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.
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 decompress response 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.
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.