Developers guide

Chapter 13: Remote Sockets
Overview
Psion Teklogix Mobile Devices SDK Developers Guide 79
13.1 Overview
Sockets permit applications to communicate across a network with no dependence on the network
protocol. Psion Teklogix Remote Sockets is available for narrowband systems on the following
devices:
• 7530
• 8525
• 8530
The Remote Sockets API is only available for programming in C++, not in Java or .NET.
13.2 802.11 Systems
On Psion Teklogix 802.11 systems running Windows CE, the Windows Sockets 2 API is available
from Microsoft. For further information refer to the following links on MSDN:
http://msdn.microsoft.com/en-us/library/aa454342.aspx
http://msdn.microsoft.com/en-us/library/ms740673.aspx.
13.3 Narrowband Radio Systems
On a Psion Teklogix narrowband radio system, communication between a Psion Teklogix com-
puter and the network controller uses a proprietary radio protocol. Remote sockets enable a
Windows CE-based Psion Teklogix computer to communicate with a remote host using sockets.
This implementation is a reduced Berkeley Software Distribution-style (BSD) interface.
Remote sockets require a controller-based Psion Teklogix system implementation. Remote
sockets are implemented using a proxy mechanism. Any socket calls made by the Psion Teklogix
computer are directed to the network controller. The network controller in turn makes a native
socket call to the remote host. The results of the proxy call are returned to the Psion Teklogix com-
puter by the network controller. This mechanism allows the Psion Teklogix computer to appear to
be using Windows sockets over a narrowband radio system.
This implementation has several advantages. Remote sockets allow Psion Teklogix computers to
connect to hosts, and perform many functions that would not normally be available on a narrow-
band system. The remote sockets API provides a consistent, well-known interface familiar to
software developers. The remote sockets protocol reduces the bandwidth required to less than is
needed on a wired sockets implementation. The use of remote sockets also places much of the pro-
cessing duties on the controller, which can handle multiple sockets and high volumes of data better
than the hand-held or vehicle-mounted computer.
13.3.1 Remote Sockets Proxy
The network controller runs the Remote Sockets Proxy software. This interfaces with the remote
host on behalf of Psion Teklogix hand-held computers, and relays information between them.
13.3.2 Starting A Remote Sockets Connection
PsionTeklogix::RemoteSockets::startup initializes the remote sockets feature and must be
called before any other API element.
13.3.3 Ending A Remote Sockets Connection
To end a remote sockets connection, call the PsionTeklogix::RemoteSockets::terminate func-
tion. This function must be called before the application terminates.