minor refactorings;

added null checks

src/main/java/teetime/framework/AbstractCompositeStage.java

@@ -28,6 +28,9 @@ public abstract class AbstractCompositeStage extends Configuration {
 	private final ConfigurationContext context;
 
 	public AbstractCompositeStage(final ConfigurationContext context) {
+		if (null == context) {
+			throw new IllegalArgumentException("Context may not be null.");
+		}
 		this.context = context;
 	}
 

src/main/java/teetime/framework/ConfigurationContext.java

@@ -202,9 +202,9 @@ public abstract class ConfigurationContext extends Configuration {
 		if (sourcePort.getOwningStage().getInputPorts().length == 0 && !threadableStages.contains(sourcePort.getOwningStage())) {
 			addThreadableStage(sourcePort.getOwningStage());
 		}
-		if (sourcePort.pipe != null) {
-			LOGGER.warn("Overwritting existing pipe while connecting stages " + sourcePort.getOwningStage().getId() + " and " + targetPort.getOwningStage().getId()
-					+ ".");
+		if (sourcePort.getPipe() != null || targetPort.getPipe() != null) {
+			LOGGER.warn("Overwriting existing pipe while connecting stages " +
+					sourcePort.getOwningStage().getId() + " and " + targetPort.getOwningStage().getId() + ".");
 		}
 		new InstantiationPipe(sourcePort, targetPort, capacity);
 	}

src/main/java/teetime/framework/pipe/InstantiationPipe.java

@@ -21,13 +21,16 @@ import teetime.framework.signal.ISignal;
 
 public class InstantiationPipe implements IPipe {
 
-	private final InputPort<?> target;
+	private static final String ERROR_MESSAGE = "This must not be called while executing the configuration";
+
+	private final InputPort<?> targetPort;
 	private final int capacity;
 
 	public <T> InstantiationPipe(final OutputPort<? extends T> sourcePort, final InputPort<T> targetPort, final int capacity) {
-		this.target = targetPort;
+		this.targetPort = targetPort;
 		this.capacity = capacity;
 		sourcePort.setPipe(this);
+		targetPort.setPipe(this);
 	}
 
 	public int getCapacity() {
@@ -36,67 +39,67 @@ public class InstantiationPipe implements IPipe {
 
 	@Override
 	public InputPort<?> getTargetPort() {
-		return this.target;
+		return this.targetPort;
 	}
 
 	@Override
 	public boolean add(final Object element) {
-		throw new IllegalStateException("This must not be called while executing the configuration");
+		throw new IllegalStateException(ERROR_MESSAGE);
 	}
 
 	@Override
 	public boolean addNonBlocking(final Object element) {
-		throw new IllegalStateException("This must not be called while executing the configuration");
+		throw new IllegalStateException(ERROR_MESSAGE);
 	}
 
 	@Override
 	public boolean isEmpty() {
-		throw new IllegalStateException("This must not be called while executing the configuration");
+		throw new IllegalStateException(ERROR_MESSAGE);
 	}
 
 	@Override
 	public int size() {
-		throw new IllegalStateException("This must not be called while executing the configuration");
+		throw new IllegalStateException(ERROR_MESSAGE);
 	}
 
 	@Override
 	public Object removeLast() {
-		throw new IllegalStateException("This must not be called while executing the configuration");
+		throw new IllegalStateException(ERROR_MESSAGE);
 	}
 
 	@Override
 	public void sendSignal(final ISignal signal) {
-		throw new IllegalStateException("This must not be called while executing the configuration");
+		throw new IllegalStateException(ERROR_MESSAGE);
 	}
 
 	@Override
 	public void reportNewElement() {
-		throw new IllegalStateException("This must not be called while executing the configuration");
+		throw new IllegalStateException(ERROR_MESSAGE);
 	}
 
 	@Override
 	public boolean isClosed() {
-		throw new IllegalStateException("This must not be called while executing the configuration");
+		throw new IllegalStateException(ERROR_MESSAGE);
 	}
 
 	@Override
 	public boolean hasMore() {
-		throw new IllegalStateException("This must not be called while executing the configuration");
+		throw new IllegalStateException(ERROR_MESSAGE);
 	}
 
 	@Override
 	public void waitForStartSignal() throws InterruptedException {
-		throw new IllegalStateException("This must not be called while executing the configuration");
+		throw new IllegalStateException(ERROR_MESSAGE);
 	}
 
 	@Override
 	public void waitForInitializingSignal() throws InterruptedException {
-		throw new IllegalStateException("This must not be called while executing the configuration");
+		throw new IllegalStateException(ERROR_MESSAGE);
 	}
 
 	@Override
 	public void close() {
-		throw new IllegalStateException("This must not be called while executing the configuration");
+		throw new IllegalStateException(ERROR_MESSAGE);
 	}
 
 }