G6046 Software Engineering
Seminar session: Using UML models Summary
This exercise is designed to ensure that you understand:
• The basic types of useful Unified Modelling Language (UML) models, and
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• how to apply these to solve a problem.
Key concepts
Make sure you understand these basic UML concepts:
• Use case: a simple high level model that identifies the key actors (usually people, but can be other systems). Provides a high level of key functional requirements i.e. what does a user expect to be able to achieve using the system?
• High level context model (domain model): a high level view of how a system fits into a wider ecosystem. Generally used to identify other systems and the need for interfaces with those systems.
• High level class diagram: A simple diagram that identifies key entities and the basic associations (and possibly the cardinality of those relationships, but with no analysis of fields or methods.
• Class diagram: as above but with details of fields and attributes.
• Sequence diagram: A timeline diagram that shows the sequence or chain or method calls
between classes/objects that enables the user to achieve the functionality set out in the use
case diagram.
• State diagram model: A diagram intended to help a developer understand how a process
within the system is intended to operate.
This case study concerns a weather station. This is the context model for the weather station:
We are only concerned with the design. of the weather station. In turn, the weather station forms part of a bigger weather monitoring and information system.
We are then given a use case analysis for the weather station. We can represent that easily using the standard UML use case diagram, but we could use a tabular use case format as an alternative.
Now we are given some information about an OO class analysis for the weather station entity. First, a user requirement is given:
“A weather station is a package of software controlled instruments which collects data, performs some data processing and transmits this data for further processing. The instruments include air and ground thermometers, an anemometer, a wind vane, a barometer and a rain gauge. Data is collected periodically.
When a command is issued to transmit the weather data, the weather station processes and summarises the collected data. The summarised data is transmitted to the mapping computer when a request is received.”
From that we produce a proposed basic class diagram:
OK, but is the class diagram “fit for purpose”? Does it “work”?
Consider the use case where the Weather Information System needs to be able to “Report Weather”. So the Weather Information System is a user of the Weather Station entity. Try to construct a sequence diagram showing the chain of events for this use case.
There is no single right answer. An example answer is shown on Canvas.
Dr Kingsley Sage Dr
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