Late binding

Abstract: Dynamic evolution of workflow models due to process (re)engineering activities and dynamic changing situations of the real process is one of the most important challenges in workflow management. The authors present an approach for the management of evolving workflow specifications which copes with the evolution of a workflow schema and the dynamic modification of workflow instances. The approach is based on the integrated modeling of workflow schema and instance elements, the separated definition of 'what to do' and 'how to do' in the workflow schema, late binding of workflows at run-time, and the versioning of the workflow schema. On this basis, they support lazy, eager, and selective propagation as well as local customization of instances and their upward propagation. Furthermore, they address the problem of managing consistent configurations of the versioned entities of a workflow schema. In their workflow-specific versioning approach, the consistency of the workflow configuration is guaranteed and hence the version mechanism is transparent to the user.

Abstract: SmallEiffel is an Eiffel compiler which uses a fast simple type inference mechanism to remove most late binding calls, replacing them by static bindings. Starting from the system's entry point, it compiles only statically living code, which saves compiling and then removing dead code. As the whole system is analyzed at compile time, multiple inheritance and genericity do not cause any overhead.SmallEiffel features a coding scheme which eliminates the need for virtual function tables. Dynamic dispatch is implemented without any array access but uses a simple static binary branch code. We show that this implementation makes it possible to use modern hardware very efficiently. It also allows us to inline more calls even when dynamic dispatch is required. Some more dispatch sites are removed after the type inference algorithm has been performed, if the different branches of a dispatch site lead to the same code.The advantage of this approach is that it greatly speeds up execution time and considerably decreases the amount of generated code.

Abstract: It has been recognized in several works that a slice of behavior affecting a set of collaborating classes is a better unit of reuse than a single class. Different techniques and language extensions have been suggested to express such slices in programming languages. We propose delegation layers, an approach that scales the OO mechanisms for single objects, such as delegation, late binding, and subtype polymorphism, to sets of collaborating objects. Technically, delegation layers combine and generalize delegation and virtual class concepts. Due to their runtime semantics, delegation layers are more flexible than previous compile time approaches like mixin layers.

Abstract: An SQL program executor and an SQL compiler both include options for avoiding recompilations of execution plans whenever the runtime object and the compile time object referenced by an execution plan meet predefined schema similarity criteria. Thus, recompilation is sometimes avoided even though the compile time object has been altered or the run time object is not the same object as the compile time object. To enable late binding, schema information is stored in each execution plan for each object to be accessed by the execution plan. The stored schema information is a subset of the full object schema, and includes information about all the aspects of the objects to be accessed which must remain unchanged in order for the execution plan to be operable. While executing a compiled program, the SQL executor avoids recompilations of execution plans whenever the runtime object and the compile time object referenced by an execution plan meet predefined schema similarity criteria. When a recompilation of an SQL program is required, only the execution plans which do not meet the schema similarity criteria are recompiled if the compiled program has been assigned appropriate runtime parameters. The late binding features of the SQL executor also enable a compiled program to access objects distinct from the objects referenced by the program at compile time. Similarly, the SQL compiler includes the ability to recompile only those execution plans which do not meet the schema similarity criteria and thus are inoperable.