[td-td] process and discrete manufacturing standards

In respect to our landscape survey, we should take a look at the standards and approaches that have been developed for process and discrete manufacturing. It would be well worth searching for people with first hand expertise in these areas and considering what the IoT and the Web of Things has to offer compared to the existing standards for these domains.

The Electronic Device Description Language (EDD) is widely used along with the Field Device Tool (FDT) approach to defining software interfaces between applications and field devices. EDD is a vendor neutral text based format covering device descriptions, simple business logic and user interface elements, and can be compared to HTML. Interpreters are available for handheld diagnostic tools, and for Microsoft Windows PCs. EDDL is defined by IEC 61804-3.

The process and discrete manufacturing industry developed their own connectors and cables, as well as industrial versions of wired and wireless Ethernet LANs (PROFINET) for IP based communications. IEC 61499 defines a connected component architecture where connections pass events or values like booleans, numbers and strings. Each component has a control program that relates its inputs to its outputs. PROFINET component description (PCD) files are based upon XML.

The Web of Things provides a richer basis for defining components based upon W3C’s Resource Description Framework for semantics and metadata, along with a clean separation of the application logic from the communication patterns and protocols. The Web of Things can be compared with IEC 61499 in the way that things are modelled in terms of their events, properties and actions.

For the Web of Things, control programs can be written in general purpose programming languages or as state transition networks and similar formalisms. These operate on local proxies for things on other servers.  One thing can read or set a property on another thing, or invoke an action on that thing.  Things can likewise listen for events on other things.  Actions can be considered as analogous to passing a event to an IEC 61499 component, however, the Web of Things also allows actions to asynchronously return responses.

This suggests that IEC 61499 can be mapped into the Web of Things, but the reverse mapping will in general be harder.  The Web of Things is more general, and applicable to a broader range of devices, platforms and application domains. It provides a framework for discussion on how to handle security, trust, privacy, resilience, payments and so forth, as well as for discovery and composition from an open market of services on a global scale.

Any volunteers to help with a more detailed survey and analysis?

—
   Dave Raggett <dsr@w3.org <mailto:dsr@w3.org>>