SEL Ada reuse analysis and representations

Overall, it was revealed that the pattern of Ada reuse has evolved from initial reuse of utility components into reuse of generalized application architectures. Utility components were both domain-independent utilities, such as queues and stacks, and domain-specific utilities, such as those that implement spacecraft orbit and attitude mathematical functions and physics or astronomical models. The level of reuse was significantly increased with the development of a generalized telemetry simulator architecture. The use of Ada generics significantly increased the level of verbatum reuse, which is due to the ability, using Ada generics, to parameterize the aspects of design that are configurable during reuse. A key factor in implementing generalized architectures was the ability to use generic subprogram parameters to tailor parts of the algorithm embedded within the architecture. The use of object oriented design (in which objects model real world entities) significantly improved the modularity for reuse. Encapsulating into packages the data and operations associated with common real world entities creates natural building blocks for reuse

Proceedings of the Fifteenth Annual Software Engineering Workshop

The Software Engineering Laboratory (SEL) is an organization sponsored by GSFC and created for the purpose of investigating the effectiveness of software engineering technologies when applied to the development of applications software. The goals of the SEL are: (1) to understand the software development process in the GSFC environment; (2) to measure the effect of various methodologies, tools, and models on this process; and (3) to identify and then to apply successful development practices. Fifteen papers were presented at the Fifteenth Annual Software Engineering Workshop in five sessions: (1) SEL at age fifteen; (2) process improvement; (3) measurement; (4) reuse; and (5) process assessment. The sessions were followed by two panel discussions: (1) experiences in implementing an effective measurement program; and (2) software engineering in the 1980's. A summary of the presentations and panel discussions is given

Patterns of component evolution

Contemporary software systems are composed of many components, which, in general, undergo phased and incremental development. In order to facilitate the corresponding construction process, it is important that the development team in charge has a good understanding of how individual software components typically evolve. Furthermore, software engineers need to be able to recognize abnormal patterns of growth with respect to size, structure, and complexity of the components and the resulting composite. Only if a development team understands the processes that underpin the evolution of software systems, will they be able to make better development choices. In this paper, we analyze recurring structural and evolutionary patterns that we have observed in public-domain software systems built using object-oriented programming languages. Based on our analysis, we discuss common growth patterns found in present-day component-based software systems and illustrate simple means to aid developers in achieving a better understanding of those patterns. As a consequence, we hope to raise the awareness level in the community on how component-based software systems tend to naturally evolve

Mediterranean Outflow Water and contourites over two analog climate cycles in the Gulf of Cadiz

International audienceThe Contourite Depositional Systems (CDSs) in the Gulf of Cadiz are unique archives of the Mediterranean Outflow Water (MOW) variability since the opening of the Gibraltar gateway at the end of the Miocene (5.33 Ma). The construction of these systems involves the upper (MUW) and lower (MLW) branches of the MOW. Drilling of these CDSs during IODP Expedition 339 (2011-2012) enables to investigate the MOW dynamics over an extended time period of the late Cenozoic. This study is centered on the sedimentological and facies characteristics of contourite beds over two periods with similar astronomic configurations (MIS1-2 and MIS 11-12) in order to compare the behavior and circulation regime of the MOW over two contrasted climatic cycles and their associated deglaciation. Sedimentological and facies analysis of different CDSs in the Gulf of Cadiz are based on an extensive set of data including grain size, petrographic (?) analyses of sandy components and clay assemblages, thin sections of contourite sequences, XRF core-scanner data, natural gamma ray data and biostratigraphy based on planktonic foraminifers. The results show a different behavior of the MOW between MIS 1/2 and MIS 11/12. For instance, in the Faro Drift (upper MOW), MIS 11 is characterized by the presence of several fine grained contourites (silt/ fine sand) while they are rare during MIS 1. During MIS 2 and MIS 12, only one contourite bed is recorded. These time periods are also characterized by different types of contourite beds in terms of grain size and composition: some are carbonate-rich whereas others are enriched in siliciclastic/terrigenous or/and authigenic particles. Different patterns of component evolution are also observed showing both changes in MOW velocity and availability of different sources of sediment involved