Database middleware systems require the deployment of application-specific data types and query operators to the servers and clients in the system. Existing middleware solutions rely on developers and system administrators to port and manually install all this application-specific functionality to all sites in the system. This approach cannot scale to an environment in which there are hundreds of data sources, such as those accessed by the Web and even more custom-tailored applications, since the complexity and the cost involved in maintaining a code base system-wide are enormous. This paper describes a novel metadata-driven framework designed to automate the deployment of all application-specific functionality used by a middleware system. We used Java and XML to implement this framework in MOCHA, a middleware system developed at the University of Maryland. We first present the kind of services, metadata elements and software tools used in MOCHA to automate code deployment. Then, we describe how the features of MOCHA simplify the administration and reduce the management cost of a middleware system in a large scale environment.