Hi, I am using Database Queries in several parts of a complex workflow (i.e. in different composite actors). Because the queries are all sent to the same database, I am creating a single database connection and send it to all actors needing it. Some of the composite actors which have a Database Query inside need to be fired several times, therefore I am using the repeat actor to send the database connection token several times.
But the Database Query actor only takes the first token and once it has a database connection it does not read tokens from the dbcon port anymore. Looking deeply into the bowels of the SDF kernel I found out that each port has a queue and the capacity of this queue may be finite or infinite, where infinite capacity is the default. For some reason the capacity of the dbcon port of the Database Query actor is set to one (strangely, this happens only the first time I run the workflow after opening it, in every following run it is not set explicitely and therefore infinite). Now what happens should be clear: When the composite actor (containing the Database Query) is fired the first time, the db connection token is send to and taken by the Database Query. When fired the second time, again a db connection token is send to the Database Query but it is not taken. When fired the third time, another db connection token shall be sent to the Database Query, but as the queue capacity is one and there is already the token from the last iteration in the queue, the token cannot be sent, which leads to an exception. How should I handle this correctly? I think in a clean solution the connection token would be sent only once. But I get an exception when trying to fire the composite actor without having sent a token to the db connection port. Is there a way to fire a composite actor without having tokens at all input ports (in SDF or DDF domain)? If not, is there a way to set the capacity of the queue of the dbcon port to infitity (I would not like this solution, but with infinite queue capacity it would at least work). Is there a totally different solution? Thanks in advance, Frank -- Dipl.-Inf. Frank Steinmann Knowledge Management Department DFKI GmbH Tel.: +49 (0)631 20575 - 114 Sekr.: +49 (0)631 20575 - 101 Fax: +49 (0)631 20575 - 103 E-Mail: Frank.Steinmann at dfki.de ----------------------------------------------------------- Deutsches Forschungszentrum f?r K?nstliche Intelligenz GmbH Trippstadter Stra?e 122, D-67663 Kaiserslautern, Germany Gesch?ftsf?hrung: Prof. Dr. Dr. h.c. mult. Wolfgang Wahlster (Vorsitzender) Dr. Walter Olthoff Vorsitzender des Aufsichtsrats: Prof. Dr. h.c. Hans A. Aukes Amtsgericht Kaiserslautern, HRB 2313 -----------------------------------------------------------
