c. IF details matched and parsing result indicate
valid .wsdl, then put this web service in a
discovered list.
3) Sends the discovered list to the decisionMakerAgent
3.2.6 decisionMakerAgent
Input: Discovered web service list.
Output: Ranked web service list.
Procedure:
1) decisionMakerAgent gets the discovered web service
list from the discoveryAgent.
2) Loop (For each and every service listed in discovered
list)
a. Fetch the QoS (availability and throughput)
results of service.
b. Calculate input membership levels.
c. Find the fuzzy rules which can be applied to the
fuzzy inputs. Evaluate the rules by using center of
gravity method (COG). These rules are as per
Table 1.
d. Defuzzify the fuzzy output to system output.
Rule | Availability | Throughput QoS
1 Bad Bad Bad
2 Bad Good Bad
3 Bad Best Good
4 Good Bad Bad
5 Good Good Good
6 Good Best Best
7 Best Bad Good
8 Best Good Best
9 Best Best Best
Table 1. Fuzzy Rules
3) Sorts the list according to final numeric value, which
gets from defuzzification step and rank it accordingly.
4) Sends the ranked web service list to the service
requestor.
4. SIMULATION OF GEO WEATHER WEB SERVICE
For validating the developed system, we have created an
environment for simulating the geo-weather web services as
described below:
1. Web Service Creation: Three geo-weather web services
were developed that provide weather information when a
corresponding city and country are provided as input.
These SOAP based web services were deployed over Web
Server.
2. Registration to UDDI: An interface to UDDI Server is
developed. The developed web services were registered to
UDDI Server.
3. WSDL Parsing- The wsdl parsing of the sample web
services was done and the results were stored.
4. Discovery & Selection of Web Service- Based on
keyword entered by the service requester the list of best
fit web services was generated. For our case, we have
entered ‘weather’ as keyword and the three sample web
services were fetched as shown in Figure 3.
On selection of wsdl results option, two web services
were listed that filters the web service that doesn’t have
syntactically correct wsdl. The fuzzy details related to
each web service can be displayed.
5. Ranking- Based on the fuzzy calculations as described in
section 3.2.6, the web services were ranked and displayed.
For simulation, we have considered two input QoS
parameters namely (Availability and Throughput).
The input fuzzy set membership function (Bad, Good,
Best) is a triangle form. The range of the input is given
below:
Bad: = {(0, 1) (60, 1) (75, 0)};
Good: = {(60, 0) (75, 1) (90, 0)};
Best: = {(75, 0) (100, 1)};
For output, the same range has been applied. For
defuzzification, we have used “Center of Gravity” method.
The overall QoS results, depicted in Figure 4 (a-c) and
Service requester feedbacks (in context to good, bad) were
listed.
6. Web Service Feedback- Service requester can provide
feedback for the respective web services.
7. Binding- We have developed a web application to bind
the highest ranked weather web service for fetching the
weather information based on city and country.
5. CONCLUSION & FUTURE SCOPE
We have developed an automated end-to-end solution to be
deployed at broker side that provides a common framework for
service registration, wsdl validation, QoS measurement,
discovery and selecting the highest ranked web service using
multi-agent system. The solution can be used for intranet as
well as internet environment.
Currently, we have considered only two QoS parameters
namely availability and throughput for implementation. In
future the other domain specific Geospatial QoS parameters
namely: accuracy of geospatial data, resolution, completeness,
and data types also be considered.
References from Books:
[1] Web services: Principles and technology - by Papazoglou,
Michael P.; Harlow, Pearson Education.
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