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Shared information systems
- 1. Dr. Himanshu Hora SRMS College of Engineering & Technology Bareilly (UP) INDIA 1
- 2. Contents 1. DATA vs. INFORMATION 2. Factors Affecting the Usefulness of Information 3. A Taxonomy of Architectural Styles 4. Data Flow Style 5. Data-Centered Style 6. Virtual Machine Style 7. Independent Component Style 8. Heterogeneous Styles 9. Types of Management Information Systems 10. Limitations of Information Systems 2
- 3. DATA vs. INFORMATION • Data –Raw, unsummarized, and unanalyzed facts. • Information –Data that are organized in a meaningful fashion 3
- 4. Attributes of Useful Information 4 Attributes Quality The accuracy and reliability of available information affects the quality of decisions that managers make using the information. Timelessness The availability of real-time information that reflects current conditions allows managers to maximize the effectiveness of their decisions. Completeness Complete information allows managers to consider all relevant factors when making decisions. Relevance Having information specific to a situation assists managers in making better decisions.
- 5. Factors Affecting the Usefulness of Information 5
- 6. Information Technology • Information Technology – set of methods or techniques for acquiring, organizing, storing, manipulating, and transmitting information 6
- 7. 7 A Taxonomy of Architectural Styles Independent Components Communicating Processes Event Systems Client/Server Peer-to-Peer Implicit Invocation Explicit Invocation Data Flow Batch Sequential Pipe and Filter Virtual Machine Interpreter Rule-Based System Data-Centered Repository Blackboard Call and Return Main Program and Subroutine Object OrientedLayered Remote Procedure Call
- 8. 8 Data Flow Style Validate Sort Update Report
- 9. 9 Data Flow Style • Has the goal of modifiability • Characterized by viewing the system as a series of transformations on successive pieces of input data • Data enters the system and then flows through the components one at a time until they are assigned to output or a data store • Batch sequential style – The processing steps are independent components – Each step runs to completion before the next step begins • Pipe-and-filter style – Emphasizes the incremental transformation of data by successive components – The filters incrementally transform the data (entering and exiting via streams) – The filters use little contextual information and retain no state between instantiations – The pipes are stateless and simply exist to move data between filters
- 10. 10 • Advantages – Has a simplistic design in the limited ways in which the components interact with the environment – Consists of no more and no less than the construction of its parts – Simplifies reuse and maintenance – Is easily made into a parallel or distributed execution in order to enhance system performance • Disadvantages – Implicitly encourages a batch mentality so interactive applications are difficult to create in this style – Ordering of filters can be difficult to maintain so the filters cannot cooperatively interact to solve a problem – Exhibits poor performance • Filter may need unlimited buffers if they cannot start producing output until they receive all of the input • Each filter operates as a separate process or procedure call, thus incurring overhead in set-up and take-down time
- 11. 11 Call-and-Return Style Main module Subroutine A Subroutine B Subroutine A-1 Subroutine A-2 Physical layer Data layer Network layer Transport layer Application layer Class WClass V Class X Class Z Class Y
- 12. 12 Call-and-Return Style • Has the goal of modifiability and scalability • Has been the dominant architecture since the start of software development • Main program and subroutine style – Decomposes a program hierarchically into small pieces (i.e., modules) – Typically has a single thread of control that travels through various components in the hierarchy • Remote procedure call style – Consists of main program and subroutine style of system that is decomposed into parts that are resident on computers connected via a network – Strives to increase performance by distributing the computations and taking advantage of multiple processors – Incurs a finite communication time between subroutine call and response
- 13. 13 • Object-oriented or abstract data type system – Emphasizes the bundling of data and how to manipulate and access data – Keeps the internal data representation hidden and allows access to the object only through provided operations – Permits inheritance and polymorphism • Layered system – Assigns components to layers in order to control inter-component interaction – Only allows a layer to communicate with its immediate neighbor – Assigns core functionality such as hardware interfacing or system kernel operations to the lowest layer – Builds each successive layer on its predecessor, hiding the lower layer and providing services for the upper layer – Is compromised by layer bridging that skips one or more layers to improve runtime performance • Use this style when the order of computation is fixed, when interfaces are specific, and when components can make no useful progress while awaiting the results of request to other components
- 14. 14 Data-Centered Style Shared Data Client A Client B Client C Client D Client E Client F
- 15. 15 Data-Centered Style • Has the goal of integrating the data • Refers to systems in which the access and update of a widely accessed data store occur • A client runs on an independent thread of control • The shared data may be a passive repository or an active blackboard – A blackboard notifies subscriber clients when changes occur in data of interest • At its heart is a centralized data store that communicates with a number of clients • Clients are relatively independent of each other so they can be added, removed, or changed in functionality • The data store is independent of the clients • Use this style when a central issue is the storage, representation, management, and retrieval of a large amount of related persistent data • Note that this style becomes client/server if the clients are modeled as independent processes
- 16. 16 Virtual Machine Style Interpretation Engine Program Data Program Instructions Program Internal State
- 17. 17 Virtual Machine Style • Has the goal of portability • Software systems in this style simulate some functionality that is not native to the hardware and/or software on which it is implemented – Can simulate and test hardware platforms that have not yet been built • Examples include interpreters, rule-based systems, and command language processors • Interpreters – Add flexibility through the ability to interrupt and query the program and introduce modifications at runtime – Incur a performance cost because of the additional computation involved in execution • Use this style when you have developed a program or some form of computation but have no make of machine to directly run it on
- 18. 18 Independent Component Style Server Client A Client B Client C Client D Peer W Peer X Peer Y Peer Z
- 19. 19 Independent Component Style • Consists of a number of independent processes that communicate through messages • Has the goal of modifiability by decoupling various portions of the computation • Sends data between processes but the processes do not directly control each other • Event systems style – Individual components announce data that they wish to share (publish) with their environment – The other components may register an interest in this class of data (subscribe) – Makes use of a message component that manages communication among the other components – Components publish information by sending it to the message manager – When the data appears, the subscriber is invoked and receives the data – Decouples component implementation from knowing the names and locations of other components
- 20. 20 Independent Component Style • Communicating processes style – These are classic multi-processing systems – Well-know subtypes are client/server and peer-to-peer – The goal is to achieve scalability – A server exists to provide data and/or services to one or more clients – The client originates a call to the server which services the request • Use this style when – Your system has a graphical user interface – Your system runs on a multiprocessor platform – Your system can be structured as a set of loosely coupled components – Performance tuning by reallocating work among processes is important – Message passing is sufficient as an interaction mechanism among components
- 21. 21 Heterogeneous Styles • Systems are seldom built from a single architectural style • Three kinds of heterogeneity – Locationally heterogeneous • The drawing of the architecture reveals different styles in different areas (e.g., a branch of a call-and-return system may have a shared repository) – Hierarchically heterogeneous • A component of one style, when decomposed, is structured according to the rules of a different style – Simultaneously heterogeneous • Two or more architectural styles may both be appropriate descriptions for the style used by a computer-based system
- 22. Types of Management Information Systems • Computer Networks – Networking • The exchange of information through a group or network of interlinked computers • Servers are powerful computers that relay information to client computers connected on a Local Area Network (LAN). • Mainframes are large computers processing vast amounts of information . • The Internet is a world wide network of computers. 22
- 23. 23 A Typical Four-Tier Information System
- 24. Six Computer-Based Management Information Systems 24
- 25. Types of Information Systems • Transaction Processing Systems – Systems designed to handle large volumes of routine transactions. • Were the first computer-based information systems handling billing, payroll, and supplier payments. • Operations Information Systems – Systems that gather, organize, and summarize comprehensive data in a form of value to managers. • Can help managers with non-routine decisions such as customer service and productivity. • Decision Support Systems – Provides computer-built models that help managers make better nonprogrammed decisions. – New productive capacity, new product development, launch a new promotional campaign, enter a new market or expand internationally 25
- 26. • Executive Support System – Sophisticated version of a decision support system designed to meet the needs of top managers • Group Decision Support System – An executive support system that links top managers so that they can function as a team. 26
- 27. Limitations of Information Systems • Loss of the Human Element – Information systems cannot present all kinds of information accurately. • Thick information, which is rich in meaning and not quantifiable, is best suited to human analysis. • Information systems should support face-to-face communication, and not be expected to replace it • Causes of Difficult Implementations – Information systems can be hard to develop and put into service. – Consistent standards for systems do not exist. • Makers of hardware use different standards which makes it hard to share information between systems 27
- 28. • To avoid problems: – List major organization goals and the information types require measure those goals. – Audit the current system to verify that information collected is accurate, reliable, timely, and relevant. – Investigate other sources of information – Build support for the system with workers. – Create formal training programs. – Emphasize that face-to-face contact is important. 28
- 29. 29 Dr. Himanshu Hora SRMS College of Engineering & Technology Bareilly (UP) INDIA