Chapter 3.docx

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Department
Information Technology Management
Course
ITM 305
Professor
Lin Ying Dong
Semester
Fall

Description
Chapter 3 – Domain Analysis Introduction  Domain analysis helps us understand the context of requirements and discover the related concepts that the product must incorporate to fulfill its objective o Doman analysis results in 1 or more domain dictionaries that organize domain concepts, explain them and categorize them for further analysis and modeling o Doman catalog is a directory of supporting domain documents o 1 set of concepts discovered thru domain analysis is business rules  Are technology-independent guidelines under which a firm operates  Needs special handling cuz a product that does not incorporate business rules will fail even if all other requirements are satisfied o Building IS includes solving problem  Issues that relate to the problems are in a space that is called the problem space/problem domain  Issues that relate to the solution are called solution space/system space  Figure 3.1 Problems, solutions and requirements Problems vs. Solutions  Solving problems involves trio of components o Problem o Solution as a method or process o Solution as answer  Ex. and figure 3.2 & 3.3 on pg 41 & 42  We have to put problem in the right context to work out the right solution as method to arrive at the right solution as answer  We need to address 3 issues b4 we can allow ourselves to find a solution o What is the real problem?  Ex. on pg 42 o What are the alternative solutions?  Ex. on pg 42-43 o Does the answer satisfy the needs in context?  A solution might have answer a specific problem quite effectively but fail in context  Ex. on pg 43 Problem space vs. Solution space  3 components of problem solving reside in 2 physically related spaces o The problem space o The solution space o Changing an element within 1 space has a ripple effect across both  Ex. on pg 43  To reduce incomplete and wrong assumptions we must model the solutions within the problem space or problem domain o Problem space is the context from which the problem arises and in which the solution must operate o Figure 3.5  After creating a model, we design the product and its components, then implement the design o Solution space/solution domain/system space is the context of the issues related to design and implantation o It defines the territory in which real decisions about the IS are made  Boundaries of the solution space are decided by the analysis model o In solution space the “what” is solved and “how” is the problem  On pg 44  What happens in 1 affects the other for 3 reasons o Requirements are usually made with a reasonable awareness of what is available or what is possible  Ex. on pg 44 o Against all expectations, we might fail to find an answer for the requirements  More on pg 44-45 o The solution satisfies every requirement, but the product proves to be partially or totally unsuitable to the task  Ex. on pg 45 Domain definition The meaning of domain  A business domain is an area of related activities that operate on a set of shared rules and concepts  Domain refers to a space or an area in a general sense  Domain is a territory where kindred rules be in power o Roman Empire was a domain o A school is a domain  In business context, some domains are o Inventory o Purchasing o Sales o Accounting  Business domains have 3 significant properties o Business domains are organized domains  The members interact and this interaction affects the domain and its members as a whole o Business domains are goal-oriented  Business domains are formed with a mission  Purchasing domain to purchase goods and services with the advantageous terms  Inventory domain to stock needed goods and retrieve them correctly and on time o Business domains can change fast  It can appear, change or disappear overnight as a result of a human decision, random or not  Restructure sales on functional lines instead of geographic lines  Create a division for online sales The domain scope  It defines the boundaries that separate shared activities, rules and concepts within a domain from those on the outside  For domain analysis, we must draw lines to identify the scope of our interest  These lines are human made o Domain definition must discover and define the boundary btwn 1 area of interest and another  Ex. on pg 46 o Domain definition must impose such boundaries if the complexity of the context or the requirements threatens to overwhelm us  Ex. on pg 46  Figure 3.6  We may need to discover and define other domains if o We find that a pattern of redundancy across domains contributes to an unnecessary complexity, and o It is sensible and desirable to do so, in terms of both technology and business  Ex. on pg 47 Domains and subsystems  Domain & systems/subsystems are not same  In a system, components are connected together in an organized way, affect each other and behaviour of the system as a whole  In domain, the members are subject to the same or similar rules & display the same or similar qualities and behaviour but do not interact  Domains and systems come closer when we are dealing with a human enterprise  Domain is an area of knowledge or activity described by a set of concepts & language understood by practitioners in that area  System is a set of components organized to accomplish a specific purpose and described by a set of models, possible from different viewpoints o Ex. on pg 48 Domain analysis  Domain analysis is analyzing the context of requirements, it has 2-fold task o Identify system activities that an IS performs o Discover and define concepts that the IS must incorporate or take in account in order to meet its objectives Identify system activities  There are 3 types of events o External event  It is an event that is initiated by an external agent or actor  Ex. customer wants to check out, student wants to register a course, employee wants to check insurance policies  More detailed ex. on pg 48 o Temporal event  It is an event that takes place when a point in time is reached  Are triggered internally by reaching a set time  Ex. time to generate quarterly reports, time to change to daylight saving time  These events take place cuz a point of time is reached o State event  It is an internally triggered event and occurs when a state reaches a certain level  Ex. inventory
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