RE: [javagroups-users] Deliver to one only

[Hal \(Work\) <hal...@or...>]

Why don't you include the address of the receiving process in the message?
This provides point to point communication between members of the group. 

You can either put the address in the message, or use the send() in Channel
with the destination address non null.

> -----Original Message-----
> From: jav...@li... 
> [mailto:jav...@li...] On 
> Behalf Of Andy Hutchinson
> Sent: Friday, April 09, 2004 1:44 AM
> To: jav...@li...
> Subject: Re: [javagroups-users] Deliver to one only
> 
> Sorry, let me explain a little further.
> 
> The channel holds details about _all_ the members in a group. 
> The DT holds information about what types of services those 
> members provide. The group may be 10 in size but only 2 
> provide the link to the telemetry system, for example.
> 
> I have thought that under the hood, all messages go to all 
> members anyway so I could have just send the first 
> castMessage to all members anyway.
> 
> What I want to achieve is the same as in JMS where a message 
> is delivered to just one subscriber. Otherwise the message 
> going on to the telemetry system may be transmitted multiple 
> times and the telemetry system would see this as an 
> escalating condition as if the measured error condition was 
> hit more than once.
> 
> You might ask why I'm not using JMS and the simple answer is 
> that it doesn't guarantee that the messages is delivered only 
> once across all subscribers when the JMS is not federated. 
> SwiftMQ used to be used and this did work as we wanted but 
> the license changed and the costs for our type of 
> installation are now prohibitive. JGroups, on the other hand, 
> does work well across LANs and WANs. It was my thinking that 
> as JMS is going to be layered on top of JGroups then there 
> may be an interface already within JGroups that supports the 
> notion of delivering a single message to only one member 
> rather than to all.
> 
> Now you may say I've gone over the top and all I need to do 
> is to create a new group which is the telemetry transmitter 
> group and hey presto everything is fine. The problem is that 
> a single message is still delivered to all members of the 
> group and there are potentially 100s if not 1000s of little 
> services which would mean creating this number of groups and 
> I think that would cause problems although I have not tried this out.
> 
> Any clearer?
> 
> At 02:59 09/04/2004, Bela Ban wrote:
> >I'm not sure what you want to do, but why do you need the DT ? Looks 
> >like you're maintaining group information in it, but this info is 
> >already maintained by the channel itself. Maybe I'm misreading this ?
> >
> >
> >Andy Hutchinson wrote:
> >
> >>I'm using JGroups to implement, amongst other things, a failover 
> >>mechanism for the transmission of a message onto an industrial 
> >>telemetry system.
> >>
> >>Basically there are a number of processing nodes which want 
> to send a 
> >>message. This can be done by any number of other nodes but 
> it must be 
> >>guaranteed to be sent, but only once.
> >>
> >>Each transmission node adds a tag to a DistributedTree 
> which is then 
> >>used to create the distribution list for a MessageDispatcher and a 
> >>castMessage call where GroupRequest is GET_FIRST. This effectively 
> >>gives me the quickest node to respond and I then send the message 
> >>directly to this node. If it subsequently fails I go round 
> the loop again until it succeeds.
> >>
> >>I am aware that a JMS layer is being added to JGroups and 
> JMS has the 
> >>necessary api I'm looking for. My implementation works but it seems 
> >>very messy whereas the JMS implementation does exactly what 
> is needed. 
> >>Have I missed something or should I wait for the JMS implementation 
> >>and recode to that or have I done the best possible with 
> the current JGroups api?
> >
> >
> >
> >--
> >Bela Ban
> >http://www.jgroups.org
> >Cell: (408) 316-4459
> 
> 
> 
> -------------------------------------------------------
> This SF.Net email is sponsored by: IBM Linux Tutorials Free 
> Linux tutorial presented by Daniel Robbins, President and CEO 
> of GenToo technologies. Learn everything from fundamentals to 
> system 
> administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click
> _______________________________________________
> javagroups-users mailing list
> jav...@li...
> https://lists.sourceforge.net/lists/listinfo/javagroups-users
>