Technical Reference Manual - InduSoft

About thin clients and mobile access
• Make sure the TCP/IP Server (in the project's Tasks) is running
• Be sure IIS is set to the correct Home Page (root directory).
• Be sure the Port addresses are correct (HTTP – Port 80, HTTPS (SSL) – Port 443, Data – Port 1234)
• Make sure you firewall has these ports open
• If you are using a Windows Embedded device, be sure ISSymbol is properly loaded and registered
• Be sure your runtime license supports the Web Client configuration
• If you get a Page cannot be displayed error message,
• From the browser, ping the server IP address
• Stop and restart IIS
• Be sure the MIME types are properly set
• Make sure you updated your web pages (i.e., Save as HTML) and use the Verify Project tool if you
change any Web settings.
• Verify the Windows security settings are properly set
• Be sure that the Screen name (and Web Page name) do not have any spaces in the name
• If the web pages are incorrect:
• Be sure you are pointing to the correct primary URL
• Be sure your backup URL (if you use it) has the correct (updated) web pages
The Underlying Technology
In a IWS project, there are several components used to implement the Thin Client capability.
These components are:
Data Server
Web Server
Web Browser
ISSymbol
The Data Server is built-in to the IWS runtime. The Data Server has direct access to the IWS
Project Tags Database (runtime) and is responsible for working with ISSymbol to make sure any
Tag data being displayed on a Web page at any Thin Client is updated with the latest value(s).
IWS can support a backup or secondary Data Server that will be used should the Primary Data
Server become unavailable. The Thin Client will automatically switch over to the Secondary
without user intervention required.
The Primary Web Server is responsible for providing Web pages on demand (i.e., when requested
by the Client) through navigation to various project screens by the Thin Client. The Web Server
communicates with the Thin Client via HTTP protocol over TCP/IP. SSL (Secure Socket Layer)
encrypted communications can be enabled. The Web Server does not need to reside on the same
PC as the IWS runtime project. In fact, the Web Server could be a non-Windows corporate Web
Server. However, the Web Server needs to have access to the HTML files that are the project Web
pages.
IWS supports a Secondary Web Server that will be automatically switched to (by the Client) in
case the Primary Web Server becomes unavailable.
The Web Browser is located on the Thin Client PC and provides the graphical interface function
with the user. Web pages (HTML) is passed to the browser via demand ("pull") and data is
"pushed" to the browser by the Data Server whenever a Tag or Tags referenced on the Screen
displayed on the Web Client is updated in the Tag Database.
ISSymbol is a InduSoft-provided ActiveX Control that facilitates the interaction between the
browser on the Web Client and the Web Server as well as the Data Server. There are ISSymbol
ActiveX Control versions for Windows XP/Vista/7 and all Windows Embedded platforms.
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