Converting JSON to XML in the OSB when consuming a REST service.

In my previous post I showed you how you could consume the Google Geo service using the OSB. In that example we used XML as the return format. It was also possible to return JSON. JSON stands for JavaScript Object Notation and is smaller then XML and faster en easier to parse. The JSON text format is syntactically identical to the code for creating JavaScript objects. That is why it is used more often now by frontend frameworks such as Apache Isis for example.

In this post I will show you how you can parse the JSON returned from Google using the OSB. To convert XML to JSON and JSON to XML, you can create a helper class in Java which can do this for you. Make the convenience methods public and static so you can use them in a Java Callout in the OSB. My class looks like this:

package nl.redrock.common;

import net.sf.json.JSON;
import net.sf.json.JSONObject;
import net.sf.json.JSONSerializer;
import net.sf.json.xml.XMLSerializer;

/**
 * This class hold a couple of static methods which can be used to convert xml to json and json into xml.
 * @author Hugo Hendriks
 *
 */
public class XMLJSONConverter {

	/**
	 * Converts a Json String to a XML string
	 * @param aRootName the name of the root element in the xml
	 * @param aJson the json string
	 * @return null or a string which holds the xml representation of the json string
	 * @throws Exception
	 */
	public static String convertJSON2XML(String aRootName, String aJson) throws Exception {
		String result = null;

        XMLSerializer xmlSerializer = new XMLSerializer();
        xmlSerializer.setRootName(aRootName);
        JSON json = JSONSerializer.toJSON( aJson );
        result = xmlSerializer.write( json );
        return result;
	}

	/**
	 * Convert a XML string to a json string
	 * @param aXml the XML string
	 * @return null or a string which holds the json representation of the xml string
	 * @throws Exception
	 */
	public static String convertXML2JSON(String aXml) throws Exception {
		String result = null;

		XMLSerializer xmlSerializer = new XMLSerializer();
		xmlSerializer.setTypeHintsEnabled(false);
		JSONObject json = (JSONObject) xmlSerializer.read(aXml);
		result = json.toString();
        return result;
	}

}

I use maven as my build tool and my pom file looks like this:

	4.0.0
	nl.redrock.common
	XmlJsonConverter
	1.0
	XmlJsonConverter
	This library can be used to convert XML into JSON and back again

	
		
			net.sf.json-lib
			json-lib
			2.4
			jar
			jdk15
			compile
		
		
			org.apache.commons
			commons-io
			1.3.2
			jar
			test
		
		
			xom
			xom
			1.2.5
		
		
			junit
			junit
			4.10
			jar
			test
		
	

	
		
			
				org.apache.maven.plugins
				maven-dependency-plugin
				2.5.1
				
					
						copy-dependencies
						package
						
							copy-dependencies
						
						
							${project.build.directory}/libs
							true
							true
							true
						
					
				
			
		
	

You can see I am using the Maven dependency plugin to create a directory which holds all the dependencies jars. This is done because I need a few of these libraries on the weblogic server. In the MY_DOMAIN/lib directory to be precise.

This is the case for:

• json-lib-2.4-jdk15.jar
• ezmorph-1.0.6.jar
• xom-1.2.5.jar

You can get these from the libs directory created by maven when you run the mvn -clean -package target. The other libraries are already available in Weblogic.

After this, you can add your XMLJSONConverter library to your project.

Then you can make a java callout in which you can convert the received json into a xml string.

After that, you can parse the string to real xml by making use of the fn-bea:inlinedXML() function.

So now you know how you can convert JSON to XML and vice versa.

Example was made in 11G PS4