Hi all, I was trying to understand the working of Zend with the help of this excellent article. Its when I found out that Zend Engine was a Virtual Machine.
Now my question is whats the advantage of creating an intermediate code for scripting languages like php?
I can understand that having Intermediate Code in the case of programming languages like Java and CSharp would introduce portability across different platforms like Linux and Windows.
It is faster to execute bytecode than interpret sourcecode. This bytecode might be cached (this is done via PHP accelerators), thus giving up to 20x performance boost.
The term VM in the article is completely wrong. In reality he's describing that PHP compiles the scripts to bytecode, and this bytecode will be interpreted, there's NO vm inside of PHP.
The bytecode operations (opcode) are only an efficient representation of a php script to run the statements one after another and store the results correctly. Have a look at "Abstract Syntax Tree"s to fully understand the bytecode and their advantage for every language.