The typical user base for computer applications has transformed, over time, from mostly technically-oriented individuals to include a vast range of the world's population - the majority of whom have little to no technical proficiency. As such, user interfaces have evolved from text-based shell input into multimedia interfaces which typically provide support for receiving input from a number of disparate devices that are operated in conjunction to manipulate a given program. A problem arises when applications add in support for explicit devices; which leads to strong coupling between the underlying code and the defined set of devices that they support. In a nutshell, support for new peripherals almost always requires that the original application be recompiled and /or its internal configuration modified to incorporate the given device(s). Portal, an interaction independence framework, seeks to add a layer of abstraction between arbitrary application code and the devices they support; allowing developers to deal in the realm of abstract program actions instead of crafting code to handle a variety of concrete device inputs. This should eliminate the need for custom device-tailored code for each user-wielded peripheral that an application must support and will enable application device support to be managed via configuration changes to the Portal middleware framework, rather than being hard-coded into an application. This thesis will define the conceptual design of the Portal framework while, at the same time, elaborating on the role that web services will play within it; investigate two pervasive service-oriented architecture paradigms, SOAP and REST, in order to gauge their potential effectiveness in meeting Portal's underlying back-end data transmission requirements; provide implementations for the Portal service-oriented architecture and data model; and, finally, critically evaluate both implementations with an emphasis on their performance with regard to both efficiency and scalability. / Master of Science