Transcript SELF-SERV: A Platform for Rapid Composition of Web

A Platform for Rapid Composition of
Web Services in a Peer-to-Peer Environment
Quan Z. Sheng, Boualem Benatallah,
Eileen Oi-Yan Mak
University of New South Wales, Sydney, Australia
Marlon Dumas
Queensland University of Technology, Brisbane, Australia
1. Overview
SELF-SERV Service Manager
SELF-SERV provides a platform
for rapid composition of Web
services, where Web services are
declaratively composed, and the
resulting composite services are
executed in a peer-to-peer and
dynamic environment.
SELF-SERV distinguishes three
types of services: elementary services, composite services, and
service communities. Composite
services are described through
statecharts. Service communities perform dynamic provider
selection through selection policies.
User Layer
SOAP messages
Communication
Layer
Internet
Service registries
Directory
Layer
Conversation
Layer
Service templates
Pool of
services
and
containers
CS1
Composite
services
is registered
with
Elementary ES1
services
workflow
C3
C2
Containers C1
Service
Layer
CS2
is composed
of
ES2
database
ES4
web-accessible programs
2. Service Creation
The Service Builder provides a statechart editor for describing composite service operations. It also
offers search and browse facilities to locate operations from existing services and import them
into composite services. It provides an editor for describing service operations, loading and
configuring SELF-SERV built-in classes (e.g., linking an operation to a scoring service of a community).
3. Service Deployment
The deployment of a composite service requires the generation and deployment of routing tables (i.e.,
precondition/postprocessing tables of each state of a composite service statechart). The routing tables
(XML documents) are then uploaded into the hosts of the corresponding component services, together
with the wrapper and coordinator classes.
Complete Travel Service (CTS)
DFB
[domestic
(destination)]
Domestic Flight
Booking (DFB)
[near(major_attraction,
accommodation)]
AB
Accommodation
Booking (AB)
CTS
[not domestic
(destination)]
Intl Travel
Arrangement (ITA)
CR
[not near(
major_attraction,
accommodation)]
ITA
Attractions
Search (AS)
AS
wrapper
coordinator
Car Rental
(CR)
TI
IFB
Intl. Flight
Booking (IFB)
Travel
Insurance (TI)
Intl Travel Arrangements Service (ITAS)
4. Service Discovery Engine
Services are published in a UDDI registry and located through the Service Discovery Engine.
5. Service Execution
SELF-SERV adopts an
orchestration
model
based on peer-to-peer
interactions between
software components
hosted by the providers
participating in the
composition. The orchestration of a composition service execution involves two
types of messages:
control flow notifications and service invocations/completions.
IC
CTS
CF
CF
CF
AS
CF
CR
CF
CF
AB
CF
IC
ITA
TI
TIS
CF
IC
IC
ASS
ASS
CRS
wrapper
coordinator
IC
IC
ABS
ITAS
CF
CF
IC
IFB
CF
control-flow notification
IC
service invocation/ completion
IFBS
6. Performance Evaluation
We conducted several experiments to study the
performance of SELF-SERV using a cluster of
PCs.
The results show that the deployment speed is
acceptable, and that the peer-to-peer approach
to composite service execution leads to increased throughput through better workload distribution.
No. of component service
15
20
30
40
50
Deployment cost (second)
8.9
10.1
13.1
15.9
19.0
No. of component service
60
70
80
90
100
Deployment cost (second)
21.8 25.9
30.2
32.9
34.1
Deployment cost of composite services.
Workload allocation.
Execution time with different message sizes.