Class Channel

Utility class for working with channels in the Pregel system. Provides static methods for subscribing to channels and writing to them.

Channels are the communication pathways between nodes in a Pregel graph. They enable message passing and state updates between different parts of the graph.

Constructors

constructor

Methods

subscribeTo writeTo

Constructors

constructor

Methods

StaticsubscribeTo

  • subscribeTo(
        channel: string,
        options?: SingleChannelSubscriptionOptions,
    ): PregelNode

    Creates a PregelNode that subscribes to a single channel. This is used to define how nodes receive input from channels.

    Parameters

    Returns PregelNode

    A PregelNode configured to receive from the specified channels

    Example

    // Subscribe to a single channel
    const node = Channel.subscribeTo("messages");

    // Subscribe to multiple channels
    const node = Channel.subscribeTo(["messages", "state"]);

    // Subscribe with a custom key
    const node = Channel.subscribeTo("messages", { key: "chat" });

    Throws

    If a key is specified when subscribing to multiple channels

  • subscribeTo(
        channels: string[],
        options?: MultipleChannelSubscriptionOptions,
    ): PregelNode

    Creates a PregelNode that subscribes to multiple channels. This is used to define how nodes receive input from channels.

    Parameters

    Returns PregelNode

    A PregelNode configured to receive from the specified channels

    Example

    // Subscribe to a single channel
    const node = Channel.subscribeTo("messages");

    // Subscribe to multiple channels
    const node = Channel.subscribeTo(["messages", "state"]);

    // Subscribe with a custom key
    const node = Channel.subscribeTo("messages", { key: "chat" });

    Throws

    If a key is specified when subscribing to multiple channels

StaticwriteTo

  • writeTo(channels: string[], writes?: Record<string, unknown>): ChannelWrite

    Creates a ChannelWrite that specifies how to write values to channels. This is used to define how nodes send output to channels.

    Parameters

    • channels: string[]

      Array of channel names to write to

    • Optionalwrites: Record<string, unknown>

      Optional map of channel names to values or transformations

    Returns ChannelWrite

    A ChannelWrite object that can be used to write to the specified channels

    Example

    // Write to multiple channels
    const write = Channel.writeTo(["output", "state"]);

    // Write with specific values
    const write = Channel.writeTo(["output"], {
      state: "completed",
      result: calculateResult()
    });

    // Write with a transformation function
    const write = Channel.writeTo(["output"], {
      result: (x) => processResult(x)
    });

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