FB Series: Java Guy starting with FB development

I recently started with PHP development. Although I have had some small exposure to the
language before, this was my first real project.

What are the big differences to the Java (web) development experience?

• interpreted (no compiler to check for errors, just a parser)
• dynamically typed (->no "parse-time" type checking in the IDE ..)
• essential procedural, object handling completely rewrittten from version 4 to 5 now basic oo functionality
• hunderts of statically callable base function; e.g. very easy to download & store a file: $contents = file_get_contents($url)
  
• Very "close" to the HTTP request-response model
  
• the script execution is determined by the HTTP request (e.g. check ignore_user_abort )
  
• MySQL and Postgres integration modules for persistence
• Caching, Pooling is different due to the fact that a PHP process in its pure form only lives during one Web request:
  
  3 ways a PHP can run in a Web Server:
  - as CGI wrapper: instance of the php interpreter created and destroyed for every page request
  - module (e.g. mod_php, mod_fastcgi) in a multiprocessor web server like Apache. Apache/FastCGI can reuse php instances
  - plugin to web server
  
  This means that connection pooling is not really possible.
  Caching:
  - page scope: not necessary in php. All variables within includes are acessible
  - request scope: not supported natively, but can be implemented via session
  - session scope: see PHP Session. Data stored within a text file in php/tmp or similar. Data must be serializable (It is not possible to serialize PHP built-in objects!)
  - application scope: does not exist
  
• Generally faster code-test iterations.
• Quick infrastructure setup: Apache, php, Apache-php integration (e.g. mod_php), Editor.
• More difficult to manage complex/larger projects because:
  - interpreted & dynamically typed: errors only found at runtime
  - Exception handling difficult
  - OO-shortcomings
  - ...
  

This is just a short list of my thoughts, not striving to achive completeness.