Programming Considerations

For the most part, developing WaveLink wireless applications is no different than developing any other conventional application. Certain programming considerations must be kept in mind, though, to gain maximum performance from any WaveLink applications.

Display Size

The first programming consideration that must be taken into account is the limited and various display sizes of devices. Any information, either input or output, placed outside of these display limitations will not appear. Therefore, you must always keep in mind the display limitations of the devices that will be using your application when designing application screens. You may use the RFTerminal object to obtain display characteristics of the device. If the devices on your network use different screen sizes, you may want to use the RFTerminal object to dynamically position screen output. For example, you can program screen output one row from the bottom of the screen in lieu of setting a static row number.

Error Handling

The second programming consideration of WaveLink application development concerns function error checking.

You can check for returned error values when calling a WaveLink Development Library method within your application. To make your application function properly, you must check for returned error values after making an input call such as RFInput or GetEvent.

For example, on a disconnect command from the WaveLink Administrator a specific error message is returned to your application. This error message is returned to the first WaveLink function that communicates with the mobile device (for example, an RFIO method) before the device is physically disconnected from the network. Every subsequent WaveLink function following disconnect will then return the error message. Upon receiving this error message, you must instruct the application to exit. If this error message is not trapped at this time, the application can get caught in a loop and consume remaining system resources while waiting for further user input from a disconnected device.

File Extensions

Certain WaveLink objects will save files to RF devices using the following extensions. The extensions and their associated objects are listed below:

RFIO Object . .SCR

RFMenu Object . .MNU

RFTone Object . .TON

RFBarcode Object . .BAR

RFAuxPort Object . .CFG

When using these specified objects, it is not necessary to include these extensions when referencing files of the object types. If you reference these files using the RFFile object, though, it will be necessary to include the appropriate file extension (or ".*" for all file extensions).

User Environment Variables

The fourth and final programming consideration that must be taken into account when developing WaveLink applications concerns user environment variables. The WaveLink Server creates a set of environment variables for each connecting RF user. These WaveLink Server environment variables contain the same information about the RF user's device as that within the RFTerminal object. Since much of the information within these environment variables will remain static during a user session, it is possible to use certain device values without making a RF call as would be the case if you were to request the same information using one of the RFTerminal methods.

For example, the WaveLink Server creates a user environment variable that contains the device display width. Since a device's maximum display width will not change you can limit network traffic by using the width value from the WaveLink Server environment variable rather than making an RF call during the creation of an RFTerminal Object.

The Wavelink Server environment variables and their possible return values are listed below:

Variable Name	Type	Return Values
TERMTYPE	int	Raw terminal type. 1 – LRT 2 – VRC/PRC 3 – PDT 4 – WSXX 5 – PDT 68XX 6 – PDT61XX 11 – Palm Pilot 27 – CE, 2740 72 – CE, 7200 75 – CE, 7540 93 – Percon Falcon 5020 – Intermec Device 8000 – Windows Device 8001 – PPC 8002 – HPC 8003 – HPC Pro
TERMWIDTH	int	Terminal screen width in characters
TERMHEIGHT	int	Terminal screen height in characters
*TERMMAIN	int	Main battery state 0 - Good battery 1 - Dead battery
*TERMLITHIUM	int	Lithium battery state 0-Dead battery 1 - Good battery 2-Unit has no lithium battery
*TERMKEYSTATE	int	Terminal keyboard state 0 - Normal keyboard mode 64 - Capslock enabled
*TERMTIMEOUT	int	Keyboard timeout in seconds
*TERMBACKLIGHT	int	Backlight timeout in seconds
*TERMCURSORMODE	int	Hardware or software cursor status 0 - Hardware cursor 1 - Software cursor
*TERMCURSORSTART	int	Cursor start line
*TERMCURSOREND	int	Cursor end line
TERMID	string	Terminal ID Spectrum One - Terminal Id number Spectrum 24 - Terminal’s IP address
TERMVERSION	string	WaveLink Studio Client version installed on RF device
TERMDISK	long	Total device disk space capacity
TERMMEMORY	long	Total device memory capacity

*Use the RFTerminal methods to return the most current values for variables that may not remain static, such as a device's key state.

Additionally, the WaveLink Program Manager will also create two environment variables for each spawned application.

These environment variables are only available if your users logged in using the WaveLink Program Manager. These variables will not be available for your own custom applications.

The values for the WaveLink Program Manager environment variables are listed below:

Variable Name	Type	Return Values
USERNAME	string	The current user's name
USERSIGNON	string	The current user's sign on

You may add or remove additional environment variables to the WaveLink Program Manager at will. A recompile of the application WaveLinkPM.exe is all that is required.

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