Node

DataStorm Node

The node is the central component of any DataStorm publish–subscribe application. Every DataStorm application must start by creating a node and keep it alive for the duration of the application.

A DataStorm node maintains sessions with other connected nodes to exchange information about the topics created within each node and the readers and writers associated with those topics.

The node also acts as a registry for topics created locally and informs remote connected nodes about these topics.

From an implementation perspective, a node is simply an instance of the DataStorm::Node class. You create a node using one of its constructors and destroy it using its destructor.

The most common setup is to create a DataStorm::Node instance on the stack in your main function. It will be automatically destroyed when it goes out of scope, just before your application returns from main.

#include <DataStorm/DataStorm.h>

int
main(int argc, char* argv[])
{
    DataStorm::Node node{argc, argv};
    ...

    // Node is automatically destroyed before returning from main when
    // it falls out of scope.
}

In this example, we use the DataStorm::Node constructor that takes the argc and argv parameters. This constructor parses DataStorm command-line options and converts them into properties that are used to configure the node.

The DataStorm::Node class also provides additional constructors that allow different ways to configure the node or specify extra parameters. See the API reference for details.

After the node is destroyed, writers will no longer publish samples, and readers will no longer receive samples.

The Node::shutdown method can be used to unblock readers and writers that are waiting to receive a sample or for a peer node to connect. In this case, the waiting threads throw a NodeShutdownException exception.