WCF doesn't require IIS.
WCF can be hosted in multiple hosts:
IIS
Console app (.net)
Windows Form app (.net)
Windows Presentation app (.net)
Windows Service (.net)
Windows Activation Service
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The thing with WCF is that it's about exposing full-fleged web service interface, but not just HTTP POST handler. Which is alot different situation for data posting side.
Personally, I would prefer to code up something that is more generic (e.g. WCF) rather than coding up something very specific like a POST handler.
Although that maybe all that is needed *today*, we all know that requirements change - especially when dealing with 3rd parties.
There is definitely more than one way to skin a cat, but I generally will pick off-the-shelf solutions when I can.
Talking about personal preferences, I would prefer to discuss requirements and architectural approaches with customers and get into details. But in reality sometimes you find your customers being uncooperative to the level you hardly can explain, or even playing real freaks unwilling to say a word in addition to the couple of lines they call a requirement. Humans are so much humans.. :)
As for POST, I participated in a project where cloud API was built around POST + JSON, and that combination was really generic and flexible.
Agreed, sometimes we are forced to deal with less than ideal requirements.