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POHow to describe gen_server visually?
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  1. POHow to describe gen_server visually?
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    copied!<p><em>Disclaimer: The author is a newbie in OTP having some basic knowledge of Erlang's syntax, processes and messages.</em></p> <p>I am trying to grasp the notion of behaviours in Erlang, but a lot of questions spring in my head preventing me from understanding the whole principle of such a behaviour like gen_server.</p> <p>Okay, the official documentation for gen_server shows a nice diagram of a server and three clients connected with Query and Reply arrows: <a href="http://www.erlang.org/doc/design_principles/gen_server_concepts.html" rel="noreferrer">http://www.erlang.org/doc/design_principles/gen_server_concepts.html</a></p> <p>But each time I try to understand the concept further, I get stuck.</p> <p>There is a lot of concepts which I cannot build into one larger concept in my head:</p> <ul> <li>behaviour implementation;</li> <li>behaviour container;</li> <li>behaviour interface; </li> <li>callback module;</li> <li>callback functions;</li> <li>API functions.</li> </ul> <p>I use the following resources:</p> <ul> <li>Erlang/OTP in Action book;</li> <li>Introduction to OTP behaviours presentation, <a href="http://www.slideshare.net/gamlidek/ceug-introduction-to-otp-behaviors-part-i-genserver" rel="noreferrer">http://www.slideshare.net/gamlidek/ceug-introduction-to-otp-behaviors-part-i-genserver</a>;</li> <li>'ErlyBank' at <a href="http://spawnlink.com/articles/an-introduction-to-gen_server-erlybank/index.html" rel="noreferrer">http://spawnlink.com/articles/an-introduction-to-gen_server-erlybank/index.html</a>.</li> </ul> <p>I am still in the state "we call one function in one module, this function calls the other function, that function creates a process... stuck"</p> <p><strong>Is there any way to describe the notion of gen_server in a diagram? How can an interaction flow between clients and a server be shown visually?</strong> (to help a not so smart newcomer to understand the concept visually)</p> <p>For example like here: <a href="http://support.novell.com/techcenter/articles/img/dnd2003080506.gif" rel="noreferrer">http://support.novell.com/techcenter/articles/img/dnd2003080506.gif</a></p> <p>UPD: I have tried to draw a diagram of my own, but I still don't get the purpose of any connector in the diagram: <a href="http://postimage.org/image/qe215ric/full/" rel="noreferrer">http://postimage.org/image/qe215ric/full/</a></p> <p>UPD2: This is something similar to what I would like to see: <a href="http://cryptoanarchy.org/wiki/Worker_patterns" rel="noreferrer">http://cryptoanarchy.org/wiki/Worker_patterns</a> (The Model). However, it doesn't show the interaction between modules, functions and processes.</p>
 

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