Whether looking up a customer's account, checking to see what's in stock or verifying a price, virtually all enterprise applications need to extract data from more than one source. And to meet the demands of their users, applications must retrieve the data quickly, deliver it in a form that's meaningful, and make sure the information is off-limits to all but those authorized to access it.
             Accomplishing all that is an ongoing challenge for developers. For one thing, unless the application and the data source rely on the same syntax, the application cannot simply issue commands to call data directly [1]. To get past this hurdle, developers depend on data access technologies, such as those provided by J2EE or the .NET Framework, to enable communication between applications and data source that don't speak the same tongue. Although data access technologies are increasingly automating the process of getting the tow parties to talk - and some rely on open standards such as XML - using them still requires developers to do a fair bit of custom coding.
             A second hurdle is staying one step ahead of hackers, who misuse their smart to commit malicious acts, such as stealing credit card numbers from e-commerce sites that keep customer data on their servers. Safeguarding such information requires an ongoing effort on the part of the developers and IT professionals who must outsmart hackers to ensure ironclad security. To decide which controls to use, information system builders must examine various control techniques in relation to each other and to their relative cost-effectiveness. A control weakness at one point may be offset by a string control at another [3].
             Also complicating data access matters is the increasingly sophisticated nature of the queries posed by users of business applications [1]. Straightforward requests for information, such as a customer's account number, require an application to query a single d...