Refrigerated Containers Handheld
For a CT site refrigerated containers are crucially important. The contents must be kept refrigerated and if possible plugged in to ensure that the contents do not spoil. To enhance the monitoring of refrigerated containers an application was created for use on ruggedised handhelds. The handhelds run a version of Microsoft Windows Mobile and communicate wirelessly with a remote server to get and update information.
The application requirements were:
- Work in Windows Mobile.
- Communicate to and from a remote server using a REST interface.
- Function offline as the wireless coverage cannot be guaranteed.
- Simple and straightforward user interface.
- Display containers to be monitored at a location.
- Display detailed information on a container.
- Mark a container as missing.
- Report the current refrigeration values for a container.
The application is multi-threaded, fault tolerant and utilises a local database to store information gathered from invoking server services. Communications with the server are handled in a background thread allowing the user to continue to operate with no server communication. Refrigerated reports are queued until the device can connect.
Fork lifts are used to move containers to desired locations in a Container Terminal (CT) site. To enhance this process the upcoming container movements are transmitted wirelessly to the various fork lifts. The fork lift can choose which container movement it is going to action and then inform the controlling server with the results of the move. To handle this interaction a client application/backend server solution was constructed.
We built the application to include the following requirements:
- Able to run on both Microsoft Windows and Linux operating systems.
- Can function offline as the fork lifts move into and out of wireless coverage.
- The user interface is clearly visible in a variety of lighting conditions.
- Display a list of potential container moves.
- Able to allocate a container movement to a specific fork lift to stop several fork lifts attempting to perform the same container movement.
- Complete the container move indicating success or failure. If the move fails, then capture why it failed.
- Display supplementary information about the containers on the CT site.
- Be self updating. Application updates are loaded onto the server. The application detects the new software image when idle. The application then downloads the image, checks it for validity and installs it, updating the application automatically.
The server utilises a REST based service architecture using XML as an encoding scheme. The application is multi-threaded, fault tolerant and utilises a local database to store information gathered from invoking server services. wxWidgets is used to manage the user interface for both Microsoft Windows and Linux.