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Grid Ops Java - NodeContainer

Jakob Jenkov
Last update: 2017-03-08

The NodeContainer class in Grid Ops functions can route incoming messages to the components that are to process them. The NodeContainer will look at the node id in the incoming message and forward the message to the corresponding NodeReactor. The NodeReactor will look at the semantic protocol id + version and forward the message to the corresponding protocol reactor. The protocol reactor will look at the message type of the incoming message and forward the message to the corresponding message reactor.

The message routing is illustrated here:

NodeContainer routing of messages.

Messages are received from the outside, typically via a TcpServer and a TcpSocketsPort, and then given to the NodeContainer, which internally routes the messages to the correct MessageReactor (via the NodeReactor and ProtocolReactor instances).

Required IAP Message Fields

For this routing to work, each incoming message must contain at least the following fields:

  • Receiving Node Id
  • Semantic Protocol Id
  • Semantic Protocol Version
  • Message Type

These four fields are some of the core fields of IAP messages which IAP messages of all semantic protocols should contain.

Creating a NodeContainer

To use a NodeContainer you must first create and configure it. Here is an example that creates and configures a NodeContainer:

byte[] messageType = new byte[]{11};
MessageReactor messageReactor = new MessageReactor(messageType) {
    public void react(IonReader ionReader, IapMessage iapMessage) {
        System.out.println("Reacting to message");

byte[] protocolId = new byte[]{99};
ProtocolReactor protocolReactor = new ProtocolReactor(protocolId, messageReactor);

byte[] nodeId =  new byte[]{123};
NodeReactor nodeReactor = GridOps.nodeReactor(nodeId, protocolReactor);

NodeContainer nodeContainer = GridOps.nodeContainer();

Notice how the examples creates an instance of a MessageReactor, ProtocolReactor, NodeReactor and NodeContainer. The NodeContainer is now ready to receive incoming messages.

Jakob Jenkov

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