UC:Use cases: Difference between revisions
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In this page you learn how to contribute good '''Use Cases'''. | In this page you learn how to contribute to writing good {{rml}}-'''Use Cases'''. | ||
While the emphasis of the {{rml}}-wiki lies in documenting single elements in a | While the emphasis of the {{rml}}-wiki lies in documenting single elements in a bottom-up approach, we also try to help users to capture the concepts of {{rml}} via [[Dev:Examples|examples]] and use cases in a top down approach. | ||
==What is a use case?== | ==What is a use case?== | ||
<div id="t*"></div>A use case can be defined as ''a single task, performed by the end user of a system, that has some useful outcome''[[#*|*]]. It is described as a list of steps (actions or events) to achieve this outcome. | <div id="t*"></div>A use case can be defined as ''a single task, performed by the end user of a system, that has some useful outcome''[[#*|*]]. It is described as a list of steps (actions or events) to achieve this outcome. | ||
A use case in terms of {{rml}} is an application of data exchange between at least two IT systems in the railway domain, where {{rml}} can be used as a format and language for the data to be exchanged. The aim of the use case description is to formulate requirements on the technical implementation of the data exchange. | |||
What distinguishes a use case from an example is, that examples will typically consist of pieces of {{rml}}-code, whereas use cases will typically be formulated in natural language or ''Unified Modelling Language'' (UML). Examples are solutions to use cases. | |||
==What makes a good use case?== | ==What makes a good use case?== | ||
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==Structure== | ==Structure== | ||
Each use case is assigned to a subschema. The article name should follow the paradigm <subschema>:US:<use case>, e.g. [[IS:UC:Timetabling]]. | |||
In {{rml}}, use cases are usually presented with the following structure (which, too, can be seen in the example of [[IS:UC:Timetabling]]): | In {{rml}}, use cases are usually presented with the following structure (which, too, can be seen in the example of [[IS:UC:Timetabling]]): | ||
*Description: A sketch of the task, the necessary steps and the requirements in general. | *Description: A sketch of the task, the necessary steps and the requirements in general. | ||
:It is important to note, to which {{rml}} versions a use case or certain aspects of it apply, as use cases will | :It is important to note, to which {{rml}} versions a use case or certain aspects of it apply, as use cases will develop further with the development of {{rml}}. | ||
*Data flows and interfaces | *Data flows and interfaces | ||
*Interference with other {{rml}} schemas | *Interference with other {{rml}} schemas | ||
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==How to contribute a use case== | ==How to contribute a use case== | ||
# Please, | # Please, get in contact with the coordinator of the respective subschema before start writing a use case. Feel free to start an article in your userspace at your own risk. | ||
# Develop the use case according to the mentioned criteria (especially [[#structure]] and [[#What makes a good use case?]]). | # Develop the use case according to the mentioned criteria (especially [[#structure]] and [[#What makes a good use case?]]). | ||
# Let the subschema coordinator review the article. | # Let the subschema coordinator review the article. | ||
# | # The subschema coordinator will take care of publishing the article. He will take care to version the use case and match it with the {{rml}}-versions to which it applies — both the use case and {{rml}} will evolve in the course of time. Finally, the article will be entered into the use case collection of the respective subschema, as in [[#Lists]]. | ||
==Lists== | ==Lists== | ||
As use cases refer to certain subschemas, they are listed along this line: | As use cases refer to certain subschemas, they are listed along this line: | ||
Revision as of 14:02, 29 February 2016
In this page you learn how to contribute to writing good railML®-Use Cases.
While the emphasis of the railML®-wiki lies in documenting single elements in a bottom-up approach, we also try to help users to capture the concepts of railML® via examples and use cases in a top down approach.
What is a use case?
A use case can be defined as a single task, performed by the end user of a system, that has some useful outcome*. It is described as a list of steps (actions or events) to achieve this outcome.
A use case in terms of railML® is an application of data exchange between at least two IT systems in the railway domain, where railML® can be used as a format and language for the data to be exchanged. The aim of the use case description is to formulate requirements on the technical implementation of the data exchange.
What distinguishes a use case from an example is, that examples will typically consist of pieces of railML®-code, whereas use cases will typically be formulated in natural language or Unified Modelling Language (UML). Examples are solutions to use cases.
What makes a good use case?
A good use case should be complete, comprehensible and practically relevant. Ideally, it should be perceivable by the public (A problem that can be understood by and occur to everybody is more illustrative than one that only occurs to a small subgroup of users). Finally, the use case should be objective in the sense that it is not biased to the requirements or solutions of a certain organization or company.
Structure
Each use case is assigned to a subschema. The article name should follow the paradigm <subschema>:US:<use case>, e.g. IS:UC:Timetabling.
In railML®, use cases are usually presented with the following structure (which, too, can be seen in the example of IS:UC:Timetabling):
- Description: A sketch of the task, the necessary steps and the requirements in general.
- It is important to note, to which railML® versions a use case or certain aspects of it apply, as use cases will develop further with the development of railML®.
- Data flows and interfaces
- Interference with other railML® schemas
- Characterizing Data
- How often do the data change (update)?
- Which views are represented by the data (focus)?
- Which specific timetable data do you expect to receive/send (elements)?
How to contribute a use case
- Please, get in contact with the coordinator of the respective subschema before start writing a use case. Feel free to start an article in your userspace at your own risk.
- Develop the use case according to the mentioned criteria (especially #structure and #What makes a good use case?).
- Let the subschema coordinator review the article.
- The subschema coordinator will take care of publishing the article. He will take care to version the use case and match it with the railML®-versions to which it applies — both the use case and railML® will evolve in the course of time. Finally, the article will be entered into the use case collection of the respective subschema, as in #Lists.
Lists
As use cases refer to certain subschemas, they are listed along this line: