Next, it had to be determined if the selected software systems provided a programming interface (API) or if an interface could be developed. This was achieved by developing prototypes on the basis of the use cases and requirements, with the goal to identify opportunities for integrating the software systems with each other. For each software system, key features were defined that had to be realized by the prototype. The prototypes should show if the features of the underlying software system could be accessed through its interface.

Based on the prototypes, the effort, cost and time for the development of the whole EC/EB system could be estimated. This estimate was used to verify the "time-to-market" that was aimed for by marketing, and to plan accompanying measures like advertising etc. In the case of the IPSI electronic commerce portal, more ressources were necessary for the development of an interface to integrate MS Outlook 2000 than for the development of the communications subsystem based on Java libraries. The effort required to integrate the partner database legacy system was relatively low since the adaptor could be realized using XML [11].

However, this is not always the case. Depending on the type of legacy system, integration may be more difficult. For example, under some conditions the integration of an SAP R/2 system with an electronic commerce system can only be achieved through the generation of batch input folders.

Figure 4. Prototype development subprocess model.

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