A%20Reference%20Model%20for%20Event%20Patterns

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A Reference Model for Event Patterns

• Christian Silberbauer
• (christian.silberbauer_at_gmx.de)

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The Context

• easyCredit platform of the Teambank should detect
  cancellation of credit applications
• Solution is part of the diploma thesis of
  Hans-Martin Brandl and David Guschakowski
• Von Ammon teaches Complex Event Processing at the
  Fachhochschule Regensburg
• In this lecture we made a description of the Loss
  Pattern

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The Patterns Sources

• Christopher Alexander was the first one writing
  about patterns
• His Book The Timeless Way of Building
• He is an architect!

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Alexanders Pattern Definition
Each pattern describes a problem which occurs
over and over again in our environment, and then
describes the core of the solution to that
problem, in such a way that you can use this
solution a million times over, without ever doing
it the same way twice.
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Standards for Software Patterns

• Gamma et. Al. (GoF), 1994, Design Patterns
  Elements of Reusable Object-Oriented Software
• Buschmann et. Al., 1996,Pattern-oriented
  Software Architecture A System of Patterns

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Pattern Structure

• Gamma
• Name
• Intent
• Also Known As
• Motivation
• Applicability
• Structure
• Participants
• Collaborations
• Consequences
• Implementation
• Sample Code
• Known Uses
• Related Patterns

• Buschmann
• Name
• Also Known As
• Example
• Context
• Problem
• Solution
• Structure
• Dyanamics
• Implementation
• Example Resolved
• Variants
• Known Uses
• Consequences
• See Also

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Patterns according to Buschmann
Name The name and a short summary of the pattern.
Also Known As Other names for the pattern, if any are known.
Example A real-world example demonstrating the existence of the problem and the need for the pattern. Throughout the description we refer to the example to illustrate solution and implementation aspects, where this is necessary or useful.
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Patterns according to Buschmann
Context The situations in which the pattern may apply.
Problem The problem the pattern addresses, including a discussion of its associated forces.
Solution The fundamental solution principle underlying the pattern.
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Patterns according to Buschmann
Structure A detailed specification of the structural aspects of the pattern.
Dynamics Typical scenarios describing the run-time behavior of the pattern.
Implementation Guidelines for implementing the pattern
Example Resolved Discussion of any important aspects for resolving the example that are not yet covered in the Solution, Structure, Dynamics and Implementation sections.
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Patterns according to Buschmann
Variants A brief description of variants or specializations of a pattern.
Known Uses Examples of the use of the pattern, taken from existing systems.
Consequences The benefits the pattern provides, and any potential liabilities.
See Also References to patterns that solve similar problems, and to patterns that help us refine the pattern we are describing.
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Writing Event Patterns

• Use a standardized structure for your pattern
  description (Gamma, Buschmann)
• A pattern of a certain category of patterns has
  to have the same abstraction level
• Dont describe too general concepts (e.g.
  Monitoring, Drill down, Benefits of using Events
  in general)