Re: Infrastructure for a distributed database?

Hi,

this is very interesting. The subject of online replication has come up 
quite a number of times on this list, but no one has ever suggested a 
solution. However most people were looking for a full replication (more 
like a database distribution). I'd be interested in the triggers / 
python scipts that you use (if you care to share them...)

On the subject of replication over an insecure WAN I would generally 
suggest seting up VPNs using IPSEC. There are some open source 
implementations of IPSEC like FreeS/WAN (http://www.freeswan.org/) that 
you can use. Although jabber seems to be sufficiently secure a VPN would 
give you freedom of choice plus give you secure communication between 
head and branch offices for any other application and/or protocol.

Just a thought...

Arne

Alan Graham wrote:

> I'm building a system at the moment which has local SAP DB instances at
> various offices around Australia, connecting to a Headoffice database. 
> Links are over the public internet.  The branch offices need to
> replicate data back to head office, while head office needs to replicate
> other data out to some or all of the branch offices.
> 
> My current design is along the lines of;
> triggers on the tables to replicate, to kick off the SAP loader
> A python script to package the resulting data and pass it to a jabber
> server using XML-RPC over jabber.  
> Jabber server to server comms to give a reasonably robust queueing
> mechanism
> A python script called at the other end by the RPC, which unpacks the
> data and calls the loader to upload it into the receiving database.
> 
> This is coming together quite nicely, I have a proof of concept
> replication working well.
> 
> But it just occurred to me that someone on the list may have already
> done something like this.  So I thought I'd ask for ideas.
> 
> Has anyone solved the problem of selective database replication over an
> insecure WAN any other ways?
> 
> Can anyone see any gaping holes in my solution?
> 
> Any critiques, ideas, general comments gratefully received.
> 
> Thanks
> 
> Alan Graham
> 
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Institute of Shipping Economics and Logistics    http://www.isl.org/
Arne Gehlhaar                                mailto:[email protected]
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