Hooks

• InputHook
• OutputHook
• IOHook
• ComponentHook

• Java
• Python
• Javascript

Vertigo provides a special mechanism for hooking into component and messaging events. Hooks are objects that are added to the network configuration and receive notifications when certain events occur. All hooks implement the JsonSerializable interface which handles JSON serialization with Jackson. In most cases, users can simply implement the relevant hook interface and Vertigo will handle serialization of basic fields automatically. You can use Jackson annotations to ignore certain fields or provide custom serialization as necessary.

InputHook

Input hooks can be used to hook into message events related to the target port on a specific connection within a network configuration. Input hooks are added to the target element of a ConnectionConfig.

To define an input hook implement the InputHook interface.

public class MyInputHook implements InputHook {
  @Override
  public void handleReceive(Object message) {
  }
}

The InputHook interface requires only a single handleReceive method which will be called whenever a message is received on the connection.

To add the hook to a connection use the addHook method on a ConnectionConfig.Target instance.

network.createConnection("foo", "out", "bar", "in").getTarget().addHook(new MyInputHook());

OutputHook

Output hooks can be used to hook into message events related to the source port on a specific connection within a network configuration. Output hooks are added to the source element of a ConnectionConfig.

To define an output hook implement the OutputHook interface.

public class MyOutputHook implements OutputHook {
  @Override
  public void handleSend(Object message) {
  }
}

The OutputHook interface requires only a single handleSend method which will be called whenever a message is sent on the connection.

To add the hook to a connection use the addHook method on a ConnectionConfig.Source instance.

network.createConnection("foo", "out", "bar", "in").getSource().addHook(new MyOutputHook());

IOHook

I/O hooks are a combination of the InputHook and OutputHook interfaces. When an I/O hook is added to a connection, its methods will be called when an event occurs on either side of the connection. For the sending side of the connection, the hook will be called when a message is sent, and for the receiving side of the connection, the hook will be called when a message is received.

public class MyIOHook implements IOHook {
  @Override
  public void handleSend(Object message) {
  }

  @Override
  public void handleReceive(Object message) {
  }
}

To add the hook to a connection use the addHook method on a ConnectionConfig instance.

network.createConnection("foo", "out", "bar", "in").addHook(new MyIOHook());

ComponentHook

Components hooks are component-level hooks that implement both the InputHook and OutputHook interfaces along with some additional component-level hook methods. Since component hooks are added at the component level, the handleSend and handleReceive methods will be called each time a message is sent or received on any port. Additionally, the component hook can receive notifications of when the component has started and stopped as well.

public class MyComponentHook implements ComponentHook {
  @Override
  public void handleStart(Component component) {
  }

  @Override
  public void handleSend(Object message) {
  }

  @Override
  public void handleReceive(Object message) {
  }

  @Override
  public void handleStop(Component component) {
  }
}

The handleStart and handleStop will be passed the internal Vertigo Component instance which contains all fields available to the Java ComponentVerticle along with additional information about the component configuration.

Component hooks are added to ComponentConfig instances within the network configuration.

network.addComponent("foo", "foo.js", 2).addHook(new MyComponentHook());