Give it a REST already

Arnon Rotem-Gal-Ozhttp://arnon.me

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"

Data Management

(Resource)

Categorization App

Categorization(Resource)

Get(schema)

Schema Details (XML)

Post(Run Job)

Job Id +URL (JSON)

Layers should have some constraints on communications

Layer?

Layer?

Layer?

Layer?

Layer

Layers should have some constraints on communications

Component

Component

Layer

layer

Layer

Layers should have some constraints on communications

Component

Component

Layer

Layer

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 copybetter performance and latency

copy

copy

copy

copy

copy

copy

copy

copy

copy

The uniform interface

Document Centric messages provide the client with the

needed stateand allow stateless

communications

REST also externalize state transitions (HATEOAS)

Current Representation

E.g. Order

Link to product 1

Link to Product 2

Link to customer

321root

/

Sessions/

Abcde/

Efgh/

Resources/ Dispatchers/ Xyz/

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

Use IDs that are linkse.g. a

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?

(original) Categories REST API

Categories

Tasks

<Cat Id>

Interactions

<Task Id>

POST – create new categoryGET – List categories / search for category

POST – run discovery GET – list running categoriezations

GET– check progress/status of running categorization DELETE– abort categorization

GET– Get Category definitionPUT– update category (state or definition)DELETE – remove category

GET – search interactionsPOST – Create interactions (bulk)

<Int Id>

<Seg Id>

GET– Retrieve InteractionsPUT– Create /Update Interaction

GET– Retrieve segmentPUT– Create /Update segment (e.g. words from audio-analysis)

/ /

Technology Mapping

Jax-RS

Spring HATEOAS

Common REST misconceptions

REST = CRUD

REST is the ultimate architecture

REST = HTTP

REST will automagically make you write perfect distributed systems

REST is Simpler