Syddansk Universitet

Bo Norregaard Jorgensen

Allan Raundahl Gregersen

Michael Rasmussen

A system and method for automatic invocation of object initializers, or constructors, for superclasses featuring the ability to modify the contents of classes of existing applications at runtime, which includes adding new superclasses to the class inheritance hierarchy of the existing classes. The system redefines the content of classes of the existing classes and the new superclasses during the loading of the classes to additionally include code statements that invoke constructors of the redefined classes and the new superclasses. The invocation of the constructors at runtime performs the initialization of the objects.

System and method for automatic invocation of constructor code for superclasses

A method for dynamically transforming bytecode of Java Virtual Machine (JVM) bootstrap classes during program startup uses a JVM agent to intercept startup of a JVM compliant computer program to transform the bytecode of already loaded JVM bootstrap classes and store the resulting set of modified bootstrap classes. Subsequently, the JVM Agent intercepts all class loading events to transform the bytecode of classes declaring special program startup method '&#x3c;clinit&#x3e;', by inserting bytecode at the beginning of the method to invoke a callback method declared within the JVM Agent and passing the arguments passed to the JVM upon program startup as callback method parameters. Subsequently, when the callback method intercepts the execution flow of the computer program, the callback method starts a second JVM instance, passing parameters including the obtained input parameters, the main method arguments, and a JVM input argument for accessing the stored set of modified bootstrap classes.

Method for dynamically transforming the bytecode of Java virtual machine bootstrap classes

Under the present invention, a method, computer program product, and system for non-blocking dynamic update of statically-typed class-based object-oriented software executing as byte-code on a virtual machine within an actively running computer system is provided. A set of objects instantiated from an existing module or multiple modules (identifiable collections of application resources and class definitions in the form of byte-code representations) is ready for execution on a virtual machine in an actively running computer system. New versions of one or more modules corresponding to those already loaded into the actively running virtual machine are dynamically loaded into the virtual machine for the purpose of updating the running software. The class definitions within the loaded modules are prepared for dynamic update by inserting byte-code that enables transparent state transfer and shared object identity between objects of a former version and the new version of a class. On the event of a software update, the objects instantiated from a former version of an updated class become uninitialized surrogate objects with the potential to redirect to their future corresponding objects. Corresponding objects are created lazily on first access of the declaring class members. Besides lazy redirection of the behavior of objects and classes, non-blocking dynamic update is achieved by lazy migration of the state offormer objects and classes while locking on a temporary field access lock. Thus, the algorithm for controlling field access and state migration is completely lock-free both before and after state migration; hence the performance degradation is minimal. Finally, any unreferenced objects are removed from memory.

Method, computer program product, and system for non-blocking dynamic update of statically typed class-based object-oriented software

A method, computer program product, and system for non-blocking dynamic update of statically-typed class-based object-oriented software executing as byte-code on a virtual machine within an actively running computer system is provided. A set of objects instantiated from an existing module or multiple modules (identifiable collections of application resources and class definitions in the form of byte-code representations) is ready for execution on a virtual machine in an actively running computer system. New versions of one or more modules corresponding to those already loaded into the actively running virtual machine are dynamically loaded into the virtual machine for the purpose of updating the running software. The class definitions within the loaded modules are prepared for dynamic update by inserting byte-code that enables; transparent state transfer and shared object identity between objects of a former version and the new version of a class.

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Odense M, Denmark

Bo Norregaard Jorgensen