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greeter_client.cc | D | 12-May-2024 | 3.1 KiB | 96 | 50 | |
greeter_server.cc | D | 12-May-2024 | 3 KiB | 95 | 56 |
README.md
1# Metadata Example 2 3## Overview 4 5This example shows you how to add custom headers on the client and server and 6how to access them. 7 8Custom metadata must follow the "Custom-Metadata" format listed in 9https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md, with the 10exception of binary headers, which don't have to be base64 encoded. 11 12### Get the tutorial source code 13 The example code for this and our other examples lives in the `examples` directory. Clone this repository 14 at the [latest stable release tag](https://github.com/grpc/grpc/releases) to your local machine by running the following command: 15 ```sh 16$ git clone -b RELEASE_TAG_HERE https://github.com/grpc/grpc 17``` 18 Change your current directory to examples/cpp/metadata 19 ```sh 20$ cd examples/cpp/metadata 21``` 22 23### Generating gRPC code 24 To generate the client and server side interfaces: 25 ```sh 26$ make helloworld.grpc.pb.cc helloworld.pb.cc 27``` 28Which internally invokes the proto-compiler as: 29 ```sh 30$ protoc -I ../../protos/ --grpc_out=. --plugin=protoc-gen-grpc=grpc_cpp_plugin ../../protos/helloworld.proto 31$ protoc -I ../../protos/ --cpp_out=. ../../protos/helloworld.proto 32``` 33### Try it! 34Build client and server: 35 36```sh 37$ make 38``` 39 40Run the server, which will listen on port 50051: 41 42```sh 43$ ./greeter_server 44``` 45 46Run the client (in a different terminal): 47 48```sh 49$ ./greeter_client 50``` 51 52If things go smoothly, you will see in the client terminal: 53 54"Client received initial metadata from server: initial metadata value" 55"Client received trailing metadata from server: trailing metadata value" 56"Client received message: Hello World" 57 58 59And in the server terminal: 60 61"Header key: custom-bin , value: 01234567" 62"Header key: custom-header , value: Custom Value" 63"Header key: user-agent , value: grpc-c++/1.16.0-dev grpc-c/6.0.0-dev (linux; chttp2; gao)" 64 65We did not add the user-agent metadata as a custom header. This shows how 66the gRPC framework adds some headers under the hood that may show up in the 67metadata map. 68