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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.
The only real argument I could really find was "Java doesn't do X well, therefore PHP must be great". The author seems to live in a universe with only two choices, his straw man Java, and his favorite web language, PHP. When he does try and argue PHP's merits on its own, it seems to collapse into a PHP is good because its good argument. I don't see any part of the article addressing how PHP can benefit the developer facing real issues of large scale web development (such as the need for caching systems on high volume websites, or the maintence challenge of larger code bases on complex sites). While good arguments may exist for PHP, they just don't seem to be here.
but he didn't use the phrase "paradigm shift", so we could give him the benefit of the doubt
That man tried to kill mah Daddy
if someone wants to produce a high performance web site in Java, jsp is a bad choice. use Velocity - pure java objects - a decent DB abstraction mechanism (Hibernate, iBatis). . Plus, i used php, ok, it is easy to use and can be preferred small to medium size web sites. but call me biased, it is nowhere near the elegance of java.
Scalability is rarely that much of an issue- any halfway decent architecture (php, java, even .net) will let you scale horizontally- and Moore's law will take care of any performance problems in time.
My big issue with PHP is maintainability- I see it (perhaps incorrectly) as a glorified templating language, which places it on the same evolutionary track as ASP and cold fusion; 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.
What a strange bird is the pelican, his beak can hold more than his belly can.
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.
PHP only becomes unmaintainable if you don't know what you're doing, or if you don't plan well at the onset. The thing about PHP is that it doesn't force you to do anything, which means it doesn't force you to do anything the right way. This is not a fault. I wouldn't be a PHP developer today were it not for the ease with which I learned to write some very, very bad code. Of course, there's room to grow. The result is that the onus is on the developer, and not the language. So you're right, PHP doesn't scale. Not it's job. PHP provides the opportunity to scale, and the toolset, which are more than adequate, and improving over time.
This is particularly funny coming from a perl developer. Perl can become unmaintainable on a small project.
"I don't want to achieve immortality through my work. I want to do it by not dying." -Woody Allen
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.
.NET and others.
Yes, PHP is excellent for web development. Yes, PHP can scale to even some large web sites. But since the web is still all the rage, this is unfortunately all that many people think about. Where PHP stumbles is when you need to move off the web or when you need to write complex business logic that is not solely driven by a web tier. PHP also fails when you need to integrate diverse transactional resources in an efficient manner. Not all business applications can be suitably implemented in PHP. As examples:
- PHP, by its scripted execute-and-terminate nature, cannot schedule the execution of tasks on its own. So, for example, there is no way to schedule an email to be sent at a specified time. If you need this sort of functionality, you'll have to look beyond PHP to ugly hacks like cron jobs that call PHP. (and then PHP scripts that can automatically modify your cron scripts..) Alternatively, you could write your own scheduler in a different language.
- Somewhat related, PHP is incapable of asynchronous operation. Suppose, for example, that we have a flood of customers placing orders. Our inventory database is fully capable of keeping up with the demand, but credit card processing system is backlogged and this is out of our control. So we cannot give users an immediate response as to whether their payment was accepted upon placing the order. We also don't want to make them wait 5-10 minutes after hitting the "place order" button for a response. The proper business solution is to accept the order, but send the customer an email later if the payment was rejected. This process requires asychronous operation -- queueing of the payment validation requests and possible further action separate from user interaction. PHP has no solution for this scenario or the many others like it and thus we must look beyond the PHP domain.
- PHP is quite weak when it comes to writing a complex business logic layer. This is not to say that it is not possible, but there are no frameworks available comparable to those offered in the Java world (and I'm not just talking about EJB, btw). So this is not a question of languages, but of available tools to do the job efficiently. For example, PHP has no concept of application-level transaction management. (declarative transactions, isolation levels, etc.) Looking towards the cutting edge, it has no support for Aspect Oriented Programming, which is an enormous boon to business logic developers, available in Java, C++,
- PHP is weak on tools for developing the persistence layer. For example, it has nothing comparable to Hibernate, let alone tools for RAD employing UML.
- PHP has no pre-built solutions for caching persistent data, and certainly not objects. Once again, it is possible, but developers are left to roll their own solutions using shm extensions or writing out to the database backend. Using the database can be terribly slow and even the shm approach requires (de-)serialization on script load/terminate. While this sort of thing does not limit scalability, it does limit performance (response times).
- PHP has no means of replicating application state in a cluster other than using the backend database. While this is often of no consequence, some complex business software holds a fair amount of state which needs not be persistent.
- PHP itself cannot reasonably be used to develop non-web clients such as a GUI tool for efficient rapid data entry or greater interactivity, a PDA client, or an embedded device that interfaces with a campus security system. These sorts of clients can talk to PHP scripts via SOAP extensions, but it should be recognized that we have again left the PHP domain to meet these needs and the resulting solution may not be the most efficient.
So in closing, PHP is great for some thing