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The C based gRPC (C++, Python, Ruby, Objective-C, PHP, C#)
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64 lines
2.0 KiB
64 lines
2.0 KiB
6 years ago
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# gRPC C++ Load Balancing Tutorial
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### Prerequisite
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Make sure you have run the [hello world example](../helloworld) or understood the basics of gRPC. We will not dive into the details that have been discussed in the hello world example.
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### Get the tutorial source code
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The example code for this and our other examples lives in the `examples` directory. Clone this repository to your local machine by running the following command:
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```sh
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$ git clone -b $(curl -L https://grpc.io/release) https://github.com/grpc/grpc
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```
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Change your current directory to examples/cpp/load_balancing
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```sh
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$ cd examples/cpp/load_balancing/
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```
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### Generating gRPC code
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To generate the client and server side interfaces:
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```sh
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$ make helloworld.grpc.pb.cc helloworld.pb.cc
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```
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Which internally invokes the proto-compiler as:
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```sh
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$ protoc -I ../../protos/ --grpc_out=. --plugin=protoc-gen-grpc=grpc_cpp_plugin ../../protos/helloworld.proto
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$ protoc -I ../../protos/ --cpp_out=. ../../protos/helloworld.proto
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```
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### Writing a client and a server
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The client and the server can be based on the hello world example.
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Additionally, we can configure the load balancing policy. (To see what load balancing policies are available, check out [this folder](https://github.com/grpc/grpc/tree/master/src/core/ext/filters/client_channel/lb_policy).)
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In the client, set the load balancing policy of the channel via the channel arg (to, for example, Round Robin).
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```cpp
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ChannelArguments args;
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// Set the load balancing policy for the channel.
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args.SetLoadBalancingPolicyName("round_robin");
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GreeterClient greeter(grpc::CreateCustomChannel(
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"localhost:50051", grpc::InsecureChannelCredentials(), args));
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```
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For a working example, refer to [greeter_client.cc](greeter_client.cc) and [greeter_server.cc](greeter_server.cc).
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Build and run the client and the server with the following commands.
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```sh
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make
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./greeter_server
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```
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```sh
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./greeter_client
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```
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(Note that the case in this example is trivial because there is only one server resolved from the name.)
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