How to convert asp to php?

Why doesn't php have application variables like asp and asp.net?

• This would make possible massive improvements in performance for php applications and it was an old idea 10 years ago. edit: for php programmers who don't know what I mean, application variables are similar in functionality and usage to session variables in that they persist between requests, except they apply across the whole application scope (ie all sessions and server processes for that web application / site). The closest approximation to this functionality in php appears to be memcached which enables persistent storage of frequently used data in memory, however this is IMHO inferior to application variables since data is set and retrieved via a (relatively slow) network request where as application variables are "passed by reference" http://www.w3schools.com/asp/asp_applications.asp

• Answer:

  PHP was built on top of the "Share Nothing" architecture, meaning that running one PHP process does not affect other PHP processes in terms of memory and environment. While I'm not sure what was the reasons for developing PHP this way back then, there is no doubt that it had a major impact on PHP's rapid success in among web developers, in times when dynamic website were considered top technology: It allowed PHP to be integrated onto various web servers and technologies, commercial and open-source. It simplifies PHP coding and web-dev for beginners, low-scale projects and startups. Developers don't need to think of load multiple sessions, but rather develop as if the system is to serve one user a time. It allows distribution of PHP apps accross multiple nodes, simply and instantly, without the need to consider shared resources. I'm sure there are lots more advantages, as there are disadvantages, such as resource expensiveness, performance impact and of course, it's harder to share resources between sessions and processes. There are ways to accomplish resource sharing, such as memcache, files and other databases, but this is another topic. Edit: About memcache slow access, it's true if you plan to run your app on a single node. However, once applications expand and scale, you must find a way to share in-memory resources between processes running on different nodes. In this situation, the network cost is inevitable, whatever technology you use. Memcache is a great solution (other noSQL solutions are great also) because the network latency is relatively small and the data is stored in RAM.