SOAP achieved functional obsolescence. If you go back before 2005 JSON did not exist and nobody except a Microsoft webmail client were making dynamic HTTP calls. XML was young and growing wildly out of control.

XML had two problems. Most obviously it is verbose, but people didn’t care because XML was really smart. Amazingly smart. The second problem is that XML technologies were too smart. Most developers aren’t that smart and had absolutely no imagination necessary to implement any of this amazing smartness.

JSON kind of, but not really, killed XML. It’s like how people believe Netflix killed Blockbuster. Blockbuster died because of financial failures due to too rapid late stage expansion and format conversion. Netflix would have killed Blockbuster later had Blockbuster not killed itself first. JSON and XML are kind of like that. JSON allowed for nested data structures but JSON tried to be smart. To the contrary JSON tried to be as dumb as possible, not as dumb as CSV, but pretty close.

What amazes me in all of this is that people are still using HTTP for so much data interchange like it’s still the late 90s. Yeah, I understand it’s ubiquitous and sessionless but after that it’s all downhill and extremely fragile for any kind of wholesale large data replication or it costs too much at the thread level for massively parallel operations.