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Content is work in progress! |
Apart from using the default message builders and formatters that are shipped with WSO2 ESB, you have the flexibility to use your own custom message builder and formatter.
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Let's look at how to create a custom builder using an example a sample scenario where you need to Base64 encode an XML entry field. In this sample, you retrieve the text content from the payload and then Base64 encode the text. This is then converted to SOAP and the content is then processed in the ESB mediation flow.
You will first need to write a class
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implementing
org.apache.axis2.builder.Builder
interface in the Axis2 Kernel module
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and then override the
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processDocument
method.
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Within the
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processDocument
method, you can define your specific logic to process the payload content as required and
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then convert it to
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SOAP format.
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Code Block
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language xml package org.test.builder; import org.apache.axiom.om.OMAbstractFactory; import org.apache.axiom.om.OMElement; import org.apache.axiom.om.impl.OMNodeEx; import org.apache.axiom.om.impl.builder.StAXBuilder; import org.apache.axiom.om.impl.builder.StAXOMBuilder; import org.apache.axiom.om.util.StAXParserConfiguration; import org.apache.axiom.om.util.StAXUtils; import org.apache.axiom.soap.SOAPBody; import org.apache.axiom.soap.SOAPEnvelope; import org.apache.axiom.soap.SOAPFactory; import org.apache.axis2.AxisFault; import org.apache.axis2.Constants; import org.apache.axis2.builder.Builder; import org.apache.axis2.context.MessageContext; import org.apache.commons.codec.binary.Base64; import javax.xml.stream.XMLStreamException; import java.io.IOException; import java.io.InputStream; import java.io.PushbackInputStream; public class CustomBuilderForTextXml implements Builder{ public OMElement processDocument(InputStream inputStream, String s, MessageContext messageContext) throws AxisFault { SOAPFactory soapFactory = OMAbstractFactory.getSOAP11Factory(); SOAPEnvelope soapEnvelope = soapFactory.getDefaultEnvelope(); PushbackInputStream pushbackInputStream = new PushbackInputStream(inputStream); try { int byteVal = pushbackInputStream.read(); if (byteVal != -1) { pushbackInputStream.unread(byteVal); javax.xml.stream.XMLStreamReader xmlReader = StAXUtils.createXMLStreamReader(StAXParserConfiguration.SOAP, pushbackInputStream, (String) messageContext.getProperty(Constants.Configuration.CHARACTER_SET_ENCODING)); StAXBuilder builder = new StAXOMBuilder(xmlReader); OMNodeEx documentElement = (OMNodeEx) builder.getDocumentElement(); documentElement.setParent(null); String elementVal = ((OMElement) documentElement).getText(); byte[] bytesEncoded = Base64.encodeBase64(elementVal.getBytes()); ((OMElement) documentElement).setText(new String(bytesEncoded )); SOAPBody body = soapEnvelope.getBody(); body.addChild(documentElement); } } catch (IOException e) { e.printStackTrace(); } catch (XMLStreamException e) { e.printStackTrace(); } return soapEnvelope; } }
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- Create a JAR file of this class and add it into the classpath of the Axis2 installation i.e.
<ESB_HOME>/repository/components/lib
folder. - To enable you custom builder for content type text/xml, add the following line in the
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- Message Buillders section in
<ESB_HOME/repository/conf/axis2/axis2.xml>
file:
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<messageBuilder contentType="text/xml" class="org.apache.axis2.transport.http.CustomBuilderForTextXml"/> |
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When creating a custom Message Formatter, you will need to create a class implementing org.apache.axis2.transport.MessageFormatter
Interface and then override the writeTo
method. Similar to the Builder, you can implement your logic within the writeTo
method.
Ensure to add the following line in Message Formatters section in <ESB_HOME/repository/conf/axis2/axis2.xml>
file:
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<messageFormatter contentType= "text/xml" class= "org.apache.axis2.transport.http.SOAPMessageFormatter" /> |
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The class name used in the above line should be the name used for the class when writing the formatter. |