ProtoClient

A simple, typed gRPC Client with static code generation

const client = new ProtoClient({
  clientSettings: { endpoint: "0.0.0.0:8080" },
  protoSettings: { files: ["protos/v1/customers.proto"] },
});

const { result } = await client.makeUnaryRequest("v1.Customers.GetCustomer", {
  id: "github",
});
result; // Github Customer

Reading data from a streamed response can be done by adding a read iterator

await client.makeServerStreamRequest(
  "v1.Customers.FindCustomers",
  { name: "git*" },
  async (row) => {
    row; // Incoming response row chunk
  }
);

Streaming data to a server can be done through a write sandbox

const { result } = await client.makeClientStreamRequest(
  "v1.Customers.EditCustomer",
  async (write) => {
    await write({ id: "github", name: "Github" });
    await write({ id: "npm", name: "NPM" });
  }
);
result.customers; // List of customers updated

And duplex streams combines both paradigms above into one

await client.makeBidiStreamRequest(
  "v1.Customers.CreateCustomers",
  async (write) => {
    await write({ id: "github", name: "Github" });
    await write({ id: "npm", name: "NPM" });
  },
  async (row) => {
    row; // Incoming response row chunk
  }
);

Middleware

The ProtoClient instance provides middleware injection to adjust requests before they are sent. A great use case would be adding authentication tokens to the request metadata in one location rather than at each line of code a request is made

client.useMiddleware((request) => {
  request.metadata.set("authToken", "abc_123");
});

Events

Each request instance extends NodeJS's EventEmitter, allowing callers to hook into specific signal points during the process of a request. To extend the use case above, updates to authentication tokens can be passed back in Metadata and auto assigned in one location rather than at each line of code a request is made

let authToken = "";

client.useMiddleware((request) => {
  if (authToken) {
    request.metadata.set("authToken", authToken);
  }

  request.on("response", () => {
    const token = request.responseMetadata?.get("updatedAuthToken");
    if (token) {
      authToken = token[0];
    }
  });
});

List of Events

• ProtoRequest:
  • response: Event emitted right before the first response is sent to the caller
  • retry: Event emitted right before a retry request is started
  • aborted: Event emitted when the request has been aborted
  • end: Event emitted after the last response (or error) has been returned to the caller
• ProtoClient:
  • request: Event emitted before a request is started, but after all middleware has run. (will not emit if middleware throws an error)

Multi Service Support

For multi service architectures, ProtoClient comes with built-in support to configure which requests point to with service endpoint using a matching utility. This is purely configuration, and requires no changes to individual methods/requests

client.configureClient({
  endpoint: [
    // Matching all rpc methods of the v1.Customers service to a specific service endpoint
    {
      address: "127.0.0.1:8081",
      match: "v1.Customers.*",
    },

    // Matching all rpc methods of the v1.products.TransportationService service to a specific service endpoint
    {
      address: "127.0.0.1:8082",
      match: "v1.products.TransportationService.*",
    },

    // Matching an entire namespace to a specific service endpoint
    {
      address: "127.0.0.1:8083",
      match: "v1.employees.*",
    },
  ],
});

Automatic Retries

Every request is wrapped in a retry function, allowing for fully customized handling of timeouts and retries. Can be configured at both the overall client, and individual request levels.

• retryCount: Number of times to retry request. Defaults to none
• status: Status code(s) request is allowed to retry on. Uses default list of status codes if not defined
• retryOnClientTimeout: Indicates if retries should be allowed when the client times out. Defaults to true.

Static Code Generation

Translates .proto files into functional API calls

proto-client [options] file1.proto file2.proto ...

Options:
      --version       Show version number
  -o, --output        Output directory for compiled files
  -p, --path          Adds a directory to the include path
      --keep-case     Keeps field casing instead of converting to camel case
      --force-long    Enforces the use of 'Long' for s-/u-/int64 and s-/fixed64 fields
      --force-number  Enforces the use of 'number' for s-/u-/int64 and s-/fixed64 fields
      --help          Show help

Example

Given the following customers.proto file, running the proto-client command will generate a js/ts client scaffold for easy functional request making

syntax = "proto3";

package v1;

message Customer {
  string id = 1;
  string name = 2;
}

message GetCustomerRequest {
  string id = 1;
}

message FindCustomersRequest {
  string name = 1;
}

message CustomersResponse {
  repeated Customer customers = 1;
}

service Customers {
  rpc GetCustomer (GetCustomerRequest) returns (Customer);
  rpc FindCustomers (FindCustomersRequest) returns (stream Customer);
  rpc EditCustomer (stream Customer) returns (CustomersResponse);
  rpc CreateCustomers (stream Customer) returns (stream Customer);
}

The client.js code generated:

module.exports.v1 = {
  Customers: {
    GetCustomer: async (data) =>
      protoClient.makeUnaryRequest("v1.Customers.GetCustomer", data),

    CreateCustomers: async (writerSandbox, streamReader) =>
      protoClient.CreateCustomers(
        "v1.Customers.CreateCustomers",
        writerSandbox,
        streamReader
      ),
  },
};

To make calls:

import { protoClient, v1 } from "output/client";

// Configuring service endpoint(s)
protoClient.configureClient({ endpoint: "127.0.0.1:8080" });

// Unary Requests
const { result } = await v1.Customers.GetCustomer({ id: "github" });
result; // Customer

// Bidirectional Requests
await v1.Customers.CreateCustomers(
  async (write) => {
    await write({ name: "github", action: "Github" });
    await write({ name: "npm", action: "NPM" });
  },
  async (row) => {
    // ... each streamed row ...
  }
);