@article {96, title = {JOpera: a Toolkit for Efficient Visual Composition of Web Services}, journal = {International Journal of Electronic Commerce (IJEC)}, volume = {9}, year = {2004}, month = {Winter 2004/2005}, pages = {107-141}, abstract = {Web services are attracting attention because of their ability to provide standard interfaces to heterogeneous distributed services. Standard interfaces make it possible to compose more complex services out of basic ones. This paper tackles the problem of visual service composition and the efficient and scalable execution of the resulting composite services. The effort revolves around the JOpera system, which combines a visual programming environment for Web services with a flexible execution engine that interacts with Web services through the simple object access protocol (SOAP), described with Web services language description (WSDL) and registered with a universal description discovery and integration (UDDI) registry. The paper explains the syntax and implementation of the JOpera Visual Composition Language (JVCL) and its ability to provide different quality of service (QoS) levels in the execution of composite services. }, keywords = {JOpera, Scalable Process Execution, visual languages, Web service composition}, issn = {1086-4415 }, url = {http://www.ijec-web.org/past-issues/volume-9-number-2-winter-2004-05/ijecv9n2-6/}, author = {Cesare Pautasso and Gustavo Alonso} } @conference {94, title = {Visual composition of Web services}, booktitle = {IEEE Symposium on Human Centric Computing Languages and Environments (HCC 2003)}, year = {2003}, month = {October}, pages = {92 - 99}, publisher = {IEEE}, organization = {IEEE}, address = {Auckland, New Zealand}, abstract = {Composing Web services into a coherent application can be a tedious and error prone task when using traditional textual scripting languages. As an alternative, complex interactions patterns and data exchanges between different Web services can be effectively modeled using a visual language. In this paper we discuss the requirements of such an application scenario and we present the design of the BioOpera Flow Language. This visual composition language has been fully implemented in a development environment for Web service composition with usability features emphasizing rapid development and visual scalability.}, keywords = {JOpera, visual languages, visual service composition, Web service composition, Web services}, doi = {10.1109/HCC.2003.1260208}, url = {http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=1260208}, author = {Cesare Pautasso and Gustavo Alonso} }