Transcript CHAPTER 10
CHAPTER 9 Application Architecture Objectives List main issues that a SA should consider when an application architecture – – – – – – – – Enterprise resource planning Initial costs TCO Scalability Web integration Legacy requirements Security Processing options Objectives Describe servers, server and client based processing Explain client/server architecture Client/server tiers, cost-benefit issues Explain impact of Internet Describe online and batch processing Define network topology Objectives Explain network protocols and licensing issues Describe tools for modeling application architecture Explain system management tools Describe system design specifications Application Architecture Application requires hardware, software, data, procedures, people to accomplish organized set of functions Effective system combines those elements into an architecture – design– that is flexible, cost-effective, technically sound, and able to support information needs of the business Application Architecture Translates logical design of an information system into a physical structure that includes hardware, software, network support, and processing methods Design Checklist Enterprise resource planning Initial cost and TCO Scalability Web Integration Legacy interface requirements Security Processing options Enterprise Resource Planning Defines a specific architecture, including standards for data, processing, network and user interface design Describes specific environment (platform) is the combination of hardware and systems software used for the developed information system – Ensures hardware connectivity and easy integration of future applications, including in-house and commercial packages Initial Cost and TCO Review options to determine if outcome may be affected by new developments. Scalability Measure of system’s ability to expand, change, or downsize easily to meet changing needs. – Can drastically affect system’s life expectancy Web Integration Part of e-commerce???? Intranet based???? Legacy older systems that typically run on mainframe computers (architecture) – Interface with legacy systems How will new system communicate? Security Physical and logical security Web-based security Processing Options High capacity transaction processing system (eg. order entry) requires more network , processing and data storage resources -- 24/7 – Must consider backup and recovery procedures System updates, file maintenance and other batch processing – done off-peak – lower costs and resources Planning the Architecture – a computer that supplies data, processing services, or other support to one or more computers (client) Client – a computer that is connected to a server Mainframe architecture -- server performs all the processing Server Planning the Architecture Processing performed on a server Processing performed on a client Processing divided between server and client We must plan (advantages and disadvantages) of each design approach Planning the Architecture - Mainframe Server-based processing – relies on network technology Centralized design – remote user keystrokes transmitted to mainframe – responds by sending screen output back to user terminal Advantage – various types of terminals can communicate with mainframe and mainframe does all the work Disadvantage – character-based terminals – no GUI All data storage, access, and application programs on mainframe Planning the Architecture Clients Stand-alone LAN WAN computing Client/Server Architecture Systems that divide processing between one or more networked clients and a central server – Client handles user interface, data entry, data query, and screen presentation – Server stores data and provides data access and management functions Client/Server --- Mainframe Fat Client --- Thin Client Client / Server Architecture Client / Server Tiers Cost-Benefit Issues Performance Issues Processing Methods Online vs. Batch Processing On-line processing System in which transactions are processed when and where they occur, allows output directly to end users –also called online transaction processing or interactive processing On-line processing workstation -- either a PC or terminal connected to online processing system –online processing system verifies the transaction values and allows end user to interactively enter data and correct errors On-line processing Online file -- data file with direct or indexed organization that allows random access – sequential files not used for online processing IS must be continuously available whenever end users require processing of transactions Batch Processing IS in which data is collected and, at some later time, all the data that has been gathered is processed as a group, or batch Used extensively in 1950’s-60’s Still used today for many applications Batch Processing Any application that requires periodic processing of a large number of records is good candidate for batch processing – payroll – billing/invoicing – hard copy reports Today’s processing trends Online and batch processing combined in single IS – random access files are available for transactions that require interaction – actual files available off-line for large batch processing – copies of online files available for batch reports that don’t require update Online vs. Batch Online Advantages – data is entered and validated as it occurs – data is available sooner in more accurate form – data is up-to-date Online vs. Batch Online Disadvantages – more expensive/difficult to maintain – creation is more difficult – more sophisticated hardware – backup and recovery more difficult – effects of computer failure more disruptive NETWORK Data communications network collection of terminals, computers, and other equipment that use communication channels to share data, hardware and software Network Topology Four – – – – patterns: Hierarchical Bus Star Ring Network Topology -- Network Topology -- Network Topology -- Network Topology -- System Architecture Network Protocols Licensing issues Performance Management Designed to collect information about system resources and activity levels. – System usage – Capacity – Trends Fault Management, Backup and Disaster Recovery RAID Online Disaster Backup and Recovery plans Batching processing Backup and Recovery plans System Design Completion Software Design Stages: – System Analysis phase: functional primitives were identified and documented – System Implementation phase: Programmers determine exactly how each program will accomplish its objectives. System Design Final activities: – System Design Specification – Obtaining user approval – Delivering presentation to Management System Design Specification Management Summary System Components Details Environmental Requirements Implementation Requirements Time and Cost Estimates Appendices