Persistent data library

Abstract

Persistent Data Library (PDL) manages object persistence. PDL provides a set of data structures which transparently handles persistence. Data structures in PDL, are quite similar to data structures in Standard Template I library (STL) in C++. Such a framework is useful for a fault tolerant application. State based applications need to check point data periodically. In case of a failure, such applications need fast recovery of data. In developing such applications, each time a new state is. Introduced to the system, the programmer needs to write code to serialize and de-seri.ilize data. PDL framework helps the programmer to write less code on serialization and de- serialization. Due to the direct memory dumping technology PDL uses, the time taken to write data to the disk and recover data from the storage are minimized. The data structures are stored in files in a format that is structurally equivalent to the format of the objects on a volatile medium, such as the memory of a comp tier. Objects are stored according to data relationship with other objects. Object references aye converted to offset references before they are stored. The objects are SL red as a stream of objects and offset references. Offset references are converted to actual memory addresses when objects are retrieved into the volatile medium. A performance evaluation was carried out between PDL and STL in order to compare performance. Research results shows that there is a significant performance improvement in persisting data inside PDL data structures and loading data ink' PDL data structures.