Building an RSS Reader

1
Building an RSS Reader

• Web 2.0 and Rich Internet Applications
• Prof. Suthikshn Kumar

2
Contents

• What is RSS?
• Structure of RSS
• RSS 2.0 Channel and Item
• RSS Reader with Ajax
• RSS Reader with flex

3
What is RSS?

• Really Simple Syndication (RSS) is an XML
  specification that describes a mechanism whereby
  data such as news headlines can be syndicated
  across sites.
• RSS has enjoyed huge success in the world of
  blogging and is being more and more tightly
  coupled into the fabric of web.
• The availability of XML libraries has made
  loading and processing XML and RSS documents very
  easy.
• RSS grew out of need for content( typically a
  news headline or story) to be syndicated.

4
RSS Reader

• RSS aggregator or reader takes a list of feed
  URLs each of which exposes RSS.
• The reader then will aggregate these together and
  periodically poll for updates, allowing the
  reader to monitor content from multiple sites all
  at the same time.

5
RSS Structure ( RSS 2.0)

• RSS Structure is relatively simple.
• RSS feed consists of a node containing
  a series of nodes as
• BBC News
• http//www.bbc.co.uk
• British Broadcasting
  corp
• en-uk
• 4 dec 2007
• Man Bites dog
• .
• ..
• .
• Potatoes to rule the earth

6
The structure of RSS 2.0

• A given RSS 2.0 document or feed is made of up
  two main components a channel and one more
  items.
• The channel defines the feed content, title,
  publication date and so on. It is anologous to a
  channel on your television.
• The item represent the actual content.
• Each item might contain the details of a
  particular news item or some product information.
• An RSS document is typically referred to as an
  RSS Feed.

7
RSS Channel Mandatory Elements
8
RSS Item
9
RSS Channel and Item

• The elements required to describe a channel are
  exactly the same as those required to describe an
  item.
• Title, link and description are all that are
  required.
• The only difference is the content of the
  elements.

10
AJAX based RSS Reader

• The web is cross platform Building a web based
  aggregator ensures that anyone with a modern
  browser can access it.
• The web is centrally located one of the problems
  with conventional aggregators that are installed
  on the computer is the upkeep of data in many
  locations. If you like to read syndicated feeds
  at work and at home, you must install an
  aggregator on each computer and load it with
  appropriate feeds. A web based aggregator
  eliminates this problem because any change made
  to the feed list is seen regardless of the users
  location.
• There are two main components
• Client side
• Server side

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Client side components of Web based RSS reader

• XParser the javaScript class responsible for
  requesting information and parses it when the
  data is received.
• The user interface ties the user to their data.
  Because the user interface is essentially a web
  page the usual suspects of web browser
  technologies are used XHTML, CSS and JavaScript.
• The JavaScript code that takes the information
  XParser received and displays it.

12
The User Experience

• The user interface barrows heavily from the
  Microsoft Outlook 2003 user interface.
• It has a three pane interface where the first two
  panes are fixed while the third pane is fluid.
• Feeds pane The first pane is called feeds pane,
  displays the different feeds as links that user
  can click on.
• Items Pane When the user clicks on a feed, the
  feed items are loaded into the middle pane the
  items pane.
• Reading pane If the user single-clicks an item,
  it loads into the last pane reading pane.

13
Server Side

• The servers job is to retrieve the remote XML
  feeds for the client to use.
• The first method is called a cached feed
  architecture. The server program would act as a
  service, fetching a list of feeds at a certain
  time interval, caching them and serving the
  cached feeds to the client when requested.
• The second method is a delivery on demand
  architecture, where the server would retrieve any
  given feed when the user requests it. This may
  use more bandwidth, but it ensures the reader
  will have up-to-date information.
• This design is inline with ajax concepts and is
  what the user expects.