preparing the first OT implementation for removing leaderboard columns

java/com.sap.sailing.operationaltransformation/src/com/sap/sailing/operationaltransformation/ClientServerOperationPair.java

@@ -17,4 +17,14 @@ public class ClientServerOperationPair<O extends Operation<?>> {
     public O getServerOp() {
         return serverOp;
     }
+    
+    @SuppressWarnings("unchecked")
+    public static <O extends Operation<S>, S> O getNoOp() {
+        return (O) new Operation<S>() {
+            @Override
+            public S applyTo(S toState) {
+                return toState; // don't change anything, return state unchanged
+            }
+        };
+    }
 }

java/com.sap.sailing.operationaltransformation/src/com/sap/sailing/operationaltransformation/Operation.java

@@ -17,4 +17,5 @@ public interface Operation<S> extends Cloneable {
      * @return the state produced by applying this operation to <tt>toState</tt>
      */
     S applyTo(S toState);
+    
 }

java/com.sap.sailing.operationaltransformation/src/com/sap/sailing/operationaltransformation/Transformer.java

@@ -6,7 +6,11 @@ public interface Transformer<O extends Operation<?>> {
      * based on the same state. The complementary pair of operations is computed
      * such that if the client applies the server operation returned, and the
      * server applies the client operation returned, both end up in equal states
-     * again.
+     * again.<p>
+     * 
+     * If a resulting operation is supposed to not have any effects, return the
+     * {@link ClientServerOperationPair#getNoOp()} operation, but never <code>null</code>
+     * as any of the operations in the resulting pair.
      */
     ClientServerOperationPair<O> transform(O clientOp, O serverOp);
 }

java/com.sap.sailing.server/src/com/sap/sailing/server/operationaltransformation/AbstractLeaderboardColumnOperation.java

@@ -0,0 +1,25 @@
+package com.sap.sailing.server.operationaltransformation;
+
+
+public abstract class AbstractLeaderboardColumnOperation extends AbstractRacingEventServiceOperation {
+    private final String leaderboardName;
+    private final String columnName;
+    
+    public AbstractLeaderboardColumnOperation(String leaderboardName, String columnName) {
+        super();
+        this.leaderboardName = leaderboardName;
+        this.columnName = columnName;
+    }
+
+    public String getLeaderboardName() {
+        return leaderboardName;
+    }
+
+    public String getColumnName() {
+        return columnName;
+    }
+    
+    protected boolean affectsSameColumn(AbstractLeaderboardColumnOperation other) {
+        return getLeaderboardName().equals(other.getLeaderboardName()) && getColumnName().equals(other.getColumnName());
+    }
+}

java/com.sap.sailing.server/src/com/sap/sailing/server/operationaltransformation/AbstractRacingEventServiceOperation.java

@@ -0,0 +1,33 @@
+package com.sap.sailing.server.operationaltransformation;
+
+
+/**
+ * Performs identical transformations for all operation types by simply returning the operation passed. Subclasses need
+ * to override the transformation methods for those operation types that have an impact for them.
+ * 
+ * @author Axel Uhl (d043530)
+ * 
+ */
+public abstract class AbstractRacingEventServiceOperation implements RacingEventServiceOperation {
+    @Override
+    public RacingEventServiceOperation transformClientRenameLeaderboardColumnOp(
+            RenameLeaderboardColumn renameLeaderboardColumnClientOp) {
+        return renameLeaderboardColumnClientOp;
+    }
+
+    @Override
+    public RacingEventServiceOperation transformServerRenameLeaderboardColumnOp(
+            RenameLeaderboardColumn renameLeaderboardColumnServerOp) {
+        return renameLeaderboardColumnServerOp;
+    }
+
+    @Override
+    public RacingEventServiceOperation transformServerRemoveColumnFromLeaderboard(RemoveColumnFromLeaderboard removeColumnFromLeaderboardServerOp) {
+        return removeColumnFromLeaderboardServerOp;
+    }
+
+    @Override
+    public RacingEventServiceOperation transformClientRemoveColumnFromLeaderboard(RemoveColumnFromLeaderboard removeColumnFromLeaderboardClientOp) {
+        return removeColumnFromLeaderboardClientOp;
+    }
+}

java/com.sap.sailing.server/src/com/sap/sailing/server/operationaltransformation/AddColumnToLeaderboard.java

@@ -2,27 +2,35 @@ package com.sap.sailing.server.operationaltransformation;
 
 import com.sap.sailing.server.RacingEventService;
 
-public class AddColumnToLeaderboard implements RacingEventServiceOperation {
-    private final String columnName;
-    private final String leaderboardName;
+/**
+ * Doesn't transform for the {@link RemoveColumnFromLeaderboard} because only existing leaderboards can be removed,
+ * and adding is only possible for non-existing names.
+ * 
+ * @author Axel Uhl (d043530)
+ *
+ */
+public class AddColumnToLeaderboard extends AbstractLeaderboardColumnOperation {
     private final boolean medalRace;
     
-    
     public AddColumnToLeaderboard(String columnName, String leaderboardName, boolean medalRace) {
-        super();
-        this.columnName = columnName;
-        this.leaderboardName = leaderboardName;
+        super(leaderboardName, columnName);
         this.medalRace = medalRace;
     }
 
     @Override
     public RacingEventService applyTo(RacingEventService toState) {
-        toState.addColumnToLeaderboard(columnName, leaderboardName, medalRace);
+        toState.addColumnToLeaderboard(getColumnName(), getLeaderboardName(), medalRace);
         return toState;
     }
 
     @Override
-    public RacingEventServiceOperation transformFor(RacingEventServiceOperation peerOp) {
+    public RacingEventServiceOperation transformClientOp(RacingEventServiceOperation serverOp) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public RacingEventServiceOperation transformServerOp(RacingEventServiceOperation clientOp) {
         // TODO Auto-generated method stub
         return null;
     }

java/com.sap.sailing.server/src/com/sap/sailing/server/operationaltransformation/MoveLeaderboardColumnDown.java

@@ -1,28 +1,55 @@
 package com.sap.sailing.server.operationaltransformation;
 
+import com.sap.sailing.operationaltransformation.ClientServerOperationPair;
 import com.sap.sailing.server.RacingEventService;
 
-public class MoveLeaderboardColumnDown implements RacingEventServiceOperation {
-    private final String leaderboardName;
-    private final String columnName;
+public class MoveLeaderboardColumnDown extends AbstractLeaderboardColumnOperation {
     
     public MoveLeaderboardColumnDown(String leaderboardName, String columnName) {
-        super();
-        this.leaderboardName = leaderboardName;
-        this.columnName = columnName;
+        super(leaderboardName, columnName);
     }
 
 
     @Override
     public RacingEventService applyTo(RacingEventService toState) {
-        toState.moveLeaderboardColumnDown(leaderboardName, columnName);
+        toState.moveLeaderboardColumnDown(getLeaderboardName(), getColumnName());
         return toState;
     }
 
 
     @Override
-    public RacingEventServiceOperation transformFor(RacingEventServiceOperation peerOp) {
+    public RacingEventServiceOperation transformClientOp(RacingEventServiceOperation serverOp) {
         // TODO Auto-generated method stub
         return null;
     }
+
+
+    @Override
+    public RacingEventServiceOperation transformServerOp(RacingEventServiceOperation clientOp) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+
+    @Override
+    public RacingEventServiceOperation transformServerRemoveColumnFromLeaderboard(
+            RemoveColumnFromLeaderboard removeColumnFromLeaderboardServerOp) {
+        if (affectsSameColumn(removeColumnFromLeaderboardServerOp)) {
+            return ClientServerOperationPair.getNoOp();
+        } else {
+            return removeColumnFromLeaderboardServerOp;
+        }
+    }
+
+
+    @Override
+    public RacingEventServiceOperation transformClientRemoveColumnFromLeaderboard(
+            RemoveColumnFromLeaderboard removeColumnFromLeaderboardClientOp) {
+        if (affectsSameColumn(removeColumnFromLeaderboardClientOp)) {
+            return ClientServerOperationPair.getNoOp();
+        } else {
+            return removeColumnFromLeaderboardClientOp;
+        }
+    }
+    
 }

java/com.sap.sailing.server/src/com/sap/sailing/server/operationaltransformation/MoveLeaderboardColumnUp.java

@@ -1,28 +1,55 @@
 package com.sap.sailing.server.operationaltransformation;
 
+import com.sap.sailing.operationaltransformation.ClientServerOperationPair;
 import com.sap.sailing.server.RacingEventService;
 
-public class MoveLeaderboardColumnUp implements RacingEventServiceOperation {
-    private final String leaderboardName;
-    private final String columnName;
+public class MoveLeaderboardColumnUp extends AbstractLeaderboardColumnOperation {
     
     public MoveLeaderboardColumnUp(String leaderboardName, String columnName) {
-        super();
-        this.leaderboardName = leaderboardName;
-        this.columnName = columnName;
+        super(leaderboardName, columnName);
     }
 
 
     @Override
     public RacingEventService applyTo(RacingEventService toState) {
-        toState.moveLeaderboardColumnUp(leaderboardName, columnName);
+        toState.moveLeaderboardColumnUp(getLeaderboardName(), getColumnName());
         return toState;
     }
 
 
     @Override
-    public RacingEventServiceOperation transformFor(RacingEventServiceOperation peerOp) {
+    public RacingEventServiceOperation transformClientOp(RacingEventServiceOperation serverOp) {
         // TODO Auto-generated method stub
         return null;
     }
+
+
+    @Override
+    public RacingEventServiceOperation transformServerOp(RacingEventServiceOperation clientOp) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+
+    @Override
+    public RacingEventServiceOperation transformServerRemoveColumnFromLeaderboard(
+            RemoveColumnFromLeaderboard removeColumnFromLeaderboardServerOp) {
+        if (affectsSameColumn(removeColumnFromLeaderboardServerOp)) {
+            return ClientServerOperationPair.getNoOp();
+        } else {
+            return removeColumnFromLeaderboardServerOp;
+        }
+    }
+
+
+    @Override
+    public RacingEventServiceOperation transformClientRemoveColumnFromLeaderboard(
+            RemoveColumnFromLeaderboard removeColumnFromLeaderboardClientOp) {
+        if (affectsSameColumn(removeColumnFromLeaderboardClientOp)) {
+            return ClientServerOperationPair.getNoOp();
+        } else {
+            return removeColumnFromLeaderboardClientOp;
+        }
+    }
+
 }

java/com.sap.sailing.server/src/com/sap/sailing/server/operationaltransformation/OperationalTransformer.java

@@ -8,8 +8,9 @@ public class OperationalTransformer implements Transformer<RacingEventServiceOpe
     @Override
     public ClientServerOperationPair<RacingEventServiceOperation> transform(RacingEventServiceOperation clientOp,
             RacingEventServiceOperation serverOp) {
-        // TODO Auto-generated method stub
-        return null;
+        ClientServerOperationPair<RacingEventServiceOperation> result = new ClientServerOperationPair<RacingEventServiceOperation>(
+                clientOp.transformClientOp(serverOp), serverOp.transformServerOp(clientOp));
+        return result;
     }
 
 }

java/com.sap.sailing.server/src/com/sap/sailing/server/operationaltransformation/RacingEventServiceOperation.java

@@ -6,9 +6,34 @@ import com.sap.sailing.server.RacingEventService;
 
 public interface RacingEventServiceOperation extends Operation<RacingEventService> {
     /**
-     * Implements the specific transformation rule for the implementing subclass for the set of possible
-     * peer operations along which to transform this operation. See {@link Transformer#transform(Operation, Operation)}
-     * for the specification.
+     * Implements the specific transformation rule for the implementing subclass for the set of possible peer operations
+     * along which to transform this operation, assuming this is the client operation. See
+     * {@link Transformer#transform(Operation, Operation)} for the specification.
+     * 
+     * @return the result of transforming <code>this</code> operation along <code>serverOp</code>
      */
-    RacingEventServiceOperation transformFor(RacingEventServiceOperation peerOp);
+    RacingEventServiceOperation transformClientOp(RacingEventServiceOperation serverOp);
+
+    /**
+     * Implements the specific transformation rule for the implementing subclass for the set of possible peer operations
+     * along which to transform this operation, assuming this is the server operation. See
+     * {@link Transformer#transform(Operation, Operation)} for the specification.
+     * 
+     * @return the result of transforming <code>this</code> operation along <code>clientOp</code>
+     */
+    RacingEventServiceOperation transformServerOp(RacingEventServiceOperation clientOp);
+
+    /**
+     * Assumes this is the "server" operation and transforms the client's <code>removeColumnFromLeaderboardClientOp</code> according to this
+     * operation. The default implementation will probably pass on the untransformed client operation. However, if this
+     * operation deals with the leaderboard column being removed by <code>removeColumnFromLeaderboardClientOp</code>,
+     * the result will be <code>null</code>, meaning that this operation cannot be applied after the column has been removed.
+     */
+    RacingEventServiceOperation transformClientRemoveColumnFromLeaderboard(RemoveColumnFromLeaderboard removeColumnFromLeaderboardClientOp);
+
+    RacingEventServiceOperation transformServerRemoveColumnFromLeaderboard(RemoveColumnFromLeaderboard removeColumnFromLeaderboardServerOp);
+
+    RacingEventServiceOperation transformClientRenameLeaderboardColumnOp(RenameLeaderboardColumn renameLeaderboardColumnClientOp);
+
+    RacingEventServiceOperation transformServerRenameLeaderboardColumnOp(RenameLeaderboardColumn renameLeaderboardColumnServerOp);
 }

java/com.sap.sailing.server/src/com/sap/sailing/server/operationaltransformation/RemoveColumnFromLeaderboard.java

@@ -1,27 +1,51 @@
 package com.sap.sailing.server.operationaltransformation;
 
+import com.sap.sailing.operationaltransformation.ClientServerOperationPair;
 import com.sap.sailing.server.RacingEventService;
 
-public class RemoveColumnFromLeaderboard implements RacingEventServiceOperation {
-    private final String columnName;
-    private final String leaderboardName;
+public class RemoveColumnFromLeaderboard extends AbstractLeaderboardColumnOperation {
     
     
     public RemoveColumnFromLeaderboard(String columnName, String leaderboardName) {
-        super();
-        this.columnName = columnName;
-        this.leaderboardName = leaderboardName;
+        super(leaderboardName, columnName);
     }
 
     @Override
     public RacingEventService applyTo(RacingEventService toState) {
-        toState.removeLeaderboardColumn(leaderboardName, columnName);
+        toState.removeLeaderboardColumn(getLeaderboardName(), getColumnName());
         return toState;
     }
 
     @Override
-    public RacingEventServiceOperation transformFor(RacingEventServiceOperation peerOp) {
-        // TODO Auto-generated method stub
-        return null;
+    public RacingEventServiceOperation transformClientOp(RacingEventServiceOperation serverOp) {
+        return serverOp.transformClientRemoveColumnFromLeaderboard(this);
     }
+
+    @Override
+    public RacingEventServiceOperation transformServerOp(RacingEventServiceOperation clientOp) {
+        return clientOp.transformServerRemoveColumnFromLeaderboard(this);
+    }
+
+    @Override
+    public RacingEventServiceOperation transformServerRemoveColumnFromLeaderboard(
+            RemoveColumnFromLeaderboard removeColumnFromLeaderboardServerOp) {
+        if (affectsSameColumn(removeColumnFromLeaderboardServerOp)) {
+            // skip server's remove and hence only apply the client's remove operation
+            return ClientServerOperationPair.getNoOp();
+        } else {
+            return removeColumnFromLeaderboardServerOp;
+        }
+    }
+
+    @Override
+    public RacingEventServiceOperation transformClientRemoveColumnFromLeaderboard(
+            RemoveColumnFromLeaderboard removeColumnFromLeaderboardClientOp) {
+        if (affectsSameColumn(removeColumnFromLeaderboardClientOp)) {
+            // skip client's remove and hence only apply the server's remove operation
+            return ClientServerOperationPair.getNoOp();
+        } else {
+            return removeColumnFromLeaderboardClientOp;
+        }
+    }
+
 }

java/com.sap.sailing.server/src/com/sap/sailing/server/operationaltransformation/RenameLeaderboardColumn.java

@@ -1,30 +1,52 @@
 package com.sap.sailing.server.operationaltransformation;
 
+import com.sap.sailing.operationaltransformation.ClientServerOperationPair;
 import com.sap.sailing.server.RacingEventService;
 
-public class RenameLeaderboardColumn implements RacingEventServiceOperation {
-    private final String leaderboardName;
-    private final String oldColumnName;
+public class RenameLeaderboardColumn extends AbstractLeaderboardColumnOperation {
     private final String newColumnName;
     
     public RenameLeaderboardColumn(String leaderboardName, String oldColumnName, String newColumnName) {
-        super();
-        this.leaderboardName = leaderboardName;
-        this.oldColumnName = oldColumnName;
+        super(leaderboardName, oldColumnName);
         this.newColumnName = newColumnName;
     }
 
 
     @Override
     public RacingEventService applyTo(RacingEventService toState) {
-        toState.renameLeaderboardColumn(leaderboardName, oldColumnName, newColumnName);
+        toState.renameLeaderboardColumn(getLeaderboardName(), getColumnName(), newColumnName);
         return toState;
     }
 
+    @Override
+    public RacingEventServiceOperation transformClientOp(RacingEventServiceOperation serverOp) {
+        return serverOp.transformClientRenameLeaderboardColumnOp(this);
+    }
+
 
     @Override
-    public RacingEventServiceOperation transformFor(RacingEventServiceOperation peerOp) {
-        // TODO Auto-generated method stub
-        return null;
+    public RacingEventServiceOperation transformServerOp(RacingEventServiceOperation clientOp) {
+        return clientOp.transformServerRenameLeaderboardColumnOp(this);
     }
+
+    @Override
+    public RacingEventServiceOperation transformServerRemoveColumnFromLeaderboard(
+            RemoveColumnFromLeaderboard removeColumnFromLeaderboardServerOp) {
+        if (affectsSameColumn(removeColumnFromLeaderboardServerOp)) {
+            return ClientServerOperationPair.getNoOp(); // don't need the rename anymore when column is removed
+        } else {
+            return removeColumnFromLeaderboardServerOp;
+        }
+    }
+
+    @Override
+    public RacingEventServiceOperation transformClientRemoveColumnFromLeaderboard(
+            RemoveColumnFromLeaderboard removeColumnFromLeaderboardClientOp) {
+        if (affectsSameColumn(removeColumnFromLeaderboardClientOp)) {
+            return ClientServerOperationPair.getNoOp(); // don't need the rename anymore when column is removed
+        } else {
+            return removeColumnFromLeaderboardClientOp;
+        }
+    }
+
 }