Hi Asa,
The canonical Cap'n Proto RPC protocol is not HTTP-based -- Cap'n Proto
messages are written directly to the socket. So, there's no way to add a
/healthz endpoint to the same port as RPC.
If you want to expose HTTP, you need to create a kj::HttpServer. Here's
some rough code to start with:
#include <kj/compat/http.h>
class MyHttpService: public kj::HttpService {
public:
// ... implement interface to handle HTTP requests ...
};
int main(int argc, char* argv) {
io = kj::setupAsyncIo();
// Register headers you are interested in.
kj::HttpHeaderTable::Builder htBuilder;
kj::HttpHeaderId myHeaderId = htBuilder.add("X-My-Header");
...
kj::Own<kj::HttpHeaderTable> headerTable = htBuilder.build();
// Create server.
MyHttpService myService;
kj::HttpServer server(io.provider->getTime(), *headerTable,
myService);
// Start listening.
auto listener = io.provider->getNetwork()
.parseAddress(argv[0]).wait(io.waitScope)->listen();
server.listenHttp(*listener).wait(io.waitScope);
// Will never get here; above will wait forever.
abort();
}
Your HttpService implementation can then accept WebSockets and potentially
adapt them as RPC channels...
-Kenton
On Wed, Sep 19, 2018 at 4:49 PM Asa Hammond <[email protected]> wrote:
> Awesome, thanks for the hints. I got TwoPartyVat working just now over
> standard sockets, so I am beyond EZ! =) (really wasn't that bad).
>
> One thing I need to layer in is an http /healthz endpoint so my
> loadbalancer knows my service is alive. Prob super easy, but I am pretty
> noob at kj::async. Basically how do I add a router into an ioContext? Is
> it possible to have some http get at the same time as rpc on the same
> port? My current implementation (uwebsockets) gives me cb for onOpen,
> onConnection, onClose, and onMessage for the http and ws sides of things
> separately, so I have some separation between these sides and the http
> loadbalancer is happy cause it gets to talk to /healthz.
>
> I'll look at your gnarly prod code and see what I can skim off into my
> mind. =)
>
> been a happy capnp serializer for 4 years or so at this point, nice stuff,
> thanks!
>
> On Wed, Sep 19, 2018 at 4:16 PM Kenton Varda <[email protected]>
> wrote:
>
>> Hi Asa,
>>
>> I don't think anyone has actually implemented TwoPartyVatNetwork over
>> WebSockets yet -- at least, I haven't heard of anyone doing it. It
>> certainly should be possible, though. First you'll need to decide if you
>> want to reuse WebSocket message framing at all, or just throw away the
>> frame boundaries and treat it as a byte stream. If you want to keep the
>> framing, you'd probably need to implement a custom VatNetwork, since
>> TwoPartyVatNetwork assumes an AsyncIoStream. If you go the byte stream
>> approach, then the thing you need to do is implement AsyncIoStream as a
>> wrapper around WebSocket. That should mostly be straightforward, assuming
>> familiarity with the KJ async framework. Once you have that, you can pass
>> it into TwoPartyVatNetwork.
>>
>> If you're looking for example code that uses KJ HTTP, there is Sandstorm:
>>
>>
>> https://github.com/sandstorm-io/sandstorm/blob/master/src/sandstorm/gateway.h
>>
>> However, that's real-world code, not a simple example. Unfortunately I
>> haven't written any samples yet... I'd like to write better documentation
>> for all of KJ soon...
>>
>> Let me know if you have more specific questions, and please keep us
>> updated on your progress. :)
>>
>> -Kenton
>>
>> On Tue, Sep 18, 2018 at 10:58 PM Asa <[email protected]> wrote:
>>
>>> Are there any examples of the WebSocket service from compat/http.h that
>>> is a self contained starting point? I am trying to get my head around how
>>> to layer these components into a larger service. Basically I want to use
>>> rpc over a websocket from the browser(via wasm) to a c++ service running a
>>> TwoPartyVatNetwork. My current working implementation uses capnp
>>> serialized structs in an async service(but not interfaces/rpc), from wasm
>>> (compiled from c++) to a c++ asio websocket server. I separately brought
>>> the ezrpc service up and extended the calc example, but now I want to
>>> finish out the conversion and prototype how to replace my asio server.
>>>
>>> Any pointers on where to look for more
>>> TwoPartyVatNetwork implementations and/or docs would be great. Especially
>>> on how to save some state like a jwt token ( via an auth capability?) in
>>> the open websocket, or if there is an example somewhere of
>>> TwoPartyVatNetwork over websockets.
>>>
>>> Thanks in advance.
>>>
>>> Asa
>>>
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>>
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