Chapter 9 Designing Internet and Distributed System.pdf.pdf

Modern Systems Analysis and Design Eighth Edition, Global Edition Joseph S. Valacich Joey F. George Designing Distributed and Internet Systems Chapter 12 Copyright © 2017...

Modern Systems Analysis and Design Eighth Edition, Global Edition Joseph S. Valacich Joey F. George Designing Distributed and Internet Systems Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-1 Learning Objectives  Distinguish between file server and client/server environments and contrast how each is used in a LAN.  Describe cloud computing and other current trends that help organizations address ID infrastructure-related challenges.  Describe standards shaping the design of Internet-based systems, options for ensuring Internet design consistency, site management issues influencing customer loyalty, trustworthiness, and security. Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-2 Designing Distributed and Internet Systems FIGURE 12-1 Systems development life cycle (SDLC) Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-3 The Process of Designing Distributed and Internet Systems This process is similar to designing single- location systems. Due to multi-location deployment, numerous design issues must be considered. There is more opportunity for failure due to number of components. Main issues involve ensuring reliability, availability, survivability, performance. Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-4 Deliverables and Outcome Document that consolidates system design information:  Description of each site  Description of data usage for each site  Description of business process for each site  Contrasts of alternative IS architectures for site, data and processing needs of each site Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-5 Designing Systems for Local Area Networks (LANs) LAN: the cabling, hardware, and software used to connect workstations, computers, and file servers located in a confined geographical area  Typically within one building or campus Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-6 Designing LAN and Client/Server Systems LAN systems are either of these: LAN-based file server architecture. Client/server architecture. Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-7 File Servers File server: a device that manages file operations and is shared by each client PC attached to a LAN Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-8  FIGURE 12-3 File server model Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-9 Limitations of File Servers Excessive data movement  Entire data table must be transferred, instead of individual records. Need for powerful client workstations  Each client workstation must devote memory to a full DBMS. Decentralized data control  Record concurrency control, recovery, and security are complicated. Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-10 Designing Systems for a Client/Server Architecture Client/server architecture: a LAN-based computing environment in which central database server or engine performs all database commands sent to it from client workstations, and application programs on each client concentrate on user interface functions Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-11 File Server vs. Client/Server Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-12 File Server vs. Client/Server (cont.) Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-13 Designing Systems for a Client/Server Architecture Application processing is divided between client and server. Client manages the user interface. Database server is responsible for data storage and query processing. Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-14 Designing Systems for a Client/Server Architecture (Cont.) Database engine: the (back-end) portion of the client/server database system running on the server that provides database processing and shared access functions Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-15 Designing Systems for a Client/Server Architecture (Cont.) Client: the (front-end) portion of the client/server database system that provides the user interface and data manipulation functions Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-16 Designing Systems for a Client/Server Architecture (Cont.) Application program interface (API): software building blocks that are used to ensure that common system capabilities, such as user interfaces and printing, as well as modules are standardized to facilitate data exchange between clients and servers  Common API interface can be used by any kind of DBMS (MySQL, Sybase, or Oracle) Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-17 Client/Server Advantages Leverages benefits of microcomputer technology Processing performed close to data source  Improvesresponse time  Reduces network traffic Facilitates use of GUIs Encourages acceptance of open systems Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-18  Advanced Forms of Client/Server Architectures Applications are distributed between client and server in a variety of ways. Components of an IS:  Data management: functions that manage all interaction between software and files and databases (data retrieval/querying, updating, security, concurrency control, and recovery)  Data presentation: functions the manage the interface between system users and the software (display and printing of forms and reports, validating system inputs)  Data analysis: functions transform inputs into outputs, including simple summarization to complex mathematical modeling such as regression analysis Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-19  Advanced Forms of Client/Server Architectures (Cont.) Application server: a computing server where data analysis functions primarily reside. Virtual machine: a software emulation of a physical computer system, both hardware and operating system, that allows more efficient sharing of physical hardware resources. Virtualization: the act of creating virtual (rather than physical) versions of a variety of computing capabilities including hardware platforms, operating systems, storage devices, and networks. Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-20  Advanced Forms of Client/Server Architectures (Cont.) Three-tiered client/server: advanced client/server architectures in which there are three logical and distinct applications—data management, presentation, and analysis—that are combined to create a single information system. Middleware: a combination of hardware, software, and communication technologies that bring data management, presentation, and analysis together into a three-tiered client/server environment. Thin client: a client device designed so that most processing and data storage occur on the server. Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-21 Middleware Environments Figure 12-6 Middleware ties together diverse applications and devices Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-22 Advanced Forms of Client/Server Architectures (Cont.) Applications can be partitioned in a way that best fits the organizational computing need Easier customization: application code resides on application server, so change done only in one place Easier maintenance: data analysis is separate from user interface, so changing one can be done independently of the other Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-23 Cloud Computing Cloud computing: provision of applications over the Internet where customers do not have to invest in the hardware and software resources needed to run and maintain the applications, but are charged on a per-use basis. Amazon Example: Amazon Web Services (AWS), Simple Storage Service (S3), Elastic Compute Cloud (EC2) Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-24 Cloud Computing (Cont.) Information systems infrastructure: The hardware, software, data, facilities, human resources, and services used by organizations to support their decision making, business processes, and competitive strategy. Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-25 Cloud Computing (Cont.) Utility computing: A form of on-demand computing where resources in terms of processing, data storage, or networking are rented on an as needed basis. The organization only pays for the services used. Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-26 Cloud Characteristics On-Demand Self Service Rapid Elasticity Broad Network Access Resource Pooling Measured Service Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-27  Service Models Infrastructure as a Service (IaaS): provides basic processing, storage, and network capabilities Platform as a Service (PaaS): customers run their own applications, using tools Figure 12-10 provided by the service provider. Services by SaaS, PaaS, and IaaS providers. Software as a Service (SaaS): applications are provided by the service provider Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-28  Figure 12-11 Public clouds versus private clouds. Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-29  Managing the Cloud Issues to consider when choosing service providers:  Availability/Reliability – no cloud service is completely immune to errors, network outages, or hardware failures  Scalability – this is the promise of the cloud, but there may be limits  Viability – you want to make sure the service provider will last over time  Security, Privacy, and Compliance – these are critical (e.g. Sarbanes-Oxley, HIPAA)  Diversity of Offerings – which provider can offer services needed now and in the future?  Openness – how interoperable is the service?  Cost – how will cloud cost compare to internal, public vs. private? Chapter 12 Copyright © 2017 Pearson Education, Ltd. 12-30