Roles in the Scrum Framework

A Famous Story to understand the roles for Agile Model

Story Name : The Chicken and Pig Fable
Story going like this : A Pig and a Chicken are walking down the road.
The Chicken says, "Hey Pig, I was thinking we should open a restaurant!".
Pig replies, "Hmm, maybe, what would we call it?".
The Chicken responds, "How about 'ham-n-eggs'?".
The Pig thinks for a moment and says, "No thanks. I'd be committed, but you'd only be involved!"

The story is presented as a riddle:

Question: In a bacon-and-egg breakfast, what's the difference between the Chicken and the Pig?

Answer: The Chicken is involved, but the Pig is committed!

Here we have two roles one is Chicken and second one Pig.
Chicken refers to : 

• Ancillary roles 
• Involved in success of the goal.
• Not dedicated to it, though.
• Managers and observers

Pig Refers to :

• Core roles.
• Committed to success of the goal.
• Team, Scrum Master, Product Owner

The fable is referenced to define two types of project members by the scrum agile management system: pigs, who are totally committed to the project and accountable for its outcome, and chickens, who consult on the project and are informed of its progress.  

A successful project needs both chickens and pigs. However, given the sacrifice required of being a pig —forswearing other projects and opportunities—they can be difficult to collect. Thus, the construction of a successful project-team must ensure that the project has sufficient "pigs" and that they are empowered to drive the project in return for committing to and taking accountability for it.

For a Scrum project, Scrum Master, Product Owner, and Team are considered as people who are committed to the project while customers and executive management are considered as involved but not committed to the project.