Message propogation with Router Network
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Posted By:   David_McCullough
Posted On:   Friday, March 31, 2006 02:14 AM

Hello, My questions relate to what messages are sent between routers in a SwiftMQ router network under certain conditions. I'm trying to get a sense of how much network bandwidth will be taken up by the message exchanges. Say we have a simple network with 3 routers: A, B, and C. A is directly connected to B, and B is directly connected to C. Also, we have a topic T defined in each of the routers, with client apps on A and B publishing and subscribing to T. 1. If the client connected to A publishes a message on T. I know that B will get the message, but does the message get shuttled over the network to C, even though no one there is currently subscibing to it? I thought I read somewhere in the docs that    More>>

Hello,


My questions relate to what messages are sent between routers in a SwiftMQ router network under certain conditions. I'm trying to get a sense of how much network bandwidth will be taken up by the message exchanges.


Say we have a simple network with 3 routers: A, B, and C. A is directly connected to B, and B is directly connected to C. Also, we have a topic T defined in each of the routers, with client apps on A and B publishing and subscribing to T.


1. If the client connected to A publishes a message on T. I know that B will get the message, but does the message get shuttled over the network to C, even though no one there is currently subscibing to it? I thought I read somewhere in the docs that it would not, but I just looked at them again quickly and couldn't find that statement.


2. How about the same scenario as 1, but now with a client connected to C that is subscribing to T, but with a message selector that happens to filter out the messages being sent by A. Now, I know the C client won't get any of the messages, but will they be sent over the network from A to B to C? What I'm wondering is if there is some sort of message selector 'back propagation' that would eliminate even sending messages across the network that ulimately wouldn't make it to a client anyway.


Thanks.

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Re: Message propogation with Router Network

Posted By:   Andreas_Mueller  
Posted On:   Friday, March 31, 2006 03:43 PM

1) SwiftMQ has dynamic subscription propagation (static remote subscriptions can also be defined but that's not the issue here). So, C will not get a message because it doesn't have a subscription.


2) Dynamic subscription propagation is done on so-called root topics. For example: for topic "iit.sales.us" the root topic is "iit". If there is some subscription under that root topic, a message copy is sent to the topic manager of that router which propagates it to it's local subscribers. So always a single copy is sent if there is some subscriber. No copy is sent if there are none subscribers.


Nice weekend!
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