Distributed Systems

Lecture 13


Today Lecture
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AN AEROSPACE COMPANY
Case example: Client-Server Systems

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CHUBB & SON INSURANCE COMPANY
Case example: Internet-Based Computing

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THE SABRE GROUP
Case example: Internet-Based Computing

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The IT Infrastructure


AN AEROSPACE COMPANY
Case example: Client-Server Systems

•

Systems group’s goal = never build monolithic
applications again

•

Builds client-server systems with:
–
Application code on the clients
–
Data on the servers


AN AEROSPACE COMPANY
Case example: Client-Server Systems
Cont..
–

–

•

Communication middleware software
shared.
Object oriented technology, most from a
library

Data = at the heart of the architecture is a
repository which allows the reuse of objects




AN AEROSPACE COMPANY
Case example: Client-Server Systems
cont.

•

Network = integral part of the architecture. Each
company site has three components:
–
Desktop machines
–

Servers

–

One or more site hubs


AN AEROSPACE COMPANY
Case example: Client-Server Systems
cont.

•

Architecture = ‘remote data management’. Data
resides on servers and applications reside on
clients


•

Company uses the distribution function and
remote data management because they minimize
total costs


Types of Distributed Systems:
5. Client-Server Systems cont.
n

Benefits of Client-Server Computing:
¨ Better

n

access to information:

Allow companies to compete better.


Types of Distributed Systems:
5. Client-Server Systems cont.

n

Improved customer service
¨ Ability

to communicate customer needs, and


¨ Anticipate

n

customer needs.

Reduce cycle times and


Types of Distributed Systems:
5. Client-Server Systems cont.

¨ Empowered

employees:

n

Blend autonomy of PCs with system wide rules
and connectivity of traditional IS.

n

Shifts focus of computing to users


Types of Distributed Systems:
5. Client-Server Systems cont.
n


Benefits of Client-Server Computing (cont.):
¨ Increases

organizational flexibility:

n

allows new technology to be added more easily
without affecting rest of system

n

streamlines work flow between functional areas

n

encourages people to work together via networks

n

Supports new organizational structures via its


Types of Distributed Systems:
5. Client-Server Systems cont.
n

Drawbacks:
¨ Not


lower in cost than mainframes because they
entail so much coordination

¨ Easier

for users, far more complex for IS
(drawback?)

¨ What

looked like simple connections have turned
into large, often fragile, complex systems


Types of Distributed Systems:
6. Internet-Based Computing

n

In the late 1990s, the client-server trend was
‘interrupted’ (augmented?) by the ‘Internet’

n

Model of a distributed system includes the Internet
(heart?)

n


The tenets of client-server remain

n

Network-centric computing = a computer and a cloud
(Figure 5-11)



Types of Distributed Systems:
6. Internet-Based Computing cont.

n

Network computers have (had?) not taken off
(desktops) but the concept of utilizing programs off
the Internet has
–

‘Network’ computers (thin clients, toasters etc.)
now = coming into their own!


Types of Distributed Systems:
6. Internet-Based Computing cont.
–

Thin clients = logical for hand held but now =
increasingly popular for the ‘desktop’
§


Updating new versions of software

§

Authorized software (firm and purchased)

§

‘One copy’ of software


CHUBB & SON INSURANCE COMPANY
Case example: Internet-Based Computing

•

The company took advantage of the
Internet by converting their legacy cargo
certificate issuance system to a Javabased extranet application


CHUBB & SON INSURANCE COMPANY
Case example: Internet-Based Computing
Cont..

•

It has also done the same with other
applications.


•

All the apps feed into Chubb’s mainframe
but have a Java-based Web front end so
that client machines only need access to
the Web to perform the application


THE SABRE GROUP
Case example: Internet-Based Computing

•

This airline reservation company is working with
Nokia (the handheld phone manufacturer) to create a
real-time, interactive travel service delivered via
mobile phone


THE SABRE GROUP
Case example: Internet-Based Computing
Cont..

•

The service draws on SABRE’s online corporate
travel purchasing system and Nokia’s server (which
transmits the travel information to a wireless network
and to its Internet-enabled phones).


•

Qantas etc. also have and doesn’t need to be webenabled mobiles e.g. text messaging


Types of Distributed Systems:
6. Internet-Based Computing cont.
Server-Based Computing
With more use of laptops which do not have strong
security features

n

–

Updating en masse is not easy

–

Even individual downloads can require helpdesk
support


Types of Distributed Systems:
6. Internet-Based Computing cont.
Solution = server based computing

n


–

Applications reside on corporate servers rather
than on laptops.

–

Applications can be securely accessed by any
device, they can be updated directly on the server,
and they do not have to be tailored to run on
specific machines


3i
Case example: Server-Based Computing
(mobile)

•

UK based venture capital firm.

•

Needed to give its investment professionals anytimeanywhere access to its systems

•

Remote employees dial in (secure modem).

•


Using Windows terminal server software and Citrix
software = the create a ‘virtual office’ for themselves


Types of Distributed Systems:
6. Internet-Based Computing cont.
Peer-to-Peer Computing

n

This form of Internet computing distributes a task over
a wide number of computers (peers) connected to the
Internet.

n

This grassroots movement, like the open source
movement, is now taken seriously by some
corporations. It became famous with Napster, the
music swapping P2P network


Types of Distributed Systems:
6. Internet-Based Computing cont.
Peer-to-Peer Computing

n

The main issue now is how to make money in this

environment. One answer: subscriptions, where
people pay for access rather than for ownership