Phases of Deployment

Spectrum of packaging

It’s no surprise that continuous deployment first arose in companies that use PHP. A deployment in a PHP application can be as simple as copying some files onto a production host. The very next request to that host picks up the new files. The only thing to worry about is a request that comes in while the file is only partially copied. Near the other end of the spectrum, think about a five-million-line Java application, built into one big EAR file. Or a C# application with a couple hundred assemblies. These applications will take a long time to copy onto the target machine and then a large runtime process to restart. They’ll often have in-memory caches and database connection pools to initialize. We can fill in the middle part of the spectrum as shown in this diagram. Go further to the right, and the degree of packaging increases. At the extreme end of the spectrum, we have applications that are deployed as whole virtual machine images.