Changing Java programs.

This paper describes a tool we developed enabling the distribution of updated versions of Java class libraries. To draw up its specification, we analyzed pathological code fragments, some taken from SUN Microsystems' own documentation. We classified the integration problems that could arise when old applications (clients) are executed against new Java libraries. The tool could anticipate these problems and seek compatible components from a central repository. Subsequently SUN Microsystems modified the Java runtime environment so as to overcome the most significant of these problems and updated their documentation to reflect the others