Core Toolkit Design Changes for 2.1.3

Version: 1.1
Author: Ivan R. Judson <judson@mcs.anl.gov>
Status: Draft

Abstract

This document proposes design modifications to the existing Core Toolkit Design to make it more solid, with a factoring that allows an easier transition to GT3 or other network interfaces. It applies well known patterns, leveraging the pattern terminology to keep the code as clear as possible and also abstracts the persistence solution for the venues.

Overview

There are a few reorganizations that can be done within the AG module. These will result in a reasonably clean and simple set of logical sub-modules with interfaces defined among them. The separations that are proposed in this enhancement include:

  1. Separating interfaces and implementations

The proposed naming is for interfaces to have the name format:

  • <Network Protocol><Class Name>I, or
  • <Network Protocol><Class Name>Interface

(e.g. SOAPVenueServerI or SOAPVenueServerInterface) then the Venue Server implementation can retain the name VenueServer. This allows the creation of many interfaces with clear naming, for the same implementation object and the additional syntax is retained where it is needed for clarification.

  1. Creating a SOAP interface base class with two methods:
  • a constructor that registers the implementation with interface and the interface with the implementation, and
  • an authorization method that is used by default, the proposed policy is that the default authorization method disallow incoming actions.
  1. Move AppDatabase from Toolkit to VenueClient [Done]
This is the appropriate place for it to go.
  1. Update to latest version of pyGlobus
  2. Update to GT2.4.3 on Linux, Mac OS X
  3. Update to GT2.4.3+ on Windows
Updating these pieces of software should make it easier for us to maintain, and it will make it easier to migrate in the future.

Summary of Modifications

Modified:

These objects need to have their interfaces separated from the implementation.

Removed:

New:

Module Organization

  • AccessGrid
    • hosting
      • pyGlobus [Nothing required now]
        • tests
          • tclient.py
          • test_invalid.py
          • tserver.py
      • <pyGridware> (Future Addition)
  • SOAPpy [standard SOAPpy install]
    • wstools [standard wstools install
  • pyGlobus [standard pyGlobus install]

Specifications

SOAPInterface:
    def __init__(self, impl):
    def _authorize(self, *args, **kw):

VenueServer

in the __init__ method, this object creates a SOAPVenueServerI object 
passing self. This effectively creates a single SOAP interface 
(self.interface), later when we support multiple interfaces per object this
should be removed and replaced with self.interfaces = list() and 
AddInterface(self, interface).

The server also has a authorize(subject, actionName) that exposes the
mechanism for the SOAP layer to do authorization.

Venue

in the __init__ method, this object creates a SOAPVenueI object 
passing self. This effectively creates a single SOAP interface 
(self.interface), later when we support multiple interfaces per object this
should be removed and replaced with self.interfaces = list() and 
AddInterface(self, interface).

The venue also has a authorize(subject, actionName) that exposes the
mechanism for the SOAP layer to do authorization.

Security Issues

None, this set of modifications should in no way affect the security of the system.

Interoperability Issues

The refactoring in this proposal should not affect the interoperability of the client with servers and services. This is an internal refactoring.

References

  1. Design Patterns: Elements of Reusable Object-Oriented Software, Erich Gamma, Richard Helm, Ralph Johnson, John Vlissides. Addison-Wesley Professions Computing Series, Addison Wesley Longman, Inc, Reading, MA, 1995.
  2. Python Enhancement Proposals