OPC to Web using AJAX
DataHub Web Browser - AJAX support
Using the DataHub Web Server you can easily create dynamic web pages that can be viewed on any browser, including web enabled phones and hand-held devices. AJAX technology has been around for a few years and is fast becoming the platform on which the next generation of Internet applications will be delivered.
Javascript code embedded in the page is interpreted by the web browser. The Javascript code periodically sends commands to the DataHub to update the data on the page. The data updates automatically, without the need to refresh the page. This is also called "client-side scripting".
The DataHub Web Server supports both traditional Polling AJAX and our new Streaming AJAX displays that significantly reduce the load on the server when dealing with a large number of display points and fast update rates. Polling AJAX and Streaming AJAX differ as follows:
- Polling AJAX web pages make requests for new data to the DataHub on a polling cycle. This means there is usually a higher load on the CPU compared with Streaming AJAX, but in many cases the update speeds are comparable.
- Streaming AJAX web pages are highly efficient at moving data, which means they use very little system resources and much less network bandwidth compared to Polling AJAX applications.
We provide you with simple examples that show how to get your data into a web page using regular JavaScript and a standard web browser.
Demo OPC to Web on your own computer
Want to demo this technology on your own computer? It takes only a few minutes to download and install the new DataHub Web Server Demo. No programming required. |
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Server-side benefits:
- Streaming AJAX technology significantly reduces the load on the server compared to Polling AJAX, especially with higher update rates and a larger number of display points on the page.
- Polling AJAX remains an attractive option to many users who do not need high update rates.
- No other web server software needs to be installed.
- No point count limitations. Supports virtually an unlimited number of data points.
- Web sites can be password protected and connections secured using SSL.
Browser-side benefits:
- AJAX is supported by nearly all web browsers on the desktop, hand-held devices and cellphones.
- No special plug-in or ActiveX objects need to be downloaded.
- Page starts to display real-time data as soon as the connection to the DataHub is established.
- Standard AJAX implementation allows for completely customizable web pages.
- Fully bi-directional data flow, so you can read and write data in the web page.
- No page refresh required. The web page continues to display new values as soon as they change in the DataHub, without the user having to do anything.
More Information
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