Using Java with JDOM to write a SOAP header. Either finds and replaces or adds a SOAP header containing a session ID.

message1.xml

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:ns1="http://xml.avaya.com/ws/session"
  xmlns:ns2="http://xml.avaya.com/ws/SystemManagementService/2008/07/01">
  <SOAP-ENV:Header>
    <ns1:sessionID>47644894fd76c34ab59556df351bde6f</ns1:sessionID>
  </SOAP-ENV:Header>
  <SOAP-ENV:Body>
    <ns2:submitRequestResponse>
      <return>
        <result_code>0</result_code>
        <result_data>
          <RegisteredIPStations>
            <Station_Extension>11993</Station_Extension>
            <Station_IP_Address>172.18.137.79</Station_IP_Address>
          </RegisteredIPStations>
        </result_data>
        <message_text/>
      </return>
    </ns2:submitRequestResponse>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

message2.xml

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:ns1="http://xml.avaya.com/ws/session"
  xmlns:ns2="http://xml.avaya.com/ws/SystemManagementService/2008/07/01">
  <SOAP-ENV:Header/>
  <SOAP-ENV:Body>
    <ns2:submitRequestResponse>
      <return>
        <result_code>0</result_code>
        <result_data>
          <RegisteredIPStations>
            <Station_Extension>11993</Station_Extension>
            <Station_IP_Address>172.18.137.79</Station_IP_Address>
          </RegisteredIPStations>
        </result_data>
        <message_text/>
      </return>
    </ns2:submitRequestResponse>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

message3.xml

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:ns1="http://xml.avaya.com/ws/session"
  xmlns:ns2="http://xml.avaya.com/ws/SystemManagementService/2008/07/01">
  <SOAP-ENV:Body>
    <ns2:submitRequestResponse>
      <return>
        <result_code>0</result_code>
        <result_data>
          <RegisteredIPStations>
            <Station_Extension>11993</Station_Extension>
            <Station_IP_Address>172.18.137.79</Station_IP_Address>
          </RegisteredIPStations>
        </result_data>
        <message_text/>
      </return>
    </ns2:submitRequestResponse>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

SOAPRewriteDemo.java

package demo;

import java.io.InputStream;

import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.Namespace;
import org.jdom2.input.SAXBuilder;
import org.jdom2.output.Format;
import org.jdom2.output.XMLOutputter;


public class SOAPRewriteDemo {

  private static final String NEW_SESSION_ID = "blah-blah-blah";
  
  private static final Namespace SOAP_NS = 
      Namespace.getNamespace("http://schemas.xmlsoap.org/soap/envelope/");
  
  private static final Namespace SESSION_NS = 
      Namespace.getNamespace("http://xml.avaya.com/ws/session");

  private static final String SOAP_HEADER_ELEMENT = "Header";
  private static final String SESSION_ID_ELEMENT = "sessionID";

  public static void main(String... args) throws Exception {
    InputStream inputStream = SOAPRewriteDemo.class.getClassLoader()
        .getResourceAsStream("message1.xml");
    
    XMLOutputter outputter = new XMLOutputter(Format.getPrettyFormat());
    SAXBuilder builder = new SAXBuilder();
    Document document = builder.build(inputStream);

    System.out.println("BEFORE:");
    outputter.output(document, System.out);
    
    Element root = document.getRootElement();

    // find or create the soap header
    Element header = root.getChild(SOAP_HEADER_ELEMENT, SOAP_NS);
    if (header == null) {
      header = new Element(SOAP_HEADER_ELEMENT, SOAP_NS);
      root.addContent(0, header);
    }
    
    // find and update or create the session ID
    Element sessionId = header.getChild(SESSION_ID_ELEMENT, SESSION_NS);
    if (sessionId != null) {
      sessionId.setText(NEW_SESSION_ID);
    }
    else {
      sessionId = new Element(SESSION_ID_ELEMENT, SESSION_NS);
      sessionId.setText(NEW_SESSION_ID);
      header.addContent(sessionId);
    }

    System.out.println();
    System.out.println("AFTER:");
    outputter.output(document, System.out);
  }

}