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On PHP and Scaling
jpkunst writes "Chris Shiflett at oreillynet.com summarizes (with lots of links) a discussion about scalability, brought about by Friendster's move from Java to PHP. Chris argues that PHP scales well, because it fits into the Web's fundamental architecture. 'I think PHP scales well because Apache scales well because the Web scales well. PHP doesn't try to reinvent the wheel; it simply tries to fit into the existing paradigm, and this is the beauty of it.' (The article is also available on Chris' own website.)"
PHP inherntely will not lead to scalability, however, if you ever try to create any applications that use a DFS-type algorithm, it can happen. PHP (I know it is web-based, shouldn't ask too much) does not allow for extremely simple soloutions in DFS type algorithms that are apparent to most users. Many will end up with too many "while()" statements and bring down script efficency exponetialy.
I've seen a friendster stack trace before, when the app was running slow at 5 am. For those of you who don't know what this is, it's when Java runs into an error and tells you were your program died. It was really funny. Basically there was a servlet and a call to Database.java and on line 8000 of database.java they were calling mysql directly. Real nice architecture, NOT!
I worked in a small shop developing web apps, and while it wasn't mission critical stuff like banking, it wasn't exactly brainless "dump data from MySQL" stuff either. I was lucky that my boss wasn't picky about languages. But if anyone I work with doubts the power and simplicity of PHP, I usually bring up Yahoo.
IMHO, PHP rocks. It's suitable for pretty much any and all web development. It can be used for quick hacks, or you can code it like a pro with objects and stuff.
The term "scalable" has become an industry buzzword. It is fruitless to argue whether something is scalable or not if there is no clear defination. It's like arguing whether you believe in freedom or not. Of course most people in the world will say they believe in freedom, but if you ask 100 people to define it you will get 100 different answers (the Bush administration has had a field day with this because the minute you oppose them, they accuse you of not believing in freedom; their defination of course).
It is impossible to say php is or is not scalable unless a defination can be agreed on. And with "scalable's" current buzzword status, I don't see that happening very soon.
developers will tend to munge sql calls into the templates, blow off any MVC separation, and get a system that is very hard to keep going for more than a few revisions.
Yes, that is tempting. But, conversely, it's a very useful capability for small projects. For larger projects, you just need to ensure you have the discipline not to use the capabilities.
For instance, here is a site I developed in PHP using a strict model-view separation. There is direct linkage between view and controller and controller and model -- I couldn't be bothered to sort that out for a project of limited size like that one. In a larger project, I'd probably devise some kind of mechanism for that.
You can write unmaintanable code in any language you choose. Discipline is the key.
I think to settle this debate is a possible real-world example. Look at the story on the Jboss Nukes Project. It explains the CPU utilization and speed of the PHP version and how moving to a J2EE implementation decreased the wait times dramatically.
Its difficult to argue with facts.
Even better than JSP and other technologies is to use Jakarta's Tapestry as the presentation layer. Tapestry rocks and I look forward to having something like that on PHP. Right now PHPTal is close. The ability to define a page as components (almost in GUI terms) and then define event call-backs and so forth really makes life better.
Tapestry for the view, Spring for the control, and Hibernate for the model is a combination hard to beat with php. Sooner or later all these technologies will be used no matter what underlying language.