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Two histories of enterprise computing
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A history of enterprise computing I: Calculation systems
1950s-80s Single purpose Eliminate tedious human work Examples: Payroll, General ledger, Inventory Technology used: Mainframes, magnetic tapes, batch processing
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A history of enterprise computing II: Functional systems
(say) Use computers to improve operations Applications: Human resources, order entry, manufacturing resource planning Technologies: Mainframes, PC’s, LAN’s
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Functional systems Typically contained within a department
Islands of automation Applications independently developed and deployed Driving force: availability of mini-computers
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Functional system applications
Human resources System Accounting and finance systems Sales and marketing System Operations management System Manufacturing Systems
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History part III: Pressures on business forced integration
It becomes less and less possible to think about isolated systems. The world is becoming more joined up. eCommerce Need to allow access to customers Out sourcing Need to integrate with 3rd party systems Mergers and acquisitions Regulation Post-9/11 and Sarbanes-Oxley requires must better integration and reporting Post-credit crunch regulation still emerging
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Organisational systems
2000-date (say) Use computers to drive efficiency and support control across organisations and beyond to partners and suppliers Applications: Risk management, customer relationship management, supply chain management Technologies: Middleware, business intelligence, data integration technologies 7
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Types of Organizational information Systems
Administrative systems Scheduling / Transaction systems Value oriented systems Reporting and controlling systems Analysis and information systems Planning and decision support systems
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Exercise Each group chose a different business function within the organisation. Define how a customer will be represented. Personal details 1 or more details specific to your selected business function
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Problems with function based application
Sharing of data between systems Data duplication Data inconsistency Applications that don’t talk to one another Limited or lack of integrated information Isolated decisions lead to overall inefficiencies Increased expenses HR Sales Manufacturing Stovepipe systems
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Cloud computing On-demand access to a shared pool of configurable computing resources Exercise: Is cloud computing the next stage beyond organisational systems?
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An architectural history of computing
1 tier architecture Presentation, application logic, and resource management were merged into a single tier Often associated with ‘legacy’ mainframe systems 2 tier architecture Separation of presentation tier from other 2 tiers (app + resource) 'client/server' systems 3 tier architecture Separation of application logic and resource management tier
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Tiers of an architecture
Browser Client <html> ... </html> Presentation tier Visualise Application logic tier Calculate information system Resource management tier Store
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Tiers of an architecture
Browser Client How the data should appear to the user and how the user should interact with the interface The sequence of screens presented to the user and the data entered by the user The starting point for most tasks E.g. Entering an order, adding an employee Presentation tier Application logic tier information system Resource management tier
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Tiers of an architecture
Client Calculate Data Processing (Business Logic & calculation) The algorithms are implemented in this tier This tier is often referred to as Services, Business logic, Business rules, Server Were the ‘work’ of the application occurs E.g. Calculating the value of the order, creating the record to be entered into the employee database Presentation tier Application logic tier information system Resource management tier
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Tiers of an architecture
Client Store Deals with and implements different data sources of Information Systems The 'data layer' in a restricted interpretation as in JEE or Database Management System Can also be a gateway to recursively using other Information systems Where the business data which will persist is stored E.g. The completed order, the employee record Presentation tier Application logic tier information system Resource management tier
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Adding tiers Advantages Disadvantages
With growing number of tiers one gains: Flexibility Add servers in each tier to meet demand Functionality Introduce new functionality to each tier without changing the other tiers Possibilities for distribution Able to locate servers near to main users Disadvantages Each tier increases communication costs Network traffic increases Complexity rises leading to higher cost and risk Higher complexity of development: Now need to consider where functionality is located and how to communicate between tiers Higher complexity of management and tuning Redundancy increases Potentially have too many servers in each tier which will be under-utilised
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Design of 1 – Tier Architecture
Presentation, application logic, and resource management were merged into a single tier Advantages: Simplicity easy to optimise performance on a single server no compatibility issues between tiers no client development, maintenance and deployment cost Disadvantages: Difficult to manage/modify Poor scaling on system is on a single system lack of qualified programmers for these systems (for 1-tier ‘legacy’ systems) Client Presentation layer Application logic layer information system Resource management layer
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2 - Tier Architectures fig 1.7 p.12 Client Presentation layer
Information system Presentation layer fig 1.7 p.12 Resource management layer Application logic layer Server
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2 - Tier Architectures Separation of presentation layer from other 2 layers (app + resource) Client/server systems with thin clients/fat clients Must use RPC (Remote Procedure Call) to communicate between client and server tiers Need for standardisation for inter-tier communication Advantages portability no need for context switches or calls between component for key operations Disadvantages Increased complexity Risk of incompatibilities between clients developed at different times
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3 - Tier Architectures client presentation layer information system
application logic layer information system middleware resource management layer
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3 - Tier Architectures Separating RM (resource management) from application logic layer Additional middleware layer between client and server integration logic application logic Lead to the introduction of clear RM layer interfaces Good at dealing with integration of different resources
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Business logic resides in middle tier
Alternatives Client tier leads to Fat clients Reimplementing it for each different type of client Redistributing clients after each software update Data tier leads to Vendor and technology dependence grows Different applications have different needs for the same data Performance issues in resource usage
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3 - Tier Architectures Advantages Disadvantages
scalability by running each layer on a different server scalability by distributing application logic tier across many servers Flexibility to introduce multiple application logic servers running different application logic Disadvantages performance loss if distributed widely over intranet or internet Complexity of managing 3 tier systems
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3 - tier Architectures GUI clients C++, VB, Java Middleware Server
information system client GUI clients C++, VB, Java presentation layer resource management layer application logic layer Middleware Server middleware Databases Legacy Systems
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Middleware Middleware refers to the software which is common to multiple applications and builds on the network transport services to enable ready development of new applications and network services. Middleware typically includes a set of components such as resources and services that can be utilised by applications either individually or in various subsets. Examples of services: Security, Directory and naming, end-to-end quality of service, support for mobile code. Examples: OMG’s CORBA J2EE - Java 2 Enterprise Edition Microsoft’s .Net
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Middleware features Allows communication
through a standard language across different platforms between legacy and modern applications Make 3-tier architecture safe by ensuring data/communication between tiers is protected by taking care of transactions between servers data conversion authentication communications between computers
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Middleware features Makes it easier to write 3-tier applications by providing runtime environment for components in the middle-tier Component lifecyle and management Transaction, event and security services Provides connections to databases, mainframes and legacy systems Separates client-tier from the data source Clean separation of user-interfaces and presentation logic from the data source
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n - tier How many tiers? 3 tier systems rarely exist as most systems connect to other applications or databases to complete the processing task E.g. An airline booking system connects with VISAcard systems to collect payment N-tier extends 3-tier to allow for connections to these additional tiers
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Adding tiers Advantages Disadvantages
With growing number of tiers one gains: Flexibility Add servers in each tier to meet demand Functionality Introduce new functionality to each tier without changing the other tiers Possibilities for distribution Able to locate servers near to main users Disadvantages Each tier increases communication costs Network traffic increases Complexity rises leading to higher cost and risk Higher complexity of development: Now need to consider where functionality is located and how to communicate between tiers Higher complexity of management and tuning Redundancy increases Potentially have too many servers in each tier which will be under-utilised
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Exercise Why is performance a harder issue to resolve with n-tier systems than with 1-tier systems? Classify cloud computing in terms of the number of tiers
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Classification of Information systems
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Classification of Information Systems
Organisational Hierarchy Organisational Structure and departmental organisation Business processes
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Information System from business perspective
Types of system Groups Served STRATEGIC LEVEL SENIOR MANAGERS MANAGEMENT LEVEL MIDDLE MANAGERS KNOWLEDGE LEVEL KNOWLEDGE & DATA WORKERS OPERATIONAL OPERATIONAL LEVEL MANAGERS SALES & MANUFACTURING FINANCE ACCOUNTING HUMAN MARKETING & ENGINEERING RESOURCES
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Four General Kinds of System
Operational-level systems support operational managers by monitoring the day-to-day’s elementary activities and transactions of the organization. e.g. TPS. Knowledge-level systems support knowledge and data workers in designing products, distributing information, and coping with paperwork in an organization. e.g. KWS, OAS Management-level systems support the monitoring, controlling, decision-making, and administrative activities of middle managers. e.g. MIS, DSS Strategic-level systems support long-range planning activities of senior management. e.g. ESS
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Information System from business perspective
Types of system Groups Served STRATEGIC LEVEL SENIOR MANAGERS MANAGEMENT LEVEL MIDDLE MANAGERS Vertical information flows KNOWLEDGE LEVEL KNOWLEDGE & DATA WORKERS OPERATIONAL OPERATIONAL Horizontal information flows LEVEL MANAGERS SALES & MANUFACTURING FINANCE ACCOUNTING HUMAN MARKETING & ENGINEERING RESOURCES
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Management Structures and Information Requirements
Higher up the pyramid, the less structured the decision Less defined External orientation More summarized information Future oriented Less frequent Less accurate Lower down the pyramid, the more structured the decision More defined Internal orientation More detailed information Historical More frequent More accurate
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A Framework for classification of IT system
Executive Support Systems (ESS) Management Information Systems (MIS) Decision Support Systems (DSS) Knowledge Work Systems (KWS) Office Automation Systems (OAS) Transaction Processing Systems (TPS)
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Transaction Processing Systems (TPS)
Computerized system that performs and records the daily routine transactions necessary to conduct the business; these systems serve the operational level of the organization TYPE: Operational-level INPUTS: transactions, events PROCESSING: updating OUTPUTS: detailed reports USERS: operations personnel, supervisors DECISION-MAKING: highly structured EXAMPLE: payroll, accounts payable
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Typical Applications of TPS
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Office Automation Systems (OAS)
Computer system, such as word processing, electronic mail system, and scheduling system, that is designed to increase the productivity of data workers in the office. TYPE: Knowledge-level INPUTS: documents, schedules PROCESSING: document management, scheduling, communication OUTPUTS: documents; schedules USERS: clerical workers EXAMPLE: document imaging system
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Decision Support Systems (DSS)
Information system at the management level of an organization that combines data and sophisticated analytical models or data analysis tools to support semi-structured and unstructured decision making. TYPE: Management-level INPUTS: low volume data PROCESSING: simulations, analysis OUTPUTS: decision analysis USERS: professionals, staff managers DECISION-MAKING: semi-structured EXAMPLE: sales region analysis
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Characteristics of Decision-Support Systems
1. DSS offer users flexibility, adaptability, and a quick response. 2. DSS operate with little or no assistance from professional programmers. 3. DSS provide support for decisions and problems whose solutions cannot be specified in advance. 4. DSS use sophisticated data analysis and modelling tools.
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Management Information Systems (MIS)
Information system at the management level of an organization that serves the functions of planning, controlling, and decision making by providing routine summary and exception reports. TYPE: Management-level INPUTS: high volume data PROCESSING: simple models OUTPUTS: summary reports USERS: middle managers DECISION-MAKING: structured to semi-structured EXAMPLE: annual budgeting
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Characteristics of Management information Systems
1. MIS support structured decisions at the operational and management control levels. However, they are also useful for planning purposes of senior management staff. 2. MIS are generally reporting and control oriented. They are designed to report on existing operations and therefore to help provide day-to-day control of operations. 3. MIS rely an existing corporate data-and data flows. 4. MIS have little analytical capability. 5. MIS generally aid in decision making using past and present data. 6. MIS are relatively inflexible. 7. MIS have an internal rather than an external orientation.
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Executive Support Systems (ESS)
Information system at the strategic level of an organization that address unstructured decision making through advanced graphics and communications. TYPE: Strategic level INPUTS: aggregate data; internal and external PROCESSING: interactive OUTPUTS: projections USERS: senior managers DECISION-MAKING: highly unstructured EXAMPLE: 5 year operating plan
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However, the world is not that straight forward
A single software package like Microsoft Office or even an application like Microsoft Excel could be classified as any or all of the following: DSS, TPS, MIS, or ESS (albeit, a trivial ESS, DSS, etc.) When considering classification, consider how the tool is used, not what it could be used for. A tools meets a need posed by the enterprise A service is provided by the tool is a solution.
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Classification of IT System by Organizational Structure
Departmental Information Systems Enterprise Information System Inter-organizational Systems SWIFT (mostly network level) SABRE
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Classification of IT System by Functional Area
The accounting information system The finance information system The manufacturing (operations, production) information system The marketing information system The human resources information system
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e.g. Sales & Marketing Systems
Systems that help the firm identify customers for the firm’s products or services, develop products and services to meet customer’s needs, promote products and services, sell the products and services, and provide ongoing customer support.
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Classification of IT system by Business Processes
A business process is a set of coordinated tasks and activities, conducted by both people and equipment, that will lead to accomplishing a specific organizational goal. Business process management (BPM) is a systematic approach to improving those processes.
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Examples of Business Processes
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