Connecting the dots surrounding XML/Web services

Engineered Systems, May, 2004 by Ken Sinclair

What is XML? Why should I care? How did it become the hottest tool these days in controls? Also, what about SOAP or oBIX? How do they fit in? Who is doing all of this anyway, and where is it going? All fair questions. Whether you are new to XML as a concept or not, this article provides some background on its life thus far in our industry, on the other acronyms that pop up along the way, and on the multiple efforts to make the most of the little language that can enable big things.

For the usually slow moving building automation industry, the latest XML (extensible markup language)/Web services movement has been a bit of a blur, spawning a number of dot coms and dot orgs to share information with our industry. The purpose of this article is to provide you history, connection, and insight into these valuable resources.

IN THE BEGINNING, THERE WAS AN IDEA

I first heard about XML/Web services at the 2001 AHR Expo in Atlanta in a brief meeting with Eric Craton and Steve Tom of Auto mated Logic, held in the hallway of the convention center. Craton explained his vision of how Web services would change everything. I can still see the excitement in his eyes. As I grasped what he was talking about, my excitement also started to build. Craton warned me that all this stuff was pretty bleeding edge, and that many conventions needed to be established by the IT industry to make it really useful. Automated Logic's early entry into Web-based control with a full Java platform allowed them to provide a strong lead in how Web services might unfold. In January 2002, Craton helped me create a Web services forum on the Auto matedBuildings.com website.

Here is an excerpt of an article, titled "Information Model: The Key to Integration" by Craton and Dave Robin (also with Automated Logic), which provided the cornerstone of our Web services forum (htttp://www.automatedbuildings.com/news/ jan02/art/alc/alc.htm):

"What is the future of Web services in building automation? Let's look at the four trends in terms of Web services:

   * Content is becoming dynamic. A Web
   service has to be able to combine con
   tent from many different sources. That
   may include furniture inventories,
   maintenance schedules and workorders,
   energy consumption and forecasts,
   as well as traditional building
   automation information.

   * Bandwidth is getting cheaper. A Web
   service can now deliver types of content
   (streaming video or audio, for example)
   that was unthinkable a few years
   ago. As bandwidth continues to grow,
   Web services must adapt to new content
   types.

   * Storage is getting cheaper. A Web service
   must be able to deal with massive
   amounts of data intelligently. That
   means using technologies such as data
   base replication, LDAP directories,
   caches, and load balancing
   software to make sure flint scalability
   isn't an issue.

   * Enterprise computing is becoming more important. A Web service
   can't require that users run a traditional browser on some
   version of Windows. Web services have to serve all sorts of
   devices, platforms, and browser types, delivering content over a
   wide variety of connection types for a wide variety of purposes.

"The hypertext markup language (HTML) format was designed for webpages to be read by humans. Like a universal word processor format, HTML combines text, pictures, and formatting information so a browser can display it on a screen. HTML is not adequate for information exchange between computers, however, because it provides no information about the data that may be contained on the screen and no way to search for specific pieces of data. For Web services to address all of these needs, two other, more flexible technologies are crucial:

   * XML--XML is a technology for moving structured data across
   the Web or a corporate network. Like the object-oriented protocols
   described previously, XML documents include more than
   just raw data. An XML document includes a definition of the
   data structure, so the receiving computer knows what information
   is contained in which fields.

   * SOAP (simple object access protocol)--While XML is basically
   a file format, SOAP is a way of using XML over a network.
   SOAP provides a computer application with a tool that can
   read the data definitions in awe XML document and extract the
   required data. SOAP is to XML, what hypertext transfer protocol
   (HTTP) is to HTML.

"All of the major enterprise software vendors are fielding products and platforms that support the Web services architecture using XML and SOAP, including Microsoft.NET, IBM WebSphere, Sun Microsystems SunOne, Hewlett Packard Web services platform, Oracle 9i, and BEA Systems WebLogic, among others."

NEW GROUPS AND ALLIES

This blueprint for the industry was a harbinger of change, and at the 2002 AHR Expo in Atlantic City, I met with Paul Ehrlich of Trane. Ehrlich explained his vision for his company of building product based on Web services and how industry standards were required for this to happen. Committees and organizations, larger than the present industry, would be required.