mirror of https://github.com/grpc/grpc-java.git
223 lines
8.0 KiB
Markdown
223 lines
8.0 KiB
Markdown
gRPC-Java - An RPC library and framework
|
|
========================================
|
|
|
|
[](https://travis-ci.org/grpc/grpc-java)
|
|
[](https://coveralls.io/github/grpc/grpc-java?branch=master)
|
|
|
|
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](SECURITY.md).
|
|
|
|
Download
|
|
--------
|
|
|
|
Download [the JAR][]. Or for Maven, add to your `pom.xml`:
|
|
```xml
|
|
<dependency>
|
|
<groupId>io.grpc</groupId>
|
|
<artifactId>grpc-all</artifactId>
|
|
<version>0.8.0</version>
|
|
</dependency>
|
|
```
|
|
|
|
Or for Gradle, add to your dependencies:
|
|
```gradle
|
|
compile 'io.grpc:grpc-all:0.8.0'
|
|
```
|
|
|
|
[the JAR]: https://search.maven.org/remote_content?g=io.grpc&a=grpc-all&v=0.8.0
|
|
|
|
Development snapshots are available in [Sonatypes's snapshot
|
|
repository](https://oss.sonatype.org/content/repositories/snapshots/).
|
|
|
|
For protobuf-based codegen integrated with the Maven build system, you can use
|
|
[maven-protoc-plugin][]:
|
|
```xml
|
|
<pluginRepositories>
|
|
<pluginRepository>
|
|
<releases>
|
|
<updatePolicy>never</updatePolicy>
|
|
</releases>
|
|
<snapshots>
|
|
<enabled>false</enabled>
|
|
</snapshots>
|
|
<id>central</id>
|
|
<name>Central Repository</name>
|
|
<url>https://repo.maven.apache.org/maven2</url>
|
|
</pluginRepository>
|
|
<pluginRepository>
|
|
<id>protoc-plugin</id>
|
|
<url>https://dl.bintray.com/sergei-ivanov/maven/</url>
|
|
</pluginRepository>
|
|
</pluginRepositories>
|
|
<build>
|
|
<extensions>
|
|
<extension>
|
|
<groupId>kr.motd.maven</groupId>
|
|
<artifactId>os-maven-plugin</artifactId>
|
|
<version>1.2.3.Final</version>
|
|
</extension>
|
|
</extensions>
|
|
<plugins>
|
|
<plugin>
|
|
<groupId>com.google.protobuf.tools</groupId>
|
|
<artifactId>maven-protoc-plugin</artifactId>
|
|
<version>0.4.2</version>
|
|
<configuration>
|
|
<!--
|
|
The version of protoc must match protobuf-java. If you don't depend on
|
|
protobuf-java directly, you will be transitively depending on the
|
|
protobuf-java version that grpc depends on.
|
|
-->
|
|
<protocArtifact>com.google.protobuf:protoc:3.0.0-alpha-3.1:exe:${os.detected.classifier}</protocArtifact>
|
|
<pluginId>grpc-java</pluginId>
|
|
<pluginArtifact>io.grpc:protoc-gen-grpc-java:0.8.0:exe:${os.detected.classifier}</pluginArtifact>
|
|
</configuration>
|
|
<executions>
|
|
<execution>
|
|
<goals>
|
|
<goal>compile</goal>
|
|
<goal>compile-custom</goal>
|
|
</goals>
|
|
</execution>
|
|
</executions>
|
|
</plugin>
|
|
</plugins>
|
|
</build>
|
|
```
|
|
|
|
[maven-protoc-plugin]: http://sergei-ivanov.github.io/maven-protoc-plugin/
|
|
|
|
For protobuf-based codegen integrated with the Gradle build system, you can use
|
|
[protobuf-gradle-plugin][]:
|
|
```gradle
|
|
apply plugin: 'java'
|
|
apply plugin: 'com.google.protobuf'
|
|
|
|
buildscript {
|
|
repositories {
|
|
mavenCentral()
|
|
}
|
|
dependencies {
|
|
classpath 'com.google.protobuf:protobuf-gradle-plugin:0.6.1'
|
|
}
|
|
}
|
|
|
|
protobuf {
|
|
protoc {
|
|
// The version of protoc must match protobuf-java. If you don't depend on
|
|
// protobuf-java directly, you will be transitively depending on the
|
|
// protobuf-java version that grpc depends on.
|
|
artifact = "com.google.protobuf:protoc:3.0.0-alpha-3.1"
|
|
}
|
|
plugins {
|
|
grpc {
|
|
artifact = 'io.grpc:protoc-gen-grpc-java:0.8.0'
|
|
}
|
|
}
|
|
generateProtoTasks {
|
|
all()*.plugins {
|
|
grpc {}
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
[protobuf-gradle-plugin]: https://github.com/google/protobuf-gradle-plugin
|
|
|
|
How to Build
|
|
------------
|
|
|
|
If you are making changes to gRPC-Java, see the [compiling
|
|
instructions](COMPILING.md).
|
|
|
|
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](https://github.com/google/grpc-java/blob/master/compiler) 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
|
|
|
|
[Stream Observer](https://github.com/google/grpc-java/blob/master/stub/src/main/java/io/grpc/stub/StreamObserver.java)
|
|
|
|
### 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
|
|
|
|
* [Metadata - headers & trailers](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/Metadata.java)
|
|
* [Status - error code namespace & handling](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/Status.java)
|
|
|
|
#### Client
|
|
* [Channel - client side binding](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/Channel.java)
|
|
* [Client Call](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/ClientCall.java)
|
|
* [Client Interceptor](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/ClientInterceptor.java)
|
|
|
|
#### Server
|
|
* [Server call handler - analog to Channel on server](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/ServerCallHandler.java)
|
|
* [Server Call](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/ServerCall.java)
|
|
|
|
|
|
### 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:
|
|
|
|
1. The [Netty-based](https://github.com/google/grpc-java/blob/master/netty)
|
|
transport is the main transport implementation based on
|
|
[Netty](http://netty.io). It is for both the client and the server.
|
|
2. The [OkHttp-based](https://github.com/google/grpc-java/blob/master/okhttp)
|
|
transport is a lightweight transport based on
|
|
[OkHttp](http://square.github.io/okhttp/). It is mainly for use on Android
|
|
and is for client only.
|
|
3. The
|
|
[inProcess](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/inprocess)
|
|
transport is for when a server is in the same process as the client. It is
|
|
useful for testing.
|
|
|
|
#### Common
|
|
|
|
* [Stream](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/internal/Stream.java)
|
|
* [Stream Listener](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/internal/StreamListener.java)
|
|
|
|
#### Client
|
|
|
|
* [Client Stream](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/internal/ClientStream.java)
|
|
* [Client Stream Listener](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/internal/ClientStreamListener.java)
|
|
|
|
#### Server
|
|
|
|
* [Server Stream](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/internal/ServerStream.java)
|
|
* [Server Stream Listener](https://github.com/google/grpc-java/blob/master/core/src/main/java/io/grpc/internal/ServerStreamListener.java)
|
|
|
|
|
|
### Examples
|
|
|
|
Tests showing how these layers are composed to execute calls using protobuf
|
|
messages can be found here
|
|
https://github.com/google/grpc-java/tree/master/interop-testing/src/main/java/io/grpc/testing/integration
|