Web gateway: a platform for industry services over Internet

This paper presents a novel approach for the integration of industrial applications over LANs, WANs and the Internet, based on emerging proven and robust technologies. Industrial applications are traditionally viewed with reference to a four layer hierarchical model. Fieldbus control networks are used in order to interconnect field and control devices at the two lower layers of the industrial communication hierarchy. The OPC technology is utilized in order to provide a universal I/O driver/interface for heterogeneous control networks. Different OPC objects deal with real time data (OPC DA), historical data (HDA) as well as Alarms and Events. DCOM presents the middleware connectivity software for the seamless integration of applications locally over the LAN. Due to the DCOM lack in firewall friendliness, the authors propose the use of pure HTTP and the development of a special entity, the Web Gateway, that presents a single point of entry for all different users, e.g. service providers, for the provision of integrated services in a uniform way. This gateway takes into account user profiles and utilizes a dynamic parser for the generation of dynamic html according to user rights. The presented architecture has been the core of a pilot implementation.