A composer of integrated systems solves the technical problem of enabling graphical user interface applications (GAPs) to interoperate (e.g., exchange information) with each other and web services over the Internet, effectively and non-invasively. The system provides a user friendly visualization mechanism that interacts with an accessibility layer to enable organizations to economically and easily define web service driven information exchange between GAPs, by performing point-and-click, drag-and-drop operations on GAPs. The system allows users to rapidly create integrated systems composing GAPs enabled to interoperate with other GAPs and web services, so that organizations extend the life-cycle use of their legacy GAPs in business operations.