Patterns in Integration of Applications

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Patterns in Integration of Applications

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Based on Object oriented Modeling Design
for Database Application By Michael Blaha
William Premerlani
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Content

• Motivation for Integration
• Integration types
• benefits of Integration
• Integration process stages
• Integration problems (Example)
• Common Integration Patterns

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Motivation for Integration

• Most corporate information systems consist of
  many islands of automation (separate
  applications).
• Software is developed to service the needs of a
  single application with little regard for the
  effect on the corporation as a whole.
• In the Justice Department of Israel there are 83
  separate applications who operate without
  integration at all.

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Motivation for Integration

• Applications perform well alone no
  collaboration for the overall benefit of the
  organization.

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Types of integration

• Data integration integrating the data found on
  the separate applications DBs
• Behavior integration forcing common look
  feel of the applications.

• Data integration is the common type of
  integration while behavior integration is a
  future technology.
• The purpose of data integration is to allow
  exchange of common data between the
  applications.

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Benefits of integration

• Cost reduction integration can reduce multiple
  entry of data.
• Data integrity by reconciling applications
  integration can improve consistency.
• Greater flexibility applications are inflexible
  when they are balkanized.
• More functionality integration enables
  effective information mining and decision
  support.

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Integration process stages

• Application modeling develop analysis models
  for each individual application
• Enterprise modeling create a model that spans
  applications
• Integration techniques choosing a combination
  of integration techniques.
• Data warehouse use the integrated applications
  as foundation for DW.

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Enterprise model
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Enterprise model

• describes the entire organization or major aspect
  of it.
• abstracts multiple applications, reconciling
  their logical content.
• provides high level understanding of
  relationship between applications.

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Integration problems

• Naming conflicts the same concept may appear in
  different names or the same name applies to
  different concepts.
• Domain conflicts conflict in data types, field
  length, units of measure etc.
• Multiplicity conflicts attributes and roles may
  be optional or mandatory.

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Example of conflicts
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Example of conflicts (cont)

• This simple example illustrates many kinds of
  integration problems
• naming conflicts customerLocation corresponds
  to address, city corresponds to cityName.
• Domain conflicts in the postal application city
  and state are classes while in the customers
  application they are attributes

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Common Integration Patterns

• Master database all of the applications store
  data in a single database
• Point-to-point interfaces connecting pairs of
  applications directly
• Indirect integration using enterprise database
  and metadata for integration.

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Master database

• The most obvious approach to integration is to
  require that all applications store data in
  single database
• Each application operates on its own view of the
  enterprise database
• The view can be created in two ways
• RDBMS views
• Physically materialize an application database
  using
• long transaction

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Master database
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Master database

• Can be achieved when standards organization
  promotes acceptance of the master model
• can be used only for a small group of
  applications
• Impractical for large number of applications
  since developers must revise or rewrite too many
  applications

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Master database pros cons

• Pros
• few inconsistencies between applications
• the thorough integration is readily apparent to
  end user.
• Cons
• suitable only for a small group of applications
• requires revising or rewriting of the
  applications

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Point-to-point interfaces

• Each pair of applications that must exchange data
  have two interfaces
• One interface reads from application A and writes
  to B and the second does the opposite.
• Does not require an enterprise model

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Point-to-point interfaces
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Point-to-point interfaces

• The interfaces can be realized in different ways
  
• RDBMS stored procedures
• separate programs that wrap around application
  execution
• Very straightforward understand and implement
• Preferred approach when there is little
  commonality

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Point-to-point interfaces pros cons

• Pros
• deal only with two applications at a time
• efficiently connect applications with high
  volume traffic
• Cons
• creates a network of dependencies as many as
  n(n-1)
• as the number of applications grows adding new
  application becomes harder

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Indirect integration

• The most complex approach, yet provides robust
  scalable integration
• Applications communicate through an enterprise
  database
• The enterprise database holds metadata that maps
  read write requests between applications

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Indirect integration

• Does not require application modification but
  instead superimposes integration layer
• can be done in two ways
• hard-coding mapping between applications using
  RDBMS triggers stored procedures (methods in
  oo-DBMS)
• elevate mapping data into metalevel and use
  generic code
• The enterprise database can be used as staging
  area or store data permanently

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Indirect integration
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Indirect integration((five-Scheme architecture
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Indirect integration pros cons

• Pros
• high scalability adding two interfaces for
  each new application (read write)
• does not require modifications of applications
• Cons
• high complexity metadata and generic software
  are difficult to implement
• becomes harder when application models and
  implementations greatly dissimilar

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Summary

• Integration is critical capability for large,
  complex information systems
• With the current state of the art, the focus is
  on integrating data
• OO-modeling is critical for technology for
  achieving integration
• All three integration techniques are helpful, but
  the most significant technique is indirect
  integration

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