Representations and Patterns_ Chapter 2
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Why are representations and modeling important for understanding enterprise info systems?
We can't understand enterprise info systems w/o models that serve as representations of the systems and their underlying reality.
Surrogates for the real contruct (aka, symbol for the contstruct)
Representations may symbolize what or what? (Different levels of abstraction)
may symbolize individual objects or categories of objects.
- Individual objects. Individual instance of something, such as Fred's Little Red Corvette
Token level relationship
A token level relationship shows each individual instance in the reality represented as a separate token.
Categories of objects, such as Car. Shape. (vs. token level of red corvette, triangle.)
An arrangement of repeated or recognizably consistent objects or actions.
What is the purpose of a pattern?
Patterns allow us to make predictions about future events and to make sense of the present based on our past experiences.
- A common language. A specification of conceptualization. A generally understood means of representing enterprise patterns and scripts.
- Example in class about terminology on tv. medical dramas. Depending on the domain you are in , words take on different meanings.
Basically a simplified view of something. Abstract. Simplified view of the world that we wish to represent for some purpose. Like our sua.
Representation (slide version)
The symbols used to portray the concepts of interest. Means something larger. Nike Swoosh. American Flag.
Pattern (slide version)
- A consistent characteristic form, style, or method as a composite of traits or features characteristic of an individual or group.
- Putting Symbols together creates a pattern
- Scattershot of the symbols. No time/order reference yet.
Scripts (slide version)
- A pattern of sequences of events that typically occur in combination
- Scripts put symbols in order, whereas patterns do not impose an order on the symbols.
Purpose of associating like objects with each other. In conceptual modeling, object patterns consist of expected groupings of things and the relationships between them.
Script patterns (book)
Wheras object patterns focus on objects and relationships between them, script patterns are sequences o events that typically occur in combination w/ ea other.
REA ontology views enterprises @ 4 levels of detail:
- 1.Value System level
- 2. Value Chain level
- 3. Business Process level
- 4. Task level
Value system -
focuses on the resources that are exchanged between the enterprise and it's various external business partners. Shows the agents and the resources.
Value chain level
INTERNAL. Ripping the roof off. Accounting level, basically.
Focuses on the resource flows between interconnected business processes and on the economic events that accomplish the resource flows.
Business process (general)
- Broad term. Can mean anything from a single activity to a transaction cycle. For this chapter we use transaction cycle. Common:
- Financing process
- Acquisition/payment (purch) process
- HR/Payroll process
- Conversion (mfg) process
- Sales/Collection (Revenue) process
Business Process Level
- Third level of detail. Focuses more on one or more transaction cycles in an enterprise's value chain. Expands on the Value chain level to include some external elements.
- Shows resources, events, and agents and the relationships among them.
- Focuses on workflow/script.
- individual steps used to accomplish events in an enterprise.
What kind of pattern does Value System Level use?
Object pattern (macro level)
What kind of pattern does Value Chain level use?
- Script pattern. The value chain level models should be created with this overall script in mind but adjusted as appropriate for particular enterprise.:
- *Enterprise gets some money and engages in value added exchanges
- 1: buy equip and raw mater.
- 2. Purch labor
- 3. Mfg finished goods
- 4. Sell finished goods
- *Enterprise pays back money and takes home profit
What is the pattern at task level?
No pattern has been identified at task level yet
More about the 4 levels
- Value system - company as whole vs external agents and what resources flow
- Value chain - internal view only. different business processes (like departments) and how they interact w/each other. What resources flow and what are some of the events.
- Business process - Drill down into one department and view the resources, economic events, and agents, relationships (stockflow ec.) Merged and converted to relational database.
- Task level- Task detail. Workflow. Introduce flowcharting
Modeling accounting phenomenon is:
a combination of script patterns and object patterns that together enable us to model enterprises and to understand and work with existing enterprise models///levels of models slide
Business process level (slides)
Drilldown into a function/PROCESS and observe what econmomic exchanges take place
Business process level (object based pattern) snapshot approach
- •A pattern to which the reality of
- most (perhaps all) enterprises conform
- •The key is mapping the objects in
- the enterprise to the pattern in order to generate the model from which a
- database is designed.
- •*****Timing not included here.
- Business process level model is a snapshot. It doesn’t care about the timing,
- just that the interaction exists.
- •This is an REA MODEL. Resources on the left, events
- in the center, agents (internal/external people involved) on the right.
Value system, value chain, business processes, and task level. Which imposes an order of events?
- Task level – basically a
- script/flowchart LEVEL 4
Difference between this and other models is thatthis is the only one that implies a sequence of timing. ****
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