First implementation of simple BB Client

bulletin-board-client/src/main/java/meerkat/bulletinboard/SimpleBulletinBoardClient.java

@@ -0,0 +1,163 @@
+package meerkat.bulletinboard;
+
+import com.google.protobuf.ByteString;
+import meerkat.comm.CommunicationException;
+import meerkat.crypto.Digest;
+import meerkat.crypto.concrete.SHA256Digest;
+import meerkat.protobuf.BulletinBoardAPI.*;
+import meerkat.rest.*;
+
+import java.util.List;
+
+import javax.ws.rs.client.Client;
+import javax.ws.rs.client.ClientBuilder;
+import javax.ws.rs.client.Entity;
+import javax.ws.rs.client.WebTarget;
+import javax.ws.rs.core.Response;
+
+/**
+ * Created by Arbel Deutsch Peled on 05-Dec-15.
+ */
+public class SimpleBulletinBoardClient implements BulletinBoardClient {
+
+    //TODO: Make this general
+    private static String SQL_SERVER_POST = "sqlserver/postmessage";
+    private static String SQL_SERVER_GET = "sqlserver/readmessages";
+
+    private List<String> meerkatDBs;
+
+    private Client client;
+
+    private Digest digest;
+
+    /**
+     * Stores database locations and initializes the web Client
+     * @param meerkatDBs is the list of database locations
+     */
+    @Override
+    public void init(List<String> meerkatDBs) {
+
+        this.meerkatDBs = meerkatDBs;
+
+        client = ClientBuilder.newClient();
+        client.register(ProtobufMessageBodyReader.class);
+        client.register(ProtobufMessageBodyWriter.class);
+
+        digest = new SHA256Digest();
+
+    }
+
+    /**
+     * Post message to all DBs
+     * Make only one try per DB.
+     * @param msg is the message,
+     * @return the message ID for later retrieval
+     * @throws CommunicationException
+     */
+    @Override
+    public MessageID postMessage(BulletinBoardMessage msg) throws CommunicationException {
+
+        WebTarget webTarget;
+        Response response;
+
+        // Post message to all databases
+        try {
+            for (String db : meerkatDBs) {
+                webTarget = client.target(db).path(SQL_SERVER_POST);
+                response = webTarget.request(Constants.MEDIATYPE_PROTOBUF).post(Entity.entity(msg, Constants.MEDIATYPE_PROTOBUF));
+
+                // Only consider valid responses
+                if (response.getStatusInfo() == Response.Status.OK
+                        || response.getStatusInfo() == Response.Status.CREATED) {
+                    response.readEntity(BoolMsg.class).getValue();
+                }
+            }
+        } catch (Exception e) { // Occurs only when server replies with valid status but invalid data
+            throw new CommunicationException("Error accessing database: " + e.getMessage());
+        }
+
+        // Calculate the correct message ID and return it
+        digest.reset();
+        digest.update(msg.getMsg());
+        return MessageID.newBuilder().setID(ByteString.copyFrom(digest.digest())).build();
+    }
+
+    /**
+     * Access each database and search for a given message ID
+     * Return the number of databases in which the message was found
+     * Only try once per DB
+     * Ignore communication exceptions in specific databases
+     * @param id is the requested message ID
+     * @return the number of DBs in which retrieval was successful
+     */
+    @Override
+    public float getRedundancy(MessageID id) {
+        WebTarget webTarget;
+        Response response;
+
+        MessageFilterList filterList = MessageFilterList.newBuilder()
+                .addFilter(MessageFilter.newBuilder()
+                    .setType(FilterType.MSG_ID)
+                    .setId(id.getID())
+                    .build())
+                .build();
+
+        int count = 0;
+
+        for (String db : meerkatDBs) {
+            try {
+                webTarget = client.target(db).path(SQL_SERVER_GET);
+
+                response = webTarget.request(Constants.MEDIATYPE_PROTOBUF).post(Entity.entity(filterList, Constants.MEDIATYPE_PROTOBUF));
+
+                if (response.readEntity(BulletinBoardMessageList.class).getMessageCount() > 0){
+                    count++;
+                }
+
+            } catch (Exception e) {}
+        }
+
+        return count;
+    }
+
+    /**
+     * Go through the DBs and try to retrieve messages according to the specified filter
+     * If at the operation is successful for some DB: return the results and stop iterating
+     * If no operation is successful: return null (NOT blank list)
+     * @param filterList return only messages that match the filters (null means no filtering).
+     * @return
+     */
+    @Override
+    public List<BulletinBoardMessage> readMessages(MessageFilterList filterList) {
+        WebTarget webTarget;
+        Response response;
+        BulletinBoardMessageList messageList;
+
+        // Replace null filter list with blank one.
+        if (filterList == null){
+            filterList = MessageFilterList.newBuilder().build();
+        }
+
+        for (String db : meerkatDBs) {
+            try {
+                webTarget = client.target(db).path(SQL_SERVER_GET);
+
+                response = webTarget.request(Constants.MEDIATYPE_PROTOBUF).post(Entity.entity(filterList, Constants.MEDIATYPE_PROTOBUF));
+
+                messageList =response.readEntity(BulletinBoardMessageList.class);
+
+                if (messageList != null){
+                    return messageList.getMessageList();
+                }
+
+            } catch (Exception e) {}
+        }
+
+        return null;
+    }
+
+    @Override
+    public void registerNewMessageCallback(MessageCallback callback, MessageFilterList filterList) {
+        callback.handleNewMessage(readMessages(filterList));
+    }
+}

meerkat-common/src/main/java/meerkat/bulletinboard/BulletinBoardClient.java

@@ -8,7 +8,14 @@ import java.util.List;
 /**
  * Created by talm on 24/10/15.
  */
-public interface BulletinBoard {
+public interface BulletinBoardClient {
+
+    /**
+     * Initialize the client to use some specified servers
+     * @param meerkatDBs is the list of database locations
+     */
+    void init(List<String> meerkatDBs);
+
     /**
      * Post a message to the bulletin board
      * @param msg
@@ -27,22 +34,21 @@ public interface BulletinBoard {
      * Note that if messages haven't been "fully posted", this might return a different
      * set of messages in different calls. However, messages that are fully posted
      * are guaranteed to be included.
-     * @param filter return only messages that match the filter (null means no filtering).
+     * @param filterList return only messages that match the filters (null means no filtering).
-     * @param max maximum number of messages to return (0=no limit)
      * @return
      */
-    List<BulletinBoardMessage> readMessages(MessageFilter filter, int max);
+    List<BulletinBoardMessage> readMessages(MessageFilterList filterList);
 
     interface MessageCallback {
-        void handleNewMessage(BulletinBoardMessage msg);
+        void handleNewMessage(List<BulletinBoardMessage> msg);
     }
 
     /**
      * Register a callback that will be called with each new message that is posted.
      * The callback will be called only once for each message.
      * @param callback
-     * @param filter only call back for messages that match the filter.
+     * @param filterList only call back for messages that match the filter.
      */
-    void registerNewMessageCallback(MessageCallback callback, MessageFilter filter);
+    void registerNewMessageCallback(MessageCallback callback, MessageFilterList filterList);
 
 }

settings.gradle

@@ -3,3 +3,5 @@ include 'voting-booth'
 include 'bulletin-board-server'
 include 'polling-station'
 include 'restful-api-common'
+include 'bulletin-board-client'
+