Schemas - The story so far… Steve Fisher / RAL

1. Schemas - The story so far…Steve Fisher / RAL www.eu-egee.org EGEE is a project funded by the European Union under contract IST-2003-508833

2. Principles • Should be simple • Conceptually • Practically • Should be reasonably safe • Low network traffic and load on servers • Avoid human intervention • No masters • No ability for one component to block everything

3. Operations to consider • createTable • Should be fairly quick • dropTable • Can be slow – provided it does not impede createTable • alterAuthorization • Must be acted upon rapidly • It may be enough that new operations get the new authz – i.e. don’t worry about existing streaming • This could be a frequent operation – but for now we have to guess

4. Three ideas so far • 2PC and Master – from John • Complete but does not do too well against my criteria • Versioned tables – from Steve F • Not at well worked through as John’s • Tightly coupled or Versioned tables – from Steve H • First solution is like John’s and second like mine

5. 2PC and master • createTable • Goes via master and is fanned out to slaves • dropTable • 2PC including registries • alterAuthorization • Probably 2PC • Pros • Fairly completely worked out • createTable is fast • Cons • Single point of failure • Manual intervention

6. Versioned Tables • createTable • 2 PC on schema – each table is identified by a number for all time • No master • dropTable • 2PC on schema – leave registries to get on with their job • alterAuthorization • 2PC on schema • Pros • No humans and no masters • Schema and registry well separated • Cons • Not fully worked out • Create table could be blocked • Interesting • Producers and Consumers talk to the schema – the Registry does not