Con­tin­u­ous In­te­gra­tion vs. Con­tin­u­ous Delivery vs. Con­tin­u­ous De­ploy­ment

Software de­vel­op­ment processes are expensive. When the finished code cannot be smoothly in­te­grat­ed into the existing software it can mean that de­vel­op­ment costs skyrocket. The modern ap­proach­es of con­tin­u­ous in­te­gra­tion, delivery, and de­ploy­ment provide a solution. These rely on val­i­dat­ing the code multiple times as it is being developed. Working in several smaller de­vel­op­ment phases also allows pro­to­types of the desired product to be delivered to the customer. This allows the customer to adjust its re­quire­ments through­out the de­vel­op­ment and see if the software is de­vel­op­ing as desired.

Modern software de­vel­op­ment models all began with the concept of agile software de­vel­op­ment. This is an approach that is intended not only to ac­cel­er­ate software de­vel­op­ment, but also to make it more trans­par­ent. The goal of the agile approach is to develop software that the customer really needs. Pro­to­types provided during each phase of de­vel­op­ment allow the customer to check whether the software actually does what it is supposed to do and whether it is com­pat­i­ble with existing software. Customer re­quire­ments that only arise during the de­vel­op­ment process can also be taken into account with agile methods.

The trend towards agile de­vel­op­ment is also picking up momentum in corporate cultures. There are several ap­proach­es that are intended to ac­cel­er­ate de­vel­op­ment processes within the company. One of them is DevOps, made up of the words “de­vel­op­ment” and “op­er­a­tions”. The goal of this corporate culture is for the actual de­vel­op­ment teams to work together with an operation’s or­ga­ni­za­tion­al team through­out the software de­vel­op­ment phase and beyond. This way any software in­te­gra­tion problems can be avoided from the outset. It also makes it easier to maintain and deploy the finished programs. In addition to con­tin­u­ous de­vel­op­ment, rep­re­sen­ta­tives of DevOps rely on con­tin­u­ous in­te­gra­tion and con­tin­u­ous de­ploy­ment.

The concept of con­tin­u­ous in­te­gra­tion aims to in­cor­po­rate changes to a software project into the entire software as quickly as possible. The code is therefore updated daily by the de­vel­op­ers. For this purpose, in addition to various con­tin­u­ous in­te­gra­tion tools, version control systems such as GitHub are primarily used. These allow local copies of the entire project to be stored on one’s own computer. Pro­gram­mers can make changes to the code and upload them to the version control system. Af­ter­wards, the entire program can be subjected to various tests. This means that any in­te­gra­tion problems can be avoided in advance.

The con­tin­u­ous delivery concept goes one step further than the con­tin­u­ous in­te­gra­tion approach. Not only is the code updated daily and every change in­te­grat­ed as quickly as possible, but the customer is also provided with a prototype as soon as possible. The con­tin­u­ous in­te­gra­tion vs. con­tin­u­ous delivery com­par­i­son shows that the focus of con­tin­u­ous delivery is primarily on customer feedback. By being able to deliver the finished partial code early, it makes it possible to test the system software in its real en­vi­ron­ment. Anything that the customer does not like can be adjusted during further de­vel­op­ment. If the customer likes the partial code, it is sub­se­quent­ly handed over manually.

Con­tin­u­ous de­ploy­ment follows a similar, but even more extended approach. This method uses automated tests that are in­te­grat­ed directly into the de­vel­op­ment process. The com­par­i­son of con­tin­u­ous delivery vs. con­tin­u­ous de­ploy­ment makes it clear that with con­tin­u­ous de­ploy­ment there is no time delay between the time of testing and the time the code is released. Due to the detailed test frame­works, de­vel­op­ers do not even have to wait for feedback from the customer - they can deploy their partial code directly after it has been developed in an automated manner.

Which de­vel­op­ment model is best depends entirely on the project’s specific re­quire­ments. Overall, however, all three models offer the most ad­van­tages if the customer and de­vel­op­ers can work closely together.

Con­tin­u­ous de­ploy­ment is expensive due to the elaborate testing pro­ce­dures, but it means that the customer is able to see daily im­prove­ments to the software. In addition, the de­vel­op­ment process is ac­cel­er­at­ed because it is not in­ter­rupt­ed at any point. This means that it is often possible to recoup the ad­di­tion­al costs for the test frame­works in the end. With con­tin­u­ous delivery, the customer still has a great deal of room for maneuver - re­quire­ments can also be specified ret­ro­spec­tive­ly without causing any problems. Small changes to the code are also easy to make.

A com­par­i­son of con­tin­u­ous in­te­gra­tion vs. con­tin­u­ous delivery shows that con­tin­u­ous delivery com­plete­ly forgoes interim code release. This process is therefore par­tic­u­lar­ly suitable for smaller projects where constant updating is not important or may even be a hindrance.