Revision as of 13:38, 24 July 2013

Dynamic route proposal

Changes

• Remove existing extensions and move routes mapped into base API app. Ex: instances/<instance_id>/users
• Add code to inspect instance_id and map it to an instance type.. Redis Postgres MySQL etc.
• Have "proxy" route dynamically load a service for each database type either with importlib or stevedore whatever.
• Have the route dynamically accept requests for special edge cases for differing database engines.
  • Ex: Default database required for postgres on user create while MySQL does not use one.

Why do it this way?

• Does not change existing API URL spec.
• Fewer routes in API vs having prefix/namespace based approach for commonly supported requests like users or backup.
  • Ex /instances/<instance_id>/mysql/users.
  • Ex /instances/<instance_id>/postgres/users.
  • Ex /instances/<instance_id>/mongodb/users.
• Allows for multiple versions or forks of different Database engines more easily.
  • Ex: Allow multiple versions of a Database engine that have differing user create requirements.. (Can't think of anything that exactly matches that scenario so maybe this is a bad example. However, it does allow for differing versions of one database application.)
  • This could be true of the namespaced option as well
• Allows the interface for users who only want to support one DB engine to be simplified.
  • Ex: No database type specific URI prefix.
  • This could be true of the namespaced option as well
• Allows the base URI mappings to be the same for all databases that have a common type.
  • Ex: users, backups etc.
• Conrad likes this one more =P.

Cons

• Less explicit then using database specific prefixes.
• Post body may vary significantly based on database type

Alternative Solutions

Use a db-specific/namespaced routing methodology

Changes

• Remove or deprecate existing extensions and move routes mapped into base API app. Ex instances/<instance_id>/<db_type>/users
• Add code to inspect instance_id and verify it's instance type.. Redis Postgres MySQL etc.
• Have "proxy" route dynamically load a service for each database type either with importlib or stevedore whatever.
• Have the route accept requests for differing database engines. Ex. Default database for postgres on user create while MySQL does not use one.

Why do it this way?

• More explicit than dynamic type mapping.
• Might be easier to write docs as each URI is explicit rather than implicit based off of its type.
• Contract is explicit for each URI rather than variable based on database type.
• Databases with similar functionality could use polymorphism to override or extend functionality of the routing modules
• hub_cap is all about this one!
• Kenneth is currently on this side of the fence

Cons

• Potential api version change. (If existing extentions and routes are removed)
• Could be wonky for users only using one DB type.
  • A solution for that edge case may be to implement aliasing for instances/<instance_id>/<action> and that is the same as supporting dynamic type resolution essentially.
• Lots of routes to manage depending on how we decide to implement the routing.
  • These could be handled by routing modules for each database type
• Need to know what type db is in order to know what uri to post to.

Client Examples

Client interaction flow with dynamic type resolution for user add example

• Determine type from instances listing.
• post to instances/<instance_id>/users with db specific body.
• validate input.
• 404 if db does not have concept of users.
• 2** if all is well

Client interaction flow with namespaced routes for user add example

• Determine type from instance listing.
• post to instances/<instance_id>/<db_type>/users with db specific body.
• validate input.
• 404 if db does not have concept of users.
• 2** if all is well.