FUNCTIONAL MODELING Alajas, Sophiya Ann Allego, Keefer Lloyd Maningo, Patrick Sage Pleños, John Enrick CPE 51ASATURDAY 7:30 – 10:30ENGR. ARNOLD ROSO

What is functional modeling and what does it do?

 is a tool that allows a team or an individual to produce a behavioral/operational model of an existing or planned system  The resulting model shows the system functionality and the logical interconnections between that functionality.  In essence, it describes how the system functionality has to cooperate to deliver the Operational Requirements of the system. Functional Modeling

By constructing the model it is possible to:  Functional perspective -Symbols: Process, Store, Flow, External Entity  Functional decomposition

Functional Modeling uses three sub-tools to construct a model of the system of interest 1. Function Flow Diagram (FFD) 2. Flow Dictionary (FD) 3. Function Specification (FS)

Function Flow Diagram (FFD)  is a network representation of the system.  It portrays the system in terms of its component functions and the logical interdependencies or “flows” between the functions.  It uses simple diagramming conventions.  This minimum set enables the team to concentrate on discovering and understanding the system rather than the modeling technique.

Function Flow Diagram Modeling Conventions  FUNCTION - transforms input flows into output flows that is internal to the System of Interest  TERMINATOR - described as a function or object that is a source or destination of flows external to the System of Interest  FLOW - an input or output quantity (information, control, material or energy) FUNCTION TERMINATOR FLOW

Flow Dictionary (FD)  complements the Functional Flow Diagrams by documenting the flows found on any of the diagrams.  It is a set of definitions which declare the component elements of each flow, and the relationships that apply among them.  The flows represent the logical interfaces of the system some of which some will become real interfaces.

Function Specification (FS)  specifies the component functions by defining the transformation that converts inputs to outputs..

Why do functional modeling?

 provides a way of logically exploring such requirements in order to address their deficiencies  helps build a complete and consistent set of measurable system design requirements  This exploration leads to generation of new requirements and the clarification of existing requirements.  The result is a model of the system requirements that emphasizes the functional operation of the system. Functional Modeling…

What are the benefits of Functional Modeling?

 It helps the modelling team logically work through the functionality of the proposed or existing system  it identifies the potential interfaces of a system and encourages their clear definition  it encourages the team to consider not only the system of interest but also the wider system.  it can help to gain more understanding about the system of interest and what all the customers’ expect  models that can help in showing the customer that you understand what they are after  when used within a team context, it allows the whole team to share information and agree at a common understanding Functional Modeling Benefits…

Where and when to use Functional Modeling?

 limited information from the customer such as an operational requirement or idea of a potential operational requirement.  The need to check for completeness and consistency of requirement. Functional Modeling is used to help understand and engineer a set of requirements. It is particularly useful when we have: Functional Modeling can be used in three situations:  Analysis and modeling of an existing system  Analysis of an existing system together with the development of modifications to that system  Analysis and modeling of an entirely new system.

How to do Functional Modeling?

DIAGRAMMING : Modeling Concepts

INFORMATION HIDING: Modeling Concepts  Hide design decisions within modules especially when changes are expected  Access to internal modules is only provided via well defined interfaces which reveal only that information which is required to use the module  Emphasizes communication through controlled interfaces

ABSTRACTION: Modeling Concepts  refers to the diagramming conventions whereby a single convention is used to represent different real world items.  For example: the single diagramming convention of an arrow to represent an input or output flow is used represent material, energy, information and control type flows.

Process of Function Modeling

1.Collect and generate information about the system of interest Process of Function Modeling The first step is to collect information about the system of interest. This is achieved via a variety of means that include:  Viewpoint Analysis  Customer Requirements documents  Textual Analysis  Use Cases  Involving customers and users  Involving experienced staff

2.A. Draw functional Flow Diagrams Process of Function Modeling  The role of the FFD is to present a description of the system in terms of its component functions and how those functions have to interact (the flows)to deliver the intended system outcome (the operational requirement).

2.B. Compile Flow Dictionary Process of Function Modeling  The Flow Dictionary is used to specify precisely what is meant by every flow on every Functional Flow Diagram.  In particular it specifies the elements which are contained in each flow. The flows can represent different input/output quantities of:  Materials  Energy  Information/data  Control

2.C. Generate Functional Specifications Process of Function Modeling  to describe in more detail what has to happen inside a particular function on a Functional Flow Diagram.  It defines the policy governing transformation (what has to be done) but not the method of implementing it (how it is to be done).

FUNCTIONAL MODELING EXAMPLE PURCHASER 1 CREATE ORDER APRROVE ORDER PURCHASING OFFICER PURCHASER 2 EXPEDITE ORDER VENDOR ORDER approval Purchase request Purchasing data Purchase order status verification Delivery agenda approval