Current Network Programming

1
Current Network Programming

• New Technologies

2
AJAX (Asynchronous Javascript and XML)?

• Interactive way to develop web applications
• Goes beyond CGI into cleaner web UI
• No full refresh of entire page
• Started in early browsers, but coined in 2005
• Started as DHTML (Dynamic HTML)?
• Main goal is to display pages faster
• less data in first get/post
• only get what you need, then get more
  later......
• Ability to get more rich client than thin
  client

3
AJAX Advantages/Disadvantages

• Advantages
• User Interface faster loading
• Bandwidth usage less since you only get what
  you need
• Separation of data, format, style and function
• Disadvantages
• Browser integration
• Response time (what if it takes too long per
  get?)?
• Search engines don't work
• Accessibility

4
AJAX What is it?

• Javascript Needed to work behind the scenes
• Superset of ECMAScript (just more functions)?
• Loose typed object oriented scripting language
• Run in the browser, meaning client side
• DOM Document Object Model
• API for HTML and XML documents
• Language neutral
• Gives programmer access to web page elements
• Put them together...... AJAX

5
AJAX Code Example

• function getTextFromXML( oNode, deep )
• var s ""
• var nodes oNode.childNodes
• for (var i 0 i lt nodes.length i)
• var node nodesi
• if (node.nodeType Node.TEXT_NODE)
• s node.data
• else if (deep true (node.nodeType
  Node.ELEMENT_NODE node.nodeType
  Node.DOCUMENT_NODE
• 
  node.nodeType Node.DOCUMENT_FRAGMENT_NODE))
• s getTextFromXML(node, true)
• return s

6
AJAX Where to Get More Info

• Google Suggest
• Mozilla
• http//www.w3schools.com/ajax
• Simply google AJAX

7
RSS / ATOM

• RSS stands for
• .90 RDF Site Summary
• .91 Rich Site Summary
• 2.0.1 Really Simple Syndication
• ATOM
• Took up where RSS left off....
• RSS 2.0 is frozen and ATOM extends RSS

8
RSS / ATOM Compared

• ATOM was designed to solve issues with RSS such
  as
• versioning
• plaintext and escaped HTML in RSS no way to
  differentiate
• ATOM
• autodiscovery
• XML namespace XML schema
• Global unique Ids
• xmlbase for relative URIs

9
RSS Example

• lt?xml version"1.0"?gt
• ltrss version"2.0"gt
• ltchannelgt
• lttitlegtLiftoff Newslt/titlegt
• ltlinkgthttp//liftoff.msfc.nasa.gov/lt/linkgt
• ltdescriptiongtLiftoff to Space
  Exploration.lt/descriptiongt
• ltlanguagegten-uslt/languagegt
• ltpubDategtTue, 10 Jun 2003 040000
  GMTlt/pubDategt
• ltlastBuildDategtTue, 10 Jun 2003 094101
  GMTlt/lastBuildDategt
• ltdocsgthttp//blogs.law.harvard.edu/tech/rsslt/d
  ocsgt
• ltgeneratorgtWeblog Editor 2.0lt/generatorgt
• ltmanagingEditorgteditor_at_example.comlt/managingEd
  itorgt
• ltwebMastergtwebmaster_at_example.comlt/webMastergt
• ltitemgt
• lttitlegtStar Citylt/titlegt
• ltlinkgthttp//liftoff.msfc.nasa.gov/news/2003
  /news-starcity.asplt/linkgt
• ltdescriptiongtHow do Americans get ready to
  work with Russians aboard the
• International Space Station? They take a
  crash course in culture, language
• and protocol at Russia's Star
  City.lt/descriptiongt

10
ATOM Example

• lt?xml version"1.0" encoding"utf-8"?gt
• ltfeed xmlns"http//www.w3.org/2005/Atom"gt
• lttitlegtExample Feedlt/titlegt
• ltsubtitlegtA subtitle.lt/subtitlegt
• ltlink href"http//example.org/"/gt
• ltupdatedgt2003-12-13T183002Zlt/updatedgt
• ltauthorgt
• ltnamegtJohn Doelt/namegt
• ltemailgtjohndoe_at_example.comlt/emailgt
• lt/authorgt
• ltidgturnuuid60a76c80-d399-11d9-b91C-0003939e0af6
  lt/idgt
• ltentrygt
• lttitlegtAtom-Powered Robots Run Amoklt/titlegt
• ltlink href"http//example.org/2003/12/13/atom0
  3"/gt
• ltidgturnuuid1225c695-cfb8-4ebb-aaaa-80da344efa
  6alt/idgt
• ltupdatedgt2003-12-13T183002Zlt/updatedgt
• ltsummarygtSome text.lt/summarygt

11
Servlet Technology

• Around since 1997
• Stems from CGI
• Ability to build applications past simple CGI
• Java
• Allows for client to become Java Objects in
  server
• Nice abstraction from CGI for
• State
• Authentication
• URL re-writing
• Ability to use GET and POST, POST preferred
• WAR file web application (from tar in Unix, but
  Web)?

12
Servlet Technology lifecycle of

• Servlet class created from container
• Container calls init() to start (only once)?
• Servlet container gets client requests (services)
  
• doGet()?
• doPost()?
• Container calls destroy() to shutdown
• Each client connection will invoke a Java Object
  and can be extended to contain many other objects
  and methods

13
Servlet Technology Types of Containers

• Non-Commercial
• Apache Tomcat most popular
• Java System Application Server Sun Microsystems
• Geronimo Another Apache
• Commercial
• BEA WebLogic
• Borland Enterprise Server
• IBM WebSphere
• MacroMedia Jrun
• Commercial Open Source
• Jboss RedHat

14
Servlet Technology Java Server Pages

• Compiled into Java Servlets
• Used to extend the Servlet API to do whatever you
  want....
• Components of JSP
• Static HTML/XML
• Include directives
• Scripting elements and variables
• JSP Actions
• Tags

15
Servlet Technology Java Server Pages - Example

• // Example of input to a servlet JSP
• lt_at_ page errorPage"myerror.jsp" gt
• lt_at_ page import"com.foo.bar" gt
• lthtmlgt
• ltheadgt
• lt! int serverInstanceVariable 1gt
• ...
• lt int localStackBasedVariable 1 gt
• lttablegt
• lttrgtlttdgtlt "expanded inline data " 1
  gtlt/tdgtlt/trgt
• ...

16
Servlet Technology Java Server Pages - Example

• //Example Servlet Code
• import com.foo.bar //imported as a result of lt_at_
  page import"com.foo.bar" gt
• import ...
• class _myservlet implements javax.servlet.Servlet
  , javax.servlet.jsp.HttpJspPage
• //inserted as a
• //result of lt! int serverInstanceVariable
  1gt
• int serverInstanceVariable 1
• ...
• public void _jspService( javax.servlet.http.H
  ttpServletRequest request,
• javax.servlet.http.H
  ttpServletResponse response )?
• throws javax.servlet.ServletException,
• java.io.IOException
• javax.servlet.ServletConfig config
  ...//get the servlet config
• Object page this
• PageContext pageContext ...//get the
  page context for this request
• javax.servlet.jsp.JspWriter out
  pageContext.getOut()

17
Servlet Technology Java Server Faces

• Technology for creation of User Interfaces
• One of many ways to build UIs
• Others include (struts, ASP.NET, Tapestry,
  etc...)?
• Implementations like MyFaces (Apache), Sun RI
• Ability to use backend beans for added
  functionality
• Current trends are merging AJAX to create Dynamic
  Faces
• Project GlassFish - Open Source Java EE 5
  Application Server

18
SOA Service Oriented Architecture

• Architecture that uses loosely coupled services
• Used in technologies such as
• CORBA
• DCOM
• Web Services
• Ability to connect to network functions or
  objects
• Think of it as a general use network based API
  that is somewhat language neutral

19
SOA Service Oriented Architecture
20
SOA Service Oriented Architecture

• Principles
• Reuse, granularity, modularity, composability,
  componentazation, and interoperability
• Compliance to standards
• Services identification and categorization,
  provisioning and delivery, monitoring and
  tracking
• Usually used with SOAP and Web Services

21
Web 2.0 Putting it all together!
22
Web 2.0 Putting it all together!

• 2nd Generation of Web Based applications

23
Web 2.0 Putting it all together!

• Key Principles
• Web as an application platform
• Data is driving force
• Architecture is based on participation
• Innovation by pulling distributed components
  together
• THE END OF THE SOFTWARE ADOPTION CYCLE!!!!
• (the perpetual BETA program!!)?
• Easy to pick up by the early adopters

24
Web 2.0 Putting it all together!

• Tim O'Reilly Four plus one levels of hierarchy
• Level 3 Applications that ONLY exist on the
  Internet
• e.g. craigslist, ebay, Wikipedia
• Level 2 Can live offline, but gain value online
• e.g. Flickr
• Level 1 Can live offline, but gain features
  online
• e.g. Google spreadsheets/etc..
• Level 0 Work as well offline
• e.g. MapQuest, Google Maps

25
Web 2.0 Futures?

• MAYA Design Most Advanced, Yet Acceptable
• www.maya.com
• Group formed from 3 Carnegie Mellon University
  colleagues
• Concept of Information Commons
• Trying to reduce complexity of data
• Internet Zero MIT Center for Bits and Atoms
• Emerging standard for connecting everything
• IP in the physical world
• Multi-disciplinary team and approach

26
SaaS (Software as a Service)?

• SaaS salesforce.com CRM example
• Reduces the need for
• Capital expenditures
• Maintenance costs
• Upgrade (hardware and software)?
• Integration (possibly)?
• Negative
• You get what you get
• Usually not a good integration point

27
SaaS (Software as a Service)?

• SaaS salesforce.com CRM example
• Reduces the need for
• Capital expenditures
• Maintenance costs
• Upgrade (hardware and software)?
• Integration (possibly)?
• Negative
• You get what you get
• Usually not a good integration point

28
Mashups

• Ability to plug in web2.0 components into a
  single page
• Normally seen in Wiki pages
• Current examples
• www.mapdango.com
• Technologies to mash
• Facebook
• Twitter
• YouTube
• Google
• Wikis