REST - Http x Json

TL; DR :

• No
• No
• No
• No

Not so short version:

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  Http is Rest?

HTTP is an application protocol that specifies behavior and hypertext traffic; REST is an architectural style whose focus is data elements. REST can be implemented over HTTP, but HTTP can be used to implement many other architectures - SOAP, for example.

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  Is JSON and XML just the return format of a Rest operation?

While the vast majority of current REST implementations use JSON and XML as consumer data exchange formats, they are not only used in REST structures. Any process that requires data serialization (disk archiving or authentication, for example) can benefit from these two formats.

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  REST x Web Services: are the same things?

A WebService can be implemented containing REST endpoints, but not exclusively. As mentioned earlier, SOAP endpoints (among others) are valid practices.

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  SOAP would be the opposite of HTTP?

No. Since SOAP is an XML-based format, the vast majority of implementations occur over HTTP.