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// Copyright (c) 2013, Kenton Varda <temporal@gmail.com>
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef CAPNP_EZ_RPC_H_
#define CAPNP_EZ_RPC_H_
#include "rpc.h"
namespace kj { class AsyncIoProvider; class LowLevelAsyncIoProvider; }
namespace capnp {
class EzRpcContext;
class EzRpcClient {
// Super-simple interface for setting up a Cap'n Proto RPC client. Example:
//
// # Cap'n Proto schema
// interface Adder {
// add @0 (left :Int32, right :Int32) -> (result :Int32);
// }
//
// // C++ client
// int main() {
// EzRpcClient client("10.0.1.2:3456");
// Adder::Client adder = client.getCap<Adder>("adder");
// auto request = adder.frobRequest();
// request.setLeft(12);
// request.setRight(34);
// auto response = request.wait(client.getWaitScope());
// assert(response.getResult() == 46);
// return 0;
// }
//
// // C++ server
// class AdderImpl: public Adder::Server {
// public:
// kj::Promise<void> frob(FrobParams::Reader params, FrobResults::Builder results) {
// results.setResult(params.getLeft() + params.getRight());
// return kj::READY_NOW;
// }
// };
//
// int main() {
// EzRpcServer server(":3456");
// server.exportCap("adder", kj::heap<AdderImpl>());
// kj::NEVER_DONE.wait(server.getWaitScope());
// }
//
// This interface is easy, but it hides a lot of useful features available from the lower-level
// classes:
// - The server can only export a small set of public, singleton capabilities under well-known
// string names. This is fine for transient services where no state needs to be kept between
// connections, but hides the power of Cap'n Proto when it comes to long-lived resources.
// - EzRpcClient/EzRpcServer automatically set up a `kj::EventLoop` and make it current for the
// thread. Only one `kj::EventLoop` can exist per thread, so you cannot use these interfaces
// if you wish to set up your own event loop. (However, you can safely create multiple
// EzRpcClient / EzRpcServer objects in a single thread; they will make sure to make no more
// than one EventLoop.)
// - These classes only support simple two-party connections, not multilateral VatNetworks.
public:
explicit EzRpcClient(kj::StringPtr serverAddress, uint defaultPort = 0);
// Construct a new EzRpcClient and connect to the given address. The connection is formed in
// the background -- if it fails, calls to capabilities returned by importCap() will fail with an
// appropriate exception.
//
// `defaultPort` is the IP port number to use if `serverAddress` does not include it explicitly.
// If unspecified, the port is required in `serverAddress`.
//
// The address is parsed by `kj::Network` in `kj/async-io.h`. See that interface for more info
// on the address format, but basically it's what you'd expect.
EzRpcClient(struct sockaddr* serverAddress, uint addrSize);
// Like the above constructor, but connects to an already-resolved socket address. Any address
// format supported by `kj::Network` in `kj/async-io.h` is accepted.
explicit EzRpcClient(int socketFd);
// Create a client on top of an already-connected socket.
~EzRpcClient() noexcept(false);
template <typename Type>
typename Type::Client importCap(kj::StringPtr name);
Capability::Client importCap(kj::StringPtr name);
// Ask the sever for the capability with the given name. You may specify a type to automatically
// down-cast to that type. It is up to you to specify the correct expected type.
kj::WaitScope& getWaitScope();
// Get the `WaitScope` for the client's `EventLoop`, which allows you to synchronously wait on
// promises.
kj::AsyncIoProvider& getIoProvider();
// Get the underlying AsyncIoProvider set up by the RPC system. This is useful if you want
// to do some non-RPC I/O in asynchronous fashion.
kj::LowLevelAsyncIoProvider& getLowLevelIoProvider();
// Get the underlying LowLevelAsyncIoProvider set up by the RPC system. This is useful if you
// want to do some non-RPC I/O in asynchronous fashion.
private:
struct Impl;
kj::Own<Impl> impl;
};
class EzRpcServer {
// The server counterpart to `EzRpcClient`. See `EzRpcClient` for an example.
public:
explicit EzRpcServer(kj::StringPtr bindAddress, uint deafultPort = 0);
// Construct a new `EzRpcServer` that binds to the given address. An address of "*" means to
// bind to all local addresses.
//
// `defaultPort` is the IP port number to use if `serverAddress` does not include it explicitly.
// If unspecified, a port is chosen automatically, and you must call getPort() to find out what
// it is.
//
// The address is parsed by `kj::Network` in `kj/async-io.h`. See that interface for more info
// on the address format, but basically it's what you'd expect.
//
// The server might not begin listening immediately, especially if `bindAddress` needs to be
// resolved. If you need to wait until the server is definitely up, wait on the promise returned
// by `getPort()`.
EzRpcServer(struct sockaddr* bindAddress, uint addrSize);
// Like the above constructor, but binds to an already-resolved socket address. Any address
// format supported by `kj::Network` in `kj/async-io.h` is accepted.
EzRpcServer(int socketFd, uint port);
// Create a server on top of an already-listening socket (i.e. one on which accept() may be
// called). `port` is returned by `getPort()` -- it serves no other purpose.
~EzRpcServer() noexcept(false);
void exportCap(kj::StringPtr name, Capability::Client cap);
// Export a capability publicly under the given name, so that clients can import it.
//
// Keep in mind that you can implicitly convert `kj::Own<MyType::Server>&&` to
// `Capability::Client`, so it's typicall to pass something like
// `kj::heap<MyImplementation>(<constructor params>)` as the second parameter.
kj::Promise<uint> getPort();
// Get the IP port number on which this server is listening. This promise won't resolve until
// the server is actually listening. If the address was not an IP address (e.g. it was a Unix
// domain socket) then getPort() resolves to zero.
kj::WaitScope& getWaitScope();
// Get the `WaitScope` for the client's `EventLoop`, which allows you to synchronously wait on
// promises.
kj::AsyncIoProvider& getIoProvider();
// Get the underlying AsyncIoProvider set up by the RPC system. This is useful if you want
// to do some non-RPC I/O in asynchronous fashion.
kj::LowLevelAsyncIoProvider& getLowLevelIoProvider();
// Get the underlying LowLevelAsyncIoProvider set up by the RPC system. This is useful if you
// want to do some non-RPC I/O in asynchronous fashion.
private:
struct Impl;
kj::Own<Impl> impl;
};
// =======================================================================================
// inline implementation details
template <typename Type>
inline typename Type::Client EzRpcClient::importCap(kj::StringPtr name) {
return importCap(name).castAs<Type>();
}
} // namespace capnp
#endif // CAPNP_EZ_RPC_H_