CSSE490 Web Services Development Introductions, REST, and Back-end - - PowerPoint PPT Presentation

CSSE490 Web Services Development

Introductions, REST, and Back-end tools

Motivation for this course

• Sabbatical at Software Engineering Professionals
• Worked on a variety of projects
• Programming locks for businesses so they can use Apple HomeKit to

access locks

• Discovery Windows 8 Desktop application to assess ability to bid on

client project

• Internal AngularJS front-end, Java back-end web application to help

managers manage resources.

• Backbone-marionette enrolment and registration front-end

application for financial institution

• Study groups and special interest groups

Motivation for this course

• Sabbatical at Software Engineering Professionals
• Became fascinated with evolution of the web
• New technologies, approaches, modules, libraries
• Node.js
• Evolution of JavaScript as front-end & back-end development

platform

• Web 2.0
• REST architectural style

Motivation for this course

• Limited experience with Web courses at Rose
• Introduction to Web Programming (CSSE280)
• Web App Frameworks with AppEngine (CSSE480)
• Decided to use lessons learned from sabbatical experience to introduce

course on Web Services Development: q MEAN Technology stack q REST architectural style q Jasmine unit testing for front-end q Bootstrap for html-and css-based styling of front-end views q SASS (Syntactically Awesome Style Sheets) as CSS language q Mocha for testing back-end application

REST

• Representational State Transfer (REST) architectural

style for distributed hypermedia system

• Characterized by 6 constraints:
• Client-Server:
• Separation of concerns is the principle behind the client-server

constraints

• Separating the UI concerns from the data storage concern improves

portability

• Stateless:
• No client context is stored on the server between requests
• Each request contains all the information needed to service the

request

• Cacheable:
• Require that the data within a response to a request be implicitly or

explicitly labeled as cacheable or non-cacheable

REST

• Characterized by 6 constraints:
• Layered System:
• Allows an architecture to be composed of hierarchical layers
• Each component cannot "see" beyond the immediate layer with

which it is interacting

• A client cannot ordinarily tell whether it is connected directly to the

end server, or to an intermediary along the way.

• Intermediary servers may improve system scalability by enabling load-

balancing and by providing shared caches. Layers may also enforce security policies.

• Uniform Interface:
• Central feature that distinguishes the REST architectural style from
• ther network-based styles
• Defines the interface between clients and servers
• Simplifies and decouples the architecture, which enables each part

to evolve independently

REST Guiding principles

• Resource-Based
• Individual resources are identified in requests using URIs as resource

identifiers.

• The resources themselves are conceptually separate from the

representations that are returned to the client.

• For example, the server does not send its database, but rather, some

JSON , XML that represents some database

REST Guiding principles

• Manipulation of Resources Through Representations
• When a client holds a representation of a resource, including any

metadata attached, it has enough information to modify or delete the resource on the server, provided it has permission to do so.

• Verbs that make up REST Uniform Interface:
• GET
• POST
• PUT
• DELETE

REST Guiding principles

• Self-descriptive Messages
• Each message includes enough information to describe how to process

the message.

• For example, which parser to invoke may be specified by an Internet

media type (previously known as a MIME type).

• Responses also explicitly indicate their cache-ability.

REST Guiding principles

• Hypermedia as the Engine of Application State

(HATEOAS)

• Clients deliver state via body contents, query-string parameters, request

headers and the requested URI (the resource name).

• Services deliver state to clients via body content, response codes, and

response headers.

• This is technically referred-to as hypermedia (or hyperlinks within

hypertext).

REST

• Characterized by 6 constraints:
• Code-on-demand (only optional constraint):
• Server can temporarily extend client
• Server transfer logic or executable to client
• Client executes logic
• For example: Java Applet, JavaScript
• Compliance with REST constraints allows:
• Scalability
• Simplicity
• Modiafiability
• Visibility
• Portability
• Reliability

http://joaopsilva.github.io

Editor

• Editor – Sublime Text 3
• http://www.sublimetext.com/3
• To configure:
• Preferences à Settings – User
• Whitespace settings: insert 4 spaces for tab

Backend Tools: Node.js

• A JavaScript runtime built on Chrome’s V8

JavaScript engine

• https://nodejs.org/en/
• Install with Homebrew (http://brew.sh/) on Mac
• brew install node
• Will install NPM – Node Package Manager - https://docs.npmjs.com/
• Testing Node.js installation
• node –v
• node
• Enter node statements
• Press ‘CTRL’ + ‘c’ TWICE to exit

Backend Tools: express.js

• Node.js web application server framework
• http://expressjs.com/
• Is typically installed locally or each backend web development project
• $ npm install express --save OR
• Follow instructions posted at http://expressjs.com/starter/installing.html
• Hello world example at http://expressjs.com/starter/hello-world.html

Backend Tools: mongoDB

• MongoDB – NoSQL Cross platform document-
• riented database
• http://docs.mongodb.org/manual/installation/ - installation instructions
• https://docs.mongodb.org/manual/ - Documentation
• https://docs.mongodb.org/getting-started/shell/ - Getting started with

MongoDB

• MongoDB Shell
• Import Example Dataset