Networking & Communications

XML's Promise

November 1, 2005 By: Tom Kevan Sensors

Tom Kevan

Tom Kevan

We will reap the full benefits of this data integration tool when the software that collects our data speaks the right language. And the right language to facilitate sharing information is XML.

Information is the name of the game. It's the Holy Grail, the currency that we all trade in, from the shop floor to the boardroom. Everything in the data chain, from a 30¢ sensor to a $1 million enterprise software package, is designed with the ultimate goal of getting the right information to the right people. The best route to get us there is the Internet-or at the very least, the network. And right now, one of the flashiest vehicles on the highway conveying that information is XML, or Extensible Markup Language.

One of the first explanations I came across described XML as a meta-language, written in SGML, that lets you design a markup language. For most of us, that's clear as mud. A more accessible explanation would start by saying that XML is about defining the content of

XML, or Extensible Markup Language, can help you share your data more efficiently, both within your company and across your industry. Here?s what you need to know.

documents. When you define content, you create structured information. This concise, easy-to-understand data-description language provides a standard method of organizing and marking up data in a way that clearly indicates its structure and meaning. XML achieves this by letting you create customized information labels, called tags, to describe the meaning of the information being conveyed. For example, you might have an alert message containing a <sensor fault> tag. This ability to create customized, context-rich tags makes XML better than other document format languages, such as HTML.

XML's system-agnostic architecture enables data exchange across heterogeneous platforms, languages, and applications, simplifying the distribution of information within companies and their applications.

But we're not out of the woods yet. While XML provides a general language description it doesn't provide tags specific to any industry. To extend these language descriptors, a number of vertical standards committees were formed to define tags that describe the topology of information exchanges specific to their businesses. For example, leading information technology companies have defined and implemented a common set of standards called RosettaNet for e-business, supporting their processes between supply chain partners. Another group created a standard called OPC, or OLE for Process Control, to facilitate the types of interactions typical of process I/O hardware, such as PLCs, DCSs, and direct I/O boards. In doing so, the OPC Foundation customized XML for device communications.

So where do sensors fit into the picture? Most sensors don't have the intelligence to handle XML, but XML crosses their path where they link with a controller or an I/O board. The sensor's signal goes through an I/O board or PLC, which takes the analog or digital signal and changes it into the language of the network, or 8-bit bytes. The controller (e.g., PLC, DCS) or I/O board converts the sensor's data to XML and communicates those data with other applications running on the factory floor.

XML holds great promise, but it's too soon to get giddy about the situation. Steve Sprague, vice president of product strategy for Seeburger Inc., an execution enterprise software vendor, recently told me, "XML is not a panacea to allow applications to share information. Remember that the majority of applications that companies use are not XML-enabled. However, software vendors are trying to make their new software packages XML based. Leading software providers like SAP and Oracle are going that way."

XML needs more work and time before we can make use of the data-integration benefits it promises, but we are headed in the right direction. According to Chris Will, CTO and Vice President of Engineering for Apriso Corp., an execution enterprise software vendor, "The trend is toward XML everywhere."

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