ABSTRACT
While chapter 2 described concepts in database systems essential to web data management and chapter 3 discussed data mining and its impact on the web, this chapter describes interoperability technologies that are also essential to understanding web data management. The different database systems have to interoperate with each other on the web. Therefore, in this chapter we discuss various types of multi database systems. First we provide an overview of distributed databases. Then we discuss interoperability of heterogeneous database systems. Multi-database systems also include federated database systems and client-server databases. All these database systems have to operate in the web environment. Finally we provide an overview of the issues involved in migrating legacy database systems. This is because the legacy databases and applications on the web also have to be migrated to take advantage of new hardware and software.
