Reliable Sequencing Of Application Programs - Symbol MK2000 MicroKiosk Product Reference Manual

MK2000 MicroKiosk Product Reference Guide
Table 3-3. Startup Program, Parameter Descriptions (Continued)
Parameter
Waiting For Whether the startup sequence should wait for this program to complete before
Completion launching the next one, typically set to FALSE. See Reliable Sequencing of
Application Programs on page 3-6 for a more detailed description.

Reliable Sequencing of Application Programs

The Delay before launch and Wait for Completion parameters can be used to set the startup
process parameters:
• If an application requires a definitive order of execution
• To provide a signal between components to detect failures
• To verify that local or networked resources are available before the main
application launches.
The Delay Before Launch parameter can be used to achieve a fixed delay in the launch
sequence. However, this is not a robust way to ensure correct system operation. The
recommended method is to write a separate program, with or without a user interface, that
performs whatever checks are required, and then terminates, possibly setting a registry
value or filesystem flag to indicate success. Set the Wait For Completion flag for this
program and run it before running the main application(s).
For example: use the program to confirm connection to a database server or web site that
the application relies on before launching the application. This is suitable for web-based
applications where lack of control over the application software limits the ability to build
contingency into the startup process.
For failure recovery, the application could be set to reboot the unit after a timeout was
exceeded if a necessary resource became unavailable, and a startup program could check
for its return, possibly presenting an "Out Of Service" screen. When the resource returns,
the application would launch normally.
3-6
Description