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Develop a new application that calls the REST interface.

Enable the system application.

Parent

Share data across two sessions with REST APIs

Develop a new application that calls the REST interface. To simplify building code to interact with the REST API, JAXB can be run on the schema to automatically generate classes that represent the REST request, response and other related classes.


Example

For an example, we can install the PlantsByWebSphere Ajax Edition for CEA (PlantsByWebSphereAjax) sample application. With this sample application, we can install, view, and use the CEA widgets to see how they actually work in an online application. For more information about the sample application, see the supporting documentation provided in the PlantsByWebSphere directory of the CEA samples package that we can download from the WAS Samples page. Additionally, read about setting up and using the communications enabled application samples. 

package sample.code;

import java.util.Date;
import com.ibm.ws.commsvc.servlet.jaxb.*;

public class SampleCode {

 public static final String rootUrl = "http://localhost:9080/CommServlet/";
 
 public void runSample() {
  String url = null;
  HttpRequest httpRequest = null;
  CommRestResponse callerResponse = null;
  CommRestResponse calleeResponse = null;
  CommRestRequest restRequest = null;

  try {
   // Enable collaboration for caller.
   url = rootUrl + "collaborationSession";
     httpRequest = new HttpRequest("PUT", url, null);
   callerResponse = httpRequest.send();
 
   // Start up collaboration from the callee using peer uri.
   url = rootUrl + callerResponse.getForPeerCollaborationUri();
      httpRequest = new HttpRequest("GET", url, null);
   calleeResponse = httpRequest.send();
 
   // Wait for collaboration establishment
   waitForCollaborationEstablishment(calleeResponse.getCollaborationServiceUri());
   waitForCollaborationEstablishment(callerResponse.getCollaborationServiceUri());
      
      // Send data from callee to caller    url = rootUrl + calleeResponse.getEventUri();
   restRequest = new CommRestRequest();
   restRequest.setCollaborationData("test message");
   httpRequest = new HttpRequest("POST", url, restRequest);
   calleeResponse = httpRequest.send();
 
   // Fetch data on the caller.
   calleeResponse = waitForDataEvent(callerResponse.getEventUri());
   if (calleeResponse.getEventList().getEvents().get(0).getData().equals("test message"))
    System.out.println("Successfully exchanged collaboration data.");
 
   // End collaboration from caller.
   url = rootUrl + callerResponse.getCollaborationServiceUri();
      httpRequest = new HttpRequest("DELETE", url, null);
      callerResponse = httpRequest.send();
  } catch (Exception e) {
   System.out.println("Error occurred: " + e);
  }
 }

 // Utility method which waits for a collaboration established event.
 public boolean waitForCollaborationEstablishment (String uriExtension) {
     String url = null;
  HttpRequest request = null;
  CommRestResponse response = null;
  boolean success = false;

  long startTime = System.currentTimeMillis();  
  while ((success == false) && ((System.currentTimeMillis() - startTime) < 10000)) {
   try {    
       url = rootUrl + uriExtension;
       request = new HttpRequest("GET", url, null);
       response = request.send();
    success = response.getCollaborationStatus().equals("ESTABLISHED");
       if (success == false)
        Thread.sleep(250);
   } catch (Exception e) {
    break;
   }
  }
  return success;
 }

 // Get an event without specifying anything extra in the request.
 public CommRestResponse waitForDataEvent(String eventUri) throws Exception {
  EventList eventList = null;
  Event event = null;
  boolean foundEvent = false;
  CommRestResponse restResponse = null;
  Date startDate = new Date();
  String url = rootUrl + eventUri;
  HttpRequest httpRequest = new HttpRequest("GET", url, null);

  for (int i = 0; i < 5; i++) {
   // Fetch status on the call and determine if any events came back.
   restResponse = httpRequest.send();
   eventList = restResponse.getEventList();
   if (eventList != null) {
    // Iterate the events looking for a data event.
    for (int j=0; j<eventList.getEvents().size(); j++) {
     event = eventList.getEvents().get(j);
     if (event.getType() == EventType.DATA_EVENT) {
      foundEvent = true;
      break; // Break out of inner loop of events.
     }
    }
    if (foundEvent)
     break; // Break out of outer loop waiting for events.
   }
   
   Date currentDate = new Date();
   if ((currentDate.getTime() - startDate.getTime()) > 5000)
    break;
   
   Thread.sleep(1000);
  }
  return restResponse;
 }
}

package sample.code;

import java.io.*;
import java.net.*;
import javax.xml.bind.*;
import com.ibm.ws.commsvc.servlet.jaxb.*;

public class HttpRequest {
 private String method = null;
 private URL url = null;
 private CommRestRequest restRequest = null;
 private String requestBody = "";
 public static Unmarshaller xmlResponseUnmarshaller = null;
 public static Marshaller xmlRequestMarshaller = null;
 
 // Static block to set up the XML marshaller and unmarshaller.
 static {
  try {
   JAXBContext jc = JAXBContext.newInstance((new CommRestResponse()).getClass().getPackage().getName()); 
   xmlResponseUnmarshaller = jc.createUnmarshaller();
   xmlRequestMarshaller = jc.createMarshaller();
  } catch (Exception e) {
   System.out.println("Error setting up XML marshaller or unmarshaller. " + e);
  }
 }

 // Constructor
 public HttpRequest(String inputMethod, String inputUrl, CommRestRequest inputRequest) throws Exception {
  method = inputMethod;
  url = new URL(inputUrl);
  restRequest = inputRequest;
  if (restRequest != null)
   requestBody = marshalRestRequest(restRequest);
 }
 
 // Send the request and return the response in object form.
 public CommRestResponse send() throws Exception {
  // Set up the connection.
  HttpURLConnection connection = (HttpURLConnection)url.openConnection();
  connection.setRequestMethod(method);
  connection.setUseCaches(false);
  connection.setDoInput(true);
  if (method.equals("POST") || method.equals("PUT")) {
   connection.setRequestProperty("Content-Type", "text/html");
   connection.setDoOutput(true);
   // Send the request.
   DataOutputStream out = new DataOutputStream(connection.getOutputStream()); 
   out.writeBytes(requestBody);
   out.flush(); 
   out.close(); 
  } else {
   // Must set this to false for GET (or it will default to POST) and DELETE.
   connection.setDoOutput(false);   
  }
  // Read the response.
  BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
  String response = new String();
  String line = reader.readLine(); 
  while(null != line) {
      response += line;
      line = reader.readLine(); 
  }
  reader.close();
  // Convert the string response into an object form.
  return unmarshalRestResponse(response);
 }

 // Marshal the CommRestRequest object into XML formatted text.
 public static synchronized String marshalRestRequest(CommRestRequest request) throws Exception {
  ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
  xmlRequestMarshaller.marshal(request, outputStream);
  return outputStream.toString();
 }

 // Unmarshal the XML text into a CommRestResponse object.
 private static synchronized CommRestResponse unmarshalRestResponse(String text) throws JAXBException {
  return (CommRestResponse)xmlResponseUnmarshaller.unmarshal(new ByteArrayInputStream(text.getBytes()));
 }
}


What to do next

Install and start the new application.


Subtopics


Related tasks

  • Assembling applications