The Internet Encyclopedia (Volume 3)

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766 WEBSERVICES

Storage Pool

Cluster Pool

Firewall Pool

Load Balancer Pool

NAS Pool

Storage

Virtualization

Network

Virtualization

Data Center Management

INTERNET INTRANETS

Figure 8: Architecture of a utility data center Web services

platform infrastructure.

storage containing deployed service arrangements;

and

Dynamic capacity sizing of Web services—By the ability to

automatically launch additional service instances ab-

sorbing additional load occurring to the service. Ser-

vice instances are launched by first allocating spare

machines from the pool maintained in the data center,

wiring them into the specific environment of the Web

service, attaching appropriate storage to those ma-

chines, and launching the applications obtained from

that storage. Web server farms are a good example for

such a “breathing” (meaning dynamically adjustable)

configuration (Andrzejak, Graupner, Kotov, & Trinks,

2002; Graupner, Kotov, & Trinks, 2002).

IBM’s Autonomic Computing vision is to provide for

self-managing systems. The intent is to create systems

that respond to capacity demands and system glitches

without human intervention. These systems intend to

be self-configuring, self-healing, self-protecting, and self-

optimizing (IBM Autonomic Computing, 2002).

CONCLUSION

The Web services paradigm has evolved substantially be-

cause of concerted efforts by the software community. The

genesis of Web services can be traced back to projects like

e-speak, Jini, and TSpaces. Although progress has been

made in Web service standardization, the full potential of

Web services remains unrealized. The future will see the

realization of Web services as a means of doing business

on the Web, the vision of dynamic composition of Web

services, personalized Web services, end-to-end manage-

ment of Web service interactions, and a dynamically

reusable service infrastructure that will adapt to varia-

tions in resource consumption.

GLOSSARY

Business process execution language for Web services

(BPEL4WS) A standard business process descrip-

tion language that combines features from WSFL and

XLANG.

Composition Creating composite Web services when

Web services outsource their functionalities to other

Web services.

Conversation A set of message exchanges that can be

logically grouped together.

Description Describing Web services in terms of the op-

erations and messages they support, so that they can

be registered and discovered at UDDI operator sites or

by using WS-Inspection.

End-to-end management Protocol required to track

and manage Web service composition leading to a

transaction being subdivided amongst multiple Web

services.

Orchestration Web service to Web service interaction

that leads to the coupling of internal business pro-

cesses.

Personalization Personalizing or customizing Web ser-

vices to user/client profiles and requirements.

Platform One or more execution engines over which a

Web service implementation is executed.

Service level agreement (SLA) An agreement that

specifies quality-of-service guarantees between parties.

Simple object access protocol (SOAP) A standard for

messaging between Web services.

Web service conversation language (WSCL) A lan-

guage to describe Web service conversations.

Web services flow language (WSFL) A language to de-

scribe business processes.

CROSS REFERENCES

SeeClient/Server Computing; Common Gateway Interface

(CGI) Scripts; Electronic Payment; Java; Perl; Personal-

ization and Customization Technologies; Secure Electronic

Transmissions (SET).

REFERENCES

Andrzejak, A., Graupner, S., Kotov, V., & Trinks, H. (2002).

Self-organizing control in planetary-scale computing.

InIEEE International Symposium on Cluster Comput-

ing and the Grid (CCGrid), 2nd Workshop on Agent-

based Cluster and Grid Computing (ACGC). New York:

IEEE.

Austin, D., Barbir, A., & Garg, S. (2002, 29 April).Web

services architecture requirements. Retrieved November

2002 from http://www.w3.org/TR/2002/WD-wsa-reqs-

20020429

Banerji, A., Bartolini, C., Beringer, D., Chopella, V., Govin-

darajan, K., Karp, A., et al. (2002, March 14).WSCL

Web services conversation language. Retrieved Novem-

ber 2002 from http://www.w3.org/TR/wscl10

Bartel, M., Boyer, J., Fox, B., LaMacchia, B., & Si-

mon, E. (2002, February 12).XML signature syntax

and processing. Retrieved November 2002 from http://

http://www.w3.org/TR/2002/REC-xmldsig-core-20020212