Architectural Roadmap

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Architectural Roadmap

• B. Ramamurthy

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Review

• Last lecture we discussed
• Definitions of SOA by experts in the field
• Our own simple definition of an SOA
• types of services
• In todays lecture we will discuss
• Details of the various types of services
• Architecting an SOA (stages)
• Chapters 5 and 6

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Basic / horizontal Services

• Fundamental services
• Maintain no conversational state
• Data-centric services
• Encapsulates business data
• purpose of data centric services is to handle
  persistent data typically stored in an Enterprise
  Information System (EIS).
• An EIS could be a simple data base or integrated
  data base from several sources.
• A file system relational data base or a object
  relational mapping, data access objects and
  layering all these fall under this category.
• For example, store operation from a user web
  service could invoke a data-centric service that
  stores the data in the resource defined in the
  operational environment.
• What is a resource in this context?
• A data stream, relational DB data source, a data
  queue
• A store on a business object (BO) may results
  many physical writes to (one or more distributed)
  data bases. Data-centric service takes care of
  this.

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Horizontal services

• Logic centric services
• Encapsulate algorithms for complex calculations
  or business rules.
• Consider the example of Insurance Product Engine
  (fig.5.3) (For example Geico or Progressive
  Insurance)
• We will discuss three alternative approaches to
  providing this function and why services-based
  one is advantageous. (pp.72-74)

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Insurance Product Engine
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Intermediary Services

• Stateless services that bridge the technological
  inconsistencies and design gaps in an
  architecture.
• Gateways, adapters, facades, and functionality
  adding services

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Technology gateway service
Technology A Tech Gateway Technology B
Technology B Basic Service
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Façade Intermediary Service
Facade
Basic service 1
Basic service 2
Basic service 3
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Process centric services

• Process centric services can encapsulate the
  knowledge of the organizations business
  processes.
• Stateful they contain and maintain state
• These are project-specific
• Requires careful design satisfying the domain
  rules and business policies

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Process-centric service (contd.)
Application Frontend
Process-centric service
service 1
service 2
service 3
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Process-centric service (contd.)
service 1
service 2
service 3
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Enterprise level services

• Security
• Accounting
• Billing
• SLAs (service level agreements), service metering
• We will refer to these as horizontal services,
  i.e., common domain-independent utility services

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Enterprise Services layers (fig.5.9, 5.10)
Enterprise layer
Process layer
Intermediary layer
Basic layer
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The architectural roadmap The stages in
development

• Fundamental SOA
• Design fundamental services
• Networked SOA
• Add intermediary services
• Process-enabled SOA
• Add process-centric services, front-ends
• These three stages reach maturity at different
  rates, services gain more responsibility as the
  system matures.
• Advantages of using service-orientation will be
  apparent as the stages evolve independently of
  each other

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Fundamental SOA

• Excellent starting point for introduction SOA in
  an organization
• A fundamental SOA consists of two layers
• Enterprise layer that consists of front-ends, and
  
• The basic layers that consists of basic services

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Airline Enterprise
Enterprise Layer
Basic layer
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Expanded Airline Enterprise
Enterprise Layer
Basic layer
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Fundamental SOA Summary

• Base on which future expansion can take place
• Simple to implement
• Complex front-end
• Increased maintainability
• Shared services can make data replication largely
  obsolete
• Good starting point/entry point to SOA

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Networked SOA

• It deals with backend complexity in addition to
  technical and conceptual integration.
• If offers flexibility in integrating software
  assets of an enterprise.
• Enables loose coupling
• Addition of intermediary layer with services that
  handle
• distributed transactions, (fig.6.6)
• bridge technology gaps, (fig 6.7)
• database integration, (fig 6.9)
• Add new functionality, (fig 6.10)
• Wrap legacy applications/service (fig.6.10)

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Networked SOA
Enterprise Layer
Intermediary layer
BookAndBill
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Process-enabled SOA

• The key feature is the maintenance of a process
  state in process-centric services.
• Stateful services (server-side state)
• Encapsulates complexity of processes (Ex
  runExperiment in a complex scientific lab
  experiment)
• Possibility of sharing states between clients
  (Ex research whiteboard)
• Handling long-living processes (Ex auction
  framework)
• Enables the IT and business alignment

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Process-enabled SOA
Business Layer
BookingProcess
Intermediary layer
BookAndBill
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Process-enabled SOA (contd.)
Business Layer
B2B process
mobileprocess
BookingProcess
Intermediary layer
BookAndBill
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Process-enabled SOA (contd.)
Business Layer
cancellation process
Mobile process
BookingProcess
Basic layer
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Process-enabled SOA summary

• Enables light-weight frontends (handles only user
  interaction)
• Encapsulates complexities of business processes
• Abstracts complexities of backend systems
• Enables separation of business logic from
  technology complexities
• Is required for integration of independent
  organizations and implementation of complex
  processes

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Enterprise Services layers (fig.5.9, 5.10)
Enterprise layer
Process layer
Intermediary layer
Basic layer
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Airline Enterprise
Enterprise Layer
Basic layer
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Expanded Airline Enterprise
Enterprise Layer
Basic layer
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Networked SOA
Enterprise Layer
Intermediary layer
BookAndBill
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Process-enabled SOA
Business Layer
BookingProcess
Intermediary layer
BookAndBill
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Process-enabled SOA (contd.)
Business Layer
B2B process
mobileprocess
BookingProcess
Intermediary layer
BookAndBill
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Process-enabled SOA (contd.)
Business Layer
cancellation process
Mobile process
BookingProcess
Basic layer