The slideshow cover the concepts of designing REST APIs using MuleSoft ESB Jersey component

2. AGENDA
• Discuss REST Architecture Principles
• Discuss REST API Design Approach
• Discuss JAX – RS Standards
• Discuss Mule REST Component for REST API

3. REST ARCHITECTURE – PRINCIPLES
Rest Architecture
Principle
Description
Addressability Every resource in the system is reachable by a unique
identifier.
Uniform Constrained
Interface
Constraints on the methods of application protocol to
access operations on the published service for e.g. GET,
POST, PUT, DELETE, HEAD, OPTIONS
Representation
Oriented
Resource representations between the client and server
can be XML, JSON or YAML
Communicate
Statelessly
No client information is stored in the sessions on the
server
HATEOAS Support to embed inside the resource representation, the
links other services.

4. REST API DESIGN
 Design the URIs for all the resources in the system
 Define the resource representation – XML, JSON etc.
 Assign HTTP Methods to the resources
 Version the REST API
 Choose the REST API URL root
 Filtering / limiting results returned from the API on the basis of request
parameters
 Define authentication strategy e.g. Oauth 1.0
 Develop documentation for the REST APIs
 Track Analytics on REST API usage

5. JAX-RS ANNOTATIONS
JAX-RS Annotation Description
@Path URI to the Rest API
@Consumes / @Produces Defines the media type of the message payload
accepted / produced by the API
@GET,@POST,@PUT,@DEL
ETE…
HTTP methods assigned to API
@QueryParam Binds query parameters from http request to API
method parameters
@DefaultValue Default value of the query parameter
@PathParam Maps the URI template parameter to resource
method parameter or resource class field
@FormParam Maps the form parameter to resource method
parameter or resource class field

6. JAX-RS ANNOTATIONS CONTD…
JAX-RS
Annotation
Description
@CookieParam Extracts information from the cookies declared in the http
headers
@HeaderPara
m
Maps the value from an http header to a resource method
parameter or a resource class field.
@BeanParam JAX-RS parameter aggregator value object . Injects the bean into
a resource class field or property
@EncodedPara
m
Disables automatic decoding of parameters bound to
QueryParam, PathParam, FormParam or Matrix Param
@MatrixParam Maps the URI matric parameter / path segment to a method
parameter or resource class field or resource bean property

7. JAX-RS CONTENT HANDLERS
JAX-RS has built in handlers for marshalling and unmarshalling of certain Java
types
• Content Marshalling – Following are objects used for API I/O
• javax.ws.rs.core.StreamingOutput
• java.io.InputStream, java.io.Reader
• java.io.File
• byte[]
• char[]
• JAXB
• Custom Marshalling – Implement the following interfaces
• javax.ws.rs.ext.MessageBodyWriter
• javax.ws.rs.ext.MessageBodyReader

8. CONTENT NEGOTIATION
• Content Negotiation
Clients can request for a specific media type when querying the server
for
information
• Preference Ordering
The server assumes that the client always wants a more specific media type over
a wild card specified media type
• Language Negotiation
Clients use the ACCEPT-Language header to specify the language in
which the information is expected
• Encoding Negotiation
Clients specify the Accept Encoding header to specify the message
body
encoding for e.g. GZIP, to save on network bandwidth

9. JAX-RS & MULE
Jersey JAX-RS Transport:
Mule uses Jersey for REST API development. Mule 3.6 uses Jersey v2.11
Following is the piece of code that hosts the REST API using Jersey:
<jersey:resources>
<component class="org.mule.module.jersey.HelloWorldResource"/>
</jersey:resources>
The HelloWorldResource is the resource that use JAX-RS annotations to map
HTTP
verbs to resource methods.

10. JAX-RS EXAMPLE
@Path("/customer")
public class CustomerResource {
@GET
@Produces("text/plain")
@Path("/{customerId}")
public String getCustomer(@PathParam("customerId") String customerId){
Map<String, String> customerDetailsMap = new HashMap<String,String>();
customerDetailsMap.put("C0001", "TOM");
customerDetailsMap.put("C0002", "JERRY");
return customerDetailsMap.get(customerId);
}
}
Path to URI
Http Verb
Media Type
Path Variable

11. Thank You !!