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Jump Start IT
How you can use XML and Web Services to empower business systems with plant information
03/19/2003
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Here's a list of frameworks suppliers, and a synopsis of their offerings:
* Citect (http://www.citect.com): Its framework works with CitectSCADA software and Oracle databases, and uses .Net and XML to connect systems and SQL Server 2000 to access the database. Modules currently running on the .Net framework include Plant2Business Historian and Downtime Monitoring, an application that analyzes plant operations. Citect says that more .Net modules are in the pipeline. A framework system running at BHP Billiton's silver and lead mine in Queensland, Australia, uses all the software noted to monitor and analyze operations.
* Invensys/Foxboro (http://www.invensys.com): Invensys' framework is ArchestrA, and it includes Baan Protean ERP, I/A Series Batch Suite, .Net, SQL Server, XML, OPC servers, and Wonderware HMI/SCADA software. Invensys is a little unusual among control system vendors in that it has its own ERP system. The company enthusiastically embraced the new BatchML standard developed by the World Batch Forum and was able to demonstrate a working XML-based system based on its Baan ERP and an I/A Series DCS.
* Honeywell (http://www.acs.honeywell.com): Honeywell says XML, .Net, and Web Services are not enough to provide direct integration between plant floor systems and IT. Intervening software is needed. Therefore, Honeywell offers a range of software including Uniformance PHD, Business.Flex, OptiVision, and POMS, all of which can communicate with ERP systems via a "message-passing middleware approach." Honeywell says it uses elements of .Net, XML, and Web Services. For example, it uses XML to help integrate with Oracle systems.
* ABB (http://www.us.abb.com): ABB's Industrial IT framework is based on Microsoft technologies such as OPC, and is being updated to include XML, .Net, and Web Services. The services are based on the OPC XML DA specification, and will be made compliant as soon as OPC completes the spec. ABB also provides Web Services for data access and historians, all implemented under .Net.
* Emerson (http://www.emersonprocess.com): Emerson claims that it does not have a framework-type product. Instead, officials say Microsoft technologies are sufficient, so they have built XML, .Net, and Web Services into all their products. To support the exchange of information between its process automation systems and IT, Emerson offers PlantWeb Messenger, which is a XML/Web Services system. Emerson recently formed a partnership with Decision Management Intl. (http://www.dmius.com) to go after the FDA-regulated process industry. Both companies use the Microsoft .Net architecture, so it was easy to integrate DMI's web-based Regulus process manufacturing software with Emerson's DeltaV control systems, and with LIMS and ERP systems.
Get on the Edge
We said the third way for you to connect your control system to IT was via XML and Web Services. Just about every piece of new PC-based hardware or software you buy today will come with the Microsoft .Net architecture, so you get all the tools for XML and Web Services with it.
And, since almost everybody else in the software world is connecting everything via XML and Web Services, there is no reason why you shouldn't do the same. All you have to do is invoke Rule No. 3 (see sidebar, "Rules for Working With IT").
Unless, of course, you don't trust Microsoft. Or vendors in our industry.
"Be prepared for lots of people to say they are Web Services or .Net-compatible," warns Kennedy. "The vendors learn the buzzwords before the users."
Still, we are almost there with XML and Web Services:
* The standards-makers are coming up with XML schema that will work in a process plant. It's not all here yet, but it's coming, like a big freight train.
* XML schema is public, not proprietary, so you can't be tied up by a proprietary vendor system.
* IT vendors are opening up their software to allow XML and Web Services communications. SAP was the biggest holdout, but now it's on board. SAP made it legit.
* The software business has gotten a lot more competitive, and vendors are willing to bend over backward to land customers. You are in a perfect situation to demand concessions from vendors, so go for it.
Even if you are not ready to launch an integration project, you should prepare for the future:
* Only buy software that supports XML and Web Services.
* Only buy hardware that supports Ethernet communications.
* Don't buy anything that reeks of being a proprietary product. Stay open.
* Do it yourself (Rule No. 3).
XML and Web Services are the bleeding edge of technology, but they certainly are the wave of the future. Like the Windows operating system, Ethernet communications, objects, and fieldbus technology, to ignore XML and Web Services at this stage would be foolish. Sure, there are more tried, true, and reliable older solutions today, but Web Services is the future. Avoid using it at your peril.
Sidebar:
XML and Web Services
All data is encoded in some way. Standard text and numbers have been encoded in ASCII for years. In recent times, the computer wizards created markup languages such as HTML and XML.
In general, HTML describes how information is rendered; XML describes what it is and how it is used. If you have ever designed a web page, you've worked in HTML, which defines fonts, type sizes, and format. For example, PV1 = says that "PV1" will be printed in 10 pt. Book Antiqua. If a document containing this HTML code is retrieved by any web browser, it will be displayed in the proper font and type size.
XML, on the other hand, defines what the variable is; for example, flow>PV1. Any compatible software program receiving this variable will know, from the XML code, that it is a flow variable. Other XML definitions will provide units of measurement, date of last calibration, time the measurement was taken, and so on. Be advised that all these definitions are still in the works.
Here's an example of XML as defined by the World Batch Forum's schema (see sidebar, "Is XML Ready for Prime Time?"):
Schema definition:
Don't worry, you don't have to encode it. Software programs do that for you (see below). Once a data file is encoded in XML, it becomes a document. A DTD (document type definition) describes its contents, such as the XML version of SAP's NetWeaver system. Most likely,
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