- [Json serialization](src/main/java/io/grpc/examples/advanced)

- <details>

<summary>Hedging</summary>

The [hedging example](src/main/java/io/grpc/examples/hedging) demonstrates that enabling hedging

can reduce tail latency. (Users should note that enabling hedging may introduce other overhead;

and in some scenarios, such as when some server resource gets exhausted for a period of time and

almost every RPC during that time has high latency or fails, hedging may make things worse.

Setting a throttle in the service config is recommended to protect the server from too many

inappropriate retry or hedging requests.)

The server and the client in the example are basically the same as those in the

[hello world](src/main/java/io/grpc/examples/helloworld) example, except that the server mimics a

long tail of latency, and the client sends 2000 requests and can turn on and off hedging.

To mimic the latency, the server randomly delays the RPC handling by 2 seconds at 10% chance, 5

seconds at 5% chance, and 10 seconds at 1% chance.

When running the client enabling the following hedging policy

```json

"hedgingPolicy": {

"maxAttempts": 3,

"hedgingDelay": "1s"

}

```

Then the latency summary in the client log is like the following

```text

Total RPCs sent: 2,000. Total RPCs failed: 0

[Hedging enabled]

========================

50% latency: 0ms

90% latency: 6ms

95% latency: 1,003ms

99% latency: 2,002ms

99.9% latency: 2,011ms

Max latency: 5,272ms

========================

```

See [the section below](#to-build-the-examples) for how to build and run the example. The

executables for the server and the client are `hedging-hello-world-server` and

`hedging-hello-world-client`.

To disable hedging, set environment variable `DISABLE_HEDGING_IN_HEDGING_EXAMPLE=true` before

running the client. That produces a latency summary in the client log like the following

```text

Total RPCs sent: 2,000. Total RPCs failed: 0

[Hedging disabled]

========================

50% latency: 0ms

90% latency: 2,002ms

95% latency: 5,002ms

99% latency: 10,004ms

99.9% latency: 10,007ms

Max latency: 10,007ms

========================

```

</details>

- <details>

<summary>Retrying</summary>

The [retrying example](src/main/java/io/grpc/examples/retrying) provides a HelloWorld gRPC client &

server which demos the effect of client retry policy configured on the [ManagedChannel](

../api/src/main/java/io/grpc/ManagedChannel.java) via [gRPC ServiceConfig](

https://github.com/grpc/grpc/blob/master/doc/service_config.md). Retry policy implementation &

configuration details are outlined in the [proposal](https://github.com/grpc/proposal/blob/master/A6-client-retries.md).

This retrying example is very similar to the [hedging example](src/main/java/io/grpc/examples/hedging) in its setup.

The [RetryingHelloWorldServer](src/main/java/io/grpc/examples/retrying/RetryingHelloWorldServer.java) responds with

a status UNAVAILABLE error response to a specified percentage of requests to simulate server resource exhaustion and

general flakiness. The [RetryingHelloWorldClient](src/main/java/io/grpc/examples/retrying/RetryingHelloWorldClient.java) makes

a number of sequential requests to the server, several of which will be retried depending on the configured policy in

[retrying_service_config.json](src/main/resources/io/grpc/examples/retrying/retrying_service_config.json). Although

the requests are blocking unary calls for simplicity, these could easily be changed to future unary calls in order to

test the result of request concurrency with retry policy enabled.

One can experiment with the [RetryingHelloWorldServer](src/main/java/io/grpc/examples/retrying/RetryingHelloWorldServer.java)

failure conditions to simulate server throttling, as well as alter policy values in the [retrying_service_config.json](

src/main/resources/io/grpc/examples/retrying/retrying_service_config.json) to see their effects. To disable retrying

entirely, set environment variable `DISABLE_RETRYING_IN_RETRYING_EXAMPLE=true` before running the client.

Disabling the retry policy should produce many more failed gRPC calls as seen in the output log.

See [the section below](#to-build-the-examples) for how to build and run the example. The

executables for the server and the client are `retrying-hello-world-server` and

`retrying-hello-world-client`.

</details>

- <details>

<summary>Health Service</summary>

The [health service example](src/main/java/io/grpc/examples/healthservice)

provides a HelloWorld gRPC server that doesn't like short names along with a

health service. It also provides a client application which makes HelloWorld

calls and checks the health status.

The client application also shows how the round robin load balancer can

utilize the health status to avoid making calls to a service that is

not actively serving.

</details>

- [Hedging example](src/main/java/io/grpc/examples/hedging)

- [Retrying example](src/main/java/io/grpc/examples/retrying)

- [Health Service example](src/main/java/io/grpc/examples/healthservice)

- [Keep Alive](src/main/java/io/grpc/examples/keepalive)

- [Cancellation](src/main/java/io/grpc/examples/cancellation)

- [Custom Load Balance](src/main/java/io/grpc/examples/customloadbalance)

- [Deadline](src/main/java/io/grpc/examples/deadline)

- [Error Details](src/main/java/io/grpc/examples/errordetails)

- [GRPC Proxy](src/main/java/io/grpc/examples/grpcproxy)

- [Load Balance](src/main/java/io/grpc/examples/loadbalance)

- [Multiplex](src/main/java/io/grpc/examples/multiplex)

- [Name Resolve](src/main/java/io/grpc/examples/nameresolve)

- [Pre-Serialized Messages](src/main/java/io/grpc/examples/preserialized)

### <a name="to-build-the-examples"></a> To build the examples

1. **[Install gRPC Java library SNAPSHOT locally, including code generation plugin](../COMPILING.md) (Only need this step for non-released versions, e.g. master HEAD).**