Better Use Case Diagrams by Using Work System Snapshots

Better Use Case Diagrams by Using Work System Snapshots

Narasimha Bolloju (LNM Institute of Information Technology, Jaipur, India) and Steven Alter (School of Management, University of San Francisco, San Francisco, CA, USA)
DOI: 10.4018/IJITSA.2016070101


Research to date shows significant variability in the success of applying the common technique of use case diagramming for identifying information system scope in terms of use cases performed by actors interacting with an information system or performed automatically by the information system. The current research tests a) the benefits of using a work system snapshot, a basic analytical tool from the work system method, before producing use case diagrams, and b) the additional benefits of enhancing use case diagramming constructs to distinguish between automated activities, activities supported by the information system, and relevant manual activities. Teams of student subjects in an experiment produced substantially better use case diagrams - containing far more use cases and qualitatively better use cases than did the teams in control group - when provided with a work system snapshot that summarized a test scenario in terms of work system concepts.
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Identifying specific processes and activities to be supported by an information system is often a daunting task in requirements determination. Too frequently, important information system functionalities are omitted or misstated (e.g., Rubinstein, 2007). According to system theorists such as Ackoff (1971, 1973), Checkland (1999), and Churchman (1970), understanding any system requires understanding of the larger system that it serves. Information systems are computerized artifacts that are used by participants in work systems. Therefore, understanding of the work system that is supported is a good starting point for understanding an information system and its significance. An understanding of the relationship between the information system and the work system needs to consider different types of activities to be supported or automated by the information system as part of the work system.

Use case diagrams are used widely for defining and depicting the scope of an information system in terms of a set of use cases corresponding to activities supported or automated by the information system. Although there is no totally standard definition of use case, there are several working definitions such as the following (OMG, 2010 – p 628):

A use case is the specification of a set of actions performed by a system, which yields an observable result that is, typically, of value for one or more actors or other stakeholders of the system.

At the beginning of an attempt to identify use cases within a particular work system, it is often unclear what the boundaries of the information system will be, i.e., which activities will be automated or supported by the information system, and which activities are part of the work system but will not be automated or supported directly by the information system. Consequently, the specification of use cases within a use case diagram created at the beginning of an object-oriented analysis should start with identification of the work system and then should identify different types of activities.

A good approach for doing this is to summarize the (“as is” or “to be”) work system using a work system snapshot (a basic analytical tool from the work system method (Alter, 2006; 2008; 2013), and then to delve more deeply into each of the activities within the work system snapshot, to identify use cases to be automated or supported by the information system, and then to look at them in more depth to clarify specific functionality required in the information system (see Appendix 1 for a brief introduction to the work system framework and work system snapshots). Thus, our proposed approach recommends summarizing the business situation using a work system snapshot before developing use case diagrams. For this purpose, we propose enhancements to use case diagramming constructs to distinguish between work system and information boundaries, and to differentiate various types of use cases. Evidence from the current research implies that producing a work system snapshot before developing use case diagrams may help analysts identify more use cases that are also of higher quality, thereby help in better determination of the scope and function of the information system to be developed.

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