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FAQ: Does Ultra Messaging Transport Sessions pass through Dynamic Routers?

Ultra Messaging (UM) transports end at the boundary of the Topic Resolution Domain (TRD).  Effectively, Dynamic Routers (DROs) provide connectivity between the TRDs and the UM transports end at the DRO.​

More Information

UM Router and Transport Sessions

When the DRO creates proxy receivers for message forward​ing, be aware that the transport sessions carrying those messages are not extended to the destination TRD. Instead, the proxy receiver simply takes the messages from the originating transport sessions and transfers them to the destination DRO's proxy sources. The proxy sources create new transport sessions for those outgoing messages.

The proxy sources' outgoing transport sessions are unrelated to the originating sources' transport sessions. They can even use different transport types, performing a protocol conversion. In fact, a single DRO transport session can contain multiple sources from different originating publishing applications for the same topic. Alternatively, multiple sources from the same originating publishing application which are mapped to the same originating transport session can be split into multiple transport sessions by the proxy sources in a remote TRD.

One consequence of the independence of incoming and outgoing transport sessions is that TCP flow control does not transit the UM Router. A slow receiver in a remote TRD cannot "push back" on a fast source. In cases where a TCP transport session is slowed down due to one or more slow receivers, an intermediate UM router will buffer and may eventually have to drop messages.


A single source's "source string" will be different in different TRDs connected by UM Routers. See the "Source Strings in a Routed Network" section in the Dynamic Routing Guide for more details.

Applies To
Product: Ultra Messaging
Problem Type: Connectivity
User Type: Developer
Project Phase: Configure; Implement
Product Version:
Operating System:
Other Software:


Dynamic Routing Guide​ 


Last Modified Date:1/14/2020 11:17 AMID:613413
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