Don’t use Venn diagrams like this

by Sebastian Benthall

Today I saw this whitepaper by Esri about their use of open source software. It’s old, but still kept my attention.

There’s several reasons why this paper is interesting. One reason is that it reflects the trend of companies that once used FUD tactics around open source software to singing a soothing song of compatibilism. It makes an admirable effort to explain the differences between open source, proprietary software, and open standards to its enterprise client audience. That is the good news.

The bad news is that since this new compatibilism is just bending to market pressure after the rise of successful open source software complements, it lacks an understanding of why the open source development process has caused those market successes. Of course, proprietary companies have good reason to blur these lines, because otherwise they would need to acknowledge the existence of open source substitutes. In Esri’s case, that would mean products like the OpenGeo Suite.

I probably wouldn’t have written this post if it were not for this Venn diagram, which is presented with the caption A hybrid relationship:

I don’t think there is a way to interpret this diagram in a way that makes sense. It correctly identifies that Closed Source, Open Source, and Open Standards are different. But what do the overlapping regions represent? Presumabely they are meant to indicate that a system may both be open source and use open standards, or have open standards and be closed, or…be both open and closed?

It’s a subtle point but the semantics of set containment implied by the Venn diagram really don’t apply here. A system that’s a ‘hybrid’ between a closed and open software is not “both” closed and open the same way closed software that uses open standards is “both” closed and open. Rather, the hybrid system is just that, a hybrid, which means that its architecture is going to suffer tradeoffs as different components have different properties.

I don’t think that the author of this whitepaper was trying to deliberately obscure this idea. But I think that they didn’t know or care about it. That’s a problem, because it’s marketing material like this that clouds the picture about the value of open source. At a pointy-haired managerial level, one can answer the question “why aren’t you using more open source software” with a glib, “oh, we’re using a hybrid model, tailored to our needs.” But unless you actually understand what you’re talking about, your technical stack may still be full of buggy and unaccountable software, without you even knowing it.