Time Travel for OWSM Administrators
By Antony Reynolds-Oracle on Nov 25, 2008
Time Travel for Oracle Web Services Manager Administrators
I watched the Sarah Jane Adventures, a Doctor Who spinoff, with my family this week in which Sarah Jane has the opportunity to travel back in time to see her parents before they died. Of course it all goes horribly wrong as usual and Sarah-Jane and her young assistants will have to save the world, again! Reminds me of IT, you do something which seems like a good idea only to discover that it is a disaster. Fortunately many of the tools we use have some sort of versioning that allows us to rollback the changes and restore the world to the way we want it.
Oracle Web Services Manager has just such a facility. Every time a change is made to policies applied to a component in OWSM the previous set of policies is saved as a version, stored, ready and waiting to be restored if the change causes the fabric of space time to unravel. When reviewing the policies applied to a component there is a View Versions label next to a link labelled Version.
If after reviewing a previous policy set and the steps associated with the policies we realise that we need to restore that policy we can do so by selecting the restore link from the list of previous policy sets.
Note that the current policy set is not obvious from the Versions page. To check exactly what is being applied you need to open up the current policy and verify it is the version that you want before clicking OK.
You can drill down into the View Details to make absolutely sure that it is doing what you think before you commit the changes and so publish the new policies to the policy enforcement points.
So now you can travel back in time to correct errors in your OWSM policies. But wait, there is more. When Sarah Jane went back in time she saved her parents and as a result destroyed her own future. Similarly when we rolled back our policy to a previous time, we may also have lost the service mappings that relate policies to service endpoints. The policy versions are actually policy set versions. A policy set is the collection of policies available to a component. If you fall back to a policy set that does not include a policy that you have applied to an endpoint, then that policy to endpoint mapping is also lost. In the TV show Sarah Jane went back in time to undo her change. Similarly you can also reverse your meddling in time by restoring a later policy and any lost endpoint mappings will also reappear.
Happy time travelling.