To integrate heterogeneous distributed systems, there exist various researches and developments for the purpose of its adoption into enterprise environment. However, when web service technologies are applied, it is difficult to adopt directly existing software system development methodologies, because of the peculiar architecture of web services, such as service provider, service requester, and service repository. M4WSD(Method for Wes Services Development) is a web service development process model and involves procedures and guidelines to develop web services based on a Use Case model that is elicited from a business domain in requirement analysis. In this paper, we focus on how to determine key realization decisions for each service. The assessment guidelines help you to structure the problem of determining implementation strategy.