206572113
Measuring distance between program features
We present a metric to determine the distance between the features of a software system. Such a measurement can elucidate how features of the system being examined are close to each other. We first use an execution slice-based technique to identify a set of code (basic blocks in our case) that is used to implement each feature. Then, depending on whether the execution frequency of each block is considered during the construction of such sets of code, a static as well as a dynamic distance is computed for each pair of features. These two types of distance differ in that the former computes the distance between two features only by how these features are implemented in the system, while the latter also takes into account how each feature is executed based on a user's operational profile. In other words, the static distance quantitatively gives the closeness of two features from the system implementation point of view, whereas the dynamic distance presents such closeness from the users' execution point of view. To illustrate the use of our metric, we report a case study on a Symbolic Hierarchical Automated Reliability and Performance Evaluator (SHARPE). The results of our study suggest that the distance metric discussed in this paper can provide a good measurement, in a quantitative way, of how close two program features are. Such information can also serve as a good start to understanding how a modification made to one feature is likely to affect other features.
39945640
Smart debugging software architectural design in SDL
Statistical data show that it is much less expensive to correct software bugs at the early design stage rather than the late stage of the development process when the final system has already been implemented and integrated together. The use of slicing and execution histories as an aid in software debugging is well established for programming languages like C and C++; however, it is rarely applied in the field of software design specification. We propose a solution by applying the source code level technologies to debugging software designs represented in a high-level specification and description language such as SDL. More specifically, we extend execution slice-based heuristics from source code-based debugging to the software design specification level. Suspicious locations in an SDL specification are prioritized by their likelihood of containing faults. Locations with a higher priority should be examined first rather than those with a lower priority as the former are more likely to contain the faults. A debugging tool, SmartD/sub DSL/, with user-friendly interfaces was developed to support our method. An illustration is provided to demonstrate the feasibility of using our method to effectively debug an architectural design.
13223545
Quantifying the closeness between program components and features
Abstract One of the most important steps towards effective software maintenance of a large complicated system is to understand how program features are spread over the entire system and their interactions with the program components. However, we must first be able to represent an abstract feature in terms of some concrete program components. In this paper, we use an execution slice-based technique to identify the basic blocks which are used to implement a program feature. Three metrics are then defined, based on this identification, to determine quantitatively , the disparity between a program component and a feature, the concentration of a feature in a program component, and the dedication of a program component to a feature. The computations of these metrics are automated by incorporating them in a tool ( χ Suds), which makes the use of our metrics immediately applicable in real-life contexts. We demonstrate the effectiveness of our technique by experimenting with a reliability and performance evaluator. Results of our study suggest that these metrics can provide an indication of the closeness between a feature and a program component which is very useful for software programmers and maintainers to better understand the system at hand.
31350744
Redesigning legacy systems into the object-oriented paradigm
Object-oriented/sup 1/ languages support many modern programming paradigms such as information hiding, inheritance, polymorphism, and dynamic binding. As a result, software systems implemented in OO languages are more reusable and reliable than those in non-OO. Many legacy software systems were created before OO programming became popular and needed to be redesigned and updated to OO programs. The process of abstracting OO designs from the procedural source code was often done manually or with limited assistance from program structural diagrams. Most reengineering focuses on the functionality of the original program, and the OO redesign often results in a completely new design based on the designers' understanding of the original program. Such an approach is not sufficient, for it not only takes time and effort for designers to become familiar with the original program, but the approach itself is also mistake-prone due to the human involvement. This paper presents a computer-aided semi-automatic method that abstracts OO designs from the original procedural source code. More specifically, it is a method for OO redesign based on program structural diagrams, visualization, and execution slice. We conducted a case study by applying this method to an inventory management software system. Results indicate that our method can effectively and efficiently abstract an appropriate OO design out of the original C code as well as re-generate part of the system in C++ code based on this new OO design.
16024151
An adaptable architecture for secure delivery of converged services
We present an approach for secure delivery of multimodal services to end users over heterogeneous converged networks. Our approach leads to an easily adaptable and extensible system architecture, in which system components interact with each other through loosely coupled interfaces based on asynchronous exchange of messages. It also effectively separates service logic from service delivery, through the introduction of a secure broker between the end user devices and the enterprise level application that contains the service logic. This separation also provides additional levels of security at the application level. This paper describes how our approach provides the features mentioned above. We have also validated our approach through the implementation of a prototype system, a description of which is also provided.
2760120
Mutation Testing Applied to Validate SDL Specifications
Mutation Testing is an error-based criterion that provides mechanisms to evaluate the quality of a test set and/or to generate test sets. This criterion, originally proposed to program testing, has also been applied to specification testing. In this paper, we propose the application of Mutation Testing for testing SDL specifications. We define a mutant operator set for SDL that intends to model errors related to the behavioral aspect of the processes, the communication among processes, the structure of the specification and some intrinsic characteristics of SDL. A testing strategy to apply the mutant operators to test SDL specifications is proposed. We illustrate our approach using the Alternating-Bit protocol.
2377420
Cooperative-diversity slotted ALOHA
We propose a cooperative-diversity technique for ad hoc networks based on the decode-and-forward relaying strategy. We develop a MAC protocol based on slotted ALOHA that allows neighbors of a transmitter to act as relays and forward a packet toward its final destination when the transmission to the intended recipient fails. The proposed technique provides additional robustness against fading, packet collisions and radio mobility. Network simulations confirm that under heavy traffic conditions, in which every radio always has packets to send, the proposed cooperative-diversity slotted-ALOHA protocol can provide a higher one-hop and end-to-end throughput than the standard slotted-ALOHA protocol can. A similar advantage in end-to-end delay can be obtained when the traffic is light. As a result, the proposed cooperative-diversity ALOHA protocol can be used to improve these measures of quality of service (QoS) in ad hoc wireless networks
5758182
Cooperative Instruction Scheduling with Linear Scan Register Allocation
Linear scan register allocation is an attractive register allocation algorithm because of its simplicity and fast running time. However, it is generally felt that linear scan register allocation yields poorer code than allocation schemes based on graph coloring. In this paper, we propose a pre-pass instruction scheduling algorithm that improves on the code quality of linear scan allocators. Our implementation in the Trimaran compiler-simulator infrastructure shows that our scheduler can reduce the number of active live ranges that the linear scan allocator has to deal with. As a result, fewer spills are needed and the quality of the generated code is improved. Furthermore, compared to the default scheduling and graph-coloring allocator schemes found in the IMPACT and Elcor components of Trimaran, our implementation with our pre-pass scheduler and linear scan register allocator significantly reduced compilation times.
44855762
Optimizing floating point operations in Scheme
It is well known that dynamic typing in languages like Lisp is costly in terms of performance. Besides the cost of tag checking, the other major source of inefficiency comes from the need to place and retrieve data from dynamically allocated objects, i.e. boxing and unboxing. This makes it unacceptable in general to write numerical code in Lisp. Such programs involve ''tight'' loops in which boxing, unboxing and tag checking will dominate the computation time. With advances in the compilation of Lisp programs, it has been suggested that type checking and inference can be used to alleviate the problem. In this paper we shall examine a sub-problem, namely using type inference to aid compilation of numerical intensive Lisp code. A type inference algorithm for floating point operations will be described. This has been implemented in a Scheme compiler. Implementation issues and performance results on fairly large numerical code will also be reported. The results suggest that significant performance gains can be obtained. It is our hope that as an augmentation to other general type inferencing scheme, it will contribute towards the realization of highly optimizing Scheme compilers.
8187290
Model-driven SoC design via executable UML to SystemC
We present a system level description mechanism based on UML-notations from which one can automatically extract SystemC code. Our modelling framework is based on a restricted set of UML diagram types and some standard extensions influenced by the communication infrastructure of SystemC. The system specifications are developed using the UML-compatible tool, Rhapsody (2004). We then translate the internal representation of the design generated by Rhapsody into SystemC code. The extensions we have implemented using the stereotype feature of the Rhapsody tool pull up the communication infrastructure and timing features of SystemC to the UML-level. Consequently, we can describe executable platforms at the UML-level as well as translate UML-based application descriptions to SystemC level.
6423442
Rule-based anomaly pattern detection for detecting disease outbreaks
This paper presents an algorithm for performing early detection of disease outbreaks by searching a database of emergency department cases for anomalous patterns. Traditional techniques for anomaly detection are unsatisfactory for this problem because they identify individual data points that are rare due to particular combinations of features. When applied to our scenario, these traditional algorithms discover isolated outliers of particularly strange events, such as someone accidentally shooting their ear, that are not indicative of a new outbreak. Instead, we would like to detect anomalous patterns. These patterns are groups with specific characteristics whose recent pattern of illness is anomalous relative to historical patterns. We propose using a rule-based anomaly detection algorithm that characterizes each anomalous pattern with a rule. The significance of each rule is carefully evaluated using Fisher's Exact Test and a randomization test. Our algorithm is compared against a standard detection algorithm by measuring the number of false positives and the timeliness of detection. Simulated data, produced by a simulator that creates the effects of an epidemic on a city, is used for evaluation. The results indicate that our algorithm has significantly better detection times for common significance thresholds while having a slightly higher false positive rate.