Web Services

I keep talking to large organizations that all have the same need. They want a standard way to access all the devices on their network. They want to be able to identify a device, change its configuration, download new firmware, view diagnostics and everything else in an open standard way where they can use the same tool.


That’s a pretty tall order…


It’s tougher for an organization that relies on lots of devices from outside vendors. If you’re a diaper manufacturer, for example, it’s not as hard. If you’re Kimberly Clark or Procter and Gamble, you pretty much have a lot of control over the entire machine, packaging included. You have XX diaper machines and they are nearly all alike.


But if you’re a major food manufacturer making endless variety of foods, every machine is very different. You’re baking cookies over here. You’re frying potato chips over there. And the packaging is very different.


And a lot of the time these machines are short runners. They exist for 18 months and the snack food is discontinued to be replaced by something totally different. You think you have problems on the factory floor? How would you manage your manufacturing process in a world like that?


Web Services could be your answer.


Web Services allow different applications and different platforms to exchange data. Web Services provide you with:


  • Standard application components that can be executed remotely
  • A standard that is built on all the standard protocols you already have in your system. It’s an application interface to your devices built on HTTP (what your internet browser uses), XML (eXtensible Marking Language) and SOAP (Simple Object Access Protocol).
  • Components that are self-describing. The services can be identified and described by interrogating a device from the network.


Web Services go a lot farther than the diagnostics example I described above. Because they are built on a standard encoding mechanism (XML) and a standard transport mechanism (SOAP) they allow completely non-compatible platforms (ARM & QNX) to talk to a Oracle Database on a small business server.


You need 3 basic services running on your platform to implement web services.


SOAP – A standard way of exchanging data and application commands using XML over HTTP interface.


WSDL (Web Services Description Language) – A mechanism for locating Web Services components.

UDDI  (Universal Discovery, Description and Integration) – Essentially a directory of all the web services that are available to you.


Needless to say this is a very complex topic that could take a week to describe fully; much more than I have in this forum. The big take away from this discussion is that there are mechanisms for opening up vendor devices and easily integrating them using standard mechanisms into your factory automation system.