Hi Mike, > We also have a requirement to cancel an asynchronous request. It is a > query tool, and users will be able to cancel queries once they have > already started running. MDB seemed like the ideal choice for > submitting queries asynchronously, but I think this requirement of > being able to cancel a running query seems to spoil it. Or,does anyone > know how we could/should still do MDB?
How about something like having a flag, either in a database, or in some global object (in jndi for 'properness'). And so the sequence goes something like: a) client sends message with id b) mdb gets message and starts processing c) client wishes to cancel message d) client sets flag in global object mentioned above e) as mdb is processing, it checks at designated points for the flag f) if mdb finds the flag it consumes the message but doesn't 'do' anything how does that sound? at what point might a client cancel the request? would the request have already started (as above), or do you simply want to be able to remove messages from the queue? hth dim > > Thanks, > Mike > > --- Nicholas <[EMAIL PROTECTED]> wrote: > > I do not know of any specific MDB perfomance issues. > > Can you elaborate ? > > > > Also, technically, if the message has been sent to a > > queue, and you have somehow persisted or "remembered" > > any uniquer attributes of the message (like mesage ID > > for example), you could use a queue browser to remove > > the message before it is processed. However, I would > > imaguine it unlikely that you would be able to grab > > the message before it was processed if you do have > > decent performance. > > > > In general, I am in the same mind as Chan. You should > > cancel undesired asych requests before they are sent. > > It is a difficult proposal to cancel any sort of > > asynch request without going out of band. > > > > //Nicholas > > > > --- Chan Philip <[EMAIL PROTECTED]> > > wrote: > > > The Request should has been cancelled before, not > > > after, it is sent. > > > > > > -----Urspr�ngliche Nachricht----- > > > Von: Alvin Wang [mailto:[EMAIL PROTECTED]] > > > Gesendet: Montag, 18. M�rz 2002 19:52 > > > An: [EMAIL PROTECTED] > > > Betreff: Re: [EJB-INT] Is MDB the best choice for > > > asynchronous request > > > handling in EJB? > > > > > > > > > For example, I cannot cancel a request in the queue, > > > and the performance > > > issue... > > > > > > -----Original Message----- > > > From: A mailing list for Enterprise JavaBeans > > > development > > > [mailto:[EMAIL PROTECTED]]On Behalf Of Johan > > > Eltes > > > Sent: Monday, March 18, 2002 12:57 PM > > > To: [EMAIL PROTECTED] > > > Subject: Re: Is MDB the best choice for asynchronous > > > request handling in > > > EJB? > > > > > > > > > What kind of limitations are you experiencing? > > > > > > /Johan > > > > > > -----Original Message----- > > > From: A mailing list for Enterprise JavaBeans > > > development > > > [mailto:[EMAIL PROTECTED]]On Behalf Of Alvin > > > Wang > > > Sent: den 18 mars 2002 16:41 > > > To: [EMAIL PROTECTED] > > > Subject: Is MDB the best choice for asynchronous > > > request handling in EJB? > > > > > > Hi! We need to do some asynchronous request handling > > > work in EJB. For > > > example, the user sunmits a request and quits, and > > > later he comes back and > > > check the status/result of his request. Currently we > > > are using MDB to do > > > this. However, we feel that there are some > > > limitations in MDB and JMS. Is > > > MDB the most natural way to handle asynchronous > > > request in EJB? Can any guru > > > give us some alternative design strategies? Thanks! > > > > > > Alvin > > > > > > > > > ==========================================================================To > > > unsubscribe, send email to [EMAIL PROTECTED] and > > > include in the body > > > of the message "signoff EJB-INTEREST". For general > > > help, send email to > > > [EMAIL PROTECTED] and include in the body of the > > > message "help". > > > > > > > > > ===== > > Nicholas Whitehead > > Home: (973) 377 9335 > > Cell: (201) 615 2716 > > Work: (212) 235 5783 > > [EMAIL PROTECTED] > > > > __________________________________________________ > > Do You Yahoo!? > > Yahoo! Sports - live college hoops coverage > > http://sports.yahoo.com/ > > > > > =========================================================================== > > To unsubscribe, send email to [EMAIL PROTECTED] and include in > > the body > > of the message "signoff EJB-INTEREST". For general help, send email > > to > > [EMAIL PROTECTED] and include in the body of the message "help". > > > > > __________________________________________________ > Do You Yahoo!? > Yahoo! Sports - live college hoops coverage > http://sports.yahoo.com/ > > =========================================================================== > To unsubscribe, send email to [EMAIL PROTECTED] and include in the body > of the message "signoff EJB-INTEREST". For general help, send email to > [EMAIL PROTECTED] and include in the body of the message "help". > =========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff EJB-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
