Writing custom queries to retrieve data from WSO2 Governance Registry

WSO2 Governance Registry is a big part of wso2 governance product stack. Even though it is primarily aimed at managing, versioning, rating, and commenting on SOA artifacts it can also be used as a simple data store. with the 3.0 version the G-Reg gave support to custom query execution from the client side. This feature helps immensely when you use the registry for non-standard tasks. For me I had to do some pagination work for the comments that belongs to a particular resource, hence my approach was to write few custom quires to get the job done. The code is as follows.

	/**
	 * Returns a chunk of comments
	 * 
	 * @param resPath	Path to the comment
	 * @param start		The beginning index
	 * @param size		Size of the chunk
	 * @return			an array of comments
	 */
 public Comment[] getCommentSet(String resPath, int start, int size) {
		Registry registry = null;
		try {
			registry = ; // get an instance of the registry 

			Resource comQuery = registry.newResource();

                        // The Sql Statement
			String sql = "SELECT REG_COMMENT_ID FROM REG_RESOURCE_COMMENT RC, REG_RESOURCE R, REG_PATH P WHERE "
					+ "RC.REG_VERSION=R.REG_VERSION AND "
					+ "R.REG_NAME=? AND "
					+ "P.REG_PATH_VALUE=? AND "
					+ "P.REG_PATH_ID=R.REG_PATH_ID LIMIT ?, ?";

			// Set SQL statement as the resource content
                        comQuery.setContent(sql);

                       // Setting the media type and properties
			comQuery.setMediaType(RegistryConstants.SQL_QUERY_MEDIA_TYPE);
			comQuery.addProperty(RegistryConstants.RESULT_TYPE_PROPERTY_NAME, RegistryConstants.COMMENTS_RESULT_TYPE);

			registry.put("system/myQueries/query", comQuery);
                 String resourceName = "testResource";
                 String pathToResource = "/system/myResources"

			Map params = new HashMap();

                        //Setting the parameters
			params.put("1", resourceName);
			params.put("2", pathToResource);
			params.put("3", start);
			params.put("4", size);

                       // Executing the SQL statement
			Collection qResults = registry.executeQuery("system/myQueries/query", params);

			String[] qPaths = (String[]) qResults.getContent();

			Comment[] comments = new Comment[qPaths.length];
                        // Loading the comment data to comment object array 
			for (int i = 0; i < qPaths.length; i++) {
				if (registry.resourceExists(qPaths[i])) {
					comments[i] = (Comment) registry.get(qPaths[i]);
				}
			}

			return comments;

		} catch (Exception e) {
			String errorMsg = "Backend server error - could not get comment set";
			log.error(new MyTestException(errorMsg, e));
			return null;
		}

	}

Yeah simple as that you get your resources set without much effort. A big thank goes to Dimuthu

Best of SOA Summer School

During this entire summer, WSO2 conducted a series of trainings on SOA best practices, How-Tos and trends, titled “SOA Summer School“. With the dawn of the autumn the series of online summer classes came to an end. With the popular demand, a 3 hour session is going to be held tomorrow the 13th August summarizing the 8 weeks of lessons and highlighting their key areas.

Untitled
for a better insight I have attached tomorrow’s agenda, and it is conducted by Samisa Abeysinghe, Ruwan Linton, Prabath Siriwardena, Keith Chapman and Nandika Jayawardena. The online trainings are totally free and any one who is interested in SOA and EA can gain a good knowledge of its dynamics.