Technical Reference Manual - InduSoft

About thin clients and mobile access
The ISSymbol ActiveX Control is used for both the Internet Explorer-based and Secure Viewerbased
browsers.
Web Tunneling Gateway
The (Primary) Web Tunneling Gateway is a bridge between the Web Server and the Data Server
that is used in one of two situations. The first is whenever data security is required (e.g., IWS
data exchanged with the Thin Client needs to be encrypted). The second situation is when the
Data Server is "hid" behind a corporate firewall, and only the Web Server IP address (or URL) is
exposed.
IWS supports a backup (Secondary) Web Tunneling Gateway to be used if the Primary Web
Tunneling Gateway becomes unavailable. The Thin Client will automatically switch over to the
secondary Web Tunneling Gateway.
The Web Tunneling Gateway is automatically installed when InduSoft Web Studio is installed on
your PC if the installation program detects that IIS is present.
Note:
• The Web Tunneling Gateway is automatically installed if IIS is detected during the installation
process. Otherwise, it must be manually installed.
• The main function of the Web Tunneling gateway is to encapsulate data packets in HTTP or
HTTPS for communication through a firewall.
ISSymbol Control Layer
ISSymbol is a component designed by InduSoft that is able to display the screens created with IWS in the Web
browser and exchange data (tag values and history data) with the TCP/IP server module of the project. On the
Thin Client station, the Web browser (e.g., Internet Explorer) is the container that hosts the ISSymbol control.
ISSymbol works as a control layer between the project and the Web browser — equivalent to the Java Virtual
Machine for Java-based applications. This approach provides a high level of security because ISSymbol does
not allow the project to access the operating system directly.
When the Web browser downloads the HTML page specified by the user, it checks for ISSymbol control
registration on the current computer. If it does not find it, the browser attempts to download registration
from the URL specified in the project settings (Thin Client on the Project tab of the ribbon). The Web browser is
not able to display the screens from the project if the ISSymbol control is not properly registered in the Thin
Client station.
Caution: Make sure your Web browser is enabled to download signed ActiveX controls, in order to
download ISSymbol automatically. Otherwise, you will need to register ISSymbol manually in the
Thin Client station. Check your Web browser's documentation about security settings if you have
questions about how to configure these settings.
Manually Installing the ISSymbol Control
You can also install the ISSymbol control manually in the Thin Client station. The procedure to install
ISSymbol in each operating system is described below:
Windows PC
1. Copy the following files…
• […]\InduSoft Web Studio v7.1\Bin\ISSymbolReg.exe
• […]\InduSoft Web Studio v7.1\Bin\ISSymbolVM.cab
…into any directory of the Thin Client station. Make sure that both files are stored in the same directory.
2. Run ISSymbolReg.exe to register the ISSymbol control on the PC.
Windows Embedded
1. Determine the OS version and processor type of the Windows Embedded device, and then find the
corresponding redistribution folder in the IWS program directory:
[…]\InduSoft Web Studio v7.1\Redist\CE_version\processor_type\Bin\
InduSoft Web Studio Page 441