You can have a loop on a different stream. It's not always the best thing to do (deadlock possibilities from buffers) but we have a production topology that has that kind of pattern. In our case, one bolt acts as a coordinator for recursive search.
Michael Rose (@Xorlev <https://twitter.com/xorlev>) Senior Platform Engineer, FullContact <http://www.fullcontact.com/> mich...@fullcontact.com On Fri, Jun 6, 2014 at 2:28 PM, Abhishek Bhattacharjee < abhishek.bhattacharje...@gmail.com> wrote: > I am sorry for the late reply. > Yes , you can't have a loop. You can have a chain though( which doesn't > close upon itself ! ). > > Thanks :-) > > > > On Wed, May 7, 2014 at 12:50 PM, shahab <shahab.mok...@gmail.com> wrote: > >> Thanks Abhishek. But this also implies that we can not have a loop ( of >> message processing stages) using Storm, right? >> >> best, >> /Shahab >> >> >> On Mon, May 5, 2014 at 9:45 PM, Abhishek Bhattacharjee < >> abhishek.bhattacharje...@gmail.com> wrote: >> >>> I don't think what you are trying to do is achievable. Data in storm >>> always move forward so you can't give it back to a bolt from which it >>> originated. That is a bolt can subscribe from bolts which were created >>> before it's creation. So, I think you can create another object of the A >>> bolt say D and then assign the o/p of C to D. >>> >>> >>> On Mon, May 5, 2014 at 8:11 PM, shahab <shahab.mok...@gmail.com> wrote: >>> >>>> Hi, >>>> >>>> I am trying to define a topology as following: >>>> S : is a spout >>>> A,B,C : are bolts >>>> --> : means emitting message >>>> >>>> S -->A >>>> A -->B >>>> B -->C >>>> C -->A >>>> >>>> I am declaring the Spouts and Bolts in the above order in my java code >>>> , first S, then A , B and finally C. >>>> >>>> I am using globalGrouping("BoltName", StreamID) for collecting >>>> messages to be collected by each bolt, >>>> >>>> The problem is that I receive an error, while defining bolt "A" saying >>>> "that subscribes from non-existent component [C]" . >>>> >>>> I guess the error is happening because component "C" is not defined yet! >>>> but what could be the solution to this? >>>> >>>> best, >>>> /Shahab >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>> >>> >>> -- >>> *Abhishek Bhattacharjee* >>> *Pune Institute of Computer Technology* >>> >> >> > > > -- > *Abhishek Bhattacharjee* > *Pune Institute of Computer Technology* >
