• queuing models;
• activity patterns.
Once defined, variants of a service model can be generated in order to tailor a service to a customer’s specific needs.
Functions, processes and roles
The terms function, process and role are often confused. This is not surprising since they are so intertwined. In addition, the way the words are used in ITIL is precise, and may be confused with the way these words are used in a more
general context.
FUNCTION
A team or group of people and the tools they use to carry out one or more processes or activities (e.g. the service desk or IT operations).
In this context a function is a structural part of an organisation (e.g. a division or a business unit) established to do specific things. For example, the service desk is a function that is created to perform defined activities and produce specified
outcomes. People within a function have defined roles that they perform to
deliver the outcomes required. By their nature, functions are specialised and have their own disciplines, skills, performance measures and knowledge base. Functions perform activities that are elements of processes. Individual functions may perform an entire process or, quite commonly, share processes with other
functions.
PROCESS
A process is a structured set of activities designed to accomplish a specific objective. A
process takes one or more defined inputs and turns them into defined outputs. A process may include any of the roles, responsibilities, tools and management controls required to reliably deliver the outputs. A process may define policies, standards, guidelines, activities and work instructions if they are needed.
A process consists of a set of coordinated activities using resources and capabilities to produce an outcome, which, directly or indirectly, creates value for an external customer or stakeholder.
Every process consists of a number of elements, as shown in Figure 1.6. A process takes inputs and transforms them, using the appropriate enablers, to produce the required outputs in a closed-loop system that allows for feedback