Wednesday, March 23, 2016

Property Changes In TDI - On The Fly

This week, I was asked if it was possible to update a TDI property while the TDI server was still running and, if so, how to go about doing it.

The reason for wanting to do so was akin to injecting a property into TDI at run-time so that it would "safely" shutdown an Assembly Line at a sensible point of processing. Now, there are many ways to address this actual requirement, but the fundamental question of how to inject a property into TDI is certainly something that can be explained easily.

tdisrvctl
The tdisrvctl command is a terrific command for communicating with a running TDI server. In order to communicate with the TDI server, you merely need to supply some key information, such as the Port Number that the TDI Server API is listening on, and some means to identify yourself using the TDI keystores. Finally, you supply an "operation" for the TDI Server to perform. Manipulating properties can be performed with the "prop" operation. In summary, tdisrvctl needs the following parameters:

  • -p {port}
  • -K {keystore}
  • -P {keystore password}
  • -T {trust store}
  • -W {trust store password}
  • -op prop


I set up a Project in TDI called propertyhandling, with an assemblyline called propertyhandling and a property in the propertyhandling properties file called status with a value of run.

In my AL, I created a conditional WHILE loop with this code:

if (system.getExternalProperty("status") == "run") {
      return true;
} else {
      return false;
}

I ran the AL and it trundles along nicely doing nothing but looping and consuming all available CPU. You got to love never-ending loops!

I then ran this command:

tdisrvctl.bat -p 1091 -T C:\TDISOL\testserver.jks -W server -K C:\TDISOL\serverapi\testadmin.jks -P administrator -op prop -c propertyhandling -o propertyhandling -g all

The -c, -o and -g options after the prop operation need a little explaining:

  • -c this is the Solution Name for my configuration, in this case propertyhandling
  • -o this is the name of the properties collection, in this case propertyhandling
  • -g this tells the TDI Server to return the property value for the property named, in this case all means return the values for all the properties in the properties file


When I run the command, the result I get on-screen is this:

--- propertyhandling ---

status=run

This is excellent news, I'm able to query the current properties held in this particular properties file. Swapping that -g argument for a -s argument means I can now manipulate the status property as such:

tdisrvctl.bat -p 1091 -T C:\TDISOL\testserver.jks -W server -K C:\TDISOL\serverapi\testadmin.jks -P administrator -op prop -c propertyhandling -o propertyhandling -s status=stop

The -s require a property/value pair to be supplied. In this case, -s is telling the TDI Server to set the value of property status to stop. When I run this command, I get this result:

CTGDJB070I The property status has been set and committed.

That looks positive and when I check whether my assemblyline is still running, I find that it has indeed come to an end - as expected. Thanks goodness, says my CPU!

Of course, there are a myriad of use cases for injecting properties at run time... safe shut-down of an assemblyline is just one.
Post a Comment