Dynamic Service Selection &

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3 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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Dynamic Service Selection &
Analyze

Weina

Ma

June 6
th
, 2013

Paper 1


“Web Service Discovery with Implicit
QoS

Filtering”


Problem


Traditional WS discovery supported by WSDL and
UDDI API is insufficient


UDDI API is keyword
-
based query


This paper proposed a framework for WS
selection based on
QoS

properties
collected
by a distributed
agent
-
based

system.

Framework


Personal Agent (PA) accepts requests from client and send goal to Register.


Matching Agent provides list of candidate services which satisfy client’s
goal. It keeps history of requests and provides information searched for
the similar service before.


Service Mediator (SM) collects statistics about WS invocations.


PA

ranks the services and invokes the best one.

Conclusion


Agent
-
based technology is extremely suitable
for WS performance evaluation of cloud
environment.


Matching Agent can learn from experience.

Paper 2


“Web Service Competition: A New Approach to
Service Selection”


Problem


Service description is expressed inaccurate, globally
and statically, no depending on client’s needs and
contexts


This paper proposes a service selection approach,
using generic service representative technology,
to compare services based on their performance
in a specific client context
.

Methodology

Methodology Continue

Conclusion


Security and privacy challenges between
service provider and representative.


Increase network traffic.


Centralized competition desk fits comparing
performance of algorism, but not real
computing and traffic performance because of
the difference between WS running
environment.

Paper 3


“A Simple Approach for Testing Web Services
Based Applications”


Problem


A Web Application might invoke multiple web services
located on different servers with no design, source
code, or interface available.


This paper presents how to test web services
when building composited web application.


Two
-
level abstraction model to represent a web
application.


Three sets of test cases are generated automatically.

Web Application Representation


Task Precedence Graph (TPG)


Each

node represents a web service, like Main Component (MC), Hotel Reservation (HR), Car
Reservation (CR) and Weather Prediction (WP).


An

edge means the flow of actions (transitions)


Each

edge is labeled with an action and its timing constrain.

Single Web Service Representation


Time
d Labeled Transition System (TLTS)


TLTS represents

transitions from one state to another.


Node

means a state


Each edge is labeled with an action and its timing constrain.

Test Cases Generation


The first set of test cases are generated based
on boundary value testing analysis of WSDL


The second set of test cases are all possible
actions in each individual service, by
traversing all paths going from initial state of
TLTS to be fulfilled.


The third set of test cases are generated by
traversing all paths going from the initial state
of the TPG.

Web Service Testing Framework

Conclusion


Web service testing at stage of building
composited web application rather than
during invocation time.


Full
-
coverage test cases generated
automatically.


Paper 4


“Runtime Monitoring of Web Service Conversations”


This paper proposes to use
runtime monitoring

of
conversations

between partners as a means of
checking behavioral correctness
of the entire web
application.


Describe a specification language,
UML 2.0 Sequence
Diagrams (SDs)
, for dynamic analysis of web services.


Focus on monitoring finitely terminating behaviors and
capturing safety and
liveness

properties.


Sequence Diagrams


Sequence Diagrams (SDs) is to model
behavioral scenarios by describing sequences
of messages communicated between different
objects over time.


BasicSD
, par, alt, strict
seq
, weak
seq
, loop,
consider and ignore are terminal symbols.


E is a set of SD messages.



Formalizing Sequence Diagrams


NFA (Nondeterministic Finite Automaton) is a
finite state machine where from each state and a
given input symbol the automaton may jump into
several possible next states.


DFA (deterministic finite automaton) is a finite
that accepts/rejects finite strings of symbols and
only produces a unique computation (or run) of
the automaton for each input string.


An NFA A receive a trace of sequence diagram as
input and changes its current state according to
its transition relation

Architecture of Framework


User create UML SDs with help

of
PropertyM
.


Monitoring
M

converts NFA to DFA.


Message
M obtains interaction events from SCAM and directs to
MonitoringM
, in turn, update the state of every active monitor automaton,
until an error has been found or all partners terminate.

Conclusion


Not require any code instrument


Not significantly affect the performance of
monitored system


Requiring a distributed monitoring framework