Appendix E: External Server and Remote Services
WebRelay-10 Users Manual
Appendix E: External Server and Remote Services
Note: The following methods are supported by WebRelay-10; however, Xytronix Research & Design,
Inc. does not provide or support custom third party applications, or external web servers.
Accessing WebRelay-10 with Custom Software or Third Party Applications
Custom applications can send commands to WebRelay-10 for monitoring and control. The application
interface can be used to provide a custom user interface, access to multiple units in a single screen, and
allow for automation, logging, and other application-specific features.
Using an External Web Server
Rather than accessing WebRelay-10 directly from a computer, an external web server can be used. The
term “external” web server is used here to mean a separate web server (such as Apache or IIS) that is
not the web server built into WebRelay-10. In this scenario, users access custom web pages that reside
on the external web server and the external web server communicates with WebRelay-10.
An external web server can integrate multiple ControlByWeb products into a single control page. In
other words, the user may not be aware that he/she is using multiple ControlByWeb™ devices, but
rather the user sees an integrated control page for the entire system. In addition, the use of an external
web server allows programmers to create custom user interfaces that take advantage of the additional
resources typically available on larger web servers, including more memory and various web
programming languages.
There are two approaches that an external server can use to communicate with WebRelay-10 and other
ControlByWeb™ devices, Direct Server Control and Remote Services.
Direct Server Control
The first approach is for the external server to create a TCP connection whenever it needs to access
WebRelay-10. In this case, the external server opens the connection, sends commands and/or reads the
device, and closes the connection.
This method is ideal when the the web server and all of WebRelay-10 devices are on the same network
(without routers between them). In this case, the server can communicate with WebRelay-10 devices
directly and securely since data never has to leave the local network.
When the server and WebRelay-10 are on different networks, routers must be configured to allow
appropriate access. If a public network is used, such as the Internet, security precautions should be
considered.
Remote Services
The second approach is for WebRelay-10 to initiate a connection using the “Remote Services.” The
settings under the
Advanced Network
tab in the setup pages will enable the WebRelay-10
TM
to open a
TCP connection with an external server. Once the connection is open, the external server can send
commands and/or read the device. The external server can leave the connection open (so that it never
closes) or close the connection.
“Remote Services” is ideal for installations where the server and WebRelay-10 are installed on different
networks. This is especially useful when each
WebRelay-10 is installed on a separate private network. For example, if the user doesn't control the
network connections where WebRelay-10 is installed, “Remote Services” would initiate a TCP
connection over the Internet with the control computer. Since WebRelay-10 initiates the connection, the
control computer doesn't have to know the IP address of WebRelay-10. This means that WebRelay-10
can be installed using DHCP. In addition, no special router configuration is required. This makes the
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