In order to make a start on the design of registry replication, I have
put together the following requirements and their implications. Please
feel free to alter, add or delete. I'll assume silence to mean
approval...
- Distributed
- It probably doesn't make sense to store all of the registry data
in every registry. This implies a distributed model of registry
searching and maintenance.
- Self maintaining
- The registries should place the absolute minimum burden upon the
data centres where they run. On-going maintenance costs are
mostly those relating to support personnel, so the less human
intervention the better.
- Registries should where possible manage their own data integrity
(backups etc)
- Self maintenance almost certainly implies a peer network of
registries.
- Extensible
- It must be easy to add a new registry to the registry network
(but see below).
- It should also be a design goal to make changes to the registry
metadata design relatively painless.
- Robust
- The registry network should continue working even when some
registries are not available. This implies a certain level of
data redundancy.
- Registries will be visible to the Internet. They must therefore
provide sufficient security to protect the integrity of their
data (see also Self Maintaining) without hindering access to
those data.
- Registries must also resist other forms of attack for example
"Denial of Service" attacks or providing a host for "Man in the
Middle" attacks.
- Reliable
- Users should be confident that the queries they issue to
registries will return valid, useful data. It is therefore
important to manage the membership of the "registry club" and
not let arbitrary registries join the network unchecked.
- Flexible
- Registries should support rich data enquiries.
- A registry should also support "data harvesting" by other
registries. This allows registry data to be copied and expanded
as required as well as supporting data redundancy through data
replication.
Based upon this list I have started to develop use cases, activity
diagrams and a domain model to support these operations.
Please note I have NOT started work on the registry query schema as I
need help on this one!
Keith.
--
Keith Noddle Phone: +44 (0)116 223 1894
AstroGrid Technical Lead Fax: +44 (0)116 252 3311
Dept of Physics & Astronomy Mobile: +44 (0)7721 926 461
University of Leicester Email: ktn-at-star.le.ac.uk
Leicester, UK LE1 7RH Web: http://www.astrogrid.org
Received on 2003-04-24Z12:35:24