Basic resource handling server with Californium/Java

proxy/src/netpp/Handler.java

@@ -1,42 +1,50 @@
 package netpp;
 
-import java.io.*;
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
 import java.net.URI;
 import java.util.Date;
 
-import javax.json.*;
-import org.eclipse.californium.core.*;
+import javax.json.Json;
+import javax.json.JsonArray;
+import javax.json.JsonObject;
+import javax.json.JsonReader;
+
+import org.eclipse.californium.core.CoapHandler;
+import org.eclipse.californium.core.CoapResponse;
 
 public class Handler implements CoapHandler {
 	
-	private URI uri; 
+	private URI uri;
+	private Resource resource;
 	
-	public Handler(URI uri) {
+	public Handler(URI uri, Resource resource) {
 		this.uri = uri;
+		this.resource = resource;
 		System.err.println("[D] new handler for " + this.uri);
 	}
 
 	@Override
 	public void onLoad(CoapResponse response) {
 		String content = response.getResponseText();
-		// System.out.println("[D]  resource: " + uri);
-		// System.out.println("    new value: " + content);
-		System.out.println("update" + new Date());
+		System.out.println("[D] from " + this.uri + " update received at " + new Date() + " > " + content);
 		
 		JsonArray jsonSenML = null;
 		try {
 			InputStream is = new ByteArrayInputStream(content.getBytes());
-			System.out.println("0");
 			JsonReader reader = Json.createReader(is);
-			System.err.println("1: " + content);
 			jsonSenML = reader.readArray();
-			System.out.println("2");
 			reader.close();
 			
-			System.out.println("Java Json Object");
-			System.out.println(jsonSenML.getJsonObject(0).getString("n"));
-			System.out.println(jsonSenML.getJsonObject(0).getJsonNumber("v"));
+			/* in this application, SenML contains only one resource -- see RFC8428 for further details */
+			JsonObject res = jsonSenML.getJsonObject(0);
+			String res_name = res.getString("n");	// name of resource
+			int res_value = res.getJsonNumber("v").intValue();	// value of resource
+
+			resource.setName(res_name);
+			resource.setValue(res_value);
 		} catch (Exception ex) {
+			ex.printStackTrace();
 			System.err.println("[E] " + ex);
 		}
 	}

proxy/src/netpp/Main.java

@@ -1,6 +1,8 @@
 package netpp;
 
-import java.util.*;
+import java.util.ArrayList;
+
+import org.eclipse.californium.core.CoapServer;
 
 public class Main {
 	public final static String COOJA_MAGIC = "c30c";
@@ -31,9 +33,16 @@ public class Main {
 		for (int i = 2; i <= n; i++) {	// node 1 is the gateway, skip. And mind the <=
 			String uri_string = "coap://[" + prefix + ":" + COOJA_MAGIC + "::" + Integer.toString(i, 16) + "]" + resource;
 			System.err.println("[I] subscribing to " + uri_string);
-			nodeList.add(new Node(uri_string));
+			nodeList.add(new Node(i, uri_string));
 		}
 		
+		/* run server */
+		CoapServer server = new CoapServer();
+		for (Node node : nodeList) {
+			server.add(node.getResource());
+		}
+		server.start();
+		System.err.println("[D] server started");		
 		
 		/* thread sleep */
 		try {

proxy/src/netpp/Node.java

@@ -3,19 +3,25 @@ package netpp;
 import java.net.URI;
 import java.net.URISyntaxException;
 
-import org.eclipse.californium.core.*;
+import org.eclipse.californium.core.CoapClient;
+import org.eclipse.californium.core.CoapObserveRelation;
+import org.eclipse.californium.core.CoapResource;
 
 public class Node {
 	private URI uri;
+	private int quickname;
 	private CoapClient client;
 	private CoapObserveRelation relation;
 	private Handler handler;
+	Resource resource;
 	
-	public Node(String uriString) {
+	public Node(int quickname, String uriString) {
 		try {
 			this.uri = new URI(uriString);
 			this.client = new CoapClient(uri);
-			this.handler = new Handler(this.uri);
+			this.quickname = quickname;
+			this.resource = new Resource(this.quickname); /* this name will be overwritten when an update is received */
+			this.handler = new Handler(this.uri, resource);
 			this.relation = client.observe(handler);
 		} catch (URISyntaxException e) {
 			System.err.println("[F] Invalid URI: " + e.getMessage());
@@ -23,6 +29,10 @@ public class Node {
 		}
 	}
 	
+	CoapResource getResource() {
+		return this.resource;
+	}
+	
 	/* be kind with the poor resource constrained node */
 	@Override
 	public void finalize() {

proxy/src/netpp/Resource.java

@@ -0,0 +1,29 @@
+package netpp;
+
+import org.eclipse.californium.core.CoapResource;
+import org.eclipse.californium.core.server.resources.CoapExchange;
+
+public class Resource extends CoapResource {
+
+	private int value;
+
+	public Resource(int quickname) {
+		super(Integer.toString(quickname, 16));
+		// setObservable(true); // TODO -- do we need to make this observable?
+		System.err.println("[D] resource created: " + super.getName());
+	}
+	
+	public void handleGET(CoapExchange exchange) {
+		// TODO build the proper JSON object
+		exchange.respond("TODO: " + this.getName() + " : " + this.getValue());
+	}
+	
+	public int getValue() {
+		return this.value;
+	}
+
+	public void setValue(int value) {
+		this.value = value;
+	}
+
+}