An overview of the environment in which enterprise applications operate and some architectural factors affecting their design.

1. The Landscape of Enterprise
Applications
- a personal view
Geoff Sharman
© geoffrey.sharman@bcs.org
www.dcs.bbk.ac.uk/~geoff/

2. Enterprise Apps = Web Apps?
Web servers Application Database
Servers Servers
Requests
from web
browsers Member
DB
Auction DB
 Static pages served from web server/content management
system
 Dynamic pages assembled by applications on application servers
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3. Did you do any of these today?
Buy something in a supermarket?
Buy a ticket for travel or entertainment?
Make a telephone call (mobile or fixed)?
Use a cash machine or debit card?
Pay for something with a credit card?
Use electricity, gas or water?
The chances are you used a traditional online
transaction system (running on a mainframe?)
→ Which had nothing to do with the Internet
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4. Hybrid Enterprise Systems
●
Many systems have an Internet front end
connected to a applications and data running
on an online transaction system back end,
eg.
– Airline flight bookings
– Utility billing systems
– Supermarket home delivery systems
– Internet banking
– Etc.
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5. What is an Enterprise, or an
Enterprise System?
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6. What is a System?
Inputs Outputs
information information
control function
energy energy
internal organisation,
possibly including
material sub-systems material
Physical, chemical, biological, social systems - real-time dynamic behaviour
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7. An Enterprise is a System
for delivering economic & social outputs
Inputs Outputs
Information, products,
finance services
Control function
Labour, information
energy
internal organisation,
possibly including
Materials sub-systems employment,
,services financial
returns
Related pairs of inputs & outputs are often referred to as transactions
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8. Interesting
What is an Enterprise?

Large numbers of customers

Large numbers of transactions

Large financial throughputs

Complex behaviour/operations

Sustainable operation

High scale for an extended period
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9. An Enterprise System
is the automated part of an enterprise
= a real-time model of (part of) the enterprise
Inputs Outputs
Information, products,
finance services
Control function
Labour, information
energy
hardware/software
Materials, Enterprise System employment,
services financial
returns
automated
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10. Where would you find an ES?
 Probably not here: (primary industry, 5% of economy)
 Agriculture, fisheries, forestry, water extraction
 Mining, oil & gas extraction
 Possibly here: (secondary industry, 40% of economy)
 Construction, utilities
 Transport, distribution, communications
 Manufacturing (discrete & continuous)
 Probably here: (tertiary industry, 55% of the economy)
 Financial & business services, media, retail
 Education, healthcare, tourism, entertainment
 Public admin
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11. Brief History of Enterprise
Systems
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12. Pioneers of Enterprise Systems

1952 – Joe Lyons & Co. Leo system
- batch accounting & payroll operations

1965 – American Airlines Sabre system
- online flight reservations & check in

199x – Amazon.com, eBay.com
- direct customer service, just-in-time delivery

2001 – Google.com
- customised search using large amounts of data

2008 – Apple iPhone
- mobile applications
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13. Enterprise (Systems) Topology
All enterprises have a many-to-one relationship with their
customers – although the customer would like it to be one-to-one!
Premier
Customer
Representative
Premier Flyers
F.F.
AirlineReservations Routing Customer
function Representative
Frequent Flyer
Members
Regular
Customer
Representative
Regular
Members

14. Getting Closer to the Customer
6
5
4
System Type 1=Batch, 2=Online,
3 3=Network, 4=Web,
5=Social/mobile
2
1
0
1960s 1970s 1980s 1990s 2000s
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15. What were the Key Innovations?

1950s – main storage (delay lines, ferrite cores),
secondary storage (magnetic tape), batch job
scheduler

1960s – operating system, direct access storage,
database management, time sharing terminals

1970s – TP monitor, relational database

1980s – personal computer, networking

1990s – World Wide Web

2000s – search engine, social networking, mobile
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16. How do you write applications
for Enterprise Systems?
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17. Programming Paradigms
Enterprise applications have to serve large
numbers of users concurrently
This requires lots of program code to support
communications, scheduling, concurrency and
data access
Programmers can't write all this code for each new
application, so they use frameworks based on a
number of programming paradigms (aka
design patterns)
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18. Time Sharing/Conversational

At logon time, operating system allocates:

Memory address space for user application

Operating system process

Files, communications channels, etc.

These remain dedicated to user until logoff

Paradigm is widely used in programming
development systems, but:

Limited sharing of resources

Not scalable beyond a few hundred users

So not useful for production systems
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19. Transaction Processing Monitor

Monitor acquires & retains shared resources

Applications, memory, processes, threads, files,
databases, communication channels, etc.

On receipt of transaction request, provides
concurrent access to resources

Frees resources when output message sent

So application is one-in-one-out, or implements
a “pseudo conversation”

Highly scalable to tens of thousands of users

Requires stateless application programming

Conversation state held in “scratchpad” files
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20. What are Stateless Applications?
REQUEST: find information about “flights”
RESPONSE: list of links to flight web sites
TRANSACTION: request + response
FINAL STATE: all memory of transaction lost;
next request starts with a clean sheet
PSEUDO CONVERSATION: chain of transactions
linked by scratchpad data
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21. Representational State Transfer

Underlying paradigm for Web hypertext
applications

Commonly abbreviated as REST

Web servers manage network & provide
concurrent access

Defines stateless clients for rendering data

Highly scalable to 10s of thousands of users

Pure REST does not define how to build update
applications on the Web, so we have to modify

Disallows “cookies” - no scratchpad

Does not define server application model
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22. Google Applications

Underlying paradigm for Google search and
other applications

Uses GAE (Google App engine)

Requires stateless clients

Concurrent access to “scratchpad” storage via
GFS/BigTable

Highly scalable to 10s of thousands of users

Especially suitable for applications using read-
only data, e.g. search data, maps, etc.
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23. Why do these Paradigms Work?

All these paradigms embody the many-to-one
relationship between customers and the
enterprise

The TP, REST, & Google paradigms provide
scalable concurrency & enable the enterprise to
exploit economies of scale

But none of them is a complete recipe for what
modern enterprise systems need
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24. What Paradigm is Needed?

Stateless applications provide the highest
scalability and work well for read only requests

But commercial applications, e.g. web shopping,
need conversation state & concurrent update

Use HTTP because it supports any-client-to-any
server, unlike object-based protocols

Hold state on client or replicated server file
system

Collect updates that form part of a transaction

Permanently save data at end of conversation
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25. Current Enterprise System
Challenges
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26. Enterprise Business Challenges
Business people care about two main objectives:

Reducing costs:

automating/eliminating internal processes

reducing operating costs for enterprise systems

reducing ownership costs for enterprise
systems

Increasing revenue:

Winning new customers

Retaining existing customers

Getting more business from existing customers
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27. Enterprise System Challenges
1) Multi-channel applications
- acting consistently to the customer
2) Multi-business service
- providing multiple offers consistently
3) Effective customer knowledge
- acting more intelligently to the customer
4) Effective market knowledge
- foreseeing what customers will want next
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28. Multi-Channel Applications

Many enterprise systems are designed to
support particular sales channels, eg.:

Store checkout systems

Kiosk/ticketing systems

Call centre systems

Web based systems

Mobile systems

Business offer may depend on channel, but

Applications should treat the customer
consistently, whichever channel he/she uses
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29. Typical M Architecture 2
sync msgs
async msgs
sync msgs
Line of business
Presentation / Integration server Application and
Channel server(s) - Tight coupling Data server(s)
- Static/ Dynamic web - Loose coupling
pages - Stand-in processing
- Portals - Flow ctrl/compensation
- Channel specific
M2 = Multi-Channel, Multi-Business
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30. Customer Knowledge

Many web systems allow customer to explore
options before & after a transaction:

high “browse to buy” ratio in web shopping

evaluations of product, service, etc.

If we identify the customer, we can study:

search patterns

history of actual transactions

customer likes & dislikes

May enable better offers to the customer

need more data & real time parallel computation
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31. Market Knowledge

Many enterprise systems collect data about a
mass of customer transactions:

Collected/refined in data warehouse

Linked with tools for analytics / Bus Intelligence

Used to produce periodic reports & analyses

This process may be ineffective:

Too slow/costly for business needs

Only structured data – much unstructured data

New methods use very large data sets

Best practice uses highly parallel processing
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32. “Highly Parallel” Processing

Google is the best known exponent

Many processes crawling the Web in parallel

Combine results using MapReduce technique

Store results in Google File System

Substitutes concurrency for parallelism

Also widely used in scientific applications, eg:
– SETI @Home used subscriber PCs
– IBM “Blue Gene” protein modelling project

4K processors generated 10 μsec simulation

Uses hardware cluster plus GPRS
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33. Summary

When building an Enterprise System, we are
building a model of (part of) the enterprise:

Model must be real time and scalable

Customer can use anywhere, anytime, any device

Access any business offering consistently

Know and respond intelligently to each customer

Also need a “Meta-Enterprise System” (i.e.
control function) which analyses ES & the
behaviour of customers

Detect trends and respond to them
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