You're absolutely right about questioning PHP for larger applications. It works great in very small teams, no more than handful at most (and with very low churn). The same is true for code size, the bigger the code base, the more your productivity drops.

PHP starts off with higher productivity (assuming very small team and small code base) but quickly falls apart as you scale up (team and code base - I'm not talking about performance here). Java on the other hand is the opposite. It's a little slower to start, but as you grow it doesn't skip a beat, development continues at the same pace.

If you're interested, I wrote a pretty detailed comparison between static and dynamically typed languages (which is basically what Java versus PHP is about - that's the difference that allows a large portion of the features within the languages) at: http://www.followsteph.com/2008/07/06/why-you-cant-just-compare-languages-with-lines-of-code/ In it, I suggest that they both have their places, you just need to decide where you want to go ;)

I am a Java developer too. I have done most of XML processing, JMS, AtomPub, Lucene in Java. But when I am working a web project. PHP is always an option. In PHP, everything is a string, just like web pages and the printable data itself.

PHP can be easy, quick and dirty for dirty tasks that you don't care about software archtecture, design pattern and OO principles. Get things done.

However, nothing prevents you from doing any serious OO software with it. Like this

http://devzone.zend.com/article/3510-Zend_Acl-and-MVC-Integration-Part-II-Advanced-Use

or like this

http://www.symfony-project.org/tutorial/1_1/my-first-project

Love buzzwords like AOP and Dependency Injection, take a look at http://www.slideshare.net/rlmp/aspectoriented-programming-and-depedency-injection

PHP allows me to do things in a simple manner first. Then it allows me to make things complicated myself if I want. Try closure: http://wiki.php.net/rfc/closures

PHP 5.3 can be downloaded at http://snaps.php.net

I hate commenting just to correct, but pcdinh is wrong about "everything is a string" in PHP. PHP supports all of the standard primitives as well as being fully object oriented; php6 also includes namespaces. And XML and XSL processing is pretty simple in PHP.

I've written enterprise applications using PHP and maintain a couple of others and it works very well; developers just need more discipline because the language is so flexible. I started on C++/Java which I still love, and also struggled with the dynamic typing of PHP when I first started, coming from a background in statically typed languages.

I would recommend an MVC framework to improve scalability and maintainability. I'm currently using CI, Kohana also looks promising; Cake and Zend were too big for my needs.

I admit to thinking about using a framework, but so far I've resisted since I've written (Java) frameworks and have a pretty good idea how to make something minimal that works for my needs. I use a single index page controller (another one for ajax operations) and use apache mod_rewrite to make nice urls. Basically everything /xxxx/yyy/zzz gets mapped to index.php (or ajax.php if its a REST service call).

The biggest question for scaling is caching of course; there are many options but I haven't settled on one yet. Caching is what makes this Java based blog survive even sitting atop Digg (as I did once). For PHP I am still researching choices.

I do java to pay my bills, I use PHP for moonlighting work. Using a good framework removes alot of the aruguments about code-base size, ugly code etc. Try giving kohana or Code-Igniter a try.

Frameworks help remove some of the cruft that ground up PHP code can produce. Since adopting Code Igniter for the majority of my PHP work, I've noticed my code is much cleaner and easier to read. On top of that, since the framework expects you to do things a certain way, you don't really have to worry about different people on the things to comletely different things in their code, thus rendering the code base unreadable and un-reproducable. It also gives you a fighting chance for refactorbation ;)

Code Igniter looks very usable, I will give it a try, thanks.

I also recommend CodeIgniter. I've used it on a couple test projects and it works great. The only thing is that it feels like Struts, but that's where the PHP world is at. MVC is the big thing right now. You won't find anything remotely like JSF (event based rather than action based) or GWT.

@Derek

"Everything is string" is technically wrong but I hope that you will see my point: PHP can treat most of things as string. Integer, Float, stdClass, array, boolean ... can be printed out without any hassle. It prevents PHP developers from headaches when they are working on a template.

You don't need to wait for PHP 6 to try namespaces: It is already included in PHP 5.3 which will be released on this September.

I personally don't like CodeIgniter or Kohana because It breaks PHP Coding Standard which is set by PECL, PEAR, PHP Core Library that recommend use CamelCase style for class naming, camelCase for variable and method naming.

"Method names follow the 'studlyCaps' (also referred to as 'bumpy case'

or 'camel caps') naming convention, with care taken to minimize the

letter count. The initial letter of the name is lowercase, and each

letter that starts a new 'word' is capitalized::

"

(quote form PHP Coding Standard)

A serious framework should not break the rule

@pcdinh

"(quote form PHP Coding Standard)

A serious framework should not break the rule"

It's not a rule, it's an internal recommendation for the PHP internals guys and related projects like PEAR/PECL/unit testing etc.