backend/src/main/java/djmil/cordacheckers/cordaclient/CordaClient.java

@@ -14,23 +14,17 @@ import org.springframework.http.ResponseEntity;
 import org.springframework.stereotype.Service;
 import org.springframework.web.client.RestTemplate;
 
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.JsonMappingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
 import djmil.cordacheckers.cordaclient.dao.HoldingIdentity;
 import djmil.cordacheckers.cordaclient.dao.Color;
-import djmil.cordacheckers.cordaclient.dao.GameProposal;
 import djmil.cordacheckers.cordaclient.dao.VirtualNode;
 import djmil.cordacheckers.cordaclient.dao.VirtualNodeList;
 import djmil.cordacheckers.cordaclient.dao.flow.RequestBody;
 import djmil.cordacheckers.cordaclient.dao.flow.ResponseBody;
-import djmil.cordacheckers.cordaclient.dao.flow.arguments.GameProposalCreateReq;
-import djmil.cordacheckers.cordaclient.dao.flow.arguments.GameProposalCreateRes;
-import djmil.cordacheckers.cordaclient.dao.flow.arguments.GameProposalListRes;
+import djmil.cordacheckers.cordaclient.dao.flow.arguments.CreateGameProposal;
 import djmil.cordacheckers.cordaclient.dao.flow.arguments.Empty;
-import djmil.cordacheckers.cordaclient.dao.flow.arguments.GameProposalActionReq;
-import djmil.cordacheckers.cordaclient.dao.flow.arguments.GameProposalActionRes;
+import djmil.cordacheckers.cordaclient.dao.flow.arguments.GameProposalAction;
 
 @Service
 public class CordaClient {
@@ -65,7 +59,7 @@ public class CordaClient {
      * @param holdingIdentity
      * @return GameProposals list in JSON form
      */
-    public List<GameProposal> gameProposalList(HoldingIdentity holdingIdentity) {
+    public String listGameProposals(HoldingIdentity holdingIdentity) {
 
         final RequestBody requestBody = new RequestBody(
             "list-" + UUID.randomUUID(),
@@ -73,27 +67,21 @@ public class CordaClient {
             new Empty()
             );
 
-        final GameProposalListRes listFlowResult = cordaFlowExecute(
+        final String gameProposalsJsonString = cordaFlowExecute(
             holdingIdentity,
-            requestBody,
-            GameProposalListRes.class
+            requestBody
             );
 
-        if (listFlowResult.failureStatus() != null) {
-            System.out.println("GameProposalCreateFlow failed: " + listFlowResult.failureStatus());
-            throw new RuntimeException("GameProsal: CreateFlow execution has failed");
-        }
-
-        return listFlowResult.successStatus();
+        return gameProposalsJsonString;
     }
 
-    public UUID gameProposalCreate(
+    public String createGameProposal(
         HoldingIdentity sender,
         HoldingIdentity receiver,
         Color receiverColor,
         String message
-    ) throws JsonMappingException, JsonProcessingException {
-        final GameProposalCreateReq createGameProposal = new GameProposalCreateReq(
+    ) {
+        final CreateGameProposal createGameProposal = new CreateGameProposal(
             receiver.x500Name(),
             receiverColor,
             message
@@ -105,28 +93,21 @@ public class CordaClient {
             createGameProposal
             );
 
-        final GameProposalCreateRes createResult = cordaFlowExecute(
+        final String createdGameProposalUuid = cordaFlowExecute(
             sender,
-            requestBody,
-            GameProposalCreateRes.class
+            requestBody
             );
 
-        if (createResult.failureStatus() != null) {
-            System.out.println("GameProposalCreateFlow failed: " + createResult.failureStatus());
-            throw new RuntimeException("GameProsal: CreateFlow execution has failed");
-        }
-
-        return createResult.successStatus();
+        return createdGameProposalUuid;
     }
 
-    public String gameProposalAction(
+    public String rejectGameProposal(
         HoldingIdentity self,
-        UUID gameProposalUuid,
-        GameProposalActionReq.Action action
+        String gameProposalUuid
     ) {
-        final GameProposalActionReq rejectGameProposal = new GameProposalActionReq(
-            gameProposalUuid.toString(),
-            action
+        final GameProposalAction rejectGameProposal = new GameProposalAction(
+            gameProposalUuid,
+            GameProposalAction.Action.REJECT
             );
 
         final RequestBody requestBody = new RequestBody(
@@ -135,21 +116,15 @@ public class CordaClient {
             rejectGameProposal
             );
 
-        final GameProposalActionRes actionResult = cordaFlowExecute(
+        final String createdGameProposalUuid = cordaFlowExecute(
             self,
-            requestBody,
-            GameProposalActionRes.class
+            requestBody
             );
 
-        if (actionResult.failureStatus() != null) {
-            System.out.println("GameProposalActionFlow failed: " + actionResult.failureStatus());
-            throw new RuntimeException("GameProsal: ActionFlow execution has failed");
-        }
-
-        return actionResult.successStatus();
+        return createdGameProposalUuid;
     }
 
-    private <T> T cordaFlowExecute(HoldingIdentity holdingIdentity, RequestBody requestBody, Class<T> flowResultType) {
+    private String cordaFlowExecute(HoldingIdentity holdingIdentity, RequestBody requestBody) {
 
         try {
             final String requestBodyJson = this.jsonMapper.writeValueAsString(requestBody);
@@ -159,9 +134,15 @@ public class CordaClient {
                 requestBodyJson
             );
 
-            final String flowResult = cordaFlowPoll(startedFlow);
+            final String flowExecutionResult = cordaFlowPoll(startedFlow);
 
-            return this.jsonMapper.readValue(flowResult, flowResultType);
+            // NOTE:
+            // At this point, real production code, probably should convert data between CordaFlow
+            // abstarction into ReactApp abstraction. Instead, to limit boring json shuffling, all
+            // family of Corda.List flows were deliberatly designed to return frontend frendly JSONs.
+            // At the same time, all other Corda flows, simply return plain text string with
+            // operation result.
+            return flowExecutionResult;
         } 
         catch (Exception e) {
             throw new RuntimeException("Unable to perform "+requestBody.flowClassName()
@@ -202,7 +183,7 @@ public class CordaClient {
 
         for (int retry = 0; retry < 6; retry++) {
             // Give Corda cluster some time to process our request
-            TimeUnit.SECONDS.sleep(retry*retry +2); // 2 3 6 10 18 27 sec
+            TimeUnit.SECONDS.sleep(retry*retry +1); // 1 2 5 8 17 33 sec
 
             final ResponseEntity<ResponseBody> responce = this.restTemplate.exchange(
                 "/flow/" 
@@ -223,16 +204,15 @@ public class CordaClient {
                 "CordaClient.cordaFlowPoll: empty getBody()"
             );
 
-            if (responseBody.flowError() != null) {
-                throw new RuntimeException("CordaClient.cordaFlowPoll: flow execution error: " 
-                                            +responseBody.flowError());
-            }
-
             if (responseBody.isFlowCompleted() && responseBody.flowResult() != null) {
+                System.out.println("Completed "+responseBody.flowResult());
                 return responseBody.flowResult();
+            } else
+            if (responseBody.flowError() != null) {
+                return "Flow execution error: " +responseBody.flowError();
             }
         }
 
-        throw new RuntimeException ("CordaClient.cordaFlowPoll: retry limit");
+        return "CordaClient.cordaFlowPoll: retry limit";
     }
 }

backend/src/main/java/djmil/cordacheckers/cordaclient/dao/GameProposal.java

@@ -1,15 +1,13 @@
 package djmil.cordacheckers.cordaclient.dao;
 
-import java.util.UUID;
-
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 
 @JsonDeserialize
 public record GameProposal(
-    String issuer,
-    String acquier,
-    Color acquierColor,
+    String sender,
+    String recipient,
+    Color recipientColor,
     String message,
-    UUID id) {
+    String id) {
     
 }

backend/src/main/java/djmil/cordacheckers/cordaclient/dao/flow/arguments/CreateGameProposal.java

@@ -2,6 +2,6 @@ package djmil.cordacheckers.cordaclient.dao.flow.arguments;
 
 import djmil.cordacheckers.cordaclient.dao.Color;
 
-public record GameProposalCreateReq(String opponentName, Color opponentColor, String message) {
+public record CreateGameProposal(String opponentName, Color opponentColor, String message) {
     
 }

backend/src/main/java/djmil/cordacheckers/cordaclient/dao/flow/arguments/GameProposalAction.java

@@ -1,6 +1,6 @@
 package djmil.cordacheckers.cordaclient.dao.flow.arguments;
 
-public record GameProposalActionReq(String gameProposalUuid, Action action) {
+public record GameProposalAction(String gameProposalUuid, Action action) {
     public enum Action {
         ACCEPT,
         REJECT,

backend/src/main/java/djmil/cordacheckers/cordaclient/dao/flow/arguments/GameProposalActionRes.java

@@ -1,5 +0,0 @@
-package djmil.cordacheckers.cordaclient.dao.flow.arguments;
-
-public record GameProposalActionRes(String successStatus, String transactionId, String failureStatus) {
-    
-}

backend/src/main/java/djmil/cordacheckers/cordaclient/dao/flow/arguments/GameProposalCreateRes.java

@@ -1,10 +0,0 @@
-package djmil.cordacheckers.cordaclient.dao.flow.arguments;
-
-import java.util.UUID;
-
-import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
-
-@JsonIgnoreProperties(ignoreUnknown = true)
-public record GameProposalCreateRes(UUID successStatus, String failureStatus) {
-    
-}

backend/src/main/java/djmil/cordacheckers/cordaclient/dao/flow/arguments/GameProposalListRes.java

@@ -1,12 +0,0 @@
-package djmil.cordacheckers.cordaclient.dao.flow.arguments;
-
-import java.util.List;
-
-import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
-
-import djmil.cordacheckers.cordaclient.dao.GameProposal;
-
-@JsonIgnoreProperties(ignoreUnknown = true)
-public record GameProposalListRes(List<GameProposal> successStatus, String failureStatus) {
-    
-}

backend/src/main/java/djmil/cordacheckers/gameproposal/GameProposalController.java

@@ -1,8 +1,6 @@
 package djmil.cordacheckers.gameproposal;
 
 import java.net.URI;
-import java.util.List;
-import java.util.UUID;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.ResponseEntity;
@@ -11,12 +9,9 @@ import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.util.UriComponentsBuilder;
 
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.JsonMappingException;
-
 import djmil.cordacheckers.cordaclient.CordaClient;
 import djmil.cordacheckers.cordaclient.dao.HoldingIdentity;
-import djmil.cordacheckers.cordaclient.dao.flow.arguments.GameProposalCreateReq;
+import djmil.cordacheckers.cordaclient.dao.flow.arguments.CreateGameProposal;
 import djmil.cordacheckers.cordaclient.dao.Color;
 import djmil.cordacheckers.cordaclient.dao.GameProposal;
 import djmil.cordacheckers.user.HoldingIdentityResolver;
@@ -41,9 +36,9 @@ public class GameProposalController {
     public ResponseEntity<String> findAllUnconsumed(
         @AuthenticationPrincipal User player
     ) {
-        List<GameProposal> gpList = cordaClient.gameProposalList(player.getHoldingIdentity());
+        String gpList = cordaClient.listGameProposals(player.getHoldingIdentity());
 
-        return ResponseEntity.ok(gpList.toString());
+        return ResponseEntity.ok(gpList);
     }
 
     // @PostMapping()
@@ -55,16 +50,15 @@ public class GameProposalController {
     @PostMapping()
     public ResponseEntity<Void> createGameProposal(
         @AuthenticationPrincipal User sender,
-        @RequestBody GameProposalCreateReq gpRequest,
+        @RequestBody CreateGameProposal gpRequest,
         UriComponentsBuilder ucb
-    ) throws JsonMappingException, JsonProcessingException {
+    ) {
         final HoldingIdentity gpSender = sender.getHoldingIdentity();
         // TODO: throw execption with custom type
         final HoldingIdentity gpReceiver = holdingIdentityResolver.getByUsername(gpRequest.opponentName());
         final Color gpReceiverColor = gpRequest.opponentColor();
 
-        // TODO handle expectionns here
-        UUID newGameProposalUuid = cordaClient.gameProposalCreate(
+        String newGameProposalUuid = cordaClient.createGameProposal(
             gpSender,
             gpReceiver,
             gpReceiverColor,

backend/src/test/java/djmil/cordacheckers/cordaclient/CordaClientTest.java

@@ -6,19 +6,14 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.JsonMappingException;
 
 import djmil.cordacheckers.cordaclient.dao.Color;
-import djmil.cordacheckers.cordaclient.dao.GameProposal;
 import djmil.cordacheckers.cordaclient.dao.VirtualNode;
-import djmil.cordacheckers.cordaclient.dao.flow.arguments.GameProposalActionReq.Action;
 import djmil.cordacheckers.user.HoldingIdentityResolver;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 import java.util.List;
-import java.util.UUID;
 
 import javax.naming.InvalidNameException;
 
@@ -39,51 +34,44 @@ public class CordaClientTest {
 
     @Test
     void testGameProposalList() throws JsonProcessingException {
-        List<GameProposal> gpList = cordaClient.gameProposalList(
-            holdingIdentityResolver.getByUsername("Alice"));
+        String resp = cordaClient.listGameProposals(
+            holdingIdentityResolver.getByUsername("alice"));
 
-        System.out.println("testListGameProposals\n"+ gpList);
+        System.out.println("testListGameProposals "+ resp);
     }
 
     @Test
-    void testGemeProposalCreate() throws JsonMappingException, JsonProcessingException {
-        final String gpIssuer = "alice";
-        final String gpAcquier = "bob";
-        final Color gpAcquierColor = Color.WHITE;
-        final String gpMessage = "GameProposal create test";
-
-        final UUID createdGpUuid = cordaClient.gameProposalCreate(
-            holdingIdentityResolver.getByUsername(gpIssuer),
-            holdingIdentityResolver.getByUsername(gpAcquier),
-            gpAcquierColor,
-            gpMessage
-        );
-
-        List<GameProposal> gpListSender = cordaClient.gameProposalList(
-            holdingIdentityResolver.getByUsername(gpIssuer));
-
-        assertThat(findByUuid(gpListSender, createdGpUuid)).isNotNull();
-
-        List<GameProposal> gpListReceiver = cordaClient.gameProposalList(
-            holdingIdentityResolver.getByUsername(gpAcquier));
-
-        GameProposal gp;
-        assertThat(gp = findByUuid(gpListReceiver, createdGpUuid)).isNotNull();
-
-        assertThat(gp.acquier()).isEqualToIgnoringCase(gpAcquier);
-        assertThat(gp.issuer()).isEqualToIgnoringCase(gpIssuer);
-        assertThat(gp.acquierColor()).isEqualByComparingTo(gpAcquierColor);
-        assertThat(gp.message()).isEqualTo(gpMessage);
-    }
-
-    @Test
-    void testGemeProposalReject() throws JsonMappingException, JsonProcessingException {
+    void testGemeProposalCreate() {
         final String gpSender = "alice";
         final String gpReceiver = "bob";
         final Color gpReceiverColor = Color.WHITE;
-        final String gpMessage = "GameProposal REJECT test";
+        final String gpMessage = "GameProposal create test";
 
-        final UUID gpUuid = cordaClient.gameProposalCreate(
+        final String gpUuid = cordaClient.createGameProposal(
+            holdingIdentityResolver.getByUsername(gpSender),
+            holdingIdentityResolver.getByUsername(gpReceiver),
+            gpReceiverColor,
+            gpMessage
+        );
+
+        String listResSender = cordaClient.listGameProposals(
+            holdingIdentityResolver.getByUsername(gpSender));
+
+        String listResReceiver = cordaClient.listGameProposals(
+            holdingIdentityResolver.getByUsername(gpReceiver));
+
+        assertThat(listResSender).contains(gpUuid);
+        assertThat(listResReceiver).contains(gpUuid);
+    }
+
+    @Test
+    void testGemeProposalReject() {
+        final String gpSender = "alice";
+        final String gpReceiver = "bob";
+        final Color gpReceiverColor = Color.WHITE;
+        final String gpMessage = "GameProposal create test";
+
+        final String gpUuid = cordaClient.createGameProposal(
             holdingIdentityResolver.getByUsername(gpSender),
             holdingIdentityResolver.getByUsername(gpReceiver),
             gpReceiverColor,
@@ -92,45 +80,20 @@ public class CordaClientTest {
 
         System.out.println("Create GP UUID "+ gpUuid);
 
-        assertThatThrownBy(() -> {
-            cordaClient.gameProposalAction(
-                holdingIdentityResolver.getByUsername(gpSender),
-                gpUuid,
-                Action.REJECT);
-        });
+        String listResSender = cordaClient.listGameProposals(
+            holdingIdentityResolver.getByUsername(gpSender));
 
-        final String rejectRes = cordaClient.gameProposalAction(
+        String listResReceiver = cordaClient.listGameProposals(
+            holdingIdentityResolver.getByUsername(gpReceiver));
+
+        assertThat(listResSender).contains(gpUuid);
+        assertThat(listResReceiver).contains(gpUuid);
+
+        final String rejectRes = cordaClient.rejectGameProposal(
             holdingIdentityResolver.getByUsername(gpReceiver),
-            gpUuid,
-            Action.REJECT
+            "1ed70601-c79a-486d-b907-8537f317083a"
         );
 
         assertThat(rejectRes).isEqualToIgnoringCase("REJECTED");
-
-        List<GameProposal> gpListSender = cordaClient.gameProposalList(
-            holdingIdentityResolver.getByUsername(gpSender));
-
-        assertThat(findByUuid(gpListSender, gpUuid)).isNull();
-
-        List<GameProposal> gpListReceiver = cordaClient.gameProposalList(
-            holdingIdentityResolver.getByUsername(gpReceiver));
-
-        assertThat(findByUuid(gpListReceiver, gpUuid)).isNull();
-
-        // GameProposal can not be rejected twice 
-        assertThatThrownBy(() -> {
-            cordaClient.gameProposalAction(
-                holdingIdentityResolver.getByUsername(gpSender),
-                gpUuid,
-                Action.REJECT);
-        });
-    }
-
-    private GameProposal findByUuid(List<GameProposal> gpList, UUID uuid) {
-        for (GameProposal gameProposal : gpList) {
-            if (gameProposal.id().compareTo(uuid) == 0)
-                return gameProposal;
-        };
-        return null;
     }
 }

corda/contracts/src/main/java/djmil/cordacheckers/contracts/GameProposalContract.java

@@ -3,96 +3,66 @@ package djmil.cordacheckers.contracts;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-//import djmil.cordacheckers.states.GameProposalResolutionState;
+import djmil.cordacheckers.states.GameProposalResolutionState;
 import djmil.cordacheckers.states.GameProposalState;
 import net.corda.v5.base.exceptions.CordaRuntimeException;
-import net.corda.v5.base.types.MemberX500Name;
 import net.corda.v5.ledger.utxo.Command;
-import net.corda.v5.ledger.utxo.StateAndRef;
 import net.corda.v5.ledger.utxo.transaction.UtxoLedgerTransaction;
 
 public class GameProposalContract implements net.corda.v5.ledger.utxo.Contract {
 
     private final static Logger log = LoggerFactory.getLogger(GameProposalContract.class);
 
-    public static enum Action implements Command { 
-        CREATE,
-        ACCEPT,
-        REJECT,
-        CANCEL;
-
-        public MemberX500Name getInitiator(GameProposalState gameProposalState) {
-            switch (this) {
-                case CREATE:
-                case CANCEL:
-                    return gameProposalState.getIssuer();
-                case ACCEPT:
-                case REJECT:
-                    return gameProposalState.getAcquier();
-                default:
-                    throw new RuntimeException(UNSUPPORTED_ACTION_VALUE_OF + this.name());
-            }
-        }
-
-        public MemberX500Name getRespondent(GameProposalState gameProposalState) {
-            switch (this) {
-                case CREATE:
-                case CANCEL:
-                    return gameProposalState.getAcquier();
-                case ACCEPT:
-                case REJECT:
-                    return gameProposalState.getIssuer();
-                default:
-                    throw new RuntimeException(UNSUPPORTED_ACTION_VALUE_OF + this.name());
-            }
-        }
-
-        public MemberX500Name getSender(StateAndRef<GameProposalState> utxoGameProposal) {
-            return getInitiator(utxoGameProposal.getState().getContractState());
-        }
-
-        public MemberX500Name getReceiver(StateAndRef<GameProposalState> utxoGameProposal) {
-            return getRespondent(utxoGameProposal.getState().getContractState());
-        }
-
-        public static final String UNSUPPORTED_ACTION_VALUE_OF = "Unsupported Action value: ";
-    }
+    public static class Create implements Command { }
+    public static class Accept implements Command { }
+    public static class Reject implements Command { }
+    public static class Cancel implements Command { }
 
     @Override
     public void verify(UtxoLedgerTransaction trx) {
         log.info("GameProposalContract.verify() called");
 
         requireThat(trx.getCommands().size() == 1, REQUIRE_SINGLE_COMMAND);
+        Command command = trx.getCommands().get(0);
 
-        switch ((Action)(trx.getCommands().get(0))) {
-            case CREATE: {
-                requireThat(trx.getInputContractStates().isEmpty(), CREATE_INPUT_STATE);
-                requireThat(trx.getOutputContractStates().size() == 1, CREATE_OUTPUT_STATE);
+        if (command instanceof Create) {
+            requireThat(trx.getInputContractStates().isEmpty(), CREATE_INPUT_STATE);
+            requireThat(trx.getOutputContractStates().size() == 1, CREATE_OUTPUT_STATE);
             
-                GameProposalState outputState = trx.getOutputStates(GameProposalState.class).get(0);
-                requireThat(outputState != null, CREATE_OUTPUT_STATE);
+            GameProposalState outputState = trx.getOutputStates(GameProposalState.class).get(0);
+            requireThat(outputState != null, CREATE_OUTPUT_STATE);
 
-                requireThat(outputState.getRecipientColor() != null, NON_NULL_RECIPIENT_COLOR);
-                break; }
+            requireThat(outputState.getRecipientColor() != null, NON_NULL_RECIPIENT_COLOR);
+        } else 
+        if (command instanceof Accept) {
+            // TODO outputState -> Game
+            throw new CordaRuntimeException("Unimplemented!");
+        } else 
+        if (command instanceof Reject) {
+            requireThat(trx.getInputContractStates().size() == 1, REJECT_INPUT_STATE);
+            requireThat(trx.getOutputContractStates().size() == 1, REJECT_OUTPUT_STATE);
 
-            case ACCEPT:
-                throw new CordaRuntimeException("Unimplemented!");
-                //break; 
+            GameProposalState inputState = trx.getInputStates(GameProposalState.class).get(0);
+            requireThat(inputState != null, REJECT_INPUT_STATE);
             
-            case REJECT:
-                requireThat(trx.getInputContractStates().size() == 1, REJECT_INPUT_STATE);
-                requireThat(trx.getOutputContractStates().isEmpty(), REJECT_OUTPUT_STATE);
-                requireThat(trx.getInputStates(GameProposalState.class).get(0) != null, REJECT_INPUT_STATE);
-                break;
+            GameProposalResolutionState outputState = trx.getOutputStates(GameProposalResolutionState.class).get(0);
+            requireThat(outputState != null, REJECT_OUTPUT_STATE);
 
-            case CANCEL:
-                requireThat(trx.getInputContractStates().size() == 1, CANCEL_INPUT_STATE);
-                requireThat(trx.getOutputContractStates().isEmpty(), CANCEL_OUTPUT_STATE);
-                requireThat(trx.getInputStates(GameProposalState.class).get(0) != null, CANCEL_INPUT_STATE);
-                break;
+            requireThat(outputState.outcome == GameProposalResolutionState.Resolution.REJECT, REJECT_OUTPUT_OUTCOME);
+        } else 
+        if (command instanceof Cancel) {
+            requireThat(trx.getInputContractStates().size() == 1, CANCEL_INPUT_STATE);
+            requireThat(trx.getOutputContractStates().size() == 1, CANCEL_OUTPUT_STATE);
 
-            default:
-                throw new CordaRuntimeException(UNKNOWN_COMMAND);
+            GameProposalState inputState = trx.getInputStates(GameProposalState.class).get(0);
+            requireThat(inputState != null, CANCEL_INPUT_STATE);
+            
+            GameProposalResolutionState outputState = trx.getOutputStates(GameProposalResolutionState.class).get(0);
+            requireThat(outputState != null, CANCEL_OUTPUT_STATE);
+
+            requireThat(outputState.outcome == GameProposalResolutionState.Resolution.CANCEL, CANCEL_OUTPUT_OUTCOME);
+        } else {
+            throw new CordaRuntimeException(UNKNOWN_COMMAND);
         }
     }
     
@@ -110,8 +80,10 @@ public class GameProposalContract implements net.corda.v5.ledger.utxo.Contract {
     static final String NON_NULL_RECIPIENT_COLOR = "GameProposal.recipientColor field can not be null";
 
     static final String REJECT_INPUT_STATE  = "Reject command should have exactly one GameProposal input state";
-    static final String REJECT_OUTPUT_STATE = "Reject command should have no output states";
+    static final String REJECT_OUTPUT_STATE = "Reject command should have exactly one GameProposalResolution output states";
+    static final String REJECT_OUTPUT_OUTCOME = "Reject output state should have Resolution value set to REJECT";
 
     static final String CANCEL_INPUT_STATE  = "Cancel command should have exactly one GameProposal input state";
-    static final String CANCEL_OUTPUT_STATE = "Cancel command should have no output states";
+    static final String CANCEL_OUTPUT_STATE = "Cancel command should have exactly one GameProposalResolution output states";
+    static final String CANCEL_OUTPUT_OUTCOME = "Cancel output state should have Resolution value set to CANCEL";
 }

corda/contracts/src/main/java/djmil/cordacheckers/states/GameProposalResolutionState.java

@@ -0,0 +1,63 @@
+package djmil.cordacheckers.states;
+
+import java.security.PublicKey;
+import java.util.List;
+
+import djmil.cordacheckers.contracts.GameProposalContract;
+import net.corda.v5.base.annotations.ConstructorForDeserialization;
+import net.corda.v5.base.annotations.CordaSerializable;
+import net.corda.v5.base.types.MemberX500Name;
+import net.corda.v5.ledger.utxo.BelongsToContract;
+import net.corda.v5.ledger.utxo.ContractState;
+
+@BelongsToContract(GameProposalContract.class)
+public class GameProposalResolutionState implements ContractState {
+
+    @CordaSerializable
+    public enum Resolution {
+        ACCEPT,
+        REJECT,
+        CANCEL
+    }
+
+    public final Resolution outcome;
+    public final List<PublicKey> participants;
+
+    public GameProposalResolutionState(
+        Resolution outcome,
+        GameProposalState gameProposal
+    ) {
+        this.outcome = outcome;
+        this.participants = gameProposal.getParticipants();
+    }
+
+    @ConstructorForDeserialization
+    public GameProposalResolutionState(
+        Resolution outcome,
+        List<PublicKey> participants
+    ) {
+        this.outcome = outcome;
+        this.participants = participants;
+    }
+
+    public Resolution getOutcome() {
+        return outcome;
+    }
+
+    public List<PublicKey> getParticipants() {
+        return this.participants;
+    }
+
+    public MemberX500Name getRecipient(GameProposalState gameProposal) {
+        switch (outcome) {
+            case ACCEPT:
+            case REJECT:
+                return gameProposal.getSender();
+            case CANCEL:
+                return gameProposal.getRecipient();
+            default:
+                throw new RuntimeException("Unknown Resolution value: "+outcome.toString());
+        }
+    }
+    
+}

corda/contracts/src/main/java/djmil/cordacheckers/states/GameProposalState.java

@@ -6,6 +6,7 @@ import java.util.UUID;
 
 import djmil.cordacheckers.contracts.GameProposalContract;
 import net.corda.v5.base.annotations.ConstructorForDeserialization;
+import net.corda.v5.base.annotations.CordaSerializable;
 import net.corda.v5.base.types.MemberX500Name;
 import net.corda.v5.ledger.utxo.BelongsToContract;
 import net.corda.v5.ledger.utxo.ContractState;
@@ -13,40 +14,46 @@ import net.corda.v5.ledger.utxo.ContractState;
 @BelongsToContract(GameProposalContract.class)
 public class GameProposalState implements ContractState {
 
-    MemberX500Name issuer;
-    MemberX500Name acquier;
-    Piece.Color recipientColor;
-    String message;
-    UUID id;
-    List<PublicKey> participants;
+    @CordaSerializable
+    public enum Color {
+        WHITE,
+        BLACK,
+    }
+      
+    public final MemberX500Name sender;
+    public final MemberX500Name recipient;
+    public final Color recipientColor;
+    public final String message;
+    public final UUID id;
+    public final List<PublicKey> participants;
 
     // Allows serialisation and to use a specified UUID
     @ConstructorForDeserialization
     public GameProposalState(
-        MemberX500Name issuer,
-        MemberX500Name acquier,
-        Piece.Color recipientColor,
+        MemberX500Name sender,
+        MemberX500Name recipient,
+        Color recipientColor,
         String message,
         UUID id,
         List<PublicKey> participants
     ) {
-        this.issuer = issuer;
-        this.acquier = acquier;
+        this.sender = sender;
+        this.recipient = recipient;
         this.recipientColor = recipientColor;
         this.message = message;
         this.id = id;
         this.participants = participants;
     }
 
-    public MemberX500Name getIssuer() {
-        return issuer;
+    public MemberX500Name getSender() {
+        return sender;
     }
 
-    public MemberX500Name getAcquier() {
-        return acquier;
+    public MemberX500Name getRecipient() {
+        return recipient;
     }
 
-    public Piece.Color getRecipientColor() {
+    public Color getRecipientColor() {
         return recipientColor;
     }
 

corda/contracts/src/main/java/djmil/cordacheckers/states/Piece.java

@@ -1,24 +0,0 @@
-package djmil.cordacheckers.states;
-
-import net.corda.v5.base.annotations.CordaSerializable;
-
-@CordaSerializable
-public class Piece {
-    
-    @CordaSerializable
-    public enum Type {
-        MAN,
-        KING,
-    }
-
-    @CordaSerializable
-    public enum Color {
-        WHITE,
-        BLACK,
-    }
-
-    Color color;
-    Type type;
-
-    
-}

corda/workflows/src/main/java/djmil/cordacheckers/FlowResult.java

@@ -1,28 +1,18 @@
 package djmil.cordacheckers;
 
 import net.corda.v5.application.marshalling.JsonMarshallingService;
-import net.corda.v5.crypto.SecureHash;
 
 public class FlowResult {
     public final Object successStatus;
-    public final String transactionId;
     public final String failureStatus;
 
     public FlowResult(Object success) {
         this.successStatus = success;
-        this.transactionId = null;
-        this.failureStatus = null;
-    }
-
-    public FlowResult(Object success, SecureHash transactionId) {
-        this.successStatus = success;
-        this.transactionId = transactionId.toString();
         this.failureStatus = null;
     }
 
     public FlowResult(Exception exception) {
         this.successStatus = null;
-        this.transactionId = null;
         this.failureStatus = exception.getMessage();
     }
 

corda/workflows/src/main/java/djmil/cordacheckers/gameproposal/ActionFlow.java

@@ -1,6 +1,8 @@
 package djmil.cordacheckers.gameproposal;
 
+import java.util.Arrays;
 import java.util.List;
+import java.util.Map;
 import java.util.UUID;
 import java.util.stream.Collectors;
 
@@ -8,15 +10,21 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import djmil.cordacheckers.FlowResult;
+import djmil.cordacheckers.contracts.GameProposalContract;
+import djmil.cordacheckers.states.GameProposalResolutionState;
 import djmil.cordacheckers.states.GameProposalState;
 import net.corda.v5.application.flows.ClientRequestBody;
 import net.corda.v5.application.flows.ClientStartableFlow;
 import net.corda.v5.application.flows.CordaInject;
-import net.corda.v5.application.flows.FlowEngine;
+import net.corda.v5.application.flows.InitiatingFlow;
 import net.corda.v5.application.marshalling.JsonMarshallingService;
+import net.corda.v5.application.membership.MemberLookup;
+import net.corda.v5.application.messaging.FlowMessaging;
+import net.corda.v5.application.messaging.FlowSession;
 import net.corda.v5.base.annotations.Suspendable;
 import net.corda.v5.base.exceptions.CordaRuntimeException;
-import net.corda.v5.crypto.SecureHash;
+import net.corda.v5.base.types.MemberX500Name;
+import net.corda.v5.ledger.utxo.Command;
 import net.corda.v5.ledger.utxo.StateAndRef;
 import net.corda.v5.ledger.utxo.UtxoLedgerService;
 import net.corda.v5.ledger.utxo.transaction.UtxoSignedTransaction;
@@ -25,8 +33,7 @@ import net.corda.v5.ledger.utxo.transaction.UtxoTransactionBuilder;
 import java.time.Duration;
 import java.time.Instant;
 
-import static djmil.cordacheckers.contracts.GameProposalContract.Action;
-
+@InitiatingFlow(protocol = "game-proposal-action")
 public class ActionFlow implements ClientStartableFlow {
 
     private final static Logger log = LoggerFactory.getLogger(CreateFlow.class);
@@ -38,24 +45,33 @@ public class ActionFlow implements ClientStartableFlow {
     public UtxoLedgerService ledgerService;
 
     @CordaInject
-    public FlowEngine flowEngine;
+    public FlowMessaging flowMessaging;
+
+    @CordaInject
+    public MemberLookup memberLookup;
+
+    private final static Map<GameProposalResolutionState.Resolution, Command> resoultion2command = Map.ofEntries(
+        Map.entry(GameProposalResolutionState.Resolution.CANCEL, new GameProposalContract.Cancel()),
+        Map.entry(GameProposalResolutionState.Resolution.REJECT, new GameProposalContract.Reject()),
+        Map.entry(GameProposalResolutionState.Resolution.ACCEPT, new GameProposalContract.Accept())
+    );
 
     @Override
     @Suspendable
     public String call(ClientRequestBody requestBody) {
         try {
-            final ActionFlowArgs args = requestBody.getRequestBodyAs(jsonMarshallingService, ActionFlowArgs.class);
-            final Action action = args.getAction();
+            ActionFlowArgs args = requestBody.getRequestBodyAs(jsonMarshallingService, ActionFlowArgs.class);
 
-            final StateAndRef<GameProposalState> inputState = findUnconsumedGameProposalState(args.getGameProposalUuid());
+            StateAndRef<GameProposalState> inputState = findUnconsumedGameProposalState(args.getGameProposalUuid());
         
-            final UtxoSignedTransaction trx = prepareSignedTransaction(action, inputState);
+            GameProposalResolutionState outputState = new GameProposalResolutionState(
+                args.getAction(),
+                inputState.getState().getContractState()
+                );
 
-            final SecureHash trxId = this.flowEngine
-                .subFlow( new CommitSubFlow(trx, action.getReceiver(inputState)) );
+            String trxResult = doTrunsaction(inputState, outputState);
 
-            return new FlowResult(action+"ED", trxId)  // REJECT+ED
-                .toJsonEncodedString(jsonMarshallingService);
+            return new FlowResult(trxResult).toJsonEncodedString(jsonMarshallingService);
         } 
         catch (Exception e) {
             log.warn("GameProposalAction flow failed to process utxo request body " + requestBody + 
@@ -67,7 +83,7 @@ public class ActionFlow implements ClientStartableFlow {
     @Suspendable
     private StateAndRef<GameProposalState> findUnconsumedGameProposalState (UUID gameProposalUuid) {
         /*
-         * Get list of all unconsumed aka 'active' GameProposalStates, then filter by UUID.
+         * Get list of all unconsumed aka 'actuve' GameProposalStates, then filter by UUID.
          * Note, this is an inefficient way to perform this operation if there are a large
          * number of 'active' GameProposals exists in storage.
          */
@@ -86,24 +102,26 @@ public class ActionFlow implements ClientStartableFlow {
     }
 
     @Suspendable
-    private UtxoSignedTransaction prepareSignedTransaction(
-        Action action,
-        StateAndRef<GameProposalState> inputState
-    ) {
-        UtxoTransactionBuilder trxBuilder = ledgerService.createTransactionBuilder()
+    private String doTrunsaction(StateAndRef<GameProposalState> inputState, GameProposalResolutionState outputState) {
+        UtxoTransactionBuilder txBuilder = ledgerService.createTransactionBuilder()
             .setNotary(inputState.getState().getNotaryName())
             .setTimeWindowBetween(Instant.now(), Instant.now().plusMillis(Duration.ofDays(1).toMillis()))
             .addInputState(inputState.getRef())
-            .addCommand(action)
-            .addSignatories(inputState.getState().getContractState().getParticipants());
+            .addOutputState(outputState)
+            .addCommand(resoultion2command.get(outputState.outcome))
+            .addSignatories(outputState.getParticipants());
 
-        if (action == Action.ACCEPT) {
-            // TODO
-            // .addOutputState(outputState)
-            throw new RuntimeException(action +" unimplemented");
-        }
+        UtxoSignedTransaction signedTransaction = txBuilder.toSignedTransaction();
 
-        return trxBuilder.toSignedTransaction();
+        FlowSession session = flowMessaging.initiateFlow(
+            outputState.getRecipient(inputState.getState().getContractState())
+            );
+
+        List<FlowSession> sessionsList = Arrays.asList(session);
+
+        ledgerService.finalize(signedTransaction, sessionsList);
+
+        return outputState.getOutcome()+"ED"; // REJECT+ED
     }
 
 }

corda/workflows/src/main/java/djmil/cordacheckers/gameproposal/ActionFlowArgs.java

@@ -2,7 +2,8 @@ package djmil.cordacheckers.gameproposal;
 
 import java.util.UUID;
 
-import djmil.cordacheckers.contracts.GameProposalContract;
+import djmil.cordacheckers.states.GameProposalResolutionState;
+import djmil.cordacheckers.states.GameProposalResolutionState.Resolution;
 
 public class ActionFlowArgs {
     private UUID gameProposalUuid;
@@ -14,8 +15,8 @@ public class ActionFlowArgs {
         this.action = null;
     }
     
-    public GameProposalContract.Action getAction() {
-        return GameProposalContract.Action.valueOf(this.action);
+    public Resolution getAction() {
+        return GameProposalResolutionState.Resolution.valueOf(this.action);
     }
 
     public UUID getGameProposalUuid() {

corda/workflows/src/main/java/djmil/cordacheckers/gameproposal/ActionResponder.java

@@ -0,0 +1,83 @@
+package djmil.cordacheckers.gameproposal;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import djmil.cordacheckers.contracts.GameProposalContract.Accept;
+import djmil.cordacheckers.contracts.GameProposalContract.Cancel;
+import djmil.cordacheckers.contracts.GameProposalContract.Reject;
+import djmil.cordacheckers.states.GameProposalState;
+import net.corda.v5.application.flows.CordaInject;
+import net.corda.v5.application.flows.InitiatedBy;
+import net.corda.v5.application.flows.ResponderFlow;
+import net.corda.v5.application.membership.MemberLookup;
+import net.corda.v5.application.messaging.FlowSession;
+import net.corda.v5.base.annotations.Suspendable;
+import net.corda.v5.base.exceptions.CordaRuntimeException;
+import net.corda.v5.base.types.MemberX500Name;
+import net.corda.v5.ledger.utxo.Command;
+import net.corda.v5.ledger.utxo.UtxoLedgerService;
+import net.corda.v5.ledger.utxo.transaction.UtxoSignedTransaction;
+import net.corda.v5.ledger.utxo.transaction.UtxoTransactionValidator;
+
+@InitiatedBy(protocol = "game-proposal-action")
+public class ActionResponder implements ResponderFlow {
+    private final static Logger log = LoggerFactory.getLogger(CreateResponder.class);
+
+    @CordaInject
+    public MemberLookup memberLookup;
+
+    @CordaInject
+    public UtxoLedgerService utxoLedgerService;
+    
+    @Suspendable
+    @Override
+    public void call(FlowSession session) {
+        try {
+            UtxoTransactionValidator txValidator = ledgerTransaction -> {
+                GameProposalState gameProposal = (GameProposalState) ledgerTransaction.getInputContractStates().get(0);
+
+                Command command = ledgerTransaction.getCommands(Command.class).get(0);
+
+                if (!checkParticipants(gameProposal, session.getCounterparty(), command)) {
+                    throw new CordaRuntimeException("Failed verification");
+                }
+
+                log.info("Verified the transaction - " + ledgerTransaction.getId());
+            };
+
+            // Calls receiveFinality() function which provides the responder to the finalise() function
+            // in the Initiating Flow. Accepts a lambda validator containing the business logic to decide whether
+            // responder should sign the Transaction.
+            UtxoSignedTransaction finalizedSignedTransaction = utxoLedgerService
+                    .receiveFinality(session, txValidator)
+                    .getTransaction();
+
+            log.info("Finished responder flow - " + finalizedSignedTransaction.getId());
+        }
+        // Soft fails the flow and log the exception.
+        catch(Exception e)
+        {
+            log.warn("Exceptionally finished responder flow", e);
+        }
+    }
+
+    @Suspendable
+    Boolean checkParticipants(GameProposalState gameProposal, MemberX500Name counterpartyName, Command command) {
+        MemberX500Name myName = memberLookup.myInfo().getName();
+
+        if (command instanceof Reject || command instanceof Accept) {
+            if (gameProposal.getRecipient().compareTo(counterpartyName) == 0 && 
+                gameProposal.getSender().compareTo(myName) == 0)
+                return true;
+        }
+
+        if (command instanceof Cancel) {
+            if (gameProposal.getRecipient().compareTo(myName) == 0 && 
+                gameProposal.getSender().compareTo(counterpartyName) == 0)
+                return true;
+        }
+
+        return false;
+    }
+}

corda/workflows/src/main/java/djmil/cordacheckers/gameproposal/CommitResponderFlow.java

@@ -1,95 +0,0 @@
-package djmil.cordacheckers.gameproposal;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import djmil.cordacheckers.states.GameProposalState;
-import net.corda.v5.application.flows.CordaInject;
-import net.corda.v5.application.flows.InitiatedBy;
-import net.corda.v5.application.flows.ResponderFlow;
-import net.corda.v5.application.membership.MemberLookup;
-import net.corda.v5.application.messaging.FlowSession;
-import net.corda.v5.base.annotations.Suspendable;
-import net.corda.v5.base.exceptions.CordaRuntimeException;
-import net.corda.v5.base.types.MemberX500Name;
-import net.corda.v5.ledger.utxo.UtxoLedgerService;
-import net.corda.v5.ledger.utxo.transaction.UtxoLedgerTransaction;
-import net.corda.v5.ledger.utxo.transaction.UtxoSignedTransaction;
-import net.corda.v5.ledger.utxo.transaction.UtxoTransactionValidator;
-
-import static djmil.cordacheckers.contracts.GameProposalContract.Action;
-
-@InitiatedBy(protocol = "game-proposal")
-public class CommitResponderFlow implements ResponderFlow {
-    private final static Logger log = LoggerFactory.getLogger(CommitResponderFlow.class);
-
-    @CordaInject
-    public MemberLookup memberLookup;
-
-    @CordaInject
-    public UtxoLedgerService utxoLedgerService;
-    
-    @Suspendable
-    @Override
-    public void call(FlowSession session) {
-        try {
-            UtxoTransactionValidator txValidator = ledgerTransaction -> {
-                final Action action = ledgerTransaction.getCommands(Action.class).get(0);
-
-                final GameProposalState gameProposal = getGameProposal(ledgerTransaction); 
-
-                checkSessionParticipants(session, gameProposal, action);
-
-                /*
-                 * Other checks / actions ?
-                 */
-
-                log.info("Verified the transaction - " + ledgerTransaction.getId());
-            };
-
-            UtxoSignedTransaction finalizedSignedTransaction = utxoLedgerService
-                    .receiveFinality(session, txValidator)
-                    .getTransaction();
-
-            log.info("Finished responder flow - " + finalizedSignedTransaction.getId());
-        }
-        catch(Exception e) {
-            log.warn("Responder flow failed: ", e);
-        }
-    }
-
-    @Suspendable
-    void checkSessionParticipants(
-        FlowSession session,
-        GameProposalState gameProposal,
-        Action action
-    ) {
-        final MemberX500Name myName = memberLookup.myInfo().getName();
-        final MemberX500Name otherName = session.getCounterparty();
-
-        if (action.getRespondent(gameProposal).compareTo(myName) != 0)
-            throw new CordaRuntimeException("Bad GameProposal acquirer: expected '"+myName+"', actual '" +gameProposal.getAcquier() +"'");
-        
-        if (action.getInitiator(gameProposal).compareTo(otherName) != 0)
-            throw new CordaRuntimeException("Bad GameProposal issuer: expected '"+otherName+"', actual '"+gameProposal.getIssuer()+"'");
-    }
-
-    @Suspendable
-    GameProposalState getGameProposal(UtxoLedgerTransaction trx) {
-        final Action action = trx.getCommands(Action.class).get(0);
-        
-        switch (action) {
-            case CREATE:
-                return (GameProposalState)trx.getOutputContractStates().get(0);
-
-            case ACCEPT:
-            case REJECT:
-            case CANCEL:
-                return (GameProposalState)trx.getInputContractStates().get(0);
-
-            default:
-                throw new RuntimeException(Action.UNSUPPORTED_ACTION_VALUE_OF +action);
-        }
-
-    }
-}

corda/workflows/src/main/java/djmil/cordacheckers/gameproposal/CommitSubFlow.java

@@ -1,60 +0,0 @@
-package djmil.cordacheckers.gameproposal;
-
-import java.util.Arrays;
-import java.util.List;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import net.corda.v5.application.flows.CordaInject;
-import net.corda.v5.application.flows.InitiatingFlow;
-import net.corda.v5.application.flows.SubFlow;
-import net.corda.v5.application.messaging.FlowMessaging;
-import net.corda.v5.application.messaging.FlowSession;
-import net.corda.v5.base.annotations.Suspendable;
-import net.corda.v5.base.types.MemberX500Name;
-import net.corda.v5.crypto.SecureHash;
-import net.corda.v5.ledger.utxo.UtxoLedgerService;
-import net.corda.v5.ledger.utxo.transaction.UtxoSignedTransaction;
-
-@InitiatingFlow(protocol = "game-proposal")
-public class CommitSubFlow implements SubFlow<SecureHash> {
-
-    private final static Logger log = LoggerFactory.getLogger(CommitSubFlow.class);
-    private final UtxoSignedTransaction signedTransaction;
-    private final MemberX500Name respondenName;
-
-    public CommitSubFlow(UtxoSignedTransaction signedTransaction, MemberX500Name respondenName) {
-        this.signedTransaction = signedTransaction;
-        this.respondenName = respondenName;
-    }
-
-    @CordaInject
-    public UtxoLedgerService ledgerService;
-
-    @CordaInject
-    public FlowMessaging flowMessaging;
-
-    @Override
-    @Suspendable
-    public SecureHash call() {
-        log.info("GamePropsal commit started");
-
-        final FlowSession session = flowMessaging.initiateFlow(this.respondenName);
-
-        /*
-         * Calls the Corda provided finalise() function which gather signatures from the counterparty,
-         * notarises the transaction and persists the transaction to each party's vault.
-         */
-
-        final List<FlowSession> sessionsList = Arrays.asList(session);
-
-        final SecureHash trxId = ledgerService
-            .finalize(this.signedTransaction, sessionsList)
-            .getTransaction()
-            .getId();
-
-        log.info("GamePropsal commit " +trxId);
-        return trxId;
-    }
-}

corda/workflows/src/main/java/djmil/cordacheckers/gameproposal/CreateFlow.java

@@ -4,8 +4,8 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import djmil.cordacheckers.FlowResult;
+import djmil.cordacheckers.contracts.GameProposalContract;
 import djmil.cordacheckers.states.GameProposalState;
-import djmil.cordacheckers.states.Piece;
 import net.corda.v5.application.flows.ClientRequestBody;
 import net.corda.v5.application.flows.ClientStartableFlow;
 import net.corda.v5.application.flows.CordaInject;
@@ -13,23 +13,26 @@ import net.corda.v5.application.flows.FlowEngine;
 import net.corda.v5.application.flows.InitiatingFlow;
 import net.corda.v5.application.marshalling.JsonMarshallingService;
 import net.corda.v5.application.membership.MemberLookup;
+import net.corda.v5.application.messaging.FlowMessaging;
+import net.corda.v5.application.messaging.FlowSession;
 import net.corda.v5.base.annotations.Suspendable;
 import net.corda.v5.base.types.MemberX500Name;
-import net.corda.v5.crypto.SecureHash;
 import net.corda.v5.ledger.common.NotaryLookup;
 import net.corda.v5.ledger.utxo.UtxoLedgerService;
 import net.corda.v5.ledger.utxo.transaction.UtxoSignedTransaction;
+import net.corda.v5.ledger.utxo.transaction.UtxoTransactionBuilder;
 import net.corda.v5.membership.MemberInfo;
 import net.corda.v5.membership.NotaryInfo;
 
 import static java.util.Objects.requireNonNull;
-import static djmil.cordacheckers.contracts.GameProposalContract.Action;
 
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Arrays;
+import java.util.List;
 import java.util.UUID;
 
+@InitiatingFlow(protocol = "game-proposal-create")
 public class CreateFlow implements ClientStartableFlow{
 
      private final static Logger log = LoggerFactory.getLogger(CreateFlow.class);
@@ -49,22 +52,19 @@ public class CreateFlow implements ClientStartableFlow{
      @CordaInject
      public FlowEngine flowEngine;
 
+     @CordaInject
+     public FlowMessaging flowMessaging;
+
      @Suspendable
      @Override
      public String call(ClientRequestBody requestBody) {
           try {
                log.info("flow: Create Game Proposal");
-               final Action actino = Action.CREATE;
 
-               final GameProposalState newGameProposal = buildGameProposalStateFrom(requestBody);
+               GameProposalState gameProposal = buildGameProposalStateFrom(requestBody);
+               String trxResult = doTrunsaction(gameProposal);
 
-               final UtxoSignedTransaction trx = prepareSignedTransaction(newGameProposal);
-
-               final SecureHash trxId = this.flowEngine
-                    .subFlow(new CommitSubFlow(trx, actino.getRespondent(newGameProposal)));
-
-               return new FlowResult(newGameProposal.getId(), trxId)
-                    .toJsonEncodedString(jsonMarshallingService);
+               return new FlowResult(trxResult).toJsonEncodedString(jsonMarshallingService);
           } 
           catch (Exception e) {
                log.warn("CreateGameProposal flow failed to process utxo request body " + requestBody + 
@@ -77,10 +77,10 @@ public class CreateFlow implements ClientStartableFlow{
      private GameProposalState buildGameProposalStateFrom(ClientRequestBody requestBody) {
           CreateFlowArgs args = requestBody.getRequestBodyAs(jsonMarshallingService, CreateFlowArgs.class);
 
-          Piece.Color opponentColor = Piece.Color.valueOf(args.opponentColor);
+          GameProposalState.Color opponentColor = GameProposalState.Color.valueOf(args.opponentColor);
           if (opponentColor == null) {
                throw new RuntimeException("Allowed values for opponentColor are: "
-                    + Piece.Color.WHITE.name() +", "  + Piece.Color.BLACK.name() 
+                    + GameProposalState.Color.WHITE.name() +", "  + GameProposalState.Color.BLACK.name() 
                     + ". Actual value was: " + args.opponentColor);
           }
 
@@ -101,15 +101,24 @@ public class CreateFlow implements ClientStartableFlow{
      }
 
      @Suspendable
-     private UtxoSignedTransaction prepareSignedTransaction(GameProposalState outputGameProposalState) {     
-          final NotaryInfo notary = notaryLookup.getNotaryServices().iterator().next();
+     private String doTrunsaction(GameProposalState gameProposal) {     
+          NotaryInfo notary = notaryLookup.getNotaryServices().iterator().next();
 
-          return ledgerService.createTransactionBuilder()
+          UtxoTransactionBuilder txBuilder = ledgerService.createTransactionBuilder()
                .setNotary(notary.getName())
                .setTimeWindowBetween(Instant.now(), Instant.now().plusMillis(Duration.ofDays(1).toMillis()))
-               .addOutputState(outputGameProposalState)
-               .addCommand(Action.CREATE)
-               .addSignatories(outputGameProposalState.getParticipants())
-               .toSignedTransaction();
+               .addOutputState(gameProposal)
+               .addCommand(new GameProposalContract.Create())
+               .addSignatories(gameProposal.getParticipants());
+
+          UtxoSignedTransaction signedTransaction = txBuilder.toSignedTransaction();
+
+          FlowSession session = flowMessaging.initiateFlow(gameProposal.getRecipient());
+
+          List<FlowSession> sessionsList = Arrays.asList(session);
+
+          ledgerService.finalize(signedTransaction, sessionsList);
+
+          return gameProposal.id.toString();
      }
 }

corda/workflows/src/main/java/djmil/cordacheckers/gameproposal/CreateResponder.java

@@ -0,0 +1,72 @@
+package djmil.cordacheckers.gameproposal;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import djmil.cordacheckers.states.GameProposalState;
+import net.corda.v5.application.flows.CordaInject;
+import net.corda.v5.application.flows.InitiatedBy;
+import net.corda.v5.application.flows.ResponderFlow;
+import net.corda.v5.application.membership.MemberLookup;
+import net.corda.v5.application.messaging.FlowSession;
+import net.corda.v5.base.annotations.Suspendable;
+import net.corda.v5.base.exceptions.CordaRuntimeException;
+import net.corda.v5.base.types.MemberX500Name;
+import net.corda.v5.ledger.utxo.UtxoLedgerService;
+import net.corda.v5.ledger.utxo.transaction.UtxoSignedTransaction;
+import net.corda.v5.ledger.utxo.transaction.UtxoTransactionValidator;
+
+@InitiatedBy(protocol = "game-proposal-create")
+public class CreateResponder implements ResponderFlow {
+    private final static Logger log = LoggerFactory.getLogger(CreateResponder.class);
+
+    @CordaInject
+    public MemberLookup memberLookup;
+
+    @CordaInject
+    public UtxoLedgerService utxoLedgerService;
+    
+    @Suspendable
+    @Override
+    public void call(FlowSession session) {
+        try {
+            // Defines the lambda validator used in receiveFinality below.
+            UtxoTransactionValidator txValidator = ledgerTransaction -> {
+                GameProposalState gameProposal = (GameProposalState) ledgerTransaction.getOutputContractStates().get(0);
+                // Uses checkForBannedWords() and checkMessageFromMatchesCounterparty() functions
+                // to check whether to sign the transaction.
+                if (!checkParticipants(gameProposal, session.getCounterparty())) {
+                    throw new CordaRuntimeException("Failed verification");
+                }
+
+                log.info("Verified the transaction - " + ledgerTransaction.getId());
+            };
+
+            // Calls receiveFinality() function which provides the responder to the finalise() function
+            // in the Initiating Flow. Accepts a lambda validator containing the business logic to decide whether
+            // responder should sign the Transaction.
+            UtxoSignedTransaction finalizedSignedTransaction = utxoLedgerService
+                    .receiveFinality(session, txValidator)
+                    .getTransaction();
+
+            log.info("Finished responder flow - " + finalizedSignedTransaction.getId());
+        }
+        // Soft fails the flow and log the exception.
+        catch(Exception e)
+        {
+            log.warn("Exceptionally finished responder flow", e);
+        }
+    }
+
+    @Suspendable
+    Boolean checkParticipants(GameProposalState gameProposal, MemberX500Name counterpartyName) {
+        MemberX500Name myName = memberLookup.myInfo().getName();
+
+        if (gameProposal.getRecipient().compareTo(myName) == 0 && 
+            gameProposal.getSender().compareTo(counterpartyName) == 0)
+            return true;
+    
+        return false;
+    }
+    
+}

corda/workflows/src/main/java/djmil/cordacheckers/gameproposal/ListItem.java

@@ -10,26 +10,26 @@ import djmil.cordacheckers.states.GameProposalState;
 // and a UUID. It is possible to create custom serializers for the JsonMarshallingService in the future.
 
 public class ListItem {
-    public final String issuer;
-    public final String acquier;
-    public final String acquierColor;
+    public final String sender;
+    public final String recipient;
+    public final String recipientColor;
     public final String message;
     public final UUID id;
 
     // Serialisation service requires a default constructor
     public ListItem() { 
-        this.issuer = null;
-        this.acquier = null;
-        this.acquierColor = null;
+        this.sender = null;
+        this.recipient = null;
+        this.recipientColor = null;
         this.message = null;
         this.id = null;
     }
 
     public ListItem(GameProposalState state) {
-        this.issuer  = state.getIssuer().getCommonName();
-        this.acquier = state.getAcquier().getCommonName();
-        this.acquierColor = state.getRecipientColor().name();
-        this.message = state.getMessage();
-        this.id      = state.getId();
+        this.sender    = state.getSender().getCommonName();
+        this.recipient = state.getRecipient().getCommonName();
+        this.recipientColor = state.getRecipientColor().name();
+        this.message   = state.getMessage();
+        this.id        = state.getId();
     }
 }