source)
    at org.apache.ws.commons.schema.XmlSchema.serialize_internal(XmlSchema.java:505)
    at org.apache.ws.commons.schema.XmlSchema.write(XmlSchema.java:478)
    at org.apache.axis2.description.AxisService2WSDL11.generateOM(AxisService2WSDL11.java:215)
    at org.apache.axis2.dataretrieval.WSDLDataLocator.outputInlineForm(WSDLDataLocator.java:131)
    at org.apache.axis2.dataretrieval.WSDLDataLocator.getData(WSDLDataLocator.java:73)
    at org.apache.axis2.dataretrieval.AxisDataLocatorImpl.getData(AxisDataLocatorImpl.java:81)
    at org.apache.axis2.description.AxisService.getData(AxisService.java:2980)
    at org.apache.axis2.description.AxisService.getWSDL(AxisService.java:1653)
    at org.apache.axis2.description.AxisService.printWSDL(AxisService.java:1421)
    at org.wso2.carbon.core.transports.util.Wsdl11Processor$1.printWSDL(Wsdl11Processor.java:43)
    at org.wso2.carbon.core.transports.util.AbstractWsdlProcessor.printWSDL(AbstractWsdlProcessor.java:86)
    at org.wso2.carbon.core.transports.util.Wsdl11Processor.process(Wsdl11Processor.java:57)
    at org.wso2.carbon.transport.nhttp.api.NHttpGetProcessor.processWithGetProcessor(NHttpGetProcessor.java:137)
    at org.wso2.carbon.transport.nhttp.api.NHttpGetProcessor.process(NHttpGetProcessor.java:277)
    at org.apache.synapse.transport.nhttp.ServerWorker.run(ServerWorker.java:256)
    at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:173)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
    at java.lang.Thread.run(Thread.java:662)
[2014-05-19 17:56:10,980] ERROR - DefaultHttpGetProcessor Error processing request
org.apache.axis2.dataretrieval.DataRetrievalException: Provider net.sf.saxon.TransformerFactoryImpl not found
    at org.apache.axis2.dataretrieval.AxisDataLocatorImpl.getData(AxisDataLocatorImpl.java:85)
    at org.apache.axis2.description.AxisService.getData(AxisService.java:2980)
    at org.apache.axis2.description.AxisService.getWSDL(AxisService.java:1653)
    at org.apache.axis2.description.AxisService.printWSDL(AxisService.java:1421)
    at org.wso2.carbon.core.transports.util.Wsdl11Processor$1.printWSDL(Wsdl11Processor.java:43)
    at org.wso2.carbon.core.transports.util.AbstractWsdlProcessor.printWSDL(AbstractWsdlProcessor.java:86)
    at org.wso2.carbon.core.transports.util.Wsdl11Processor.process(Wsdl11Processor.java:57)
    at org.wso2.carbon.transport.nhttp.api.NHttpGetProcessor.processWithGetProcessor(NHttpGetProcessor.java:137)
    at org.wso2.carbon.transport.nhttp.api.NHttpGetProcessor.process(NHttpGetProcessor.java:277)
    at org.apache.synapse.transport.nhttp.ServerWorker.run(ServerWorker.java:256)
    at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:173)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
    at java.lang.Thread.run(Thread.java:662)
Caused by: javax.xml.transform.TransformerFactoryConfigurationError: Provider net.sf.saxon.TransformerFactoryImpl not found
    at javax.xml.transform.TransformerFactory.newInstance(Unknown Source)
    at org.apache.ws.commons.schema.XmlSchema.serialize_internal(XmlSchema.java:505)
    at org.apache.ws.commons.schema.XmlSchema.write(XmlSchema.java:478)
    at org.apache.axis2.description.AxisService2WSDL11.generateOM(AxisService2WSDL11.java:215)
    at org.apache.axis2.dataretrieval.WSDLDataLocator.outputInlineForm(WSDLDataLocator.java:131)
    at org.apache.axis2.dataretrieval.WSDLDataLocator.getData(WSDLDataLocator.java:73)
    at org.apache.axis2.dataretrieval.AxisDataLocatorImpl.getData(AxisDataLocatorImpl.java:81)
    ... 13 more

Reason

In one of the web service deployed in my server, it has used Saxon XML transformer implementation instead of default java XML transformer implementation.  Therefore, in it's code it has added the following static initialization block

1 2 3

static{ System.setProperty("javax.xml.transform."net.sf.saxon.TransformerFactoryImpl"); }

The setting of this system property is the reason for this error.  Also some can set this system property from command line using -Djavax.xml.transform.TransformerFactory=cnet.sf.saxon.TransformerFactoryImpl

Workaround

Remove the above static initialization block which sets the javax.xml.transfrom system property. Then, when instantiating TransfromFactory in the code, explicitly instantiate the saxon trasform factory with the full qualified class name as follows,

1	TransformerFactory fact = new net.sf.saxon.TransformerFactoryImpl()

In this way still you can use the  Saxon transform implementaion without casuing any complications. When the system property is set, all the instantiations of transform factories which not uses  the full qualified name of the transform factory class will be initialized with net.sf.saxon.TransfromerFactoryImpl and then it might lead to errors if they assume the default java xml transform implementation.

After recompiling and deployed the service the exception was not thrown