How to handle missed messages: not seeing the 5 minute Darwin snapshots on RDM

[Polly Bishop]

Hi all,

I've been looking at migrating to RDM for my real time train time application: I'm concerned about missing messages due to upgrades on my backend, and I'm not seeing any feed for the 5 minute snapshots that are available on darwin-dist-44ae45.nationalrail.co.uk via https://opendata.nationalrail.co.uk/feeds: additionally, there is a notice when logging into opendata saying it will be shutting down in 2026: will it be shut down before there are snapshots available on RDM, or should I assume my application can use opendata until snapshots are provided on RDM?

best regards

Jamie

[Peter Hicks]

Hi Jamie

On Thursday, 28 May 2026 at 10:31, Polly Bishop <po...@polly.is> wrote:

I've been looking at migrating to RDM for my real time train time application: I'm concerned about missing messages due to upgrades on my backend, and I'm not seeing any feed for the 5 minute snapshots that are available on darwin-dist-44ae45.nationalrail.co.uk via https://opendata.nationalrail.co.uk/feeds: additionally, there is a notice when logging into opendata saying it will be shutting down in 2026: will it be shut down before there are snapshots available on RDM, or should I assume my application can use opendata until snapshots are provided on RDM?

I don't think there are 5-minute snapshots available - a Darwin snapshot should be produced every few hours, with the messages sent in the meantime logged somewhere for retrieval.  What you might be referring to is a 5-minute time-to-live on messages - but it is a while since I used NRDP and I'm not sure what the expiry period of messages is.

The bigger issue for you sounds like one of resilience.  If upgrades to your system lose data, then you may need to break down your system in to smaller components.  For example, I have multiple ActiveMQ servers here which consume messages and, should one of those fail, other servers will take over.  Addressing this may fix the immediate problem you have.

That said, I wouldn't recommend migrating to RDM until you're happy there is feature parity between the two platforms.  Ideally there would be better functionality within RDM than NRDP, but the feedback I've been hearing is that it's not quite that way yet despite a extensive period of 'bedding in'.

Peter

[Polly Bishop]

Hi Peter,

Thank you for your response! Your advice about resilience through multiple consumers is really good, but even then it would be a best-effort attempt to not lose any data.

I'm referring to this feature:

https://wiki.openraildata.com/index.php/Darwin:Push_Port#Update_Data_via_FTP

If you connect to the FTP server provided on opendata, there are two directories: snapshots and pushport: both seem to contain snapshots of the push port feed which seem intended for recovery if you lose connection to the push port service, the most recent pushport entry is from 9:48am today. 

Thanks and best regards

Jamie

[Polly Bishop]

Hi all,

Just received this response from CACI:

"Dear Jamie,

Thank you for your email.

We won't be putting any snapshots onto RDM ourselves.  RDM are looking to implement their own snapshots.  Be advised that it is unlikely that we will decommission our NRDP server, and snapshots, before RDM implement their own snapshot data.

The plan is to decommission our NRDP servers once RDG have made all information available on RDM.

We don't have a timeline for when our NRDP systems will be put to rest, but is likely to be before the end of the year, as mentioned in the message you've seen on the Openraildata website.

Kind regards,

CACI - Digital Solutions"

[Polly Bishop]

Hi all,

Received an email from RDM:

"Although snapshot functionality is not yet available on RDM, it is currently in development and scheduled for release next month"

Thanks and best regards

Jamie