Information Technology Reference
In-Depth Information
Request/response aspects offer several advantages: They allow adding non-
functional requirements at the web service communication level to offer the pos-
sibility of executing aspect code on the remote host where a called web service
is running. Furthermore, they are independent of a web service's implementa-
tion language and do not assume that the web service implementation provides
related functionality. By using the aspect framework, the development of web
services is simplified. This is demonstrated by adding the non-functional require-
ment of eciently transmitting large amounts of data in a web service workflow
and thus circumventing the bottleneck at the client or workflow engine, respec-
tively. Runtime measurements for a multimedia application that requires e-
cient transmission of large amounts of data have been presented. Two further
use cases for data compression and encryption have demonstrated the benefits
of the proposed approach.
There are several areas for future work. For example, instead of transferring
the aspect-ID (
), the whole aspect could be copied either as (Java) binary
code or as an interpretable description to the remote service. Ideas like sequence
pointcuts (sophisticated management of multiple advice for the same pointcut)
and shared states between aspects executed on different hosts [15] are other in-
teresting enhancements of our approach. Finally, to prevent a congestion of a
service with aspects over time, investigations for sophisticated life cycle manage-
ment (e.g., according to wall-clock time or communication patterns) are areas
of further research.
I
Acknowledgements
This work is supported by the German Ministry of Education and Research
(BMBF, D-Grid) and by the German Research Foundation (DFG, PAK 509).
References
1. ActiveEndpoints: ActiveBPEL Business Process Execution Engine,
http://www.activebpel.org
2. Andrews, T., Curbera, F., Dholakia, H., Goland, Y., Klein, J., Leymann, F., Liu,
K., Roller, D., Smith, D., Thatte, S., Trickovic, I., Weerawarana, S.: Business
Process Execution Language for Web Services Version 1.1. Microsoft, IBM, Siebel,
BEA und SAP, 1.1 edn. (May 2003)
3. Apache Foundation: Apache Axis.,
http://ws.apache.org/axis/
4. Baligand, F., Monfort, V.: A Concrete Solution for Web Services Adaptability
Using Policies and Aspects. In: Proc. of the 2nd Intl. Conf. on Service Oriented
Computing, pp. 134-142. ACM, New York (2004)
5. Binder, W., Constantinescu, I., Faltings, B.: Service Invocation Triggers: A
Lightweight Routing Infrastructure for Decentralized Workflow Orchestration. In:
Intl. Conf. on Advanced Information Networking and Applications, vol. 2, pp. 917-
921 (2006)
6. Charfi, A., Mezini, M.: Aspect-oriented Web Service Composition with AO4BPEL.
In: Proc. of the European Conf. on Web Services, pp. 168-182. Springer, Heidelberg
(2004)
