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Request–response
In computer science, request–response or request–reply is one of the basic methods computers use to communicate with each other in a network, in which the first computer sends a ''request'' for some data and the second ''responds'' to the request. More specifically, it is a message exchange pattern in which a requestor sends a request message to a replier system, which receives and processes the request, ultimately returning a message in response. It is analogous to a telephone call, in which the caller must wait for the recipient to pick up before anything can be discussed. This is a simple but powerful messaging pattern which allows two applications to have a two-way conversation with one another over a channel; it is especially common in client–server architectures.Hohpe, Gregor. ''Enterprise Integration Patterns: Designing, Building, and Deploying Messaging Solutions''. . p. 184 Request–response pattern can be implemented synchronously (such as web service calls o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Remote Procedure Call
In distributed computing, a remote procedure call (RPC) is when a computer program causes a procedure (subroutine) to execute in a different address space (commonly on another computer on a shared computer network), which is written as if it were a normal (local) procedure call, without the programmer explicitly writing the details for the remote interaction. That is, the programmer writes essentially the same code whether the subroutine is local to the executing program, or remote. This is a form of server interaction (caller is client, executor is server), typically implemented via a request–response message passing system. In the object-oriented programming paradigm, RPCs are represented by remote method invocation (RMI). The RPC model implies a level of location transparency, namely that calling procedures are largely the same whether they are local or remote, but usually, they are not identical, so local calls can be distinguished from remote calls. Remote calls are usually o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Message Exchange Pattern
In software architecture, a messaging pattern is an architectural pattern which describes how two different parts of an application, or different systems connect and communicate with each other. There are many aspects to the concept of messaging which can be divided in the following categories: hardware device messaging (telecommunications, computer networking, IoT, etc.) and software data exchange (the different data exchange formats and software capabilities of such data exchange). Despite the difference in the context, both categories exhibit common traits for data exchange. General concepts of the messaging pattern In telecommunications, a message exchange pattern (MEP) describes the pattern of messages required by a communications protocol to establish or use a communication channel. The ''communications protocol'' is the format used to represent the message which all communicating parties agree on (or are capable to process). The ''communication channel'' is the infrastru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Messaging Pattern
In software architecture, a messaging pattern is an architectural pattern which describes how two different parts of an application, or different systems connect and communicate with each other. There are many aspects to the concept of messaging which can be divided in the following categories: hardware device messaging (telecommunications, computer networking, IoT, etc.) and software data exchange (the different data exchange formats and software capabilities of such data exchange). Despite the difference in the context, both categories exhibit common traits for data exchange. General concepts of the messaging pattern In telecommunications, a message exchange pattern (MEP) describes the pattern of messages required by a communications protocol to establish or use a communication channel. The ''communications protocol'' is the format used to represent the message which all communicating parties agree on (or are capable to process). The ''communication channel'' is the infrastr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Futures And Promises
In computer science, futures, promises, delays, and deferreds are constructs used for synchronization (computer science), synchronizing program execution (computing), execution in some concurrent programming languages. Each is an object that acts as a proxy for a result that is initially unknown, usually because the computation of its value is not yet complete. The term ''promise'' was proposed in 1976 by Daniel P. Friedman and David Wise, and Peter Hibbard called it ''eventual''. A somewhat similar concept ''future'' was introduced in 1977 in a paper by Henry Baker (computer scientist), Henry Baker and Carl Hewitt. The terms ''future'', ''promise'', ''delay'', and ''deferred'' are often used interchangeably, although some differences in usage between ''future'' and ''promise'' are treated below. Specifically, when usage is distinguished, a future is a ''read-only'' placeholder view of a variable, while a promise is a writable, single assignment container which sets the value of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contention-based Protocol
A contention-based protocol (CBP) is a communications protocol for operating wireless telecommunication equipment that allows many users to use the same radio channel without pre-coordination. The "listen before talk" operating procedure in IEEE 802.11 is the most well known contention-based protocol. Section 90.7 of Part 90 of the United States Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States government that regulates communications by radio, television, wire, internet, wi-fi, satellite, and cable across the United States. The FCC maintains j ... rules define CBP as: :A protocol that allows multiple users to share the same spectrum by defining the events that must occur when two or more transmitters attempt to simultaneously access the same channel and establishing rules by which a transmitter provides reasonable opportunities for other transmitters to operate. Such a protocol may consist of proc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CAN Bus
A controller area network bus (CAN bus) is a vehicle bus standard designed to enable efficient communication primarily between electronic control units (ECUs). Originally developed to reduce the complexity and cost of electrical wiring in automobiles through multiplexing, the CAN bus protocol has since been adopted in various other contexts. This Broadcasting (networking), broadcast-based, Message passing, message-oriented protocol ensures data integrity and prioritization through a process called Arbiter (electronics), arbitration, allowing the highest priority device to continue transmitting if multiple devices attempt to send data simultaneously, while others back off. Its reliability is enhanced by Differential signalling, differential signaling, which mitigates electrical noise. Common versions of the CAN protocol include CAN 2.0, CAN FD, and CAN XL which vary in their data rate capabilities and maximum data payload sizes. History Development of the CAN Bus (computing), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fieldbus
A fieldbus is a member of a family of industrial digital communication networks used for real-time distributed control. Fieldbus profiles are standardized by the International Electrotechnical Commission (IEC) as IEC 61784/61158. A complex automated industrial system is typically structured in hierarchical levels as a distributed control system (DCS). In this hierarchy the upper levels for production managements are linked to the direct control level of programmable logic controllers (PLC) via a non- time-critical communications system (e.g. Ethernet). The fieldbus links the PLCs of the direct control level to the components in the plant of the field level such as sensors, actuators, electric motors, console lights, switches, valves and contactors and replaces the direct connections via current loops or digital I/O signals. The requirement for a fieldbus are therefore time-critical and cost sensitive. Since the new millennium a number of fieldbuses based on Real-time Ethernet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Email
Electronic mail (usually shortened to email; alternatively hyphenated e-mail) is a method of transmitting and receiving Digital media, digital messages using electronics, electronic devices over a computer network. It was conceived in the late–20th century as the digital version of, or counterpart to, mail (hence ''wikt:e-#Etymology 2, e- + mail''). Email is a ubiquitous and very widely used communication medium; in current use, an email address is often treated as a basic and necessary part of many processes in business, commerce, government, education, entertainment, and other spheres of daily life in most countries. Email operates across computer networks, primarily the Internet access, Internet, and also local area networks. Today's email systems are based on a store-and-forward model. Email Server (computing), servers accept, forward, deliver, and store messages. Neither the users nor their computers are required to be online simultaneously; they need to connect, ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-way Radio
A two-way radio is a radio transceiver (a radio that can both transmit and receive radio waves), which is used for bidirectional person-to-person voice communication with other users with similar radios, in contrast to a broadcast receiver, which only receives transmissions. Two-way radios usually use a half-duplex communication channel, which permits two-way communication, albeit with the limitation that only one user can transmit at a time. (This is in contrast to simplex communication, in which transmission can only be sent in one direction, and full-duplex, which allows transmission in both directions simultaneously.) This requires users in a group to take turns talking. The radio is normally in receive mode so the user can hear all other transmissions on the channel. When the user wants to talk, they press a " push-to-talk" button, which turns off the receiver and turns on the transmitter; when the button is released, the receiver is activated again. Multiple channels are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Science
Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, applied disciplines (including the design and implementation of Computer architecture, hardware and Software engineering, software). Algorithms and data structures are central to computer science. The theory of computation concerns abstract models of computation and general classes of computational problem, problems that can be solved using them. The fields of cryptography and computer security involve studying the means for secure communication and preventing security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Programming language theory considers different ways to describe computational processes, and database theory concerns the management of re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
