Hi Maninda, That only works if there is single interceptor for that data stream. Often, there will be several.
--Srinath On Fri, Nov 15, 2013 at 11:43 AM, Maninda Edirisooriya <[email protected]>wrote: > Actually we should maintain the counter at the message interceptor (e.g.: > BAM mediator). Every message passes through the interception point should > increment the counter at the interceptor. The atomic integer problem comes > as there can be multiple threads running in the same interception point. > Then the counter value before the increment should be sent to the receiver > end. Yes, either we should extend the receiver API or we should send the > counter value as a correlation data field. > > > > *Maninda Edirisooriya* > Software Engineer > > *WSO2, Inc. *lean.enterprise.middleware. > > *Blog* : http://maninda.blogspot.com/ > *Phone* : +94 777603226 > > > On Fri, Nov 15, 2013 at 7:06 AM, Srinath Perera <[email protected]> wrote: > >> +1 to go with Greenwich time, or provide a option to turn it on when >> needed. >> >> Counter would not work either as there can be some time between when >> event is created and receiver received it. >> >> I think we need to live with time stamp. If time accuracy is critical >> users should sync clocks of all machines with NTP. >> >> --Srinath >> >> >> On Wed, Nov 13, 2013 at 5:30 PM, Maninda Edirisooriya >> <[email protected]>wrote: >> >>> What about using the Greenwich time with the existing timestamp? When >>> there is a timezone critical solution, Greenwich time can be used as it is >>> the same. >>> >>> Anyway in practice I don't think timestamp is the best way to order the >>> messages as it may have so many synchronization problems. Although it may >>> not be a problem in millisecond range, clock drift can happen in highly >>> moving servers due to time change according to relativity unless they have >>> special clock synchronization mechanism. (e.g. Satellites) And it is not >>> possible to order the messages passed during a single millisecond if the >>> timestamp is in millisecond range as now. >>> >>> The only solution for the activity monitoring problem can be achieved by >>> maintaining an message counter in the data agent. The counter should be >>> incremented when each message is passed through the data agent and sent to >>> the BAM. But there also we have a problem. Since data agents exists there >>> in multiple threads the counter should be incremented as a atomic variable >>> which is an expensive mechanism. >>> >>> >>> *Maninda Edirisooriya* >>> Software Engineer >>> >>> *WSO2, Inc. *lean.enterprise.middleware. >>> >>> *Blog* : http://maninda.blogspot.com/ >>> *Phone* : +94 777603226 >>> >>> >>> On Wed, Nov 6, 2013 at 7:58 AM, Srinath Perera <[email protected]> wrote: >>> >>>> Instead, can we let users decide which timezone to be used across all >>>> BAM nodes? Problem is with timestamp + timezone, the time based queries get >>>> complicated and expensive. I think indexes will not work anymore. >>>> >>>> --Srinath >>>> >>>> >>>> On Tue, Nov 5, 2013 at 8:21 AM, Dunith Dhanushka <[email protected]>wrote: >>>> >>>>> Hi all, >>>>> >>>>> Currently BAM adds its current timestamp to the events that are being >>>>> persisted to Cassandra. But there can be situations like data publishers >>>>> and BAM instances are hosted in different timezones. >>>>> For instance APIM and BAM can be hosted in two data ceneters of two >>>>> different timezones. Events published from APIM will be stored in BAM with >>>>> BAM's current timestamp. >>>>> >>>>> So it is impossible to tell from BAM side that at what time a >>>>> particular event has occured in APIM. This means the time which event has >>>>> been published from APIM, not the time that received by BAM. >>>>> But if theres a way of BAM to save its timezone with events, that >>>>> informtion(timezone + timestamp) can be used to derive the time that >>>>> events >>>>> had been published at APIM side. >>>>> >>>>> As a solution, in addition to timestamp we are going to store BAM's >>>>> system timezone alongside with events. Required changes will happen in >>>>> data-bridge componet. >>>>> >>>>> In fact, UTC offset of the system default timezone will be saved with >>>>> each event (UTC offset is the offset in milliseconds for the given time >>>>> zone to UTC, at the given time) so that it'd be easier for Hive queries to >>>>> manipulate numeric values rather than timezone name strings. >>>>> >>>>> Your feedback is highly appreciated! >>>>> >>>>> Thanks, >>>>> -- >>>>> Regards, >>>>> >>>>> Dunith Dhanushka, >>>>> Senior Software Engineer - BAM, >>>>> WSO2 Inc, >>>>> >>>>> Mobile - +94 71 8615744 >>>>> Blog - dunithd.wordpress.com <http://blog.dunith.com> >>>>> Twitter - @dunithd <http://twitter.com/dunithd> >>>>> >>>>> _______________________________________________ >>>>> Architecture mailing list >>>>> [email protected] >>>>> https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture >>>>> >>>>> >>>> >>>> >>>> -- >>>> ============================ >>>> Srinath Perera, Ph.D. >>>> http://people.apache.org/~hemapani/ >>>> http://srinathsview.blogspot.com/ >>>> >>>> _______________________________________________ >>>> Architecture mailing list >>>> [email protected] >>>> https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture >>>> >>>> >>> >>> _______________________________________________ >>> Architecture mailing list >>> [email protected] >>> https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture >>> >>> >> >> >> -- >> ============================ >> Srinath Perera, Ph.D. >> Director, Research, WSO2 Inc. >> Visiting Faculty, University of Moratuwa >> Member, Apache Software Foundation >> Research Scientist, Lanka Software Foundation >> Blog: http://srinathsview.blogspot.com/ >> Photos: http://www.flickr.com/photos/hemapani/ >> Phone: 0772360902 >> >> _______________________________________________ >> Architecture mailing list >> [email protected] >> https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture >> >> > -- ============================ Srinath Perera, Ph.D. Director, Research, WSO2 Inc. Visiting Faculty, University of Moratuwa Member, Apache Software Foundation Research Scientist, Lanka Software Foundation Blog: http://srinathsview.blogspot.com/ Photos: http://www.flickr.com/photos/hemapani/ Phone: 0772360902
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