Okay. I agree. But carefully considering your options and paying mind to your requirements is a far fetch from flat out disregaring one option simply because of

Okay. I agree. But carefully considering your options and paying mind to your requirements is a far fetch from flat out disregaring one option simply because of a detail -- overhead -- that may or may not be relevant in your situation. I still think you could refer to this as a kind of premature optimisation, although I see now that this was unhelpful, because it brought up the whole sorting thing which was kind of a tangent. > They have an interoperability requirement. Did you miss that detail of my earlier comment? Some of them do. Some of them explicitly turn off interoperability and still go with XMPP; Whatsapp (no affil) is another one of those. This just stresses the fact that efficiency/overhead is not the only consideration when it comes to protocol choice, and pretty far down the line when it comes to IM protocols.