Nowadays service-oriented architecture (SOA) has emerged as one of the main approaches to be used in software development, mainly in business process automation and systems integration. It uses loosely coupled autonomous network components called services, which can be later be reused in other solutions. These services often are exposed as XML Web services. To facilitate the development of solutions which use Web services and to increase availability of such services special registries are used, i.e. UDDI (Universal Description Discovery and Integration). Although the developer can query registries for appropriate services, the registries often offers only limited query parameters to use or do not provide information regarding to how does the web service perform its task. In these cases only input and output parameters are known. For example, there are three Web services into registry and they all return the document count, but each of them acts differently if the caller is not authenticated. To choose the most appropriate Web service, one either must know the design of all three services or try them all and then make the choice. It is possible to publish the execution algorithm of the Web service in its metadata using industry standards UML (Unified Modeling Language) and XMI (XML Metadata Interchange). The Web service developer describes it using UML activity diagram and exports it to XMI – many of UML design tools provide such functionality. When the Web service is being published in the registry, the URI to generated XMI document is appended to its metadata. After the querying the registry for appropriate web services, each XMI document of every service is then downloaded and parsed, generating an image of the execution algorithm in result. After the evaluation of these images, the developer can easily choose the most appropriate Web service to perform given task.