Changes made in the initial interfaces for further code review.

1. Especially tried to fix the callback mechanism I previously used.
2. 'long sessionID' changed to 'int requestId'
3. Introduced a generic class VotingBoothResult
4. Quite some other local changes

meerkat-common/src/main/proto/meerkat/voting.proto

@@ -28,7 +28,9 @@ message UIElement {
 	bytes data = 2;
 }
 
-// a new data structure for BallotQuestion. Need to delete the old one
+// A question in the ballot
+// is_mandatory determines whether the question may be skipped with no answer
+// description might hold information/guidlines for the voter
 message BallotQuestion {
 	bool is_mandatory = 1;
 	UIElement question = 2;

voting-booth/src/main/java/meerkat/voting/BallotOutputDevice.java

@@ -1,5 +1,6 @@
 package meerkat.voting;
 
+import com.google.common.util.concurrent.FutureCallback;
 import meerkat.protobuf.Voting.*;
 
 /**
@@ -7,13 +8,20 @@ import meerkat.protobuf.Voting.*;
  */
 public interface BallotOutputDevice {
 
-    void commitToBallot(long sessionId, EncryptedBallot encryptedBallot, VotingBooth.Callback callback);
+    /**
+     *
+     * @param requestId
+     * @param encryptedBallot
+     * @param callback
+     */
+    void commitToBallot(int requestId, EncryptedBallot encryptedBallot,
+                        FutureCallback<VotingBoothResult<Boolean>> callback);
 
-    void audit(long sessionId, EncryptedBallot encryptedBallot, BallotSecrets ballotSecrets, VotingBooth.Callback callback);
+    void audit(int requestId, EncryptedBallot encryptedBallot, BallotSecrets ballotSecrets,
+               FutureCallback<VotingBoothResult<Boolean>> callback);
 
-    void castBallot(long sessionId, VotingBooth.Callback callback);
+    void castBallot(int requestId, FutureCallback<VotingBoothResult<Boolean>> callback);
 
-    // probably has no difference than cast. Maybe drop this method
+    void cancelBallot(int requestId, FutureCallback<VotingBoothResult<Boolean>> callback);
-    void cancelBallot(long sessionId, VotingBooth.Callback callback);
 
 }

voting-booth/src/main/java/meerkat/voting/StorageManager.java

@@ -1,12 +1,13 @@
 package meerkat.voting;
 
+import meerkat.protobuf.Voting;
+
 /**
  * Created by hai on 23/02/16.
  */
 public interface StorageManager {
 
-    // should these methods be synchronous or asynchronous? Can we rely on it being immediate?
+    boolean detectAdminHardwareKey();
-    public void detectAdminHardwareKey();
 
-    public void readElectionParams ();
+    Voting.ElectionParams readElectionParams ();
 }

voting-booth/src/main/java/meerkat/voting/UI.java

@@ -1,32 +0,0 @@
-package meerkat.voting;
-
-import meerkat.protobuf.Voting.*;
-
-/**
- * Created by hai on 23/02/16.
- */
-public interface UI {
-
-
-    // Voter scenario methods
-    void introductionToVoter (long sessionId);
-
-    void chooseChannel (long sessionId, BallotQuestion question);
-
-    void askVoterQuestion (long sessionId, int questionNumber, BallotQuestion question);
-
-    void castOrAudit (long sessionId);
-
-    void showWaitForFinishScreen (long sessionId);
-
-
-    // Admin scenario methods
-    //TODO: the admin scenario still needs some more thinking
-
-
-
-    // bad thing happened scenario
-    void showErrorMessageAndHalt (String errorMessage);
-    void showErrorMessageWithCancelButton (long sessionId, String errorMessage);
-
-}

voting-booth/src/main/java/meerkat/voting/VotingBooth.java

@@ -1,6 +1,5 @@
 package meerkat.voting;
 
-import meerkat.protobuf.Voting;
 import meerkat.protobuf.Voting.*;
 
 /**
@@ -8,75 +7,21 @@ import meerkat.protobuf.Voting.*;
  */
 public interface VotingBooth {
 
-    public enum ErrorID {
+    void setComponenets (BallotOutputDevice outputDevice,
-        OUTPUT_DEVICE_OUT_OF_PAPER,
+                                VotingBoothEncryptor vbEncryptor,
-        OUTPUT_DEVICE_OUT_OF_INK,
+                                VotingBoothUI vbUI,
-        OUTPUT_DEVICE_NO_CONNECTION,
+                                StorageManager vbStorageManager);
-        OUTPUT_DEVICE_HARDWARE_NOT_FOUND,
 
-        UI_HARDWARE_NOT_FOUND
+    void initBoothParams (BoothParams boothParams);
-    }
 
-
+    void initElectionParams (ElectionParams electionParams);
-    // keeps track in which state we are
-    // internal state will also include the number of the current question and the answers we got so far,
-    // later it includes the details of the PlaintextBallot and later the Encryption and the secrets
-    public enum State {
-        INITIALIZED,
-
-        VOTER_INTRODUCTION,
-        VOTER_CHOOSE_CHANNEL,
-        VOTER_VOTING,
-        VOTER_ENCRYPTING,
-        VOTER_CAST_OR_AUDIT,
-        VOTER_CASTING,
-        VOTER_AUDITING
-
-    }
-
-    public interface Callback {
-
-        // callbacks and messages from BallotOutputDevice
-
-        public void ballotCommitResult (long sessionId, boolean result);
-        public void ballotCastResult (long sessionId, boolean result);
-        public void ballotAuditResult (long sessionId, boolean result);
-        public void ballotCancelResult (long sessionId, boolean result);
-        // other error messages, such as Printer turned-off or out-of-paper
-        public void outputDeviceReportProblem (ErrorID errorId);
-
-
-        // callbacks and messages from UI
-
-        public void introductionFinished (long sessionId);
-        public void choiceOfChannel (long sessionId, int channelNumber);
-        public void skipQuestion (long sessionId, int questionNumber);
-        public void backwardsQuestion (long sessionId, int questionNumber);
-        public void cancelVotingSession (long sessionId);
-        public void answer (long sessionId, int questionNumber, String answer);
-        public void cast (long sessionId);
-        public void audit (long sessionId);
-        // other error messages, such as hardware-not-detected
-        public void uiReportProblem (ErrorID errorId);
-
-
-        // callbacks from encryptor
-
-        public void returnEncryption (long sessionId, EncryptedBallot encryptedBallot, BallotSecrets secrets);
-
-
-        // callbacks from StorageManager
-
-        public void adminHardwareKeyDetected (boolean isKeyInserted);
-        public void loadElectionParams (ElectionParams electionParams);
-    }
 
     // this function is synchronous
-    public void start ();
+    void start ();
 
 
     // messages from Admin Console (If there is such one)
     // this function is asynchronous
-    public void shutDown();
+    void shutDown();
 
 }

voting-booth/src/main/java/meerkat/voting/VotingBoothEncryptor.java

@@ -5,9 +5,9 @@ import meerkat.protobuf.Voting.*;
 /**
  * Created by hai on 23/02/16.
  */
-public interface Encryptor {
+public interface VotingBoothEncryptor {
 
-    public void encrypt (long sessionId, PlaintextBallot plaintextBallot);
+    void encrypt (PlaintextBallot plaintextBallot);
 
     //TODO: probably needs some key generation methods as well
 }

voting-booth/src/main/java/meerkat/voting/VotingBoothResult.java

@@ -0,0 +1,17 @@
+package meerkat.voting;
+
+/**
+ * Created by hai on 02/03/16.
+ */
+public class VotingBoothResult<T> {
+    private final int m_requestId;
+    private final T m_result;
+
+    public int getRequestId () { return m_requestId; }
+    public T getResult () { return m_result; }
+
+    public VotingBoothResult (int requestId, T result) {
+        m_requestId = requestId;
+        m_result = result;
+    }
+}

voting-booth/src/main/java/meerkat/voting/VotingBoothUI.java

@@ -0,0 +1,64 @@
+package meerkat.voting;
+
+import com.google.common.util.concurrent.FutureCallback;
+import meerkat.protobuf.Voting.*;
+
+/**
+ * Created by hai on 23/02/16.
+ */
+public interface VotingBoothUI {
+
+    enum VoterQuestionChoice {
+        ANSWERED,
+        SKIP,
+        BACK,
+        CANCEL
+    }
+
+    class VoterQuestionResponse {
+        private final VoterQuestionChoice m_choice;
+        private final String m_answer;
+
+        public VoterQuestionResponse(VoterQuestionChoice choice, String answer) {
+            assert ((choice == VoterQuestionChoice.ANSWERED && answer != null) ||
+                    (choice != VoterQuestionChoice.ANSWERED && answer == null));
+            m_choice = choice;
+            m_answer = answer;
+        }
+
+        public VoterQuestionChoice getChoice () { return m_choice; }
+        public String getAnswer () { return m_answer; }
+    }
+
+
+    enum FinalizeBallotChoice {
+        CAST,
+        AUDIT
+    }
+
+    // Voter scenario methods
+    void newVoter (int requestId, FutureCallback<VotingBoothResult<Boolean>> callback);
+
+    void chooseChannel (int requestId, BallotQuestion question, FutureCallback<VotingBoothResult<Integer>> callback);
+
+    void askVoterQuestion (int requestId, int questionNumber, BallotQuestion question,
+                           FutureCallback<VotingBoothResult<VoterQuestionResponse>> callback);
+
+    void castOrAudit (int requestId, FutureCallback<VotingBoothResult<FinalizeBallotChoice>> callback);
+
+    void showWaitForFinishScreen (int requestId, FutureCallback<VotingBoothResult<Boolean>> callback);
+
+
+    // Admin scenario methods
+    //TODO: the admin scenario still needs some more thinking
+
+
+
+    // bad thing happened scenario
+    void showErrorMessageAndHalt (int requestId, String errorMessage,
+                                  FutureCallback<VotingBoothResult<Boolean>> callback);
+
+    void showErrorMessageWithButtons (int requestId, String errorMessage, String[] buttonLabels,
+                                      FutureCallback<VotingBoothResult<Integer>> callback);
+
+}