WIP. Probably need to cherry pick stuff out of here.

Added ClientConnection and server-side handshake.
Added MessageSerialiser and Deserialiser.
#story[1095]

racevisionGame/src/main/java/mock/model/SourceIdAllocator.java

@@ -0,0 +1,70 @@
+package mock.model;
+
+
+import mock.exceptions.SourceIDAllocationException;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * This class is responsible for allocating boat source IDs for use in a race, upon request.
+ */
+public class SourceIdAllocator {
+
+
+    /**
+     * This list contains all unallocated source IDs.
+     */
+    List<Integer> unallocatedIDs = new ArrayList<>();
+
+
+    /**
+     * This list contains all allocated source IDs.
+     */
+    List<Integer> allocatedIDs = new ArrayList<>();
+
+
+    /**
+     * Creates a source ID allocator, using the given list of unallocated source IDs.
+     * @param unallocatedIDs List of unallocated source IDs.
+     */
+    public SourceIdAllocator(List<Integer> unallocatedIDs) {
+        //We need to copy the list.
+        this.unallocatedIDs.addAll(unallocatedIDs);
+    }
+
+
+    /**
+     * Allocates a source ID for a boat.
+     * @return The allocated source ID.
+     * @throws SourceIDAllocationException Thrown if we cannot allocate any more source IDs.
+     */
+    public synchronized int  allocateSourceID() throws SourceIDAllocationException {
+
+        if (!unallocatedIDs.isEmpty()) {
+
+            int sourceID = unallocatedIDs.remove(0);
+
+            allocatedIDs.add(sourceID);
+
+            return sourceID;
+
+        } else {
+            throw new SourceIDAllocationException("Could not allocate a source ID.");
+
+        }
+    }
+
+
+    /**
+     * Returns a source ID to the source ID allocator, so that it can be reused.
+     * @param sourceID Source ID to return.
+     */
+    public void returnSourceID(Integer sourceID) {
+
+        //We remove an Integer, not an int, so that we remove by value not by index.
+        allocatedIDs.remove(sourceID);
+
+        unallocatedIDs.add(sourceID);
+    }
+}