Tuan:
Regarding other libraries: Indeed. I’m Zend-centric, but that’s by tradition. It might be worthwhile to consider PECL and PEAR, as well.
Regarding using URLs for paths to the Zend library: this could be possible. php has the ability to read files from http URLs, but I don’t know if the autoloader code can deal with them. Zend_Framework (and all other php libraries that I know of) use a method of naming classes that will help an Autoloader to find and then include files. This emulates Java’s class loader but is much less formalized. So, for example, suppose that I evoke an object: $cool = new Zend_Cool_Class(). The Autoloader starts looking through the path variable for zend/cool/class.php, which must then contain a class Zend_Cool_Class(). Essentially, it’s replacing underscores with slashes with some rules to make it easier for developers.
In addition, the framework allows users to create their own namespaces, for example ‘UNM_Extlearn_’, along with an optional path ‘users/el/Sites/application/modules/unm/extlearn/’. In that case if I evoke an object: $person = new UNM_Extlearn_Person(), then the framework’s Autoloader will know to look for the class code in ‘users/el/Sites/application/modules/unm/extlearn/Person.php’. The framework assumes a number of paths that are used by convention, and users are free to modify those (at their own risk) or add others. This functionality makes it easy to include other libraries, as well, and as you can see, since classes must be named correctly, namespacing is automatic.
So, it’s a tangled web and elegant in its way. I would say the bottom line is that it’s probably best to use actual filesystem paths.
Thanks,
Greg