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Archive for the ‘client/server’ Category

Starting with certain versions in the 9.0’s of Flash player, socket communication in Flex began adding additional security measures. The one I am going to discuss in the post is the socket policy file. In short, the socket policy file is an XML file that is served by default from port 843 and contains information […]

Tuesday, February 9th, 2010 at 00:04 0 comments

Client-server programming is one of my passions, and I enjoy doing it in almost any language. Which makes it fitting that Flex (ActionScript) is one of my favorite languages to develop in, because it truly is a client-side technology which pretty much means it’s open to just about any type of backend server. I suppose […]

Monday, February 8th, 2010 at 22:39 6 comments

I’ll start off by going over the basic high level architecture for my self registration procedure: There is a register.php script residing on the load balancer, accessible via HTTP. There is a deregister.php script residing on the load balancer, accessible via HTTP. There is a register_with_lb.pl script residing on the web server, in /usr/local/bin/. There […]

Thursday, February 4th, 2010 at 16:25 0 comments

I think I have to break the self-registration into two posts, it took a lot longer than I expected last night. This post deals with getting scripts to run at startup and shutdown on Linux. I did this on Fedora, I imagine the process would be similar on Ubuntu, etc. This is actually the last […]

Thursday, February 4th, 2010 at 15:18 0 comments

Load balancers are great, but they become even more powerful when servers have the ability to self-register when they come online, and deregister when they go offline. This is especially true with services such as EC2, when the size of the server group might grow or shrink in response to need. This is a tutorial […]

Wednesday, February 3rd, 2010 at 14:39 1 comment

Just this afternoon, one of my colleagues and I were discussing our feelings about the “semicolon-class” of bugs that developers will inevitably spin their wheels on from time to time. I’ve had just such an experience the past two evenings with what started out as a simple recipe from the Apache Cookbook, entitled “Load Balancing […]

Tuesday, February 2nd, 2010 at 22:09 14 comments

I created some barebones Fedora servers that I’m intending to create a load balanced cluster from using Apache’s mod_proxy_balancer. My topology will eventually look like this: load_balancer -> (ws1, ws2, ws3) -> mysql_server As you can see, it’s nothing fancy. To test the balancer, each web server has a PHP script that connects to the […]

Tuesday, February 2nd, 2010 at 11:34 18 comments

Although a TCP client is fundamentally different from a TCP server, setting up the socket is very much the same. For a server, we called these methods in this order: socket()→bind()→listen()→accept(), followed by sequences of read() and write(). For a client we will call these methods in this order: socket()→connect(), followed by sequences of write() […]

Tuesday, August 18th, 2009 at 10:15 0 comments