Web client for SCADA has exist since 90’s. Most of them uses ActiveX technology and all of them are fall under category of thick client, this mean, you cannot view anything remotely without prior installation of the proprietary content viewer. Furthermore the so called web SCADA execution and loading is so slow that practically impossible to work across Internet connection, but can only display within local area network. In those days, the available browser is the notorious IE6 even Microsoft wish to get rid of now, and the technology is either based on ActiveX or Java Applet which is too heavy for dial-up Internet connection.
Web technologies improved enormously after year 2000, especially after Scalable Vector Graphic (SVG) technology has been introduced by World Wide Web Consortium (W3C), the organization that maintaining the standard of web technologies’ specifications. W3C demonstrated an excellent case study of standardizing specification instead of standardizing proprietary product like I.E. browser. Adopting standard and open specification allows healthy competition to the benefits of end user, as we can see now you have the freedom to use Chrome, Firefox, I.E., Opera or Safari to browse the Internet. Crossed browser content further open out the competition space to smartphone and tablet industry and benefiting all of us when open technologies lowering the cost of ownership.
Some SCADA vendors that taking shortcut using anything but not maintained by W3C open standard are very much based on proprietary technologies, which including the old ActiveX and Java Applet which is now acquired by Oracle. Another newer proprietary technology by Microsoft is Silverlight but it remained closed and not platform independent. One typical failure of proprietary technology is the Adobe Flash, the large amount of Flash content was sort of replaced overnight when Apple declared discontinuation of Flash content. These SCADA vendors claimed itself as web SCADA to deceive ignorant customers but one obvious shortcoming of the so called web SCADA is they cannot run without prior download or installation of cumbersome plugin or extension. The proprietary content simply require thick client installation at client side and risking going obsolete at end user’s cost.
SVG plays one of the most significant role in making web SCADA available, simply because SCADA mimic is rich in graphic by its nature. And why is the existing gif or jpg images could not do the job? The answer lies in the name of SVG itself, SVG is vector based but gif & jpg images are raster based. Vector graphic is constructed based on mathematical instruction which can be changed on the fly which made SCADA mimic animation possible. Moreover it’s extremely lightweight as compare to raster graphic because SVG is actually text file as compare to raster graphic that is encoded in binary file.
Another advantage of SVG graphic is again lies in its name, “scalable”, this mean the graphic can zoom in for unlimited times without losing its sharpness at all. The graphic will remain crisp and clear regardless of the screen resolution, and hence made retina support possible. Since the SVG graphic can be scaled during run-time, the SCADA mimic would be able to fit according to monitor size or more accurately the screen resolution regardless of the difference between development and site machine. This get rid of a big pain of system integrators that mimic developed for one machine cannot port over to another specification of machine or else the mimic screen would either distorted, out of screen or worst case unable to display at all. This is a common pain point for legacy SCADA whereby the engineers will have to painstakingly readjust all mimic according to different screen resolution when development machine is not the same as site machine, and then the nightmare goes on and on when support is needed from office when the project has been delivered to site. Apparently this reworking of graphics hardly made known to the end user but becomes the victim to absorb the unnecessary redevelopment cost. Fortunately, the open web technologies will put the disadvantage of legacy SCADA to its end.
Credit to: Ecava IntegraXor Whitepaper