371 lines
13 KiB
Markdown
371 lines
13 KiB
Markdown
brpc可通过多种方式访问用ub搭建的服务。
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# ubrpc (by protobuf)
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r31687后，brpc支持通过protobuf访问ubrpc，不需要baidu-rpc-ub，也不依赖idl-compiler。（也可以让protobuf服务被ubrpc client访问，方法见[使用ubrpc的服务](nshead_service.md#使用ubrpc的服务)）。
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**步骤：**
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1. 用[idl2proto](https://github.com/brpc/brpc/blob/master/tools/idl2proto)把idl文件转化为proto文件，老版本idl2proto不会转化idl中的service，需要手动转化。
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```protobuf
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// Converted from echo.idl by brpc/tools/idl2proto
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import "idl_options.proto";
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option (idl_support) = true;
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option cc_generic_services = true;
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message EchoRequest {
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required string message = 1;
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}
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message EchoResponse {
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required string message = 1;
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}
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// 对于idl中多个request或response的方法，要建立一个包含所有request或response的消息。
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// 这个例子中就是MultiRequests和MultiResponses。
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message MultiRequests {
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required EchoRequest req1 = 1;
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required EchoRequest req2 = 2;
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}
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message MultiResponses {
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required EchoRequest res1 = 1;
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required EchoRequest res2 = 2;
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}
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service EchoService {
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// 对应idl中的void Echo(EchoRequest req, out EchoResponse res);
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rpc Echo(EchoRequest) returns (EchoResponse);
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// 对应idl中的uint32_t EchoWithMultiArgs(EchoRequest req1, EchoRequest req2, out EchoResponse res1, out EchoResponse res2);
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rpc EchoWithMultiArgs(MultiRequests) returns (MultiResponses);
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}
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```
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原先的echo.idl文件：
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```idl
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struct EchoRequest {
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string message;
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};
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struct EchoResponse {
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string message;
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};
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service EchoService {
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void Echo(EchoRequest req, out EchoResponse res);
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uint32_t EchoWithMultiArgs(EchoRequest req1, EchoRequest req2, out EchoResponse res1, out EchoResponse res2);
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};
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```
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2. 插入如下片段以使用代码生成插件。
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BRPC_PATH代表brpc产出的路径（包含bin include等目录），PROTOBUF_INCLUDE_PATH代表protobuf的包含路径。注意--mcpack_out要和--cpp_out一致。
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```shell
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protoc --plugin=protoc-gen-mcpack=$BRPC_PATH/bin/protoc-gen-mcpack --cpp_out=. --mcpack_out=. --proto_path=$BRPC_PATH/include --proto_path=PROTOBUF_INCLUDE_PATH
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```
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3. 用channel发起访问。
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idl不同于pb，允许有多个请求，我们先看只有一个请求的情况，和普通的pb访问基本上是一样的。
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```c++
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#include <brpc/channel.h>
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#include "echo.pb.h"
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...
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brpc::Channel channel;
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brpc::ChannelOptions opt;
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opt.protocol = brpc::PROTOCOL_UBRPC_COMPACK; // or "ubrpc_compack";
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if (channel.Init(..., &opt) != 0) {
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LOG(ERROR) << "Fail to init channel";
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return -1;
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}
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EchoService_Stub stub(&channel);
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...
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EchoRequest request;
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EchoResponse response;
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brpc::Controller cntl;
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request.set_message("hello world");
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stub.Echo(&cntl, &request, &response, NULL);
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if (cntl.Failed()) {
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LOG(ERROR) << "Fail to send request, " << cntl.ErrorText();
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return;
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}
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// 取response中的字段
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// [idl] void Echo(EchoRequest req, out EchoResponse res);
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// ^
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// response.message();
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```
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多个请求要设置一下set_idl_names。
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```c++
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#include <brpc/channel.h>
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#include "echo.pb.h"
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...
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brpc::Channel channel;
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brpc::ChannelOptions opt;
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opt.protocol = brpc::PROTOCOL_UBRPC_COMPACK; // or "ubrpc_compack";
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if (channel.Init(..., &opt) != 0) {
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LOG(ERROR) << "Fail to init channel";
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return -1;
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}
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EchoService_Stub stub(&channel);
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...
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MultiRequests multi_requests;
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MultiResponses multi_responses;
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brpc::Controller cntl;
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multi_requests.mutable_req1()->set_message("hello");
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multi_requests.mutable_req2()->set_message("world");
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cntl.set_idl_names(brpc::idl_multi_req_multi_res);
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stub.EchoWithMultiArgs(&cntl, &multi_requests, &multi_responses, NULL);
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if (cntl.Failed()) {
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LOG(ERROR) << "Fail to send request, " << cntl.ErrorText();
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return;
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}
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// 取response中的字段
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// [idl] uint32_t EchoWithMultiArgs(EchoRequest req1, EchoRequest req2,
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// ^ out EchoResponse res1, out EchoResponse res2);
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// | ^ ^
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// | multi_responses.res1().message(); |
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// | multi_responses.res2().message();
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// cntl.idl_result();
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```
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例子详见[example/echo_c++_ubrpc_compack](https://github.com/brpc/brpc/blob/master/example/echo_c++_ubrpc_compack/)。
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# ubrpc (by baidu-rpc-ub)
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server端由public/ubrpc搭建，request/response使用idl文件描述字段，序列化格式是compack或mcpack_v2。
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**步骤：**
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1. 依赖public/baidu-rpc-ub模块，这个模块是brpc的扩展，不需要的用户不会依赖idl/mcpack/compack等模块。baidu-rpc-ub只包含扩展代码，brpc中的新特性会自动体现在这个模块中。
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2. 编写一个proto文件，其中定义了service，名字和idl中的相同，但请求类型必须是baidu.rpc.UBRequest，回复类型必须是baidu.rpc.UBResponse。这两个类型定义在brpc/ub.proto中，使用时得import。
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```protobuf
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import "brpc/ub.proto"; // UBRequest, UBResponse
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option cc_generic_services = true;
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// Define UB service. request/response must be UBRequest/UBResponse
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service EchoService {
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rpc Echo(baidu.rpc.UBRequest) returns (baidu.rpc.UBResponse);
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};
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```
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3. 在COMAKE包含baidu-rpc-ub/src路径。
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```python
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# brpc/ub.proto的包含路径
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PROTOC(ENV.WorkRoot()+"third-64/protobuf/bin/protoc")
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PROTOFLAGS("--proto_path=" + ENV.WorkRoot() + "public/baidu-rpc-ub/src/")
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```
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4. 用法和访问其他协议类似：创建Channel，ChannelOptions.protocol为**brpc::PROTOCOL_NSHEAD_CLIENT**或**"nshead_client"**。request和response对象必须是baidu-rpc-ub提供的类型
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```c++
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#include <brpc/ub_call.h>
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...
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brpc::Channel channel;
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brpc::ChannelOptions opt;
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opt.protocol = brpc::PROTOCOL_NSHEAD_CLIENT; // or "nshead_client";
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if (channel.Init(..., &opt) != 0) {
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LOG(ERROR) << "Fail to init channel";
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return -1;
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}
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EchoService_Stub stub(&channel);
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...
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const int BUFSIZE = 1024 * 1024; // 1M
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char* buf_for_mempool = new char[BUFSIZE];
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bsl::xmempool pool;
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if (pool.create(buf_for_mempool, BUFSIZE) != 0) {
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LOG(FATAL) << "Fail to create bsl::xmempool";
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return -1;
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}
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// 构造UBRPC的request/response，idl结构体作为模块参数传入。为了构造idl结构，需要传入一个bsl::mempool
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brpc::UBRPCCompackRequest<example::EchoService_Echo_params> request(&pool);
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brpc::UBRPCCompackResponse<example::EchoService_Echo_response> response(&pool);
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// 设置字段
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request.mutable_req()->set_message("hello world");
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// 发起RPC
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brpc::Controller cntl;
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stub.Echo(&cntl, &request, &response, NULL);
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if (cntl.Failed()) {
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LOG(ERROR) << "Fail to Echo, " << cntl.ErrorText();
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return;
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}
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// 取回复中的字段
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response.result_params().res().message();
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...
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```
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具体example代码可以参考[echo_c++_compack_ubrpc](https://github.com/brpc/brpc/tree/master/example/echo_c++_compack_ubrpc/)，类似的还有[echo_c++_mcpack_ubrpc](https://github.com/brpc/brpc/tree/master/example/echo_c++_mcpack_ubrpc/)。
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# nshead+idl
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server端是由public/ub搭建，通讯包组成为nshead+idl::compack/idl::mcpack(v2)
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由于不需要指定service和method，无需编写proto文件，直接使用Channel.CallMethod方法发起RPC即可。请求包中的nshead可以填也可以不填，框架会补上正确的magic_num和body_len字段：
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```c++
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#include <brpc/ub_call.h>
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...
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brpc::Channel channel;
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brpc::ChannelOptions opt;
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opt.protocol = brpc::PROTOCOL_NSHEAD_CLIENT; // or "nshead_client";
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if (channel.Init(..., &opt) != 0) {
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LOG(ERROR) << "Fail to init channel";
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return -1;
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}
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...
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// 构造UB的request/response，完全类似构造原先idl结构，传入一个bsl::mempool（变量pool）
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// 将类型作为模板传入，之后在使用上可以直接使用对应idl结构的接口
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brpc::UBCompackRequest<example::EchoRequest> request(&pool);
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brpc::UBCompackResponse<example::EchoResponse> response(&pool);
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// Set `message' field of `EchoRequest'
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request.set_message("hello world");
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// Set fields of the request nshead struct if needed
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request.mutable_nshead()->version = 99;
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brpc::Controller cntl;
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channel.CallMethod(NULL, &cntl, &request, &response, NULL); // 假设channel已经通过之前所述方法Init成功
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// Get `message' field of `EchoResponse'
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response.message();
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```
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具体example代码可以参考[echo_c++_mcpack_ub](https://github.com/brpc/brpc/blob/master/example/echo_c++_mcpack_ub/)，compack情况类似，不再赘述
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# nshead+mcpack(非idl产生的)
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server端是由public/ub搭建，通讯包组成为nshead+mcpack包，但不是idl编译器生成的，RPC前需要先构造RawBuffer将其传入，然后获取mc_pack_t并按之前手工填写mcpack的方式操作：
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```c++
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#include <brpc/ub_call.h>
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...
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brpc::Channel channel;
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brpc::ChannelOptions opt;
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opt.protocol = brpc::PROTOCOL_NSHEAD_CLIENT; // or "nshead_client";
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if (channel.Init(..., &opt) != 0) {
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LOG(ERROR) << "Fail to init channel";
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return -1;
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}
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...
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// 构造RawBuffer，一次RPC结束后RawBuffer可以复用，类似于bsl::mempool
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const int BUFSIZE = 10 * 1024 * 1024;
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brpc::RawBuffer req_buf(BUFSIZE);
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brpc::RawBuffer res_buf(BUFSIZE);
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// 传入RawBuffer来构造request和response
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brpc::UBRawMcpackRequest request(&req_buf);
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brpc::UBRawMcpackResponse response(&res_buf);
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// Fetch mc_pack_t and fill in variables
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mc_pack_t* req_pack = request.McpackHandle();
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int ret = mc_pack_put_str(req_pack, "mystr", "hello world");
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if (ret != 0) {
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LOG(FATAL) << "Failed to put string into mcpack: "
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<< mc_pack_perror((long)req_pack) << (void*)req_pack;
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break;
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}
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// Set fields of the request nshead struct if needed
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request.mutable_nshead()->version = 99;
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brpc::Controller cntl;
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channel.CallMethod(NULL, &cntl, &request, &response, NULL); // 假设channel已经通过之前所述方法Init成功
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// Get response from response buffer
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const mc_pack_t* res_pack = response.McpackHandle();
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mc_pack_get_str(res_pack, "mystr");
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```
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具体example代码可以参考[echo_c++_raw_mcpack](https://github.com/brpc/brpc/blob/master/example/echo_c++_raw_mcpack/)。
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# nshead+blob
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r32897后brpc直接支持用nshead+blob访问老server（而不用依赖baidu-rpc-ub）。example代码可以参考[nshead_extension_c++](https://github.com/brpc/brpc/blob/master/example/nshead_extension_c++/client.cpp)。
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```c++
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#include <brpc/nshead_message.h>
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...
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brpc::Channel;
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brpc::ChannelOptions opt;
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opt.protocol = brpc::PROTOCOL_NSHEAD; // or "nshead"
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if (channel.Init(..., &opt) != 0) {
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LOG(ERROR) << "Fail to init channel";
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return -1;
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}
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...
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brpc::NsheadMessage request;
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brpc::NsheadMessage response;
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// Append message to `request'
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request.body.append("hello world");
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// Set fields of the request nshead struct if needed
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request.head.version = 99;
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brpc::Controller cntl;
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channel.CallMethod(NULL, &cntl, &request, &response, NULL);
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if (cntl.Failed()) {
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LOG(ERROR) << "Fail to access the server: " << cntl.ErrorText();
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return -1;
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}
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// response.head and response.body contains nshead_t and blob respectively.
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```
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或者用户也可以使用baidu-rpc-ub中的UBRawBufferRequest和UBRawBufferResponse来访问。example代码可以参考[echo_c++_raw_buffer](https://github.com/brpc/brpc/blob/master/example/echo_c++_raw_buffer/)。
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```c++
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brpc::Channel channel;
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brpc::ChannelOptions opt;
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opt.protocol = brpc::PROTOCOL_NSHEAD_CLIENT; // or "nshead_client"
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if (channel.Init(..., &opt) != 0) {
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LOG(ERROR) << "Fail to init channel";
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return -1;
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}
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...
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// 构造RawBuffer，一次RPC结束后RawBuffer可以复用，类似于bsl::mempool
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const int BUFSIZE = 10 * 1024 * 1024;
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brpc::RawBuffer req_buf(BUFSIZE);
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brpc::RawBuffer res_buf(BUFSIZE);
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// 传入RawBuffer来构造request和response
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brpc::UBRawBufferRequest request(&req_buf);
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brpc::UBRawBufferResponse response(&res_buf);
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// Append message to `request'
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request.append("hello world");
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// Set fields of the request nshead struct if needed
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request.mutable_nshead()->version = 99;
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brpc::Controller cntl;
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channel.CallMethod(NULL, &cntl, &request, &response, NULL); // 假设channel已经通过之前所述方法Init成功
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// Process response. response.data() is the buffer, response.size() is the length.
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```
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