[erlang-questions] { ProcessName, NodeName } ! Message VS rpc:call/4 VS HTTP/1.1 across Erlang Nodes

Joshua Muzaaya joshmuza@REDACTED
Wed Nov 14 17:21:20 CET 2012

thank you so much for this feedback

On Wed, Nov 14, 2012 at 6:14 PM, Konstantin Tcepliaev <f355@REDACTED> wrote:

> Hi,
> A1: Using rpc:call/4 is definitely a worst choice, as it uses a call to
> {Name, Node} with extra overhead and single registered process. HTTP
> implies lots of overhead too. I'd go with {Name, Node} ! Msg.
> A2-3: Suggested in A1 method can be improved by some (not so) clever usage
> of erlang:monitor/2 and message passing, so that your sending node knows
> whether remote registered process is alive or not, and behaves accordingly.
> Regards,
> --
> Konstantin
> 09.11.2012, 09:20, "Joshua Muzaaya" <joshmuza@REDACTED>:
> I have a setup in which two nodes are going to be communicating a lot. On
> Node A, there are going to be thousands of processes, which are meant to
> access services on Node B. There is going to be a massive load of requests
> and responses across the two nodes. The two Nodes, will be running on two
> different servers, each on its own hardware server.
> I have 3 Options: HTTP/1.1 , rpc:call/4 and Directly sending a message to
> a registered gen_server on Node B. Let me explain each option.
> *HTTP/1.1*
> Suppose that on Node A, i have an HTTP Client like Ibrowse, and on Node
> B, i have a web server like Yaws-1.95, the web server being able to
> handle unlimited connections, the operating system settings tweaked to
> allow yaws to handle all connections. And then make my processes on Node A
> to communicate using HTTP. In this case each method call, would mean a
> single HTTP request and a reply. I believe there is an overhead here, but
> we are evaluating options here. The erlang Built in mechanism called
> webtool, may be built for this kind of purpose.
> *rpc:call/4*
> I could simply make direct rpc calls from Node A to Node B. I am not very
> sure how the underlying rpc mechanism works , but i think that when two
> erlang nodes connect via net_adm:ping/1, the created connection is not
> closed but all rpc calls use this pipe to transmit requests and pass
> responses. Please correct me on this one.
> *Sending a Message from Node A to Node B *
> I could make my processes on Node A to just send message to a registered
> process, or a group of processes on Node B. This too seems a clean option.
> *Q1.* Which of the above options would you recommend and why, for an
> application in which two erlang nodes are going to have enormous
> communications between them all the time. Imagine a messaging system, in
> which two erlang nodes are the routers :) ?
> *Q2.* Which of the above methods is cleaner, less problematic and is more
> fault tolerant (i mean here that, the method should NOT have single point
> of failure, that could lead to all processes on Node A blind) ?
> *Q3.* The mechanism of your choice: how would you make it even more fault
> tolerant, or redundant?
> *Assumptions: * The Nodes are always alive and will never go down, the
> network connection between the nodes will always be available and
> non-congested (dedicated to the two nodes only) , the operating system have
> allocated maximum resources to these two nodes.
> Thank you for your evaluations
> ,
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*Muzaaya Joshua
Systems Engineer
*"Through it all, i have learned to trust in Jesus. To depend upon His Word"
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