Because of the dynamic nature of mobile ad hoc networks and the applications running on top of them, these applications have to be conceived as event-driven architectures. Such architectures are hard to program becaus...
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ISBN:
(纸本)9783642134135
Because of the dynamic nature of mobile ad hoc networks and the applications running on top of them, these applications have to be conceived as event-driven architectures. Such architectures are hard to program because coordination between concurrent and distributed mobile components has to be expressed by means of event handlers or callbacks. Applications consisting of disjoint event handlers that are independently triggered (possibly by their environment) exhibit a very implicit control flow that is hard to grasp. This paper presents a visual dataflow language tailored towards mobile applications to express the interaction between mobile components that operate on data streams. By using a visual dataflow language as a separate coordination language, the coarse grained control flow of a mobile application can be specified visually and separately from the fine grained control flow. In its turn, this allows a very explicit view on the control flow of the entire mobile application.
In recent years, many graphical approaches have been proposed to lift the inconvenience of text-based query language among end-users. The new query language called DFQL (dataflow Query Language) is a fully graphical i...
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In recent years, many graphical approaches have been proposed to lift the inconvenience of text-based query language among end-users. The new query language called DFQL (dataflow Query Language) is a fully graphical interface to the relational model based on a dataflow paradigm. It only requires users to connect some well-defined operators which have been given an equivalent one-to-one correspondent functionality (or consu"uct) in traditional query language (SQL in this case). All of the power of current query languages and sufficient expressive power and functionality are retained. But some shortcomings of DFQL user interface still exist. This thesis is to introduce a more ease-to-use and ease-to-leam user interface, so the shortcomings we found in DFQL user interface can be lifted and the productivity and power of the new version of DFQL can be increased. We have adopted object-oriented programming approach in our implementation and the benefits of using object-oriented programming in our development are also discussed.
In nearly all large organizations, the Navy and Department of Defense being no exceptions, the use of database management systems (DBMS' s) has become widespread. The prevailing data model for modern DBMS's is...
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In nearly all large organizations, the Navy and Department of Defense being no exceptions, the use of database management systems (DBMS' s) has become widespread. The prevailing data model for modern DBMS's is the relational model developed by Codd in the early 1970's. The relational model's superiority is due to its well thought out design and founding in mathematical logic. The de facto standard query language for relational DBMS's is IBM's Structured Query Language (SQL). Although SQL is the most widely used query language today, it has many problems, especially in the ease-of-use area. The purpose of this thesis is to design, implement, and test a new query language, DFQL, which will mitigate SQL's ease-of-use problems. DFQL provides a graphical query interface based on the dataflow paradigm in order to allow a user to easily and incrementally construct queries for a relational database. DFQL is relationally complete, maintains relational operational closure, and is designed to be easily extensible by the end user. DFQL has been implemented on an Apple Macintosh using an ORACLE relational DBMS. A simple human factors experiment was performed in which DFQL's ease of query writing compared favorably to that of SQL.
programming network processors is challenging. To sustain high line rates, network processors have extremely tight memory access and instruction budgets. Achieving desired performance has traditionally required hand-c...
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programming network processors is challenging. To sustain high line rates, network processors have extremely tight memory access and instruction budgets. Achieving desired performance has traditionally required hand-coded assembly. Researchers have recently proposed high-level programming languages for packet processing, but the challenges of compiling these languages into code that is competitive with hand-tuned assembly remain unanswered. This paper describes the Shangri-La compiler, which accepts a packet program written in a C-like high-level language and applies scalar and specialized optimizations to generate a highly optimized binary. Hot code paths identified by profiling are mapped across processing elements to maximize processor utilization. Since our compilation target has no hardware caches, software-controlled caches are generated for frequently accessed application data structures. Packet handling optimizations significantly reduce per-packet memory access and instruction counts. Finally, a custom stack model maps stack frames to the fastest levels of the target processor's heterogeneous memory hierarchy. Binaries generated by the compiler were evaluated on the Intel IXP2400 network processor with eight packet processing cores and eight threads per core. Our results show the importance of both traditional and specialized optimization techniques for achieving the maximum forwarding rates on three network applications, L3-Switch, MPLS and Firewall.
Reactive programming has recently gained popularity as a paradigm that is well-suited for developing event-driven and interactive applications. It facilitates the development of such applications by providing abstract...
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Reactive programming has recently gained popularity as a paradigm that is well-suited for developing event-driven and interactive applications. It facilitates the development of such applications by providing abstractions to express time-varying values and automatically managing dependencies between such values. A number of approaches have been recently proposed embedded in various languages such as Haskell, Scheme, JavaScript, Java,. NET, etc. This survey describes and provides a taxonomy of existing reactive programming approaches along six axes: representation of time-varying values, evaluation model, lifting operations, multidirectionality, glitch avoidance, and support for distribution. From this taxonomy, we observe that there are still open challenges in the field of reactive programming. For instance, multidirectionality is supported only by a small number of languages, which do not automatically track dependencies between time-varying values. Similarly, glitch avoidance, which is subtle in reactive programs, cannot be ensured in distributed reactive programs using the current techniques.
This paper deals with semantics-preserving parallelism reduction methods for cyclo-static dataflow applications. Parallelism reduction is the process of equivalent actors fusioning. The principal objectives of paralle...
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This paper deals with semantics-preserving parallelism reduction methods for cyclo-static dataflow applications. Parallelism reduction is the process of equivalent actors fusioning. The principal objectives of parallelism reduction are to decrease the memory footprint of an application and to increase its execution performance. We focus on parallelism reduction methodolo- gies constrained by application throughput. A generic parallelism reduction methodology is introduced. Experimental results are provided for asserting the performance of the proposed method.
Immersive, interactive applications require on-line processing and mixing of multimedia data. In order to realize the Immersipresence vision, we propose a generic, extensible, modular multimedia system software archit...
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ISBN:
(纸本)9781581131987
Immersive, interactive applications require on-line processing and mixing of multimedia data. In order to realize the Immersipresence vision, we propose a generic, extensible, modular multimedia system software architecture. We describe here the Flow Scheduling Framework (FSF), that constitutes the core of its middleware layer. The FSF is an extensible set of classes that provide basic synchronization functionality and composition mechanisms to develop data-stream processing components. In this dataflow approach, applications are implemented by specifying data streams and their path through processing nodes, where they can undergo various manipulations. We describe the details of the FSF data and processing model that supports stream synchronization in a concurrent processing framework. We illustrate the FSF concepts with a real-time video stream processing application.
The Unit framework uses a dataflow programming language to describe interaction techniques for highly interactive environments, such as augmented, mixed, and virtual reality. Unit places interaction techniques in an a...
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ISBN:
(纸本)9781581138832
The Unit framework uses a dataflow programming language to describe interaction techniques for highly interactive environments, such as augmented, mixed, and virtual reality. Unit places interaction techniques in an abstraction layer between the input devices and the application, which allows the application developer to separate application functionality from interaction techniques and ***'s modular approach leads to the design of reusable application-independent interaction control components, portions of which can be distributed across different machines. Unit makes it possible at run time to experiment with interaction technique behavior, as well as to switch among different input device configurations. We provide both a visual interface and a programming API for the specification of the dataflow. To demonstrate how Unit works and to show the benefits to the interaction design process, we describe a few interaction techniques implemented using Unit. We also show how Unit's distribution mechanism can offload CPU intensive operations, as well as avoid costly special-purpose hardware in experimental setups.
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