Writing Scripted Devices and Operations

BLU-ICE and the scripting engine within DCSS are both written in the TCL scripting language. One of the features of a scripting language is that code does not need to be pre-compiled to be executed. This greatly simplifies the writing and testing of scripts. BLU-ICE itself allows the user to open a command prompt, which gives the user access to the TCL interpreter running BLU-ICE. New scripts can be loaded from this command prompt and executed, allowing complicated or repetitive tasks to be somewhat automated.

There are several drawbacks to running scripts through the command prompt of BLU-ICE:

• The BLU-ICE must remain open during the duration of the script.

• The BLU-ICE executing the script must remain the active client during the duration of the script.

• Other open BLU-ICE's will not know what the intentions of the script is, and therefore would not be able to interpret intermediate results.

• The BLU-ICE running the script must have full permissions to perform all actions within the script.

• The performance of the script depends on the local machine that is running the instance of BLU-ICE.

An alternative to running a script in BLU-ICE would be to run the script as an operation within the DCSS scripting engine. This feature overcomes all of the restrictions of running a script through BLU-ICE, but it does have several drawbacks of its own:

• The name of the script must be added manually to the database.dat file.

• Changes to the script requires DCSS to be shut down and restarted.

• A user's permissions must be checked within the scripting engine before each command is issued, because the scripting engine has unlimited privileges.

In many cases, development of new scripts can be done first through BLU-ICE and ported later to DCSS when the script has been tested sufficiently.