Hi Kelvin a couple of things about your model. First of all, because of the inter-arrival times you chose for the two sources, sometimes an item will go to Sink5 when there is no item in Source1 to to be released. In those instances you would correctly see nothing happen because Source1 has yet to create it's flowitem. This will skew your inter-arrival times, if that is important to you.
Secondly, in your OnMessage trigger for Source1 you have the command releaseitem() with no parameters passed. The releaseitem() command needs to know what item to release such as releaseitem(item);. Also, note that calling release item causes Send To Port to fire. So in calling releaseitem() the Send to Port field is still being evaluated at -1, which means don't release. The releaseitem() command does allow you to specify a port as the second parameter to get around using the port specified in Send To Port.
The OnMessage trigger doesn't have its own reference to the keyword item, like some of the other triggers do. We'll have to make our own. Using the rank command we can quickly get a reference to the item inside the source waiting to be released. If you modify Source1's OnMessage trigger to look like the following, it'll work.
Code:
treenode current = ownerobject(c);
treenode item = rank(current, 1); // get a reference to the waiting item
if(objectexists(item)) // only release the item if the object exists
{
releaseitem(item, 1); // release the item through a specific port
}
That works fine because the source only creates one item at a time when using an inter-arrival time. If your model were using an inter-arrival schedule, which *can* creates several items at once, you'd have to change it so that all the items got release not just the first one.
can "do not release item" commend be used in source?