1. Documentation
2. 10.2 (Latest)10.110.09.109.99.89.79.69.59.49.39.29.19.08.28.18.07.6
3. Developers
4. Creating your own extension
5. Input and output ports
6. PortPairExtender

Dynamically Adding Ports with the PortPairExtender

Sometimes it's useful to add ports that simply pass data through the operator without changing it - 'through' ports. If your operator does not need input and output ports, best practice is to add through ports to control the process execution order. ThePortPairExtender, a sub-class ofPortExtender, ensures that the through ports are pair-wise.

ThePortPairExtenderis also used to pass input data from a super operator to its subprocesses. You can find more details in the advanced chapter aboutsuper operators.

Adding through ports

To define through ports, simply add aPortPairExtenderas a private variable, using the following code:

private final PortPairExtender dummyPorts = new DummyPortPairExtender("through", getInputPorts(), getOutputPorts());

Then, initialize the ports and add the pass through rule to handle the meta data:

dummyPorts.start(); getTransformer().addRule(dummyPorts.makePassThroughRule());

Add the command to pass the data from the input through ports to the output through ports at the end of thedoWork()method.

dummyPorts.passDataThrough();

Simple example operator with through ports

public class MyOwnOperator extends Operator { private PortPairExtender dummyPorts = new DummyPortPairExtender("through", getInputPorts(), getOutputPorts()); public MyOwnOperator(OperatorDescription description) { super(description); dummyPorts.start(); getTransformer().addRule(dummyPorts.makePassThroughRule()); } @Override public void doWork() throws OperatorException { LogService.getRoot().log(Level.INFO, "Doing something..."); // PASS THROUGH PORTS dummyPorts.passDataThrough(); } }

下一步是add parametersto your operators.