ejona86 Add build support for Java 11
It appears everything was already working on Java 11, except
build-specific and testing issues. Updating to Netty 4.1.30 (#4940)
probably fixed the last true Java 11 incompatibility.

Fixes #4933
Latest commit 959323b Oct 17, 2018


grpc Examples

The examples require grpc-java to already be built. You are strongly encouraged to check out a git release tag, since there will already be a build of grpc available. Otherwise you must follow COMPILING.

You may want to read through the Quick Start Guide before trying out the examples.

To build the examples, run in this directory:

$ ./gradlew installDist

This creates the scripts hello-world-server, hello-world-client, hello-world-tls-server, hello-world-tls-client, route-guide-server, and route-guide-client in the build/install/examples/bin/ directory that run the examples. Each example requires the server to be running before starting the client.

For example, to try the hello world example first run:

$ ./build/install/examples/bin/hello-world-server

And in a different terminal window run:

$ ./build/install/examples/bin/hello-world-client

Hello World with TLS

Running the hello world with TLS is the same as the normal hello world, but takes additional args:


USAGE: HelloWorldServerTls host port certChainFilePath privateKeyFilePath [trustCertCollectionFilePath]
  Note: You only need to supply trustCertCollectionFilePath if you want to enable Mutual TLS.


USAGE: HelloWorldClientTls host port [trustCertCollectionFilePath] [clientCertChainFilePath] [clientPrivateKeyFilePath]
  Note: clientCertChainFilePath and clientPrivateKeyFilePath are only needed if mutual auth is desired. And if you specify clientCertChainFilePath you must also specify clientPrivateKeyFilePath

Generating self-signed certificates for use with grpc

You can use the following script to generate self-signed certificates for grpc-java including the hello world with TLS examples:

# Changes these CN's to match your hosts in your environment if needed.
CLIENT_CN=localhost # Used when doing mutual TLS

echo Generate CA key:
openssl genrsa -passout pass:1111 -des3 -out ca.key 4096
echo Generate CA certificate:
# Generates ca.crt which is the trustCertCollectionFile
openssl req -passin pass:1111 -new -x509 -days 365 -key ca.key -out ca.crt -subj "/CN=${SERVER_CN}"
echo Generate server key:
openssl genrsa -passout pass:1111 -des3 -out server.key 4096
echo Generate server signing request:
openssl req -passin pass:1111 -new -key server.key -out server.csr -subj "/CN=${SERVER_CN}"
echo Self-signed server certificate:
# Generates server.crt which is the certChainFile for the server
openssl x509 -req -passin pass:1111 -days 365 -in server.csr -CA ca.crt -CAkey ca.key -set_serial 01 -out server.crt 
echo Remove passphrase from server key:
openssl rsa -passin pass:1111 -in server.key -out server.key
echo Generate client key
openssl genrsa -passout pass:1111 -des3 -out client.key 4096
echo Generate client signing request:
openssl req -passin pass:1111 -new -key client.key -out client.csr -subj "/CN=${CLIENT_CN}"
echo Self-signed client certificate:
# Generates client.crt which is the clientCertChainFile for the client (need for mutual TLS only)
openssl x509 -passin pass:1111 -req -days 365 -in client.csr -CA ca.crt -CAkey ca.key -set_serial 01 -out client.crt
echo Remove passphrase from client key:
openssl rsa -passin pass:1111 -in client.key -out client.key
echo Converting the private keys to X.509:
# Generates client.pem which is the clientPrivateKeyFile for the Client (needed for mutual TLS only)
openssl pkcs8 -topk8 -nocrypt -in client.key -out client.pem
# Generates server.pem which is the privateKeyFile for the Server
openssl pkcs8 -topk8 -nocrypt -in server.key -out server.pem

Hello world example with TLS (no mutual auth):

# Server
./build/install/examples/bin/hello-world-server-tls mate 50440 ~/Downloads/sslcert/server.crt ~/Downloads/sslcert/server.pem
# Client
./build/install/examples/bin/hello-world-client-tls mate 50440 ~/Downloads/sslcert/ca.crt

Hello world example with TLS with mutual auth:

# Server
./build/install/examples/bin/hello-world-server-tls mate 54440 ~/Downloads/sslcert/server.crt ~/Downloads/sslcert/server.pem ~/Downloads/sslcert/ca.crt
# Client
./build/install/examples/bin/hello-world-client-tls mate 54440 ~/Downloads/sslcert/ca.crt ~/Downloads/sslcert/client.crt ~/Downloads/sslcert/client.pem

That's it!

Please refer to gRPC Java's README and tutorial for more information.


If you prefer to use Maven:

$ mvn verify
$ # Run the server
$ mvn exec:java -Dexec.mainClass=io.grpc.examples.helloworld.HelloWorldServer
$ # In another terminal run the client
$ mvn exec:java -Dexec.mainClass=io.grpc.examples.helloworld.HelloWorldClient


If you prefer to use Bazel:

(With Bazel v0.8.0 or above.)
$ bazel build :hello-world-server :hello-world-client
$ # Run the server:
$ bazel-bin/hello-world-server
$ # In another terminal run the client
$ bazel-bin/hello-world-client

Unit test examples

Examples for unit testing gRPC clients and servers are located in examples/src/test.

In general, we DO NOT allow overriding the client stub. We encourage users to leverage InProcessTransport as demonstrated in the examples to write unit tests. InProcessTransport is light-weight and runs the server and client in the same process without any socket/TCP connection.

For testing a gRPC client, create the client with a real stub using an InProcessChannel, and test it against an InProcessServer with a mock/fake service implementation.

For testing a gRPC server, create the server as an InProcessServer, and test it against a real client stub with an InProcessChannel.

The gRPC-java library also provides a JUnit rule, GrpcServerRule, to do the graceful shutdown boilerplate for you.