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What is the logic being used on WMS 1.4 to determine the closest repository to a client? This information does not seem readily available.
I would be surprised if there was any such logic. As far as I know, if you want an application delivered from a certain repository, you need to set up the app policy to pull the app from that repository. It looks like you can now synchronize the repos in 1.4 but I don’t think that implies any sort of understanding of the clients to find the ‘nearest’ repo.
The issue with WMS 1.4 application/image policies, is that if you synchronize all your Repos or application/image is available on more than one repo, WMS does not show you individual repositories anymore. WMS now shows you a number that represent all the repositories that have the application/image you want to leverage in application/image policy(Pictured Below). WMS picks the closest repository to your client per some logic to deliver application/image to client. What I have noticed is that what I think is closest is not what WMS picks to deliver the application/image in policy.
Any pattern you are seeing on how WMS is picking a repository? I wonder if it just starts at the top of the list (name or order the repositories were connected in) and uses that one until the concurrent connections fill up, at which point it sends the client to the next repository in the list, and so on.
I reached out to support and I was told it is a simple subtraction formula used to determine which repository is the closest. However, it seem like this feature is currently broken.
To do the math, change IP addresses for repository and targeted thin clients(devices) to decimal format. Once that is done subtract the device decimal value from the repo decimal value. The repo with the lowest result will be the repo to service client first, and if a repo is unreachable then the next higher value repo will be used. When I do this math against all my repository IPs vs geographically dispersed clients IPs, the WMS server repo has the lowest value for multiple locations based on calculation. Even though other repos are closer to the client by subnet, and geographically. Most results where negative so not sure if negative result necessarily mean closer.
I wish this was documented somewhere. I am waiting on feedback from support. Sadly I can not move to WMS 1.4 in production until this is clarified. One workaround I was thinking to implement is to add repo identify text to similar file on different repos, so they don’t appear to WMS as the same file, and can be picked from specific repo. However, this seem like an unnecessary workaround. It would also break the seamless file sync feature recently introduced.
Sounds like the logic assumes you would put your repos onsite with clients. Might make sense in some companies, doesn’t work for me.
You don’t have to sync the repos in 1.4, it’s optional. That’s another way around this problem, just means more manual administration of repos and app policies.
Turning of file sync would not solve the problem. Once WMS see the same file on two servers, those two server will allways be grouped to deliver that file with or without file sync.
Based on my math even a server on the same subnet still shows WMS server as the lowest result. As mentioned earlier result is a negative number, server on the same subnet is the lowest positive number. So hopefully the logic does not deal with negative numbers but still TBD.
Ha, you are right! I really only use one repository so I hadn’t noticed the overlap between the repo server and WMS. What a crappy feature! 1.4 is disappointing on many levels so far.
WMS 1.4 is not all disappointing. It does have a lot of new features I like i.e.. export/import configuration groups, preserve device exception, automatic replication of repo files, application policy timeouts, etc… I would upgrade to it if it was not for this issue.
I did noticed in the WMS 1.4 Release Notes mentions this topic in section titled “Dynamic assignment of application policy to a repository”. It does confirm servers on the same subnet are prioritized “Device downloads applications from the file repository which is in the same or nearest subnet” and “If one repository is offline, the policy is pushed from the next nearest repository”.
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