Open Source - Phone Home, Phone Home

How to accurately count the number of deployments

I am often asked to determine the total number of open source deployments of a given open source product. This turns out to be a challenging problem as most open source solutions are available by download directly or indirectly from a website thus you can get a total download count; however, each download could be for multiple deployments or even none. In fact, the number of “offsite” downloads from mirrors or other sources are most likely not even known about by the people trying to count the deployments.

One obvious idea is to implement a “call-back” operation where every deployed open source product would contact a central server indicating that it is up and running. This concept is not well accepted by many in the open source world, as people don’t like the fact that the product is calling home. If all the application did was acknowledge its existence with no other information being sent then I argue this is an excellent method to solve the problem. The source code of the call-back is available to the user and if they were notified about this service during installation, with the option to turn it off, then I see no issue with this. Of course the turn off option will reduce the total count of deployments but it is a much better estimate than a simple download.

Another option is a license key exchange where the user requests a key from the open source host website for launching the application. Each key sent from the server then allows the application to run and the open source community can simply count the keys. This is a modified approach to licensing and seems to solve the call-back issue; however most people in open source would not be happy about asking for a key.

A final question, why does this matter? Is it really important to know the number of active deployments? My answer comes from a community and marketing perspective and not from a developer view, of course it does. The number of deployments in the marketplace of a given open source software is valuable information used when working with prospects considering your application as well as marketing against larger, well-funded proprietary software.

What do you think? Is the call-back that significant an issue? Is there a better way to do this? I look forward to your thoughts.

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