Category Archives for Web Services

RESTful And HATEOAS Web Services

RESTful – Representational State Transfer

RESTful Web services are an alternative to SOAP. It is designed to be simple, lightweight and fast, with the following constraint’s –

• Resources – Easily understood directory structure URI
• Uniform Interface – GET, POST, PUT and DELETE
• Messages – Can return any format – HTML, XML, plain text, …
• Stateless – Interactions not stored

Common Operations

Consider the example in my apache cxf jax rs post. The GET, PUT and PATCH operations are idempontent. This means that the same parameters should return the same results

GET – Select – Idempotent

[sourcecode]GET /customerservice/customers/1[/sourcecode]

POST – Create

[sourcecode]POST /customerservice/customers[/sourcecode]

PUT – Update or Create – Idempotent

[sourcecode]PUT /customerservice/customers[/sourcecode]

PATCH – Update only – Idempotent

[sourcecode]PATCH /mypath/1[/sourcecode]

DELETE – Remove record

[sourcecode]DELETE /customerservice/customers/1[/sourcecode]

HATEOAS – Hypermedia as the Engine of Application State

HATEOAS is a further constraint on RESTful services. It basically requires a response to return the location of the data. For example –

[sourcecode] GET customerservice/customers/1 HTTP/1.1 HTTP/1.1 200 OK

<?xml version="1.0"?>
<customer>
<id>1</id>
</customer>
[/sourcecode]

Would become –

[sourcecode lang=”xml”] <?xml version="1.0"?>
<customer>
<id>1</id>
<link rel="self" href="/customerservice/customers/1" />
</customer>
[/sourcecode]

References

http://en.wikipedia.org/wiki/Representational_state_transfer
http://en.wikipedia.org/wiki/HATEOAS
http://docs.oracle.com/javaee/6/tutorial/doc/gijqy.html
https://www.javabullets.com/2015/01/15/apache-cxf-jax-rs/
https://github.com/spring-projects/spring-hateoas