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[LDM #WYF-519931]: LDM - Future use of LDM for next generation GOES



Dan,

> I was hoping that you could please validate some statements along with
> answer a questions.
> 
> An upstream LDM has to allow a specific downstream LDM.  The set up and
> configuration to receive data isn't automatic.  Thus the LDM peer to
> peer model isn't purely subscription based, it is predefined and
> requires administrative updates to upstream LDM servers.

Not quite.  In order to reaceive data, the hostname or IP address of a 
downstream LDM must match a regular-expression in an ALLOW entry in 
the upstream LDM's configuration-file.  Because regular-expressions
are used, the upstream site is able to allow a single downstream host,
all hosts at a site, all host in a domain (e.g., ".edu"), or a list
of such specifications.

> The upstream LDM server can limit products that can be delivered to any
> downstream LDM server.  Thus a downstream user cannot request
> "everything" or denied products from an upstream server.

Correct.  Besides filtering on feedtype (an integer) the upstream site
can specify, via regular-expressions, what data-products are allowed
and what data-products are disallowed.

> Is the capability to limit users in the ldmd.conf file dynamically
> loaded, thus can the LDM server continue to run and get updates related
> to allowing/limiting access to certain data from certain users?

Because the LDM configuration-file must be reread, it is necessary to stop
and restart the LDM to accomplish this.  This can take anywhere from less
than a second to several seconds -- depending on the number of connections.

> When a third tier LDM server requests data from a second tier LDM server
> and the second tier server doesn't have it, the request for data isn't
> automatically propagated to the first tier server.

That's correct.  This will be fixed in the LDM replacement.

> A second tier server is able to connect to multiple first tier servers.
> Thus a first tier server can limit the access to the second tier and the
> third tier servers below that.

I'm not sure what you're asking.  A downsream LDM can connect to any LDM
that has an ALLOW entry that matches the feedtype and host identifier.

> Can an LDM server limit the amount of bandwidth that it takes up for
> distributing products on a per user basis?

No.  I'm thinking about adding that feature to the LDM replacement.

> Thanks for all your help.
> 
> Thanks
> dan


Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: WYF-519931
Department: Support LDM
Priority: Normal
Status: Closed


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