1. Intro to claire-protorpc
@fanyu83

2. What is claire-protorpc
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protobuf-based RPC library
non-blocking
event-driving
multi-core ready
modern C++
for x86-64 Linux
BSD license

3. Tutorial: echo
● In computer telecommunications, echo is the display or
return of sent data at or to the sending end of a
transmission. ------ from wikipedia
● Use claire-protorpc develop application and services
should do:
○ define a .proto file which declared the rpc message
structure and methods
○ use generated stub to call echo methods through
RpcChannel
○ implement echo services, and register it to RpcServer

4. Echo Client/Server
Stubs
Services
RpcChannel
RpcServer
HttpClient
HttpServer
HttpConnection

5. echo.proto
● echo.proto define
message and service.
● Use protoc compile the
echo.proto
○ generate echo.pb.h
and echo.pb.cc
// protoc --plugin=protoc-rpc-gen --rpc_out . echo.proto
package echo;
option cc_generic_services = true;
message EchoRequest {
required string str = 1;
}
message EchoResponse {
required string str = 1;
}
service EchoService {
rpc Echo (EchoRequest) returns (EchoResponse);
}

6. Echo client
● echo.pb.h define Stub
which can call Echo
service
● It need RpcChannel to
communicate remote
server.
int main(int argc, char* argv[])
{
EventLoop loop;
InetAddress server_address(argv[1], 8080);
RpcChannel channel(&loop);
channel.Connect(server_address);
echo::EchoService::Stub stub(&channel);
RpcControllerPtr controller(new RpcController());
echo::EchoRequest request;
request.set_str("0123456789ABCDEF");
stub.Echo(controller, request, boost::bind(&replied, _1, _2));
loop.loop();
}

7. Echo server
● echo.pb.h define
Abstract interface
EchoService, server side
need implement it.
● EchoService need
register to RpcServer.
int main(int argc, char* argv[])
{
::google::ParseCommandLineFlags(&argc, &argv, true);
InitClaireLogging(argv[0]);
EventLoop loop;
InetAddress listen_address(8080);
echo::EchoServiceImpl impl;
RpcServer server(&loop, listen_address);
server.set_num_threads(FLAGS_num_threads);
server.RegisterService(&impl);
server.Start();
loop.loop();
}

8. Benefits of claire-protorpc
● claire-protorpc provide:
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Define a service only need a function.
Generate stub to call remote service.
Automatic message encode/decode.
Checksum for each message.
Compress data if user set.
Very good performance, at least no obvious
bottleneck.

9. Concept
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protobuf provide server declaration but no implementation, it suggest
“provide code generator plugins which generate code specific to the
particular RPC implementation.”
claire-protorpc is one implementation of protobuf-based rpc, and supply
itself plugin to generate code for claire-protorpc only.
It implement 3 important concept of protobuf rpc:
○ RpcController
○ RpcChannel
○ RpcServer
But we do not use Google defined interface directly, instead claire-version!

10. Service
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Services themselves are abstract interfaces (implemented either by servers
or as stubs), but they subclass this base interface. The methods of this
interface can be used to call the methods of the Service without knowing
its exact type at compile time (analogous to Reflection).
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claire-protorpc use protoc-rpc-gen to generate the rpc service which
inherited from Service class(claire-protorpc’s version)

11. RpcController
● “An RpcController mediates a single method call. The
primary purpose of the controller is to provide a way to
manipulate settings specific to the RPC implementation
and to find out about RPC-level errors.”
● Now it used to declare caller specific option and get error
information.

12. RpcChannel
● “An RpcChannel represents a communication line to a
Service which can be used to call that Service's methods.
The Service may be running on another machine.
Normally, you should not call an RpcChannel directly,
but instead construct a stub Service wrapping it.”
● Now it used to communicate to RpcServer, it do message
encode/decode, health detection, compress/uncompress,
loadbalance, address resolverm, .etc .

13. RpcServer
● RpcServer used to store all registered service, and
response to all request.
○ It also provide monitor, debug, profile, flags
management features, user no need write one line
code to use these

14. Wire Format
message RpcMessage {
required MessageType type = 1;
required fixed64 id = 2;
4 bytes
4 bytes
meesage length
optional string service = 3;
checksum
optional string method = 4;
optional bytes request = 5;
RpcMessage
optional bytes response = 6;
optional ErrorCode error = 7;
optional string reason = 8;
optional CompressType compress_type = 9;
}

15. Architecture
protoc-rpc-gen
RpcController
RpcChannel
RpcServer
BuiltInService
gen-assets
HttpConnection
HttpClient
HttpServer
Resolver
LoadBalancer
TcpConnection
TcpClient
TcpServer
Inspector
ProtobufIO
Logging
EventLoop
Metrics
String
claire-protorpc
claire-netty
claire-common
System
Symbolizer
Thread
Time
File
gtest
protobuf
profiler
ctemplate
boost
external
c-ares
tcmalloc
snappy
rapidjson
gflags

16. Features
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Health Detection
LoadBalancer(Random, .etc)
Address Resolver(Dns, .etc)
Compress transport
Flags view/modify
Internal statistics view/collection
Online profile
Methods form for test/debug
All built-on Http

17. /flags
● claire use gflags manage configures.
● Through /flags, user can view and modify flags.
● Easy for modify flags of a lot of machines through /flags
post method.

18. /flags

19. Metrics
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claire-protorpc supply powerful metrics type:
○ counter
■ A counter is a value that never decreases. Examples might be
"sent bytes" or "receied bytes". You just increment the counter
each time a countable event happens, and graphing utilities
usually graph the deltas over time.
○ histogram
■ A metric is tracked via distribution, and is usually used for
timings.
claire-protorpc support graphing pages & json interface together

20. /couters

21. /histograms

22. /form
● /form page show all register services & method on
running server, user can post form to server as post
protobuf message
● Easy for test and debug

23. /form

24. /pprof
● claire-protorpc integrate with gperftools, so
it support online profiling.
○ support /pprof/profile, /pprof/heap, /pprof/growth
○ also support profile without binary file, through
/pprof/symbol & /pprof cmdlind
○ will support /pprof/contension later

25. /pprof

26. Question
github.com/robbinfan/claire-protorpc