Continuous integration

As mentioned previously, the software delivery environment is constantly changing, while the delivery cycle is getting increasingly shorter. In order to achieve this rapid delivery with a higher quality, developers and QA teams have recently started to adopt automation technologies. One of these is Continuous Integration (CI). This includes various tools, such as Version Control Systems (VCSs), build servers, and testing automation tools.

VCSs help developers keep track of the software source code changes in central servers. They preserve code revisions and prevent the source code from being overwritten by different developers. This makes it easier to keep the source code consistent and manageable for every release. Centralized build servers connect to VCSs to retrieve the source code periodically or automatically whenever the developer updates the code to VCS. They then trigger a new build. If the build fails, the build server notifies the developer rapidly. This helps the developer when someone adds broken code into the VCS. Testing automation tools are also integrated with the build server. These invoke the unit test program after the build succeeds, then notify the developer and QA team of the result. This helps to identify if somebody writes buggy code and stores it in the VCS.

The entire CI flow is shown in the following diagram:

CI helps both developers and QA teams to not only increase the quality, but also shorten the process of archiving an application or a module package cycle. In the age of electronic delivery to the customer, CI is more than enough. Delivery to the customer means deploying the application to the server.