Chapter 9 Moving to Design Part 1

Learning Objectives Explain the major components and levels of design Describe each design phase activity Describe common deployment environments and matching application architectures

Overview This chapter Completes the transition from analysis to design Discusses issues related to design of new system Describes all design phase activities Describes network and architecture design Analysis focuses on what system should do— business requirements Design is oriented toward how system will be built —defining structural components

Understanding the Elements of Design Design is process of describing, organizing, and structuring system components at architectural design level and detailed design level Focused on preparing for construction Like developing blueprints Three questions What components require systems design? What are inputs to and outputs of design process? How is systems design done?

Information Systems Architecture Information Systems Architecture is the process of making the key choices that are essential to the development of an information system. Architecture includes: Guiding Principles: Approaches/philosophies “Logical” representations of a system Hardware/Operating System Computing model: client/server vs traditional vs Web-based Tools and technologies It is key, when making these choices that they are: Requirements driven Take into consideration operational, technical and financial feasibility Made within an architectural framework

There are a lot of Drivers of Architecture Architecture Drivers There are a lot of Drivers of Architecture Business Plan Corporate Politics System Qualities Current Systems End User Requirements Emerging Technologies Architecture

Architecture to Design to Implementation Looking at the Work of Developing a System as a set of Choices, Architecture can be Described as Highest Level Choices Removal of Choices Business Strategy Line of Code / Process Step Employee / Computer Architecture Design Implementation

How is Architecture Different from Design? Its not – Architecture can be considered ‘high-level’ design Architecture includes those aspects of the design that are essential to the information system Architecture Example: Users must be able to self-serve (guiding principle) “We will use a “hub and spoke” design where data will be placed in a central data warehouse, then be propagated to one or more data marts. (approach) We will normalize data in the central warehouse and use a dimensional design in the data marts (approach) We will use Oracle 8i as our DBMS (technical architecture)

Architecture vs. Detail Design Not Architecture: The Order subject area will be composed of the following tables: order_fact, customer_dim, product_dim and time_dim The customer_dim table will have the following attributes…….

Components Requiring Systems Design

Analysis Objectives to Design Objectives

Moving from Analysis to Design Converts functional models from analysis into models that represent the solution Focused on technical issues Requires less user involvement than analysis Design may use structured or OO approaches Database can be relational, OO, or hybrid User interface issues

Traditional Structured and Object-Oriented Models (Figure 9-3)

SDLC Phases with Design Phase Activities