Transcript Lec 1 - The University of Sydney

Distributed Information
Systems – ISYS2007
Week 1 - Lecture 1
Contact details

Hugh Springford – course co-ordinator


I am part time and will be at the University on
Thursday and Friday each week
Consultation times, in G82A are:



Friday
10:00 am to 11:00 noon
My email address is [email protected]
Trevor Simpson - teaching assistant

His email address is [email protected]
Tutors

Colin Jones


Trevor Simpson


[email protected]
Hugh Springford


[email protected]
[email protected]
Md Abdur Sikder

[email protected]
Agenda for this week

Today




Define “Distributed Information Systems”
Message passing & Protocols
Course administration
Tomorrow



Client Server model
The History of DIS
Scalability & complexity
What is a Distributed
Information System?


A system where the processing
and data storage is distributed
across two or more autonomous
networked computers in such a
way that the users perceive it as a
single system
Almost all information systems in current use
are, by this definition, distributed
Workstations
Network
Servers
So why differentiate?

Because of




DIS often




the use of networks,
the distribution of data and processing across
autonomous and heterogenous processors
multiple users
Have large numbers of users
Store large quantities of data
Are spread over a large geographical area
This makes them very complex
This course will


Cover the issues that arise because of
these characteristics
Look at DIS from a design or
Information System’s perspective
An Information Systems
perspective



In this course you will learn from an
Information systems design perspective,
not as a computer scientist or engineer
From a need to meet a business objective, not
as a provider of technical services
You will learn enough of the technical stuff to
understand, say how a network will provide the
right service for your Information System, but
not enough to be a network designer or
manager
Some terminology

I will use:



“application” to describe the software at the
top layer that executes the functional tasks
the user wants
“system” to include all software, hardware,
network and procedures that make up the
full DIS
“business” to mean any organisation, not
just a commercial one
Distributing a system
- is hard and
- uses a lot of resources.
(we will discover during this course why this is so)
So why do it?
Why “distribute” a system?



To share information
To provide processing capability for
large volumes of transactions (scale)
To integrate isolated systems, thus


Reducing redundancy, and
Automating more complex processes
If Distributed Information Systems are
very complex, what is it that allows
hundreds of components from many
suppliers to be connected together,
relatively easily and work reliably?
Answer:
Protocols
Protocols

A protocol defines the format and
order of messages exchanged
between two communicating
entities, and the actions taken on
receipt or transmission of a
message.
Source Korose & Ross
Some examples of standards
& Protocols

De facto (by fact – by general acceptance)




De jure (by law – set by an officially
recognised body)



TCP/IP – managed by the Internet Engineering Task
Force (IETF)
HTTP, HTML & XML managed by the W3 Consortium
IBM PC platform – established by IBM, Intel & Microsoft
LAN standards – 802.x set by IEEE
V series (V.32, V.33) X series (X.25, X.500) ISDN set by
ITU.T used to be called CCITT set up by the United
Nations
But the boundaries are blurred
Some standard setting bodies



ITU – International Telecommunications Union – An agency of
the United Nations – Has been the major standard setter for
telephony. Examples are X.25 and V.90 (for 56kps modems)
IETF – Internet Engineering Task Force – sponsors working
groups who issue standards in the form of RFCs (requests for
comment). Examples are TCP/IP, HTTP, HTML, XML
ISO – International Organisation for Standardisation. World
federation of national standard setting bodies. Sets standards in
a wide range of areas. Major example in networking is the ISO
model. Standards Australia is a member.
There are a large number of
protocols


There are several thousand protocols
that can affect Distributed Information
Systems
And 20 or more organisations that set
or agree these protocols
Business rules


They are the internal rules and policies that govern
any organisation
Examples are:







Course pre-requisites – INFO2000 and INFO2006 for this
course
Parking fines need to be paid within 30 days
Employees who work less than 30 hours per week are
considered part-time etc
Many are very complex
They have to be coded into the system
But often not precisely defined until then
And very difficult to do – but necessary!
Course structure






Communications & Networks
- weeks 2 to 5
Distributed components and system integration
- weeks 6 to 9
Security
- week 10
Platforms, performance & reliability - week 11
International issues, ASX case study - week 12
Course review
- week 13
Text book


James F. Kurose & Keith W. Ross
“Computer Networking: A top down
approach featuring the Internet” 2nd
edition Addison Wesley 2003
Covers 50% of the course material
Reference books




Bruce Schneier “Secrets & Lies: Security in a
Networked World” John Wiley 2000
Wolfgang Emmerich, “Engineering Distributed
Objects”, Wiley 2000
David S. Linthicum, “Next Generation Application
Integratation”, Addison-Wesley 2004
Dennis E Shasha & Phillippe Bonnet, “Database
Tuning: Principles, Experiments and Troubleshooting
Techniques”, Morgan Kaufmann 2001
Course home page






PowerPoint slides
Assessment method
Tutorial questions & assignments
Definitions
Readings & useful web sites
Important notices
Formal course specification

The Web site also contains a formal
specification or description of:


The knowledge you are expected to have
when starting this course, and
The knowledge you should have when you
complete this course
What you are expected to
know

Sufficient fluency in English for you to






Understand me, the tutors and the text books
Express your understanding of the subject matter in
tutorials, assignments and exams
Understand how organisations are structured and
managed and the role of information systems in that
process
Aware of key concepts in databases
Aware of the key concepts in operating systems and
hardware
Understand how software is designed & developed
Assessment





Two tutorial presentations by groups of
four - each worth 5 marks
Two individual assignments - each
worth 15 marks
Final exam – worth 60 marks
Pass mark is 50% - no PCON grades
You must obtain 40% or greater, in the
assignments, and in the exam
Lecture content





The lecture slides will give the basics
The lectures will provide more detail and
explanation, and are indicative of the level of
knowledge you will need to pass the course.
The tutorials will re-enforce key knowledge
The text book “Kurose” covers 50% of the course
The reference books will give a more detailed
explanation of some key issues. They will help you
get a credit or distinction. They are on reserve in
the library
Learning objectives

All university courses emphasise the
need to learn:




Analysis and communication skills
The main theories and principles in the
subject matter
The detailed facts of the subject matter
These are in order of importance