@grpc/grpc-js

What is @grpc/grpc-js?

The @grpc/grpc-js package is a pure JavaScript implementation of gRPC, which stands for gRPC Remote Procedure Calls. It allows you to define service methods and their input/output types using Protocol Buffers, and it handles the networking layer transparently. This package is used to build client and server applications that communicate over the gRPC protocol, which is particularly suited for microservices and other distributed systems where performance and scalability are important.

What are @grpc/grpc-js's main functionalities?

Defining a gRPC Service

This code demonstrates how to define a gRPC service using a .proto file. The service definition includes the RPC methods that can be called remotely.

const grpc = require('@grpc/grpc-js');
const protoLoader = require('@grpc/proto-loader');

const packageDefinition = protoLoader.loadSync('your_proto_file.proto', {});
const protoDescriptor = grpc.loadPackageDefinition(packageDefinition);
const yourService = protoDescriptor.your_package.YourService;

Creating a gRPC Server

This code sample shows how to create a gRPC server, add a service to it, and start listening for client requests on a specified port.

const grpc = require('@grpc/grpc-js');

const server = new grpc.Server();
server.addService(yourService.service, {
  yourMethod: (call, callback) => {
    // Implement your method logic here
    callback(null, response);
  }
});
server.bindAsync('0.0.0.0:50051', grpc.ServerCredentials.createInsecure(), () => {
  server.start();
});

Creating a gRPC Client

This code snippet illustrates how to create a gRPC client that can call methods on a gRPC server. The client uses the service definition from a .proto file to make properly structured calls.

const grpc = require('@grpc/grpc-js');
const protoLoader = require('@grpc/proto-loader');

const packageDefinition = protoLoader.loadSync('your_proto_file.proto', {});
const protoDescriptor = grpc.loadPackageDefinition(packageDefinition);
const client = new protoDescriptor.your_package.YourService('localhost:50051', grpc.credentials.createInsecure());

client.yourMethod({ yourRequestField: 'yourValue' }, (error, response) => {
  // Handle the response or error
});

Other packages similar to @grpc/grpc-js

grpc

The 'grpc' package is the original Node.js gRPC library, which relies on the C-based gRPC core library. It provides similar functionality to @grpc/grpc-js but requires native dependencies. The @grpc/grpc-js package was created as a pure JavaScript alternative, eliminating the need for native compilation and simplifying deployment, especially in serverless environments.

protobufjs

While 'protobufjs' is not a direct alternative to @grpc/grpc-js, it is a related package that provides tools for working with Protocol Buffers, which are an integral part of gRPC. It allows you to encode and decode Protocol Buffers messages but does not handle the gRPC networking layer.

thrift

Apache Thrift is another RPC framework that can be used as an alternative to gRPC. It supports multiple programming languages and has its own interface definition language (IDL). The 'thrift' package for Node.js allows you to build clients and servers using the Thrift protocol, which, like gRPC, is designed for efficient communication between services.

README

Pure JavaScript gRPC Client

Installation

Node 12 is recommended. The exact set of compatible Node versions can be found in the engines field of the package.json file.

npm install @grpc/grpc-js

Documentation

Documentation specifically for the @grpc/grpc-js package is currently not available. However, documentation is available for the grpc package, and the two packages contain mostly the same interface. There are a few notable differences, however, and these differences are noted in the "Migrating from grpc" section below.

Features

• Clients
• Automatic reconnection
• Servers
• Streaming
• Metadata
• Partial compression support: clients can compress and decompress messages, and servers can decompress request messages
• Pick first and round robin load balancing policies
• Client Interceptors
• Connection Keepalives
• HTTP Connect support (proxies)

If you need a feature from the grpc package that is not provided by the @grpc/grpc-js, please file a feature request with that information.

This library does not directly handle .proto files. To use .proto files with this library we recommend using the @grpc/proto-loader package.

Migrating from grpc

@grpc/grpc-js is almost a drop-in replacement for grpc, but you may need to make a few code changes to use it:

• If you are currently loading .proto files using grpc.load, that function is not available in this library. You should instead load your .proto files using @grpc/proto-loader and load the resulting package definition objects into @grpc/grpc-js using grpc.loadPackageDefinition.
• If you are currently loading packages generated by grpc-tools, you should instead generate your files using the generate_package_definition option in grpc-tools, then load the object exported by the generated file into @grpc/grpc-js using grpc.loadPackageDefinition.
• If you have a server and you are using Server#bind to bind ports, you will need to use Server#bindAsync instead.
• If you are using any channel options supported in grpc but not supported in @grpc/grpc-js, you may need to adjust your code to handle the different behavior. Refer to the list of supported options below.
• Refer to the detailed package comparison for more details on the differences between grpc and @grpc/grpc-js.

Supported Channel Options

Many channel arguments supported in grpc are not supported in @grpc/grpc-js. The channel arguments supported by @grpc/grpc-js are:

• grpc.ssl_target_name_override
• grpc.primary_user_agent
• grpc.secondary_user_agent
• grpc.default_authority
• grpc.keepalive_time_ms
• grpc.keepalive_timeout_ms
• grpc.keepalive_permit_without_calls
• grpc.service_config
• grpc.max_concurrent_streams
• grpc.initial_reconnect_backoff_ms
• grpc.max_reconnect_backoff_ms
• grpc.use_local_subchannel_pool
• grpc.max_send_message_length
• grpc.max_receive_message_length
• grpc.enable_http_proxy
• grpc.default_compression_algorithm
• grpc.enable_channelz
• grpc.dns_min_time_between_resolutions_ms
• grpc.enable_retries
• grpc.max_connection_age_ms
• grpc.max_connection_age_grace_ms
• grpc.max_connection_idle_ms
• grpc.per_rpc_retry_buffer_size
• grpc.retry_buffer_size
• grpc.service_config_disable_resolution
• grpc.client_idle_timeout_ms
• grpc-node.max_session_memory
• grpc-node.tls_enable_trace
• grpc-node.retry_max_attempts_limit
• channelOverride
• channelFactoryOverride

Some Notes on API Guarantees

The public API of this library follows semantic versioning, with some caveats:

• Some methods are prefixed with an underscore. These methods are internal and should not be considered part of the public API.
• The class Call is only exposed due to limitations of TypeScript. It should not be considered part of the public API.
• In general, any API that is exposed by this library but is not exposed by the grpc library is likely an error and should not be considered part of the public API.
• The grpc.experimental namespace contains APIs that have not stabilized. Any API in that namespace may break in any minor version update.