Cost of system integration?

Question

On the software development projects that you have worked on, what has been the approximate cost (expressed as a percentage of total system cost) of system integration? System integration includes integrating with other software, databases, etc.

Answer 1

This is a very difficult value to estimate, especially when you are facing integrating with a system that you are not familiar with. The best you can do is track you or your team's past performance on similar projects and use those values to try to estimate how you will perform on new projects.

Generally, system integration will take longer if:

• It uses a protocol, database engine, operating system, etc. that you or your team have not yet worked with.
• Vendor or community support is lacking or unresponsive.
• Official system documentation is not detailed enough or is out of date.
• The system does not have large global market share. Such a system will not have a wide user base and a big footprint in online programming Q&A sites such as this one. This may include new, less popular, or highly domain-bound systems.

Answer 2

33.3% because system integration is usually associated with a fair amount of risk that is not as prevalent in other phases of the projects (coding, documentation, etc).

Answer 3

Between 0 and 99%. I have built systems with no integration at all and systems that were basically just integration of other systems. The nice thing about integration can be that it is easy to estimate. But only when the interface is fully understood. Then it is just a duplication of functionality.

There are some complicating factors, though. They can make it very expensive to impossible:

• is the system you have to integrate with well understood (do the programmers who developed it still work there?)
• is the system you have to integrate with well-refactored (and has automated unit and acceptance tests)?
• single or multiple platform?
• are domain experts available?

Answer 4

It depends on the integrated system's importance and other factors.

I've worked in systems with integration in a bunch of web services that were the application's core. If the web services were down, our system was simply useless.

I would list the following variables when trying to evaluate the cost:

• How many systems do you integrate and how frequently are they changed?
• Do you have documentation to these systems?
• Is it a third party component/service that you have no control of?
• If you have control over the integrated system, does it use too much "legacy" code, like COBOL; (just an example, at least where I work COBOL programmers are expensive);
• Are your employees experienced with the integrated system and with the application itself?
• In case of failure of the integrated service, what is the impact on your application?

How much is an employee's hour rate in these scenarios? How many hours they would need to work on these integrated systems? How much money do you have for your project? I can't say it's going to cost X% on your case without knowing these details, specially the last one.