Controlling Java and Lotusscript agents

Question

I created 2 agents, one made of Java and another made of Lotusscript. The java agent is scheduled to run every 5 minutes, while the lotusscript agent is scheduled to run every 15 minutes. Therefor there will come a time that they will simultaneously run. When that happens, the java agent must pause/wait until the lotusscript agent finished. I tried to simulate locking using Profile DOcuments and Environment Variables but to no avail. Is there a way that I can simulate locking between this two different agents? Please help. Thanks a lot!

Edit: I forgot to say that the 2 agents resides in TWO DIFFERENT databases, to complicate things more :(

Answer 1

Why not writing a third Agent (maybe in an extra Database), which runs periodically every five Minutes, which starts the other two Agents:

1. The Lotus Script Agent every time
2. The Java Agent every third run

... then you are also in control of the run order, without any complicated lock mechanisms.

Answer 2

This is a near foolproof way I have found that works for controlling the execution order of independent agents. I use a real notes document as a psuedo-lock document.

The way I have done this before is to keep a Notes document that represents a "lock". Don't use a database profile document as it's prone to replication/save conflict issues and you can't view it in a view.

The "lock" document can have a flag on it which tells the java agent whether it is allowed to run now. The java agent simply has code in it similar to this

Session s = NotesFactory.createSession();
Database db = s.getDatabase("This Server", "This database");
View vw = db.getView("(lockView)");
Document docControl = vw.getFirstDocument();
String sRunStatus = docControl.getItemValueString("runStatus");
boolean bContinue = false;
if (sRunStatus =="Go"){
    bContinue = true;
}
if(bContinue){
    //do agent code here....

    // reset the status to "wait". The lotusscript agent should then set it to "Go"
    // the other agent will execute on "wait" and then update the status to "Go" on 
    // completion to prevent simulatenous execution. Can also use different state names
    // instead of go/wait, like run0, run1, run2 etc
    docControl.replaceItemValue("runStatus", "wait");
    docControl.save(true);
}

Note that you use the agents to set "Go"/"wait" values in the "runStatus" field on a control document. You only need 1 document so you then only need to get the first document out of the view.

The equivalent logic should be even simpler to add in the LotusScript agent as well. The only downside I can find is that the java agent may not execute the code because the control document is not yet set to "go" and the "IF" test fails without running the logic, so it's not a pause as such, but prevents the Java agent from executing out of it's desired order with the lotusscript agent. But it would then fire on the next scheduled instance if the LotusScript agent has released it.

You can also extend this idea to manage a suite of agents and even chain multiple agents as well by using specific values like "RunAgent1", "RunAgent2", another benefit is that you can also capture execution start times, errors as well, or anything you require....

Answer 3

Enabling document locking in the database could work. If you can enable document locking in the database itself you can have the agents lock a specific document and check if the document is locked before/during it runs the code.

If enabling document locking in that database is not an option you can consider creating a separate database do store the document.

Why can't these agents run simultaneously? Maybe it is possible to achieve the same result while allowing the agents to run simultaneously. Trying to control agents this way will usually lead to other problems. If the database has replicas the solution might break.

Answer 4

You said that it is two databases, but really by far the simplest way to stop agents from running simultaneously is to put them in the same database. I will very often create a special database that only contains agents and log documents generated by the agents. The agents can open any database, so it really doesn't matter where they are.

I also led a project once in which we built our own control mechanism for agents which was a combination of giulio and spookycoder's ideas. Only one 'master' agent was scheduled, and it read the control document to decide which agent should run next. Let's say we have agents A, B and C. The master runs A, which immediately updates the control document to say "I am running", then it updates fields with its progress information as it goes along, and finally when it is done it updates the control document with either "B",The next time the master runs, it looks at the control document. If the progress information shows that A has finished, the master will see that it is B's turn to run. Of course, A might realize that B has no work to do, so it might have written "C" instead, in which case the master will run C. The master also has the option to re-run A if the progress information shows that it did not finish the job.