A Model for Web services Discovery with QoS

Ran, S. 2003. A model for web services discovery with QoS. SIGecom Exch. 4, 1 (Mar. 2003), 1-10. DOI= http://doi.acm.org.proxy.lib.sfu.ca/10.1145/844357.844360


Service Supplier -> provides Certifier with QoS information -> Certifier either accepts or downgrades the information -> returns the result back to the supplier -> supplier registers the service (the functional descriptions + the certified QoS) + UDDI checks with certifier the QoS.

Web services are provided by third parties and are invoked dynamicall over the intenet and thus their QoS can vary greatly.

A framework is need to capture QoS provided by supplier and QoS required by customer and try to provide a match between the two.

ISO 8402 Description for Quality: the totality of features and characteristics of a product or service that bear on its ability to satisfy stated or implied needs.

QoS: a set of non-functional attributes that may impact the quality of the service offered by a
Web service

Categories for QoS

1. Runtime related quality of service

• Scalability (related to throughput and performance)
  
• Capacity (concurrent requests)
• Performance ( speed in completing a service request)
• Response time
• Latency
• Throughput (number of completed service requests over a time period)
• Reliability
• Mean Time between Failuers
• Mean Time to Failure
• Mean Time To Transion
• Availability
• Robustness / Flexibility
• Exception Handling
• Accuracy

2. Transaction Support

• Integrity ACID ->
  
• Atomicity -> entirely executes or not at all
• Consistency -> maintains integrity
  
• Isolation -> runs as if no other transactions are present
  
• Durability -> the results are persistent

3. Configuration Management and Cost Related

• Regularity ( how well the service is aligned with the regulations)
  
• Supported Standard (if the service complies with standards)
  
• Stability / Change Cycle (frequency of change in the service in terms of interface)
  
• Cost ( the cost for using the service)
  
• Completeness (the difference between the specified set of features and the implemented set of features)

4. Security related QoS

• Authentication
• Authorization
• Confidentiality
• Accountability
• Traceability + Auditability
• Data Encryption
• Non-repudiation (A Principal can not deny requesting the service after the fact)