Hi Rakesh,
Exactly ! and that end-to-end information-priority ‘awareness’ is a unique feature of our implementation relying on us having a nodal ‘* network-scheduler’* that schedules all outgoing traffic of the node based upon actual information-*importance* (DDS TransportPriority) as well as information-*urgency* (DDS LatencyBudget). We didn’t talk about LatencyBudget yet, but this expression of ‘urgency’ is also taken into account by the scheduling of traffic over a specific network-channel (priority-band) so that we can increase efficiency by ‘packing’ multiple samples (potentially of multiple applications on the node) into single UDP-packets (and you can configure the maximum fragment-size of these packets, a value of 8 Kbyte it typically good) thus decreasing the UDP/IP protocol-processing overhead ‘per sample’ and consequently increasing efficiency. So with these logical QoS policies w.r.t. *importance* (TransportPriorityQoS) and *urgency* (LatencyBudget QoS) you have a very ‘natural’ and easy control over determinism (driven by the *importance*/TransportPriority) and efficiency (driven by the *urgency*/LatencyBudget). Regards, Hans * * *Hans van 't Hag* OpenSplice DDS Product Manager PrismTech Netherlands Email: hans.vant...@prismtech.com Tel: +31742472572 Fax: +31742472571 Gsm: +31624654078 PrismTech is a global leader in standards-based, performance-critical middleware. Our products enable our OEM, Systems Integrator, and End User customers to build and optimize high-performance systems primarily for Mil/Aero, Communications, Industrial, and Financial Markets. ------------------------------ *From:* developer-boun...@opensplice.org [mailto: developer-boun...@opensplice.org] *On Behalf Of *Rakesh pawar *Sent:* Friday, October 14, 2011 10:56 AM *To:* OpenSplice DDS Developer Mailing List *Subject:* Re: [OSPL-Dev] Priority based message publishing and Receiving hi Hans, Thanks again for the reply. So, are implying that the higher priority samples will physically reach faster than the lower priority samples? And for this I don't have to do anything specific in the logic or code other than setting the Transport Priority Qos and creating the Network Channels with priority bands, is it? Also, is "diffserv " a mandatory value ? What if the diffserv is not supported by the network hardware ? On Fri, Oct 14, 2011 at 2:09 PM, Hans van't Hag <hans.vant...@prismtech.com> wrote: Hi Rakesh, Interesting, got the same question from our partner RTTS recently, here’s the same answer J Its not that trivial to demonstrate with ‘simple’ test-program, yet here’s a YouTube video on benchmarking opensplice that demonstrates how this can be done with the OpenSplice touchstone benchmarking suite. What you want to demonstrate is that having end-to-end priority-preservation i.e. having high-priority data being ‘handled’ by separate high-priority send-threads in networking, being transported over the wire with a high diffserv setting if available, being received at the destination-machine by high-priority-threads and being inserted in the dataReader’s cache with high-priority. In order for this to become ‘visible’ you could use for instance some very big low-priority samples and show that they have little/limited impact on the latency of small high-priority samples. This is what the YouTube video on benchmarking OpenSplice explains with using the OpenSplice Touchstone benchmarking suite. Regards, Hans * * *Hans van 't Hag* OpenSplice DDS Product Manager PrismTech Netherlands Email: hans.vant...@prismtech.com Tel: +31742472572 Fax: +31742472571 Gsm: +31624654078 PrismTech is a global leader in standards-based, performance-critical middleware. Our products enable our OEM, Systems Integrator, and End User customers to build and optimize high-performance systems primarily for Mil/Aero, Communications, Industrial, and Financial Markets. ------------------------------ *From:* developer-boun...@opensplice.org [mailto: developer-boun...@opensplice.org] *On Behalf Of *Rakesh pawar *Sent:* Friday, October 14, 2011 10:31 AM *To:* OpenSplice DDS Developer Mailing List *Subject:* Re: [OSPL-Dev] Priority based message publishing and Receiving Hi Hans, Thanks for replying. So, if OpenSplice DDS has Transport Priority Qos, how do we implement it and test it. Suppose I create 3 network channels with the priority band defined in it and I have some 10 topic samples, each belonging to any of the pre defined priority group. Now if I set the Transport Priority Qos before publishing these samples, will it show the difference at the reciever end ( we would also apply the Transport Priority at Subscriber end) ? Will I get the higher priority samples first with these configurations? Is there any way of testing it on a smaller scale for demo purpose? On Fri, Oct 14, 2011 at 1:27 PM, Hans van't Hag <hans.vant...@prismtech.com> wrote: Hi Rakesh, Yes, in OpenSplice you can. OpenSplice implements the notion of priority-bands implemented by what we call ‘network-channels’ that are characterized by dedicated receive/transmit threads per network-channel as well as traffic-shaping and reactivity-control per network-channel. For all this no specific network hardware is required. There is although a benefit to be gained if you network hardware supports DIFSERV as each network-channel can be configured with its ‘own’ DIFSERV priority. The selection of the priority-band (i.e. network-channel) is done dynamically based on the DDS ‘TransportPriority’ QoS value of the dataWriter that writes a sample. This logical DDS TransportPriority QoS value is ‘matched’ against the configured ranges that each network-channel ‘manages’. So important/high-priority (i.e. high TransportPriority value) DDS-data is sent over a network-channel (aka priority-band) that’s ‘dedicated’ for high-priority-data and in this way will ‘pre-empt’ low-priority-traffic (both at sending-node as well as receiving node). Also ‘within’ a priority-band OpenSplice assures that higher-priority data is sent on the wire before lower-priority data within that priority-band. Regards, Hans * * *Hans van 't Hag* OpenSplice DDS Product Manager PrismTech Netherlands Email: hans.vant...@prismtech.com Tel: +31742472572 Fax: +31742472571 Gsm: +31624654078 PrismTech is a global leader in standards-based, performance-critical middleware. Our products enable our OEM, Systems Integrator, and End User customers to build and optimize high-performance systems primarily for Mil/Aero, Communications, Industrial, and Financial Markets. ------------------------------ *From:* developer-boun...@opensplice.org [mailto: developer-boun...@opensplice.org] *On Behalf Of *Rakesh pawar *Sent:* Friday, October 14, 2011 9:25 AM *To:* developer *Subject:* [OSPL-Dev] Priority based message publishing and Receiving Hi, I need to implement a priority based message publishing and receiving. Is it possible to achieve this in DDS without any dependence on network hardware ? -- Cheers ! Rakesh Pawar _______________________________________________ OpenSplice DDS Developer Mailing List Developer@opensplice.org Subscribe / Unsubscribe http://dev.opensplice.org/mailman/listinfo/developer -- Cheers ! Rakesh Pawar _______________________________________________ OpenSplice DDS Developer Mailing List Developer@opensplice.org Subscribe / Unsubscribe http://dev.opensplice.org/mailman/listinfo/developer -- Cheers ! Rakesh Pawar
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