asily customizable and configurable software is becoming increasingly important, and a flexible interface for searching is one way in which software is becoming more configurable. The key to achieving flexibility is through using metadata. This discussion will take a look at how you can use metadata to create a flexible interface that improves users' ability to search for stored information while minimizing the overall complexity that comes with search filters.

Consider an application that stores customer, item, and order information in a database. The interface for searching through orders could apply any number of filters, but presenting all possible combinations together can very quickly become overwhelming for users. It is often beneficial to allow some customization or configuration for choosing the appropriate filters based on several factors including the business process, the role of the individual, or those that are specific to the user's needs. With traditional query templates, the complexity grows quickly with every new search filter that is added. However, by using metadata to model a query and its filters, you can reduce the complexity of the software, while creating a more flexible solution.

Creating Filter Metadata
Metadata can be loosely defined as data about data, or in this case search-filter data about order data. The World Wide Web Consortium (W3C), the group responsible for XML standards, recommends using Resource Description Framework (RDF) for representing metadata (in XML or other formats). You can store RDF in a variety of formats, but the example discussed here will use an RDF/XML file because it has the widest support. XML tags are used to structure the file format of RDF/XML. The outer tags represent the resources, their nested tags represent properties, and inside the property tags is a property value, which may be text or another resource tag.