1. CSSSPEC6 SOFTWARE DEVELOPMENT WITH QUALITY ASSURANCE
SOFTWARE INTEGRATION
CSSSPEC6
SOFTWARE DEVELOPMENT WITH QUALITY ASSURANCE
<<professor>>

2. SERVICE-ORIENTED ARCHITECTURES
A means of developing distributed systems where the components are stand-alone services.
Services may execute on different computers from different service providers.
Standard protocols have been developed to support service communication and information exchange.
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3. Problems Addressed by a Service Oriented Architecture
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4. DIRECTIONS OF SYSTEM ARCHITECTURE
2010 – 2050
Organization Focus
Mainframe Centric
Internal Use
Unique Data
Process Focus
Client Server
Partial Connectivity
EDI File Transfer
Distributed Functions
Data Centric
Universal Interoperability
Real-time Connectivity

5. KEY CHARACTERISTICS OF SOA
Quality of service, security and performance are specified.
Software infrastructure is responsible for managing.
Services are cataloged and discoverable.
Data are cataloged and discoverable.
Protocols use only industry standards.

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WHAT IS A “SERVICE”?
A Service is a reusable component.
A Service changes business data from one state to another.
A Service is the only way how data is accessed.
If you can describe a component in WSDL, it is a Service.
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SOA AND WEB SERVICES
SERVICE-ORIENTED ARCHITECTURE IS AN ARCHITECTURAL STYLE
Derived from the client-server architectural style.
Clients (service consumers or requesters) and servers (service providers) connected by a service “bus”.
Services defined using formal interfaces (contracts).
Service bus supports point-to-point and messaging styles of communication.
Support for system qualities, e.g., security and transaction management.
WEB SERVICES
Services provided in a SOA deployed over the web.
Open source software for SOA, IONA Technologies A-Trenaman-SOA.pdf
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8. WEB SERVICE DESCRIPTION LANGUAGE
The service interface is defined in a service description expressed in WSDL. The WSDL specification defines:
What operations the service supports and the format of the messages that are sent and received by the service.
How the service is accessed - that is, the binding maps the abstract interface onto a concrete set of protocols.
Where the service is located. This is usually expressed as a URI (Universal Resource Identifier).
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9. STRUCTURE OF A WSDL SPECIFICATION
Intro
Abstract interface
Concrete
implementation
WSDL service definition XM
L namespace declarations
Type declarations
Interface declarations
Message declarations
Binding declarations
Endpoint declarations
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10. A WSDL DESCRIPTION FRAGMENT
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11. A WSDL DESCRIPTION FRAGMENT
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12. SERVICE IMPLEMENTATION AND DEPLOYMENT
Programming services using a standard programming language or a workflow language.
Services then have to be tested by creating input messages and checking that the output messages produced are as expected.
Deployment involves publicizing the service using UDDI and installing it on a web server. Current servers provide support for service installation.
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13. HOTEL BOOKING WORKFLOW
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14. STANDARDS FOR WEB SERVICE COMPOSITION
SERVICE ORCHESTRATION
WS-BPEL is an XML-based language for workflow specification.
WS-BPEL is an “orchestration” language.
Service orchestration defines the sequence and conditions in which one Web service invokes other Web services.
Can be used to create a composite service out of other services.
SERVICE CHOREOGRAPHY
WS-CDL is an XML-based language for describing service “choreography”.
Choreography defines the allowable message exchanges between services.
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15. ORCHESTRATION VS. CHOREOGRAPHY
Defines Interaction.
ORCHESTRATION A Single Director In Control.
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16. ORCHESTRATION VS. CHOREOGRAPHY
Orchestration within services
Choreography between services
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17. Example: Purchase order

18. CHOREOGRAPHY PERSPECTIVE

19. ORCHESTRATION PERSPECTIVE

20. ORCHESTRATION AND CHOREOGRAPHY

21. LEGACY SYSTEM SERVICES
An important application of services is to provide access to functionality embedded in legacy systems.
Legacy systems offer extensive functionality and this can reduce the cost of service implementation.
External applications can access this functionality through the service interfaces.
© Ian Sommerville, Software Engineering, 8th Edition, Chapter 31
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22. STEPS TO RECOVERING WEB SERVICES
Identify reusable blocks.
Evaluate for reusability.
Extract from the legacy code.
Wrap with a WSDL interface.
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23. Identifying reusable code blocks
Process
Arguments
Slicing Technique
y = f (x) Result = Processing Rule (Arguments); Processing_Rule = Allocation (Path_Expression); Path_Expression = [<Conditions>]n;
Program
Procedure
Condition
Condition
Path Expression n
Assign Or
Compute
Result
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24. Evaluating the reusability of a software building block
REUSABILITY METRIC
SYSTEM
PROGRAM
Reusability of potential procedures or classes should be > 50% .
MODULE
ENTRY
Few
Dependencies
No I/O
EXIT
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25. Salvaging components from legacy code Computer Science Department
Business Rule
Legacy Code
Input
Parameters
Relocatable
Self-controlled
Internal
Data
Output
Code
statements
traversed to
implement
rule
Data
Used by
Source effected
Results
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26. Generated Wrapper Routines
Service Request
Wrapping salvaged components
WSDL Interfaces
Generate
from
Inputs
Generate
from
Outputs
Generated Wrapper Routines
Input
Parameters
Output
Parameters
Procedural Code
(section, Procedure or Function
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27. MAJOR PITFALLS WITH SYSTEM INTEGRATION Computer Science Department
DESCRIPTION
What is expected has delay
The experience shows that the implemented elements always do not arrive in the expected order and the tests never proceed or result as foreseen; therefore, the integration strategy should allow a great flexibility.
Big-bang not appropriate
The "big-bang" integration technique is not appropriate for a fast detection of faults. It is thus preferable to verify the interfaces progressively all along the integration.
Integration plan too late
The preparation of the integration activities is planned too late in the project schedule, typically when first implemented elements are delivered.
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28. PROVEN PRACTICES WITH SYSTEM INTEGRATION Computer Science Department
DESCRIPTION
Start earlier development of means
The development of assembly tools and verification and validation tools can be as long as the system itself. It should be started as early as possible as soon as the preliminary design is nearly frozen.
Integration means seen as enabling systems
The development of integration means (assembly tools, verification, and validation tools) can be seen as enabling systems, using system definition and system realization processes . These projects can be led by the project of the corresponding system-of-interest, but assigned to specific system blocks, or can be subcontracted as separate projects.
Use coupling matrix
A good practice consists in gradually integrating aggregates in order to detect faults more easily. The use of the coupling matrix applies for all strategies and especially for the bottom up integration strategy.
Integration and design teams
The integration responsible should be part of the design team.
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