Current%20Trends%20in%20Information%20Technology

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Current Trends in Information Technology

• Paul Lewis
• phl_at_ecs.soton.ac.uk

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Aims and Unit Synopsis

• To develop a knowledge of some broad issues in
  computing and IT which are of current interest
  and of potential benefit and to enhance the
  students skill in applying some of the latest
  technology.

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Learning Outcomes

• On successful completion of the unit the students
  should be able to
• develop a web site using a web site authoring
  package
• use scripts to develop dynamic web pages
• understand some of the basic principles and
  jargon
• associated with some of the following
  topics
• information retrieval
• knowledge processing
• software agents
• object technology
• multimedia information handling
  
• communications and networks

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Syllabus

• This course is an awareness course covering a
• variety of issues in Information Technology
• including such topics as
• The World Wide Web
• AI and Knowledge Processing
• Agents and Agent technology
• Object Oriented approaches to software
  engineering
• Information retrieval and Multimedia information
  handling
• Communications and Networks

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Assessment

• The unit will be assessed completely by
  coursework, for example by a project to develop
  a modest but dynamic web site relevant to some
  other aspect of the degree course and an essay on
  a particular topic in IT.

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Format

• Each week we will have two lectures
• followed by lab sessions in
• Building 44 Room 1061

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Telecommunications and Networks

• World telecommunications network
• Largest man-made system
• Technology and services evolving
• rapidly
• Facilities for linking computers
• Data volumes increasing
• Data transfer rates increasing
• Multimedia systems (text/images/speech/vi
  deo)
• require high bandwidth

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• Early computers all stand alone
• Direct inter computer communications has led to
• electronic mail
• bulletin boards
• news services
• distributed computer systems
• the web and information sharing
• electronic funds transfer
• e-medicine
• e-commerce
• e-shopping
• e-banking

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At the computer system level

• Initially new types of system evolved
• File systems became distributed or single systems
  shared by several processors
• Facilities for file transfer
• Facilities for remote login
• Facilities for automatic interaction between
  systems
• Daemons to handle message passing over networks
• Now
• Ubiquitous / pervasive wirelessly interlinked
  computing
• computers embedded into the environment eg
  kitchen devices with internet connectivity/
  mobile computing eg on mobiles

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Common Types of Network Configuration

• Broadcast networks
• Token Ring
• Point to point links

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Broadcast Networkse.g. Ethernet

• Any computer on the net can send a message at any
  time
• message contains destination address
• Each computer checks all messages and picks up
  its own
• messages can collide and become garbled
• Sending systems detect this and rebroadcast after
  a random
• short time
• If traffic is high, extra collision traffic may
  saturate the network

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Token Ringe.g. Fibre distributed data interface
(FDDI)

• Message token is passed around the ring
• A computer can only transmit when it has the
  token
• Avoids collisions
• There is performance reduction in large rings
• Network fails totally if there is a break

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Point to Point Links

• Only two end points involved
• Some wide area networks (WANs) are connected this
  way
• One computer can typically only handle a few
  links

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Data Transfer Rates

• Transfer rate Time to transmit a 20
  page report
• (bits/sec) (36000
  bits/page say)
• 300 40 mins
• 2,400 5 mins
• 9,600 1.25mins
• 19,600 37.5 secs
• 1,000,000 0.072 secs
• Eg BT Broadband 512000 bits/sec
• a 512512 colour image with24 bits/pixel is 6
  million bits (uncompressed)
• Compression algorithms are an important key

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Local Area Networks (LANs)

• Typically used in a single laboratory or building
• Typically run over copper wire or fibre optic
  cable
• Ethernet is popular
• can now run at 1 gigabit /sec point to
  point
• computers typically attached to
  coaxial cable at tap
• points but can use twisted pair or
  fibre optic cable
• or more recently wireless
• FDDI Fibre Distributed Data Interface
• less popular than ethernet
• interfacing is more difficult
• peak rates 200 Mbits/sec

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Local Area Networks (cont)

• ATM Asynchronous Transfer Mode
• technology for high data rate
  communications
• can work at rates gtgt 100 MBits/sec
• typically used for backbone of a WAN
• (Note Ethernet and FDDI are LAN technologies not
  appropriate for WANs)

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Network Protocols

• Computers communicate over networks using
  protocols which determine the format of messages
• Protocol for the internet is TCP/IP Transmission
  Control Protocol/Internet Protocol

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The Internet

• Loosely administered network of networks
• Agreed procedures for access and
  intercommunication
• Internetworking uses gateways, routers and
  firewalls
• Gateways convert data traffic from one network
  format to another. They link LANs to WANs and
  WANs to WANs

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Routers

• Decide which route through the network a message
  should take to continue towards its destination
• - networks are now very complex
• - many different paths between points
• - routers communicate with each other about
  network faults
• - busy or broken routes can be avoided

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• telnet provides remote logon to distant computer
• ftp transfers files between computers on the
  internet
• ssh and sftp (secure shell) provides encryption
• phl/40 telnet penelope.ecs.soton.ac.uk
• Trying 152.78.68.135...
• Connected to penelope.
• Escape character is ''.
• SunOS 5.6
• login

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Host Addresses

• Computers on the Internet have a unique address
  or host number.
• E.g. 140.138.30.5
• First six digits typically identify company or
  campus
• next group identifies eg a department
• last group identifies a specific computer
• Symbolic names can be associated with these
• e.g. penelope.ecs.soton.ac.uk
• DNS Distributed name service keeps track of names
  and addresses

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Firewalls

• Used to protect local networks or individual
  computers by implementing access controls to and
  from the internet
• all traffic coming in or going out must pass
  through it
• only authorised traffic gets through

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Firewalls

• can restrict insecure network services
• restrict access to certain hosts
• log activity
• control use of internet
• limit security effort to just one or a few
  computers
• do not necessarily protect against viruses in
  files transferred by ftp

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Networks and Distributed Computing

• Networks of computers allow distributed access to
  resources
• Files may be configured so they may be seen by
  users of several machines

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Client Server Model

• Applications may be split between processors
• Client/server model is a popular architecture
• Client sends request to server for a particular
  service
• Server responds and may need to process data,
  retrieve information or make requests to other
  servers etc to service the requests

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Client Server Model (cont)

• Clients and servers are software processes which
  are really two halves of the same application
• The world wide web uses a client server model
• Browsers are clients send request to web servers
  for documents
• Remote web server software receives the request
  for a document, retrieves it and sends to client

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Client Server Model

• Clients and servers may be on the same or
  different machines
• One client may access many servers
• One server can serve many clients

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Client Server Model

• Popular as makes good use of networked resources
• Growth in internet has increased popularity
• Single repositories of data may be maintained
  more easily eg database servers
• Server typically sits on a large machine and may
  be relatively expensive
• Client can run on a small, low cost platform if
  necessary

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Usenet and the World Wide Web

• Two different application which are usually
  accessed via the internet
• Both are world wide information systems but
  different in nature

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Usenet

• Usenet is a distributed online bulletin board
  (discussion group) system begun in 1979 - a set
  of news groups hierarchically classified by
  subjects
• Users can read, contribute and reply to postings
  on almost every conceivable subject
• Contributions are posted to the newsgroups
• Newsgroups are broadcast to sites which take them
• Sites can choose which sites they take

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Usenet

• Some groups are moderated
• Most are open
• Newsreaders are similar to email software and
  allow you to select, read and respond to postings
• Unlike a bulk email, only one copy of the usenet
  feed is kept on a particular site
• Web browsers now offer facilities for accessing
  news groups without the need to receive the feed.
• Information in Usenet is mainly transient

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The World Wide Web

• Information is less transient than in Usenet
• The web is a way of sharing access to documents
  and navigating between documents using hypertext
  links
• The web has become an attempt to organise the
  bulk of the information on computers attached to
  the internet in an easily accessible way
• Invented by Sir Tim Berners-Lee in 1989 at CERN.
  He has a chair here in Southampton in the School
  of Electronics and Computer Science and at MIT
  and is giving his inaugural next month!

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The WWW

• The WWW is a client server system
• Internet Explorer and Mozilla/Firefox are
  popular web browsers (web clients)
• Web documents are held on web servers
• Web documents are usually written in HTML
  (HyperText Markup Language) or increasingly XHTML
  (eXtensible HTML) which specifies the document
  content structure, (titles, paragraphs etc) and
  any links to other documents.

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Hypertext links and the WWW

• Hypertext systems allow non-linear reading of
  information using buttons and links for
  navigation
• Links in hypertext provide an association between
  some text (the source anchor) and another
  document (the destination of the link)

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Hypertext links and the WWW

• Each document on the Web is identified by a URL
  (uniform resource locator) e.g.
• http//www.ecs.soton.ac.uk/dir1/file3.htm
• Three parts
• transfer protocol
• internet ddress of server where document is held
• the pathname of the file containing the document
• URLs are used in browsers to specify which
  documents to read
• URLs are used in documents to specify
  destinations of links

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Some Other Aspects of the Web

• Documents on the web involve more effort than
  emailing to a usenet newsgroup for example. Web
  tends to be used for more durable information
• Search engines (Google, Yahoo, AltaVista)
• Links from non text.. image maps

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Newer Aspects (Web 2.0 ?)

• Blogs or web logs - a website into which text can
  be added easily (typically using web based forms)
  and are displayed in reverse chronological order
• Blogging - keeping a web log
• Wikis -a website that allows users to easily add
  and edit content and is suitable for
  collaborative writing
• Community tagging (Flickr)
• A folksonomy is an internet based information
  retrieval methodology consisting of
  collaborativey generated, open-ended labels that
  categorize content such as Web pages, online
  photographs, and Web links.

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The Semantic Web

• "The Semantic Web is an extension of the current
  web in which information is given well-defined
  meaning, better enabling computers and people to
  work in cooperation." -- Tim Berners-Lee, James
  Hendler, Ora Lassila, The Semantic Web,
  Scientific American, May 2001

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The Semantic Web (cont)

• provides a common framework that allows data to
  be shared and reused across application,
  enterprise and community boundaries.
• collaborative effort led by W3C with
  participation from a large number of researchers
  and industrial partners.
• based on the Resource Description Framework
  (RDF), which integrates a variety of applications
  using XML for syntax and URIs for naming.

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The Grid

• Grid computing is a form of distributed computing
  that involves coordinating and sharing computing,
  application, data, storage, or network resources
  across dynamic and geographically dispersed
  organizations.
• Grid technologies promise to change the way
  organizations tackle complex computational
  problems. However, the vision of large scale
  resource sharing is not yet a reality in many
  areas
• Grid computing is an evolving area of computing,
  where standards and technology are still being
  developed to enable this new paradigm.

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The workshop Week 1

• Building 44 Room 1061
• Creating your own web pages