Web Services REST

<slideshow style="nobleprog" headingmark="⌘" incmark="…" scaled="true" font="Trebuchet MS" >

title

Web Services Basics For Non-programmers

author

Pete George (NobleProg Ltd)

</slideshow>

Day Two Schedule ⌘

1. WSDL
2. Handling Binary Content
3. RESTfull Web Services
4. Other Technologies
5. Conclusion

RESTful Web Services ⌘

Learning Objectives

• To appreciate the REST style
• To understand the principles of RESTful Web services
• To understand the structure of JSON
• To understand the benefits of using JSON in Web services

RESTful Web Services ⌘

• Web services based on REST principles
• Alternative to SOAP/WSDL
• Growing in popularity
• Implemented using XML and JSON

REST ⌘

• Representational State Transfer
• Style of architecture
• Asserts principles for how networked resources are defined and addressed

WWW Based on REST ⌘

Uniform Resource Identifier (URI) ⌘

• String that points to a resource
• Can be:

-URL = Uniform Resource Locator

-E.g. http://www.facebook.com

Resource ⌘

• Anything that can be pointed to by a URI
• Examples:

-Webpage

-Location on server that processes web forms

WWW Based on REST ⌘

Hypertext Transfer Protocol (HTTP) ⌘

• Transport protocol
• Uniform Interface

-i.e. request methods and meaning are fixed

-Get, Post, Put, etc

• NB: REST is not limited to HTTP

-(although developed alongside HTTP)

WWW Based on REST ⌘

Representations ⌘

• HTML document is a “representation” of the resource, i.e. webpage
• Encapsulates the information

-State

-Data

-Markup

• Type of representation designated by media type

-E.g. text/html

-(HTTP is an implementation of the REST style)

WWW Based on REST ⌘

Hypermedia ⌘

• HTML is hypermedia format

-i.e. provides links to browse through application

• Browser “discovers” different parts of the website application through links

-Doesn’t need prior knowledge of application

-Unlike SOA – fixed interface shared through, e.g. WSDL

• User changes state of application by selecting links

-“Hypermedia as the engine of application state”

RESTful Web Services ⌘

• A Web API

-Works by REST principles

-Uses HTTP

• Four features

-the base URI for the web API

-Internet media type -Operations supported by the web API

-Hypertext driven

A RESTful Web Service Example ⌘

• A simple RESTful Web service at:

URI = http://jmeterbook.aws.af.cm/person/list

• resource = list
• HTTP Get request to get list of persons
• Media type = application/json

(data in json format)

A RESTful Web Service Example ⌘

Create JMeter Test Plan:

A RESTful Web Service Example ⌘

Create HTTP Request

A RESTful Web Service Example ⌘

Create HTTP Header Manager

A RESTful Web Service Example ⌘

Run JMeter and view results in JSON

JSON ⌘

• RESTful Web services often use JSON for data exchange

(also use XML)

• Open standard data format
• Presents data as name:value pairs in a human readable text, e.g.

“Name” : “Value”

JavaScript Object Notation ⌘

• Originally derived from JavaScript
• Language-independent
• Available in many languages

JSON Example ⌘

Response from /person/list:
{ "id":46,  "firstName":"Pete", "jobs":
 [ { "id":5, "description":"Singer" }  ],
 "lastName":"George" },

JSON Exercise ⌘

Using Jmeter:

• Create a new HTTP Request to add a person to the list
• Need to Post to /person/save resource

Why JSON and Web Services? ⌘

• Easy to use
• Resilience
• Easily readable
• Better performance (low overhead)

Easy to Use ⌘

Basic Conventions: [] List of objects

{} An object

“key”:”value” string values of an object defined under a key

“key”:value integer values of an object defined under a key

JSON Resilience ⌘

Why JSON and Web Services? ⌘

• Easily readable

Less Performance Impact ⌘

JSON Standards ⌘

• JSON Schemas are available
• Standards not as developed as XML/SOAP
• www.json.org promotes spread of JSON

Quiz – No Prizes! No Pressure! ⌘

Exercises

REST API Exercises