Transcript lecture 13.pptx

Distributed Systems
Lecture 13
Today Lecture

AN AEROSPACE COMPANY
Case example: Client-Server Systems

CHUBB & SON INSURANCE COMPANY
Case example: Internet-Based Computing

THE SABRE GROUP
Case example: Internet-Based Computing

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.

Benefits of Client-Server Computing:
 Better

access to information:
Allow companies to compete better.
Types of Distributed Systems:
5. Client-Server Systems cont.

Improved customer service
 Ability
to communicate customer needs, and
 Anticipate

customer needs.
Reduce cycle times and
Types of Distributed Systems:
5. Client-Server Systems cont.
 Empowered
employees:

Blend autonomy of PCs with system wide rules
and connectivity of traditional IS.

Shifts focus of computing to users
Types of Distributed Systems:
5. Client-Server Systems cont.

Benefits of Client-Server Computing (cont.):
 Increases
organizational flexibility:

allows new technology to be added more easily
without affecting rest of system

streamlines work flow between functional areas

encourages people to work together via networks

Supports new organizational structures via its
Types of Distributed Systems:
5. Client-Server Systems cont.

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
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
In the late 1990s, the client-server trend was
‘interrupted’ (augmented?) by the ‘Internet’
Model of a distributed system includes the Internet
(heart?)
The tenets of client-server remain
Network-centric computing = a computer and a cloud
(Figure 5-11)
Types of Distributed Systems:
6. Internet-Based Computing cont.

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

–
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

–
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


This form of Internet computing distributes a task over
a wide number of computers (peers) connected to the
Internet.
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

The main issue now is how to make money in this
environment. One answer: subscriptions, where
people pay for access rather than for ownership
Types of Distributed Systems:
7. Web Services

This second-generation Internet-based distributed
system gives software modules URLs (Internet
addresses) so they can be called upon to perform
their function as a service via the Internet.

This development will permit widespread computerto-computer use of the Internet. One computer
program or Web Service makes a request of another
Web Service to perform its task (or set of tasks) and
pass back the answer
Types of Distributed Systems:
7. Web Services cont.

Hot topic (the future?):
1.
Next generation of distributed systems (big!)
2.
Makes the Internet the hub of computing
3.
Permits flexible systems not possible before
Types of Distributed Systems:
7. Web Services cont.
4. Releases companies from ‘building’ and
maintaining systems ‘in house’
5. Will draw on existing systems.

Wrapping – encapsulate functionality from an
existing application in an XML envelope
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Exposing – for use by others
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The promises go on! And the vying for position!
Types of Distributed Systems:
7. Web Services cont.

Web Services Standards:

Three software standards:

XML (eXtensible Markup Language)

WSDL (Web Services Definition Standard)

UDDI (Universal Discovery, Description, and
Integration
Types of Distributed Systems:
7. Web Services cont.

Web Services Standards:

Three communication standards

SOAP (Simple Object Access Protocol)

HTTP (HyperText Transfer Protocol)

TCP/IP (Transmission Control Protocol /
Internet Protocol)
Types of Distributed Systems:
7. Web Services cont.

Significance of Web Services

Viewing IS as proprietary has led to rigid
business processes, which are slow to change
and respond to market changes.

Web Services offers an IT architecture based on
the openness of the Internet. Rather than build
proprietary systems, companies can obtain the
functionality they need from the Internet
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Types of Distributed Systems:
7. Web Services cont.

This modularity permits handling a huge
variety of possibilities by mixing and
matching, and allows easier cross-company
system linking.

Companies thus only pay for the functionality
they use when they use it, which reduces the
number of IT assets companies need to
house and maintain
GENERAL MOTORS
Case Example: Web Services
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One GM executive believes that the Web Services
architecture could be used to move GM from its
supply-driven, build-to-stock business model to a
demand-driven, build-to-order business model – an
otherwise impossible feat.
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To begin, GM first enhanced its supply-driven model
by offering new functions via a Web Services
architecture.

One Web Service is a locate-to-order service that
dealers can use to easily find a specific car a
customer might want in the inventory of other GM
dealers
GENERAL MOTORS
Case Example: Web Services cont.

Another Web Service is order-to-delivery which
shortens the time to deliver a custom-ordered vehicle
 Paving
the way to eventually convert to a make to
order business model

The ‘Rewards’?:
 Cut
its $25B inventory in half
 Potentially
vehicle
shave $1,000 off the cost of each
Defining the Overall IT Architecture

The intent of an IT architecture is to bring order to the
otherwise chaotic world of information systems by
defining a set of guidelines and standards, and then
adhering to them.
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Because the architecture needs to support how the
company operates, it reflects the business strategy.
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Furthermore = as business changes, the architecture
needs to keep pace.
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Chief Technology Officer
An Enterprise Architecture Framework
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To describe the IS architecture, look at the roles
people and components play (5th edition Fig.5-12):
 Rows:
Views must be taken into account when
building complex products:

planner (scope statement)

owner (model of the enterprise)
An Enterprise Architecture Framework
Cont..
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Designer (model of the information system)
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Builder (technology model).
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Subcontractor (description of the components).
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User (functioning system).
An Enterprise Architecture Framework
cont.
•
Columns:
•
IS components:
–
Data models (what it is made of)
–
Functional models (how it works)
–
Network models (where the components are located)
–
Represent physical manifestations of the system.
An Enterprise Architecture Framework
cont..
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Also:
–
People (who)
–
Time (when)
–
Motivation (why)
An Enterprise Architecture Framework
cont..
•
Use of the framework: When IS users bring in a package
that follows a data model inconsistent with the rules of
the company, a lot will be spent fixing the package.
•
Figure 5-13 - the ‘whole’ picture
FMC CORPORATION
Case Example: IT Architecture
Development

When FMC split in two, it designed two new IT
architectures

The architecture and technology director led five
teams – for data, applications, integration, desktop,
and platform

Each created a today architecture, a tomorrow
architecture, and the “next minute” steps
FMC CORPORATION
Case Example: IT Architecture
Development

The companies have now split and the tomorrow
architecture has given FMC a standard that everyone
agrees with, making standard-setting far easier

Now it is working on a new tomorrow architecture, for
2004-2005, when voice-over IP and Web Services
kick in
THE SABRE SYSTEM
Case Example: IT Architecture

When they looked at the underlying databases
 Customer

profiles, AAdvantage, NetSAAver
= found heaps of data redundancy (common!)
leading to a huge redesign
 American
consolidated and linked these
databases to have just one profile for each flyer.
THE SABRE SYSTEM
Case Example: IT Architecture Cont..

The architecture underlying American Airline’s
Website is now modular
 The
existing SABRE computer reservation system
serves as “the reservation service” module
 Other
modules perform the functions related to the
Web
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Due to this component-based architecture, it was
fairly easy to add new functions
The Coming Architecture:
Service–Oriented Architecture
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Importance of an architecture is that it spells out the
relationships between the components of an airplane,
building, system etc.

In the past with IS these interactions have been
‘hard-coded’ point-to-point
 Efficient
but costly to maintain
 Changing
one component might require changing
the others that interact with it
The Coming Architecture:
Service–Oriented Architecture Cont..

Relatively new system architecture moves away from
this = Service Oriented Architecture (SOA)
parallels Web Services – uses the
same architectural concept
 Emergence
 Thinks
about how to expose the data and
functions in a way that other systems can easily
use

Holy Grail? Which has long eluded IS organizations
and addresses the need to be more agile
The IT Infrastructure
- What is an IT Infrastructure?
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IT infrastructure is the foundation of an enterprise’s IT
portfolio:
Provides the capability for reliable services and
sharing
Includes both the technical and managerial expertise
required to provide these services
Is linked to external industry infrastructure
 Banking payments, airline reservations etc.
The IT Infrastructure
- What is an IT Infrastructure? cont.



Shared characteristics differentiate an infrastructure
from IT investments used by just one function
Elements can include:
 Company-wide networks
 Data warehouses
 Large scale computing facilities
 EDI capabilities
Applications ‘sit on top’ and directly support the
business Vs. infrastructure ‘indirect’ support
The Importance of IT Infrastructure

Infrastructure investments are a vital part of corporate
information systems portfolios

Yet they are the most difficult to cost-justify initially
and to quantify benefits afterwards
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The Importance of IT Infrastructure
- The Structure of the IT Infrastructure

The IT infrastructure is the shared and reliable services
that provide the foundation for the enterprise IT portfolio.
IT infrastructure is very similar to public infrastructure; on
top of an IT infrastructure sit applications that perform a
business’s processes.
 The
bottom of four layers consists of technology
components, such as computers and database
management system packages.
The Importance of IT Infrastructure
- The Structure of the IT Infrastructure..
 The
third layer is the human IT infrastructure layer,
which translates the components (which technologists
can understand) into services (which business users
can understand).
 The second layer is shared IT services, which present
the infrastructure as a set of services that users can
draw upon and share to conduct business.
 The top layer is the shared and standard applications
layer, which includes stable applications (such as
accounting and HR)
The Importance of IT Infrastructure
- Similar to Public Infrastructure
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

Similar to public infrastructure:
 Roads
 Hospitals
 Sewers
 Schools
 etc.
Everyone wants but no-one wants to ‘pay’
Provided by a ‘central authority’
 Government or IT Department
 Delicate and ‘difficult’ investment balance
Three views of Infrastructure
IT investments can provide:
1. Economies of scale (utility):



2.
Infrastructure cost as an administrative expense
Minimize expense
Outsourcing may be viewed favorably because the IT
infrastructure is not seen as strategic
Support for business programs (dependent):




Infrastructure treated as business expense
Measured by short-term business benefits
Infrastructure planning in current business plan
Network = critical
Three views of Infrastructure..
3.
Flexibility to meet changes in the marketplace
(enabling):
 Primary benefit long-term flexibility
 Intended to provide the foundation for changing
direction in the future
 IT cost seen as business investment
CITY OF SUNNYVALE, CALIFORNIA
Case example: Investing in Infrastructure
•
•
Director of IT hired to “move the city into the future”
•
Provides connectivity between the city’s myriad of
IT facilities: mainframes, LANs, WANs, PCs etc.
First = get its house into order – “capturing
accurate information and delivering that information
in a timely manner”
CITY OF SUNNYVALE, CALIFORNIA
Case example: Investing in Infrastructure
•
Like a foundation for a home
–
•
•
Able to withstand all the weight, noise and
“things you want to plug into it”
Infrastructure investments are paid through
chargeback
“Super” rules guide technology investments
Conclusion


Distributing processing, databases, and
communications allow companies to move more
quickly because they can more easily “snap in” new
products and services into their existing systems
The advent of Web Services is fueling the use of the
Internet to extend the tenets of distributed systems
even further
Summary

AN AEROSPACE COMPANY
Case example: Client-Server Systems

CHUBB & SON INSURANCE COMPANY
Case example: Internet-Based Computing

THE SABRE GROUP
Case example: Internet-Based Computing

The IT Infrastructure