Method and apparatus for updating software libraries

#1. Field of the Invention

#The present invention relates to supporting updates in software libraries, and more specifically, to a method and apparatus for updating software libraries with dynamic version changes.

#2. Related Art

#Other important objects and features of the invention will be apparent from the following Detailed Description of the Invention taken in connection with the accompanying drawings in which:

#FIG. 1a is a diagram showing an example of a library update procedure and resulting class, object, and thread interactions achieved by the prior art.

#FIGS. 1b and 1c are diagrams showing examples of prior art interactions between inherited superclass code and subclass objects occurring after the update of FIG. 1a.

#The present invention relates to a method for supporting dynamic version changes for hot-swapping of software libraries. Objects produced by a first version of software can be dynamically and lazily adapted (i.e., objects are only adapted if and when necessary) for use by later versions of software, so that client threads accessing the objects and the later versions of software do not experience a disruption in service. The methodology of the invention allows for version changes in software beyond the inheritance paradigm of present object-oriented languages, since inheritance only provides for limited version changes and only allows old versions of software to access new version objects. Further, the methodology allows new methods and interfaces not provided with legacy objects to be used by the legacy objects.

#FIG. 2 is a diagram showing the methodology of the present invention, wherein an object adaptation operation and a table of version adapters provide a proxy object for use by subclass code and existing client threads. Superclass 200, representing a software library existing on any computer system known in the art, produces an object 202, which can be any data object, structure, or associated methods and procedures. The object 202 can then be accessed by thread 204 by pointer 203. Thread 204 can be any computer process running on any computer system, and can even be a process running on the same computer system on which object 202 exists.

#Subclass 208 contains code not existent in superclass 200, and is introduced into software library 200 by a software update. Subclass 208 includes procedures that may inherit functionality from procedures of superclass 200, using the object-oriented paradigm of inheritance. When the object 202 produced by superclass 200 is passed to code of subclass 208 by thread 204 via connection 205, or the code of subclass 208 is otherwise applied to object 202, the traditional downcast procedure, which, as described earlier, results in a downcast failure of object 202, is bypassed by the present invention. Rather, object 202 is passed to object adaptation operation 212. Object adaptation operation 212 then performs a query into version adapter table 214 to retrieve a coercion function (version adaptor) from version adapter table 214, based upon run-time type tags associated with object 202. Version adapter table 214 can be any data structure capable of allowing a query for one field (i.e., a version adapter), based upon the values of two or more other fields (i.e., type tags). Further, the version adapter table of the present invention can be a hash table, splay tree, array, list, 2-3 tree, or any other data structure known in the art.