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grpc.invoke

grpc.invoke allows making either a unary or server-streaming gRPC request.

There is also grpc.unary which is a convenience function for making unary requests and grpc.client for making bi-directional requests. grpc.client will also work with unary and server-streaming methods.

API Docs:

grpc.invoke(methodDescriptor: MethodDescriptor, props: InvokeRpcOptions): Request;

methodDescriptor is a generated method definition (see code generation for how to generate these).

InvokeRpcOptions:

  • host: string
    • The server address ("https://example.com:9100")
  • request: grpc.ProtobufMessage
    • The single request message to send to the server
  • metadata: grpc.Metadata
    • The metadata to send to the server
  • onHeaders: (headers: grpc.Metadata) => void)
    • A callback for headers being received
  • onMessage: (response: grpc.ProtobufMessage) => void)
    • A callback for messages being received
  • onEnd: (code: grpc.Code, message: string, trailers: grpc.Metadata) => void)
    • A callback for the end of the request and trailers being received
  • transport?: TransportFactory
    • (optional) A function to build a Transport that will be used for the request. If no transport is specified then a browser-compatible transport will be used. See transport.
  • debug?: boolean
    • (optional) if true, debug information will be printed to the console

Request:

// Close the connection to the server without waiting for any response
close(): void;

Lifecycle

A unary or server-streaming gRPC request goes through the following stages:

  • Request with optional metadata and a single message is sent to the server - invoke()
  • Server sends headers (metadata) - onHeaders callback called
  • Server responds with one (or more if non-unary) message(s) to the client - onMessage callback called
  • Server closes the request with status code and trailers (metadata) - onEnd callback called

Example:

const request = new QueryBooksRequest();
request.setAuthorPrefix("Geor");

const grpcRequest = grpc.invoke(BookService.QueryBooks, {
  host: "https://example.com:9100",
  metadata: new grpc.Metadata({"HeaderTestKey1": "ClientValue1"}),
  onHeaders: ((headers: grpc.Metadata) => {
    console.log("onHeaders", headers);
  },
  onMessage: ((message: Book) => {
    console.log("onMessage", message);
  },
  onEnd: ((status: grpc.Code, statusMessage: string, trailers: grpc.Metadata) => {
    console.log("onEnd", status, statusMessage, trailers);
  },
});

grpcRequest.close();// Included as an example of how to close the request, but this usage would cancel the request immediately