[Zope3-dev] Local Utility-Service and persistent Utilities

[Ulrich Eck]

At several parts of my work (schedule, workflow) i needed persistent 
Utilities
so i decided to start work on them.

Before i can start i need some information about the way it should be done.

General structure:

  - A Local-UtilityService that is configured with the Service Manager
  - A Component that is added to some package
  - This Component is configured with the UtilityService

My Questions:

  1. What information is needed to configure a utility-component ?
     My Guess:
      - providedInterface (the interface the component provides or choosen 
TTW)
      - utilityName (an optional name)
      - componentPath (the path to the utility-component)
     so the Configuration key would be a tuple (providedInterface, 
utilityName) ??

  2. What components can be configured as Utilities ?
     When building the Configuration Screens i need to give a choice of 
components
     that can be configured as Utilities. How do i find out which one are 
avaliable ??
     afaik there is not common Interface for Utilities.

  3. Should there be a possiblity to add persistently added 
component-instances as well
     as python-based (like global Utilities) ones ??

  4. How does resolving Utilities work when they have a name ?
     from the sources it seems, that when a utility is provided with name, 
it is not
     found when one queries only for the interface it provides .. is this 
behaviour
     correct and wanted ??

   5. How is registration/configuration handled when:
      - two utilities provide the same interface (no name) --> exclusive 
activation.
      - two utilities provide same name and interface --> exclusive 
activiation.
      - one util provides interface - no name, other provides the same 
interface with name ?
      - two utilities provide different interfaces for the same name ?

I would basically start with adapter-service as template, add specific 
configuration-code,
use the ImplementorRegistry (made persistent) to store 
Utility-configuration
and build a TTW-Config-screen.

What else should i take care of when start working on this issue ??

thanks for your comments

Ulrich Eck
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