RESTFul Services

RESTFul Services Using JAX-RS, JAX-B and Hateoas Shawn Smith director of Software Engineering AIS/ITS/PSU

How My Daughter Sees Me NERD!!!

The deep dark past

Not so long ago struct package { intmessageId; /* Format ddmmyy */ char someDate[7]; char someData[64]; char future[64]; char future[64]; };

Not so long ago module people { interface address { readonly attribute string streetAddress; readonly attribute string city; } interface person { readonly attribute string lastName; readonly attribute string firstName; readonly attribute string address; void setName(in string firstName, in string lastName); void setAddress(in address inAddress); }; };

Not So Long Ago <methodCall> <methodName>someMethod</methodName> <params> <param><value><int>7</int></value></param> <param><value><string>seven</int></value></param> </params> </methodCall>

Soap Based Web Services • Not standardized • Bloated • Uses HTTP simply for tunneling

A RESTFul Approach • Based on Roy Fielding’s doctoral dissertation • Injects consistency based on reusing HTTP’s existing verbs • Allows for context negotiation which can impact payload sizing/versioning (json vs. xml vs. user specific vs. …)

The four possible levels of ‘REST support’ (2) • “The Swamp of POX.” You’re using HTTP to make RPC calls. HTTP is only really used as a tunnel. • Resources. Rather than making every call to a service endpoint, you have multiple endpoints that are used to represent resources, and you’re talking to them. This is the very beginnings of supporting REST. • HTTP Verbs. This is the level that something like Rails gives you out of the box: You interact with these Resources using HTTP verbs, rather than always using POST. • Hypermedia Controls. HATEOAS. You’re 100% REST compliant.

JAX-RS (JSR 311/339) • Java’s portable API’s intended for use in creating REST compliant web services • Annotation based descriptors used to covert POJO objects into RESTful services • Align closely with the HTTP verbs

HTTP Verbs • OPTIONS • *POST - create a record C • GET - retrieve a record(s) R • PUT – update a record (possible create) U(C) • DELETE – delete a record D • HEAD • PATCH

HTTP Verbs - POST • Purpose – Create a new resource on the server • Return Codes – • 200 (OK) • 202 (Accepted) • 400 (Bad Request) • 409 (Conflict) • Idempotent – No Safe - No

HTTP Verbs - GET • Purpose – To retrieve a representation of a resource from a server • Return Codes – • 200 (OK) • 301 (Permanently Moved) • 303 (See Other) • 304 (Not Modified) • 307 (Temporary Redirect) • 404 (Not Found) • Idempotent – Yes Safe - Yes

HTTP Verbs - PUT • Purpose – To modify a resource on a server • Return Codes – • 200 (OK) • 202 (Accepted) • 400 (Bad Request) • 404 (Not Found) • 409 (Conflict) • Idempotent – Yes Safe - No

HTTP Verbs - DELETE • Purpose – To modify a resource on a server • Return Codes – • 204 (No Content) • 404 (Not Found) • Idempotent – Yes Safe - No

JAX-RS (JSR 311/339) • @GET • @POST • @DELETE • @PUT • @Produces • @Consumes • @Path • @ApplicationPath • @PathParam • @QueryParam • @FormParam

JAXB (JSR 222) • Java’s API’s used to bind XML (and JSON) to POJO’s • In a RESTfulenvironment JAXB is used primarily to Marshal and Unmarshall data

JAXB (JSR 222) • @XmlRootElement • @XmlAccessorType • @XmlElement • @XmlTransient • @XmlType • @XmlElementWrapper

HATEOAS • (H) Hypermedia • (A) As • (T) The • (E) Engine • (O) Of • (A) Application • (S) State

Evolution images licensed under This file is licensed under the Creative CommonsAttribution ShareAlike 3.0 License. Author commons:User:Tkgd2007 • RESTful Web APIs by Leonard Richardson, Mike Amundsen and Sam Ruby (Sep 12, 2013) • RESTful Java with JAX-RS 2.0 by Bill Burke (Nov 15, 2013) • http://timelessrepo.com/haters-gonna-hateoas • http://barelyenough.org/blog/2008/05/versioning-rest-web-services/ • http://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm • git@github.com:PennState/web-conference.git

RESTFul Services