You're very welcome.
I don't know, I sort of picked it up here and there, no formal training really. That's a pretty standard PHP command. Mostly, I learned PHP (back when it was an early version 3) from reading the php.net site since back then there were very few good resource books for PHP. That's basically what I do now, too, since even though there are probably good PHP books out there, I have yet to pick on up. PHP.net is a great resource, and so far, hasn't failed me...
I think basic concepts of client-server archetecture are pretty simple when you really think about them. I mean, the devil's in the details, as always, but at a high level, it's not really that complex. A client asks a server a question, the server responds. The fewer times the client and server have to exchange pleasentries, the better.
From there, you start asking things like, "well, what does the client say?" The answer is usually pretty straigt forward, depending on your the protocol. For example, an FTP client starts off by saying something different than an HTTP one (a web browser, for example), which is different than an SMTP one (e-mail) and so forth.
Then, you figure out why the client is asking that.... and what the server says and why,... just start digging down. When you break IT down into bitesized chunks (like any other subject in the world) so that the details aren't so overwhelming, things get much easier. Once you understand some of the details, you'll be able to assemble and synthesize those details to form a more wholist view where those disperate details make even more sense when viewed relative to each other. It just takes a determination.
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