In modern distributed computing, vast amounts of data are stored in many different formats, employing different storage solutions. OGSA-DAI 3.0 is a middleware software solution. It provides application developers with the means to access data distributed across multiple platforms with different native access mechanisms. Data integration can take place at the server and deliver results using a variety of protocols and mechanisms within OGSA-DAI. It accomplishes this by using a highly flexible and extensible framework which can accommodate different types of data resources, such as XML databases, relational databases or files, different operations such as transformation to different formats, selection or filter operations. The framework can be extended by a developer to provide customized functionality for project specific tasks while using generic functions for common tasks such as database querying. This paper presents an overview of OGSA-DAI and how it tackles data access and integration through a set of example use cases.