The days of security systems operating in splendid isolation from other organizational systems are over. Customers are increasingly demanding that security system components interoperate with each other, with their IT systems, and with a host of other systems ranging from HR to marketing to building automation. They are not content to use outmoded, patchwork technologies to accomplish such integration. Rather, they are insisting on compliance with industry standards, open interfaces, and network-friendly, IP-based solutions that leverage existing resources to their best advantage.

That's why many manufacturers' products support an XML-based Application Programming Interface (API), a tool that allows them to interoperate easily with other IT and security systems.

Using the XML markup language for data exchange, integrators can, for example, connect an access control system to virtually any other information system that supports the HTTP protocol, regardless of underlying hardware, operating system, or programming languages.

API: Tools for Computer Interoperability
Before we begin to discuss what exactly XML does, it's best to understand what an API is. An API is a set of functions that one computer program makes available to other programs so they can talk to each other directly. Put another way, it is a set of tools for programmers that allows one computer system to use the services offered by another.

An example familiar to all of us would be online services such as Google Maps or MapQuest: both provide APIs that work behind the scenes to allow your company's website to invoke dynamic mapping capabilities from either of these online services.

The types of services provided by an API depend on the type of business that designed it, or the type of problem the underlying program was meant to solve. For example, a consumer-oriented business like Amazon provides a "retail API" that allows third parties to set up their own storefronts, with Amazon processing transactions in the background. Likewise, an online access control company like Brivo offers an API that provides a range of services for managing the relationship between identities and physical security. Both examples use the same underlying technologies, but for different business purposes.