Give it a REST already

Arnon Rotem-Gal-OzVP R&D xsights

www.xsights.comwww.rgoarchitects.com/nblog

SomeTheory

Making sense of the terminology soup

Code/Detailed Design

Design

Design Patterns Architecture

Architectural PatternsArchitectural Styles

SOA vs. RESTPipes and

FiltersClient Server

Uniform Interface

Virtual Machine

DistributedAgents

LayeredSystem

Replicated Repository

Code OnDemand

StatelessComm. Cacheable

RESTSOA

REST = "Representation State Transfer"

Dispatcher

WebApp

Cache(Resource)

Put (New State in XML)

OK

Get (Latest State)

Representation(JSON)

Layers should have some constraints on communications

Layer?

Layer?

Layer?

Layer?

Layer

Layers should have some constraints on communications

Component

Component

Layer

Componet

Client/Server

Client Server

Capabilities (services)Requests initiator

Request

Reply

Replicated Repository is about having

more than one copy providing

the same service looks like one copy

better performance and latency

copy

copy

copy

copy

copy

copy

copy

copy

copy

The uniform interface

Document Centric messages provide

the client with the needed state

and allow stateless

communications

REST also externalize state transitions

Use IDs that are linkse.g. a

Technology Mapping

HTTP is the most common REST implementation

But you can create others

Waka canoe

GET = query/read a resource for a representation

PUT = create with ID set by the

client / replace

POST = Create a subordinate resource with ID set by server / update

DELETE= remove the URI (most likely delete the resource)

HEAD = GET but only retrieves

metadata (headers)

OPTIONS – The currently available

verbs / requirements for communication

Why REST?

Example – Resource Manager

http://devrig:52141/RM/Sessions/abc/

• ATOMPUB– Session details• URI (ID)• State (start/end/status etc.)• Resources

– Knows status– URI for the Resource representation on the RM– URI for the Resource itself

Common REST misconceptions

REST = CRUD

REST is the ultimate architecture

REST = HTTP

REST will automagically make you write perfect distributed systems

REST is Simpler