Load-Time Adaptation

Load-Time Adaptation (LTA) [#!Dun1999!#] uses a similar approach as BCA. The class files are modified at load time. The specialty of LTA is the point where the loading process is interrupted and adaptation is executed. BCA is implemented as a customized class loader, but LTA acts on a lower level in order to keep the loading process between virtual machine and application untouched. The intention is to redirect the operations on the class file, e.g. read(), open(), close().

The redirection of system calls is neglected because modifications of the operating system are hard to port to various platforms. The solution as proposed by [#!Dun1999!#] is to modify the dynamic library, which provides the functionality for operations on the file system. The modified library accesses the file system via system calls and performs an adaptation of the class files if necessary. This approach hides the adaptation process to the application and to the virtual machine, but supports porting the modified dynamic libraries to various platforms, because it uses only non-OS dependent functionality.

This LTA adaptation mechanism suffers on the same lack as BCA: the missing support for an environment dependent adaptation.