I am sharing a quick overview on how to model use case scenarios. I believe this will help you defined structured scenarios to your use case model drive approach. * Most important part this exercise is map scenarios to your main success scenario. For eg: http://www.slideshare.net/tarunchanchalani/simple-example-on-use-case-scenarios

1. Learn Use Case Scenarios
By Tarun Chanchalani

2. Basics
• Who – BA or the one who does business analysis or doesn’t matter
even a developers can prepare use cases scenarios to elaborate
system and its interactions with users.
• What – Requirements Modelling Technique
• When – After use case identification (typically in agile after user
stories are defined and planned)
• How – is as follows, but remember there are different ways of writing:
(next slides)
FAQ – Q. Difference Between User story and Use case [scenarios]?
User story a statement brief one scenario
(statement includes actor, business
requirement and business benefit)
Use case scenarios satisfies multiple
scenarios (main, extension and variation
paths)

3. Characteristic Information
Goal In Context: Considering the use case – where do you want to see the actor and
particular goal.
Scope: Product or Project
Level: Task or Sub Task
Pre-Condition: The Precondition section states must satisfy condition that has to be
met before executed. This is typically a constraint or properties of the
user or the state of program execution.
Success End Condition: The Success End Condition (Post-condition) section describes the
conditions, which the user story establishes.
Thus, Pre- and Post- conditions together define the contract of the
user story. A step in the user story can refer to another user story
being called.
Failed End Condition: The Failed End Condition section describes the conditions, which the
user story avoids.
Primary Actor: Entities which interact with system
Trigger Event: The event on which system starts or initiated the user story.

4. Main Success Scenario
The Main Success Scenario is the straight forward sequence of steps leading to the achievement of the user’s
goal without consideration of possible problems. With each step, possible error situation and their resolution
can be described in the Extensions section. Further, there may be different alternative ways to execute a step.
These alternatives are described in the Variations section.
Each step in a User Story corresponds to an intervention by an actor to the system or vice versa. We denote all
interventions sent by the system as Action Description. As intended in user story analysis, the main success
scenario ends with the successful achievement of the goal. Thus, the final state reached after the last step of the
user story corresponds to successful completion.
Step Actor Action Description
1 System Based on Trigger Event, always system will process the request. (Example
page load, show details etc)
2 User User process further
3 System So on ….

5. Scenario Extensions
An extension will describe a backup solution for completing a user story. A special story of this is when a Main
Success Scenario fails, because a precondition does not hold this scenario. We specify extensions with the
corresponding step in the main success scenario.
Step Condition Action Description
2a User intervention Back up item dependent on any Step of Main Success Scenario.
(Note: This Scenario Extension is dependent on Step 2 of Main Success
Scenario)

6. Scenario Variations
Variations in user stories are usually local alternatives for executing a step in the user story. In the simplest story,
a variant can be represented as an additional link between the two states delimiting (deviating) the
corresponding step in the main success scenario.
Step Variable Possible Variations
2a Variation condition Variation description

7. Example
For example refer –
http://www.slideshare.net/tarunchanchalani/simple-example-on-use-
case-scenarios

8. Thank you
Best!
Tarun Chanchalani