Appserver – Server Configuration, Dir Structure and Threads
In the first part of our Appserver series, we discussed the very high level differences of Appserver’s architecture to standard web server stacks and got you up and running with an Appserver instance. If you missed that part, please take the time to read it.
In this part, we will be exploring the Appserver architecture a bit more in depth. We will go through the concepts of the different contexts and the parts of Appserver you get out of the box, which cover some of the ground most of the popular PHP frameworks offer. We will also configure the web server and look into an application’s structure. Once we are finished, you should have a fair understanding about Appserver’s contexts in relation to threading, the web server, and its setup.
In subsequent parts, we’ll continue to go over the servlet engine in more detail, the persistence container, beans, the messaging system and the timer module. (Note: as this series evolved, the direction also changed, in order to include more practical information to break up the dry theory.)
The Contexts and Threading
As we had discussed in the first part, in today’s standard web server scenario, you will have a web server and either a web server module (mod_php) or a php process manager (PHP-FPM), to serve the PHP scripts/applications. The web server and the PHP process manager or module both handle their own work and threading to serve either the web page or the PHP application.
In this same respect, Appserver also handles threading for the client developer. However, the usage of the threads is somewhat different. The contents built within a thread aren’t constantly built and destroyed during the time appserver is running. In other words, as long as the appserver is running, the code you have given it to run, will continue to run (stay in memory) for each request. This fundamental difference is being repeated, as it is very important for understanding everything else we’ll be diving into.
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