I'm sure there are lots of ways, but here's one I just thought of:
Create an agent that runs every 5 minutes, and compares the system startup time with its own property value, and if the property value is older, the agent calls the activity. Then the agent copies the system startup time into the property and exits.
Of course the property must reside on a dedicated work object or assignment, so that normal flow processing causes the object to be written back to the db.
By the way, what is it that you actually want to do once at system startup ? For certain particular chores, there may be some more specific feature already existing to do that chore. /Eric
Assuming you already figure out which activity triggers static assembler, you can configure a startup agent by choosing Startup as the pattern and then call the static assembler. This agent activity should only be called once at startup.