|
Event-driven Architecture
Event-driven architecture (EDA) is a software architecture paradigm promoting the production, detection, consumption of, and reaction to events. Overview An ''event'' can be defined as "a significant change in state". For example, when a consumer purchases a car, the car's state changes from "for sale" to "sold". A car dealer's system architecture may treat this state change as an event whose occurrence can be made known to other applications within the architecture. From a formal perspective, what is produced, published, propagated, detected or consumed is a (typically asynchronous) message called the event notification, and not the event itself, which is the state change that triggered the message emission. Events do not travel, they just occur. However, the term ''event'' is often used metonymically to denote the notification message itself, which may lead to some confusion. This is due to Event-driven architectures often being designed atop message-driven architectures, where suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Architecture
Software architecture is the fundamental structure of a software system and the discipline of creating such structures and systems. Each structure comprises software elements, relations among them, and properties of both elements and relations. The ''architecture'' of a software system is a metaphor, analogous to the architecture of a building. It functions as a blueprint for the system and the developing project, which project management can later use to extrapolate the tasks necessary to be executed by the teams and people involved. Software architecture is about making fundamental structural choices that are costly to change once implemented. Software architecture choices include specific structural options from possibilities in the design of the software. For example, the systems that controlled the Space Shuttle launch vehicle had the requirement of being very fast and very reliable. Therefore, an appropriate real-time computing language would need to be chosen. Additiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semantic Matching
Semantic matching is a technique used in computer science to identify information which is semantically related. Given any two graph-like structures, e.g. classifications, taxonomies database or XML schemas and ontologies, matching is an operator which identifies those nodes in the two structures which semantically correspond to one another. For example, applied to file systems it can identify that a folder labeled "car" is semantically equivalent to another folder "automobile" because they are synonyms in English. This information can be taken from a linguistic resource like WordNet. In the recent years many of them have been offered. S-Match is an example of a ''semantic matching operator''. It works on lightweight ontologies, namely graph structures where each node is labeled by a natural language sentence, for example in English. These sentences are translated into a formal logical formula (according to an artificial unambiguous language) codifying the meaning of the node ta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autonomous Peripheral Operation
In computing, autonomous peripheral operation is a hardware feature found in some microcontroller architectures to off-load certain tasks into embedded autonomous peripherals in order to minimize latencies and improve throughput in hard real-time applications as well as to save energy in ultra-low-power designs. Overview Forms of autonomous peripherals in microcontrollers were first introduced in the 1990s. Allowing embedded peripherals to work independently of the CPU and even interact with each other in certain pre-configurable ways off-loads event-driven communication into the peripherals to help improve the real-time performance due to lower latency and allows for potentially higher data throughput due to the added parallelism. Since 2009, the scheme has been improved in newer implementations to continue functioning in sleep modes as well, thereby allowing the CPU (and other unaffected peripheral blocks) to remain dormant for longer periods of time in order to save energy. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactor Pattern
The reactor design pattern is an event handling pattern for handling service requests delivered concurrently to a service handler by one or more inputs. The service handler then demultiplexes the incoming requests and dispatches them synchronously to the associated request handlers. Structure ;Resources: Any resource that can provide input to or consume output from the system. ;Synchronous Event Demultiplexer: Uses an event loop to block on all resources. The demultiplexer sends the resource to the dispatcher when it is possible to start a synchronous operation on a resource without blocking (''Example:'' a synchronous call to read() will block if there is no data to read. The demultiplexer uses select() on the resource, which blocks until the resource is available for reading. In this case, a synchronous call to read() won't block, and the demultiplexer can send the resource to the dispatcher.) ;Dispatcher: Handles registering and unregistering of request handlers. Dispatches ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Staged Event-driven Architecture
The staged event-driven architecture (SEDA) refers to an approach to software architecture that decomposes a complex, event-driven application into a set of stages connected by queues. It avoids the high overhead associated with thread-based concurrency models (i.e. locking, unlocking, and polling for locks), and decouples event and thread scheduling from application logic. By performing admission control on each event queue, the service can be well-conditioned to load, preventing resources from being overcommitted when demand exceeds service capacity. SEDA employs dynamic control to automatically tune runtime parameters (such as the scheduling parameters of each stage) as well as to manage load (like performing adaptive load shedding). Decomposing services into a set of stages also enables modularity and code reuse, as well as the development of debugging tools for complex event-driven applications. See also *Event-driven architecture (EDA) *Service-oriented architecture (SOA) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event Processing Technical Society
Event Processing Technical Society (EPTS) is an inclusive group of organizations and individuals aiming to increase awareness of event processing, foster topics for future standardization, and establish event processing as a separate academic discipline. Motivation The goal of the EPTS is development of shared understanding of event processing terminology. The society believes that through communicating the shared understanding developed within the group it would become a catalyst for emergence of effective interoperation standards, would foster academic research, and creation of training curriculum. In turn it would lead to establishment of event processing as a discipline in its own right. The society is trying to follow example of the Database technology when relational theory provided theoretical foundation and homogenized the technology through introduction of Structured Query Language (SQL). The EPTS members hope that through combination of academic research, vendor exper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event Stream Processing
In computer science, stream processing (also known as event stream processing, data stream processing, or distributed stream processing) is a programming paradigm which views data streams, or sequences of events in time, as the central input and output objects of computation. Stream processing encompasses dataflow programming, reactive programming, and distributed data processing. Stream processing systems aim to expose parallel processing for data streams and rely on streaming algorithms for efficient implementation. The software stack for these systems includes components such as programming models and query languages, for expressing computation; stream management systems, for distribution and scheduling; and hardware components for acceleration including floating-point units, graphics processing units, and field-programmable gate arrays. The stream processing paradigm simplifies parallel software and hardware by restricting the parallel computation that can be performed. G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space-based Architecture
A Space-based architecture (SBA) is an approach to distributed computing systems where the various components interact with each other by ''exchanging'' tuples or entries via one or more shared spaces. This is contrasted with the more common Message queuing service approaches where the various components interact with each other by ''exchanging'' messages via a message broker. In a sense, both approaches exchange messages with some central agent, but how they exchange messages is very distinctive. An analogy might be where a message broker is like an Academic conference, where each presenter has the stage, and presents in the order they are scheduled; whereas a tuple space is like an Unconference, where all participants can write on a common whiteboard concurrently, and all can see it at the same time. * Tuple Spaces ** each space is like a 'channel' in a message broker system that components can choose to interact with ** components can write a 'tuple' or 'entry' into a space, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Service-oriented Architecture
In software engineering, service-oriented architecture (SOA) is an architectural style that focuses on discrete services instead of a monolithic design. By consequence, it is also applied in the field of software design where services are provided to the other components by application components, through a communication protocol over a network. A service is a discrete unit of functionality that can be accessed remotely and acted upon and updated independently, such as retrieving a credit card statement online. SOA is also intended to be independent of vendors, products and technologies. Service orientation is a way of thinking in terms of services and service-based development and the outcomes of services. A service has four properties according to one of many definitions of SOA: # It logically represents a repeatable business activity with a specified outcome. # It is self-contained. # It is a black box for its consumers, meaning the consumer does not have to be aware of the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Process Driven Messaging Service
A process driven messaging service (PDMS) is a service that is process oriented and exchanges messages/data calls. A PDMS is a service where jobs and triggers can be put together to create a workflow for a message. Messaging platforms are considered key Internet infrastructure elements. A concept that once mainly encompassed email and IM has evolved to embrace complex multi-media email, instant messaging, and related fixed and mobile messaging infrastructure. Arguably, everything transmitted on the Internet and wireless telecommunication links are messages. PDMS exchanges messages for the purpose of all kind of messages/data calls between systems, applications and or human beings that is based upon event-driven process chains. Structure A process driven messaging service is a service where jobs and triggers can be put together to create a workflow for a message and the workflow can be seen as a process. A workflow is executed when a trigger is prompted. The trigger causes the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event-driven Programming
In computer programming, event-driven programming is a programming paradigm in which the flow of the program is determined by events such as user actions (mouse clicks, key presses), sensor outputs, or message passing from other programs or threads. Event-driven programming is the dominant paradigm used in graphical user interfaces and other applications (e.g., JavaScript web applications) that are centered on performing certain actions in response to user input. This is also true of programming for device drivers (e.g., P in USB device driver stacks). In an event-driven application, there is generally a main loop that listens for events and then triggers a callback function when one of those events is detected. In embedded systems, the same may be achieved using hardware interrupts instead of a constantly running main loop. Event-driven programs can be written in any programming language, although the task is easier in languages that provide high-level abstractions, such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object Pascal
Object Pascal is an extension to the programming language Pascal that provides object-oriented programming (OOP) features such as classes and methods. The language was originally developed by Apple Computer as ''Clascal'' for the Lisa Workshop development system. As Lisa gave way to Macintosh, Apple collaborated with Niklaus Wirth, the author of Pascal, to develop an officially standardized version of Clascal. This was renamed Object Pascal. Through the mid-1980s, Object Pascal was the main programming language for early versions of the MacApp application framework. The language lost its place as the main development language on the Mac in 1991 with the release of the C++-based MacApp 3.0. Official support ended in 1996. Symantec also developed a compiler for Object Pascal for their Think Pascal product, which could compile programs much faster than Apple's own Macintosh Programmer's Workshop (MPW). Symantec then developed the Think Class Library (TCL), based on MacApp c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
