I keep reading about "well defined interfaces", as here, here or here, specially when talking about microservices.
What's an example of the opposite, an interface that is not well-defined?
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2Please make your question self contained (i.e. cite from the articles you have linked).πάντα ῥεῖ– πάντα ῥεῖ2020-06-21 13:19:40 +00:00Commented Jun 21, 2020 at 13:19
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1This is a good topic. But πάντα ῥεῖ is correct. We don't support link only questions. See also discuss this blog.candied_orange– candied_orange2020-06-21 14:36:31 +00:00Commented Jun 21, 2020 at 14:36
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3The links aren't necessary to understand the question. They are just in support of the claim.Karl Bielefeldt– Karl Bielefeldt2020-06-21 15:17:53 +00:00Commented Jun 21, 2020 at 15:17
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"whatever the server actually does"Stack Exchange Broke The Law– Stack Exchange Broke The Law2020-06-23 16:15:41 +00:00Commented Jun 23, 2020 at 16:15
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1 Answer
Any interface definition that isn't specific enough to determine whether a client or service implementation conforms to it is not well-defined. Some examples:
- unspecified character encoding (one side using utf-8 while the other uses iso8859-1)
- unspecified number representation (decimal point versus comma)
- implicit sequencing requirements (need to call
createFooListbefore you can calladdFoo) - incomplete specification of limits, constraints, semantic rules etc.
In general, if developers argue about the correct usage or implementation of an interface it's a good indicator that the interface is ill-defined (or that the developers didn't understand it, which also happens.)
Just being awkward or difficult to use doesn't make an interface ill-defined, though.
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... It makes ammending the interfaces definition to get it well-defined if even possible much more difficult though. And especially for the last part, +1Deduplicator– Deduplicator2020-06-21 16:51:10 +00:00Commented Jun 21, 2020 at 16:51