Efficient implementation of adaptive software

Abstract

Adaptive programs compute with objects, just like object-oriented programs. Each task to be accomplished is specified by a so-called propagation pattern which traverses the receiver object. The object traversal is a recursive descent via the instance variables where information is collected or propagated along the way. A propagation pattern consists of (1) a name for the task, (2) a succinct specification of the parts of the receiver object that should be traversed, and (3) code fragments to be executed when specific object types are encountered. The propagation patterns need to be complemented by a class graph which defines the detailed object structure. The separation of structure and behavior yields a degree of flexibility and understandability not present in traditional object-oriented languages. For example, the class graph can be changed without changing the adaptive program at all. We present an efficient implementation of adaptive programs. Given an adaptive program and a class graph, we generate an efficient object-oriented program, for example, in C++. Moreover, we prove the correctness of the core of this translation. A key assumption in the theorem is that the traversal specifications are consistent with the class graph. We prove the soundness of a proof system for conservatively checking consistency, and we show how to implement it efficiently.

Strategic programming meets adaptive programming

“…We recall that traversal specifications are composed in terms of the predicates from, to, through, and bypassing as sketched in the introduction. The semantics of AP usually refers to other primitives [18] that make clear that traversal specifications denote sets of paths in a graph with classes as nodes, and edges for subclassing and subobjects. These are the most fundamental primitives to compose traversal specifications Ë:…”

“…We will compare SP with another aspectual approach to traversal, namely adaptive programming (AP) as developed by Lieberherr and collaborators [9,18,17,11,15]. We will work towards a marriage of the ideas underlying the two aspectual approaches to traversal.…”

Controlling the complexity of software designs

“…Therefore there is no need to traverse into the inventory part and we can determine this statically based on the meta-information in the class graph. Notice that the traversal is used to enumerate efficiently all the coordinates where a Salary-object will be found [52].…”

“…Implementing traversals is more complex than it first appears [37,51,52]. The commercially successful traversal technology that is widely used is XPath.…”

“…We started with simple strategies of the form "from A bypassing X to B". Then we considered series-parallel strategies that used simple strategies and two operators: join and merge [52]. Our compilation algorithm for series-parallel strategies was limited in that it only worked on a limited set of class graph and traversal strategy combinations.…”