gRPC-Java - An RPC library and framework
gRPC-Java works with JDK 6. TLS usage typically requires using Java 8, or Play Services Dynamic Security Provider on Android. Please see the Security Readme.
| Homepage: | www.grpc.io |
| Mailing List: | grpc-io@googlegroups.com |
Download
Download the JARs. Or for Maven with non-Android, add to your pom.xml:
<dependency>
<groupId>io.grpc</groupId>
<artifactId>grpc-netty</artifactId>
<version>1.3.0</version>
</dependency>
<dependency>
<groupId>io.grpc</groupId>
<artifactId>grpc-protobuf</artifactId>
<version>1.3.0</version>
</dependency>
<dependency>
<groupId>io.grpc</groupId>
<artifactId>grpc-stub</artifactId>
<version>1.3.0</version>
</dependency>Or for Gradle with non-Android, add to your dependencies:
compile 'io.grpc:grpc-netty:1.3.0'
compile 'io.grpc:grpc-protobuf:1.3.0'
compile 'io.grpc:grpc-stub:1.3.0'For Android client, use grpc-okhttp instead of grpc-netty and
grpc-protobuf-lite or grpc-protobuf-nano instead of grpc-protobuf:
compile 'io.grpc:grpc-okhttp:1.3.0'
compile 'io.grpc:grpc-protobuf-lite:1.3.0'
compile 'io.grpc:grpc-stub:1.3.0'Development snapshots are available in Sonatypes's snapshot repository.
For protobuf-based codegen, you can put your proto files in the src/main/proto
and src/test/proto directories along with an appropriate plugin.
For protobuf-based codegen integrated with the Maven build system, you can use
protobuf-maven-plugin (Eclipse and NetBeans users should also look at
os-maven-plugin's
IDE documentation):
<build>
<extensions>
<extension>
<groupId>kr.motd.maven</groupId>
<artifactId>os-maven-plugin</artifactId>
<version>1.4.1.Final</version>
</extension>
</extensions>
<plugins>
<plugin>
<groupId>org.xolstice.maven.plugins</groupId>
<artifactId>protobuf-maven-plugin</artifactId>
<version>0.5.0</version>
<configuration>
<protocArtifact>com.google.protobuf:protoc:3.2.0:exe:${os.detected.classifier}</protocArtifact>
<pluginId>grpc-java</pluginId>
<pluginArtifact>io.grpc:protoc-gen-grpc-java:1.3.0:exe:${os.detected.classifier}</pluginArtifact>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>compile-custom</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>For protobuf-based codegen integrated with the Gradle build system, you can use protobuf-gradle-plugin:
apply plugin: 'java'
apply plugin: 'com.google.protobuf'
buildscript {
repositories {
mavenCentral()
}
dependencies {
// ASSUMES GRADLE 2.12 OR HIGHER. Use plugin version 0.7.5 with earlier
// gradle versions
classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.0'
}
}
protobuf {
protoc {
artifact = "com.google.protobuf:protoc:3.2.0"
}
plugins {
grpc {
artifact = 'io.grpc:protoc-gen-grpc-java:1.3.0'
}
}
generateProtoTasks {
all()*.plugins {
grpc {}
}
}
}How to Build
If you are making changes to gRPC-Java, see the compiling instructions.
Navigating Around the Source
Here's a quick readers' guide to the code to help folks get started. At a high level there are three distinct layers to the library: Stub, Channel & Transport.
Stub
The Stub layer is what is exposed to most developers and provides type-safe
bindings to whatever datamodel/IDL/interface you are adapting. gRPC comes with
a plugin to the
protocol-buffers compiler that generates Stub interfaces out of .proto files,
but bindings to other datamodel/IDL should be trivial to add and are welcome.
Key Interfaces
Channel
The Channel layer is an abstraction over Transport handling that is suitable for interception/decoration and exposes more behavior to the application than the Stub layer. It is intended to be easy for application frameworks to use this layer to address cross-cutting concerns such as logging, monitoring, auth etc. Flow-control is also exposed at this layer to allow more sophisticated applications to interact with it directly.
Common
Client
Server
Transport
The Transport layer does the heavy lifting of putting and taking bytes off the
wire. The interfaces to it are abstract just enough to allow plugging in of
different implementations. Transports are modeled as Stream factories. The
variation in interface between a server Stream and a client Stream exists to
codify their differing semantics for cancellation and error reporting.
Note the transport layer API is considered internal to gRPC and has weaker API
guarantees than the core API under package io.grpc.
gRPC comes with three Transport implementations:
- The Netty-based transport is the main transport implementation based on Netty. It is for both the client and the server.
- The OkHttp-based transport is a lightweight transport based on OkHttp. It is mainly for use on Android and is for client only.
- The inProcess transport is for when a server is in the same process as the client. It is useful for testing.
Common
Client
Server
Examples
The examples and the Android example are standalone projects that showcase the usage of gRPC.