Service Oriented Architecture (SOA) has become the prominent distributed computing paradigm nowadays. One of the technologies that enable the running of SOA is web services. In its nature of similar to peer-to-peer communication, web services involve customer who requests for the service and provider who provides the service. As a result, web services implementation requires a contract agreement so that both parties will get the value for money they invested. The objective of this paper is to present the literature review on monitoring for violations of this contract. Based on the literature study, this paper proposes a monitoring model to monitor compliance of vague non-functional requirements specified in the contract. The proposed research implies more realistic way of describing web services non-functional requirements and uncomplicated requirements specification as the model is focusing on inexperienced users. © 2012 IEEE.