Because many critical resources reside at the corporate data center, data center managers need to understand their companies\u2019 externalization strategies and goals.Externalization means providing selected third parties (customers, suppliers, business partners) with access to critical resources (information, applications) to enable more effective business operations.Virtually every organization is externalizing to some extent. Preliminary research from Nemertes Research\u2019s upcoming benchmark on externalizations indicates that 100% of enterprises participating in the benchmark deploy what we call \u201cshallow\u201d externalization, which is user-to-system integration. Eighty-three percent deploy \u201cintegrated externalization,\u201d or system-to-system integration. And another 8% are using \u201cdeep externalization,\u201d which is remote processing techniques using grid computing. Moreover, virtually all organizations plan to accelerate their externalization initiatives over the next 12 to 36 months.Data center managers should therefore be familiar with the architectures required to enable each of these forms of externalization.In shallow extranets, an external user interacts with a system. A typical example is an e-business Web site, in which an external user connects directly to a company\u2019s Web server (running Internet Information Server or Apache) and provides a user name and password. The user is authenticated and is given access to areas of the company\u2019s Web site that are not available to the general public.This is the simplest form of an extranet. A retailer could use such an extranet to provide clients with custom information about their account or provide a self-service function. Another company could use shallow extranets to provide information, order-entry, or billing facilities to partners or suppliers.An integrated extranet is an extranet in which two or more companies exchange data directly, system to system. The integrated extranet provides the infrastructure for communication and data translation between back-end systems. For example, an integrated extranet might connect the supply-chain management system of one company with the supply-chain management system of one of its suppliers. When a user enters an order into the system, it is transmitted electronically and is entered automatically into the ordering system of the supplier.Most business extranets today are still based on Electronic Data Interchange, but EDI is gradually being superseded by XML-based extranets. XML provides much more flexibility, modularity and component re-usability. Internal system data is either stored and manipulated in XML, or is converted from a proprietary system to XML prior to transmission to the other system. Some systems also provide EDI-to-XML translations to connect legacy EDI systems to XML extranets.Finally, leading-edge enterprises are exploring \u201cdeep extranets,\u201d which involve remote processing and computing. While most organizations scoff at the notion of deploying grid computing techniques for the purposes of externalization, indications are that this approach is starting to take hold. Data center managers: Take note.