What exactly is RESTful programming?

This is what it might look like.

Create a user with three properties:

POST /user

fname=John&lname=Doe&age=25

The server responds:

200 OK

Location: /user/123

In the future, you can then retrieve the user information:

GET /user/123
The server responds:

200 OK

<fname>John</fname><lname>Doe</lname><age>25</age>

To modify the record (lname and age will remain unchanged):

PATCH /user/123

fname=Johnny

To update the record (and consequently lname and age will be NULL):

PUT /user/123

fname=Johnny

3 years ago

An architectural style called REST (Representational State Transfer) advocates that web applications should use HTTP as it was originally envisioned. Lookups should use GET requests. PUT, POST, and DELETE requests should be used for mutation, creation, and deletion respectively.

3 years ago

RESTful programming is about:

resources being identified by a persistent identifier: URIs are the ubiquitous choice of identifier these days
resources being manipulated using a common set of verbs: HTTP methods are the commonly seen case - the venerable Create, Retrieve, Update, Delete becomes POST, GET, PUT, and DELETE. But REST is not limited to HTTP, it is just the most commonly used transport right now.
the actual representation retrieved for a resource is dependent on the request and not the identifier: use Accept headers to control whether you want XML, HTTP, or even a Java Object representing the resource
maintaining the state in the object and representing the state in the representation
representing the relationships between resources in the representation of the resource: the links between objects are embedded directly in the representation
resource representations describe how the representation can be used and under what circumstances it should be discarded/refetched in a consistent manner: usage of HTTP Cache-Control headers
The last one is probably the most important in terms of consequences and overall effectiveness of REST. Overall, most of the RESTful discussions seem to center on HTTP and its usage from a browser and what not. I understand that R. Fielding coined the term when he described the architecture and decisions that lead to HTTP. His thesis is more about the architecture and cache-ability of resources than it is about HTTP.

If you are really interested in what a RESTful architecture is and why it works, read his thesis a few times and read the whole thing not just Chapter 5! Next look into why DNS works. Read about the hierarchical organization of DNS and how referrals work. Then read and consider how DNS caching works. Finally, read the HTTP specifications (RFC2616 and RFC3040 in particular) and consider how and why the caching works the way that it does. Eventually, it will just click. The final revelation for me was when I saw the similarity between DNS and HTTP. After this, understanding why SOA and Message Passing Interfaces are scalable starts to click.

I think that the most important trick to understanding the architectural importance and performance implications of a RESTful and Shared Nothing architectures is to avoid getting hung up on the technology and implementation details. Concentrate on who owns resources, who is responsible for creating/maintaining them, etc. Then think about the representations, protocols, and technologies.

3 years ago