What is the X in the JAX-RS Rack?

Question

In the abbreviation JAX-RS, what does X mean?

I know that RS Stands for Restful Service and J are Java and A for the API . What then, what about X?

Answer 1

JAX-RS  = Java API for RESTful Web Services

Xremained part of the nomenclature. eg:.

JAXR    = Java API for XML Registries
JAXP    = Java API for XML Processing
JAXB    = Java Architecture for XML Binding
JAX-RPC = Java API for XML-based RPC
JAX-WS  = Java API for XML Web Services  

So, the letter Xis for XML.

Answer 2

It was just ported from JAX-WS, and the other is javax.ws.rs so we can say that x comes from java (x) of the java package.