Client-Server Web Apps with JavaScript and Java

Chapter 3. REST and JSON

Good fences make good neighbors.

—Robert Frost

Whenever a technology is introduced, there is an instantaneous response about what it does not do. This response can be puzzling to those who have already learned to operate within its limits. Fences can be viewed in a negative sense, as barriers that restrict or prevent movement. In the positive sense, in the quote by Robert Frost, they provide a clear, visible demarcation of a boundary and indicate the purpose, use, and dangers of a given space. In a similar manner, constraints on a software system impose limitations in the interest of providing better functionality, efficiency, and clarity of roles. Good constraints are specified not simply to block or restrict, but for the purpose of achieving a positive goal. REST is an architectural style characterized by a set of constraints that represent how the Web (or other similar construct) should work. These constraints, though limiting, promote the design of systems that are well suited to the nature of the Web itself.

Descriptions of REST are often articulated from a substantially different starting point: REST as a web services protocol. It is true that REST can be understood when compared with SOAP or other messaging services. In relation to SOAP, it is considered a minimalistic protocol, lacking extensive definitions and additional constructs required in SOAP implementations. It is characterized as relying directly upon underlying features of HTTP, including ...