Companies participating in a clinical trial usually utilize various kinds of information systems such as a repository, CDMS, EDC, ePRO, and eLab. In this paper, we develop an interfacing technology which allows those systems to exchange clinical trial data. The technology consists of a CDISC query format (CQF) schema and a clinical data agent (CDA). The CQF schema defines request and response messages for ODM and LAB data represented in XML instances, and the CDA is a software module that generates, exchanges, and interprets those messages. The CDA can be used to integrate the information systems for Web Services.