Hi Johannes,
If you have the sources for marshalling conveniently laying around, please share, I'd like to have a look at them.
Thanks, Menno
On 21-03-16 17:01, Johannes Schlatow wrote:
Hi Menno,
On Mon, 21 Mar 2016 12:52:22 +0100 Menno Valkema <menno.genode@...9...> wrote:
Hi Johannes,
This is great. Currently we're trying to accomplish a similar thing for RPC calls and Signals. The approach with statically configured proxies you take, also made most sense to us, which is what we did for RPC calls, and we're now trying to use it for Signals. Combined with your work it seems together we made the first steps towards distributed use of the fundamental IPC mechanisms provided by Genode (shared memory, rpc, and signals).
For RPC calls we took a similar approach using a client_proxy and a server_proxy. Say we have a session called abc_session this is how the components collaborate:
- Abc Rpc client connects to a client_proxy which behaves like a
abc_session/session_component 2) The client_proxy marshalls the commands into command structures with opcodes and arguments, and forwards these over a nic connection. 3) server_proxy receives the commands over a nic connection, un-marshals the commands, and forwards the requests to the server while behaving as a abc_session client. 4) the server handles the request, and returns. 5) return value is forwarded to the client in a similar way the commands were transmitted.
Where we both have some form of serialized commands (in your case it's handled by the ip backend with an enum identifying the action is being sent over), we choose, for now, not to specify any sort of transportation mechanism except a bare nic session, and send raw data over nic sessions. In case we need an ip layer, we plan to move this in a separate component which knows how to handle ip, ipsec or some other protocol. However, I like the idea of your implementation to use various back-ends which handle different transportation types.
Some challenges we're still looking into are:
- Manual marshalling. Right now we marshall the rpc calls manually.
Genode already has a great marshalling mechanism in place, however I didn't manage to re-use this, so for now I do it by hand. This seems like a bit of a waste, so in a later stage I hope to look into this again.
I also started with a generic proxy implementation for RPC some time ago and did make some progress on the marshalling. However, I dismissed the idea as RPC over a network didn't appeal to me as a very good idea, especially when distributed capabilities are required. Nevertheless, I might have some code buried in my repositories. Let me know if you're interested in that.
- Cross CPU architecture usage of arguments. How to handle integer
arguments or structs with integer arguments between big/little endian architectures, or systems with a different notion of word-lengths and struct alignment?
- We're still working on Signals.
- Routing. Presently we statically configure how the client-proxy and
the server-proxy are connected. It would be better if we had more flexibility here, like what's now being provided by init.
- Capabilities. It would be great to have some sort of distributed
capability system to have stricter control over who talks to who.
Regards, Menno
PS. I went through you source code to see how you implemented things, and it's quite clear what's going on. However when I tried to run the server by typing 'make run/test-remoterom_backend_nic_ip_server' some methods being called seemed to be missing (calculate_checksum for example), and the compiler exited with an error. It seems some of the work is not in the github repository yet?
Oh, sorry. I forgot to mention that this requires some modifications of the Ipv4_packet class, see: https://github.com/genodelabs/genode/pull/1915
Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785351&iu=/4140 _______________________________________________ genode-main mailing list genode-main@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/genode-main