Mobile Web Server Exercise CoAP Server and Client # In this exercise, you will create a CoAP server, also your will implement a simple CoAP client within the same application to test your CoAP server. In real world, client and server should be on different application or different machine. # Since the server and the client will be implemented on the same application, there should be no issue in communication. # You will be doing this by using WS4D's open source jCoAP library (http://ws4d.org/ws4d- jcoap/). # Download the source code of WS4D's CoAP library from http://kodu.ut.ee/~chang/org.zip # Extract the zip file to get 'org' folder, which contains all the source code you need to create CoAP server and client on Android. PART 1 – CoAP Server # Create a new Android Project. # Add permissions in your AndroidManifest.xml <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="e.c.coaptry01"> <!-- START OF ADDED PERMISSION --> <uses-permission android:name="android.permission.INTERNET"/> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/> <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/> <!-- END --> ... ... ... </manifest> # Copy 'org' folder you downloaded before to your project directory under src/main/java/ # Now in your src/java/, you should have: # a folder with your package name and a folder called org # and from the Android Studio view, you should see org.ws4d.coap appeared inside java directory. If you don't see it, try to refresh the list. # Create a CoAP resource in your MainActivity class //CoAP attributes private CoapResourceServer resourceServer; private BasicCoapResource bcs; # Add following content to onCreate method // CoAP resource server remove if(this.resourceServer != null){this.resourceServer.stop();} // CoAP resource server new init this.resourceServer = new CoapResourceServer(); // CoAP add resource bcs = new BasicCoapResource("/maha", "82", CoapMediaType.text_plain); this.resourceServer.createResource(bcs); bcs.registerServerListener(this.resourceServer); // CoAP Server start try { Log.v("*******", "Starting server..."); this.resourceServer.start(5683); } catch (Exception e) { e.printStackTrace(); } PART 2 – CoAP Client # Create a new Java class called TestClient within the same directory of your MainActivity class. # Import following classes: import android.util.Log; import org.ws4d.coap.core.CoapClient; import org.ws4d.coap.core.connection.BasicCoapChannelManager; import org.ws4d.coap.core.connection.api.CoapChannelManager; import org.ws4d.coap.core.connection.api.CoapClientChannel; import org.ws4d.coap.core.enumerations.CoapRequestCode; import org.ws4d.coap.core.messages.api.CoapRequest; import org.ws4d.coap.core.messages.api.CoapResponse; import org.ws4d.coap.core.tools.Encoder; import java.net.InetAddress; import java.net.UnknownHostException; # make CoapClient as your interface, e.g. public class TestClient implements CoapClient { # Copy the following content to your client class: private static final boolean exitAfterResponse = false; public void start(String serverAddress, int serverPort) { System.out.println("===START=== (Run Test Client)"); String sAddress = serverAddress; int sPort = serverPort; CoapChannelManager channelManager = BasicCoapChannelManager.getInstance(); CoapClientChannel clientChannel = null; try { clientChannel = channelManager.connect(this, InetAddress.getByName(sAddress), sPort); } catch (UnknownHostException e) { e.printStackTrace(); System.exit(-1); } CoapRequest request; if (null == clientChannel) { return; } request = clientChannel.createRequest(CoapRequestCode.GET, "/maha", true); clientChannel.sendMessage(request); } @Override public void onResponse(CoapClientChannel channel, CoapResponse response) { if (response.getPayload() != null) { Log.v("*******", "Response: " + response.toString() + " payload: " + Encoder.ByteToString(response.getPayload())); } else { System.out.println("Response: " + response.toString()); } if (this.exitAfterResponse) { Log.v("*******","===END==="); System.exit(0); } } @Override public void onMCResponse(CoapClientChannel channel, CoapResponse response, InetAddress srcAddress, int srcPort) { // TODO Auto-generated method stub } @Override public void onConnectionFailed(CoapClientChannel channel, boolean notReachable, boolean resetByServer) { Log.v("*******","Connection Failed"); System.exit(-1); } # Add new content to your MainActivity class; at the end of the onCreate() method: // Test the client - change the IP address according to your device or simply use 'localhost' new Thread(new Runnable() { public void run() { TestClient ct = new TestClient(); ct.start("192.168.2.6", CoapConstants.COAP_DEFAULT_PORT); } }).start(); # Now, run the application. # Finally, from the Logcat of your Android Studio, you should see the similar message below somewhere in your logs: V/*******: Response: ACK, Content_205, MsgId: 47186, #Options: 1 ( Content_Format) payload: 82 # which contains the CoAP request and the payload of the response is '82'. # If you cannot see the log, search for '*******' Homework Modify the response payload from the CoAP server to make the server reply a different value. e.g. the GPS value from Android API. See: https://courses.cs.ut.ee/2018/MAD/fall/Main/Homework5 .