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ISBN: 978-972-8939-25-0 © 2010 IADISannotations have been used additionally for simplifying the development process of Service-based interactiveapplications. Within the context of the FP7 project ServFace 1 , two application development approaches havebeen specified (Paternò 2010, Feldmann 2009) which explore Service annotations for reducing theinformation which has to be specified by an application developer during the design-time. Both approachesapply the annotation model described in (Janeiro et al. 2009). Just as previous annotation models, this modelfocuses exclusively on expressing recurring aspects of the user interface which can be reused in differentapplications contexts. The approach described in (Paternò 2010) goes beyond the creation of Service-basedapplications and enables arbitrary application classes, thus making the application development processcomplex. Several modeling and transformation steps have to be realized in order to create a final userinterface for accessing Web Services. In comparison, the approach described in (Feldmann 2009) focuses onpurely Service-based interactive applications. It enables a rapid development of this class of applications buthas got several shortcomings which are eliminated by our results. First of all, the approach is built upon anadditional design-time model for representing navigation and data flows between different Service frontends.This model binds the created application to a specific platform, thus making the transformation of anapplication developed once to several platforms difficult. Besides, even minor variations between differentapplications lead to the instantiation of completely separated models. Furthermore, the design-time tool usedwithin the approach targets end users without any programming skills which results in a simplification of thetool’s user interface abstracting from many technical aspects. Especially data type information is lost withinthe visual representation of the tool which is not desired in the case of developers with programming skillsand a basic technological understanding of the area of Web Services.On one hand, the goal of our research is to extend the concept of annotations for representing applicationspecificaspects instead of introducing an additional model. On the other hand, an authoring tool is developedwhich does not abstract from the underlying technology, providing more transparency for a developer.3. EXTENDED SERVICE ANNOTATIONSIt is obvious that the intention of Service annotations is changed by using them as means for representingdeveloped Service-based interactive applications. Instead of just representing recurring, applicationindependent information used in different application contexts, they become application dependent. As aresult, the disadvantages of an additional model disappear. The applied model is platform independent andonly those aspects have to be modeled which differ from the result of an automatic user interface inferenceapproach. Having a look at platform independent aspects, the models applied within the existing design-timeapproaches hold three types of information. Firstly, they specify which operations are used within the contextof the developed application, secondly, they specify the navigation flows between different operations and,thirdly, they point out the data flows connected to these navigation flows. As a consequence, the intendedService annotations have to be able to describe at least these three aspects. During our work, annotationshave been developed which fulfil this requirement. These annotations have been designed as an extension ofthe annotation model developed within the ServFace project. Thus we can apply the already existingannotations defined by this model and additionally the extended Service annotations without using differentannotation models.Figure 1 shows one of the annotations defined as an extension of the ServFace annotation model (theinterface DeltaAnnotation extends the class Annotation displayed in Figure 2 of (Janeiro et al. 2009)). Theannotation Application enables the specification of an application based on Web Service operations. Alloperations which are used within the interactive application are referenced by this annotation (via thereferences treatedOperations). Furthermore, those operations building the starting points of the navigationflow are pointed out (using the reference initialOperations). As other annotations as well, the introducedannotation can be bound to a specific language and to a specific platform. As a consequence, variations ofapplications do not lead to a complete reformulation of the developed application model but only to theintroduction of single alternative annotations.1 http://www.servface.org320