Asynchronous Service

Asynchronous Service

1 out of 1 rated this helpful - Rate this topic[Applies to: Microsoft Dynamics CRM 4.0]The asynchronous service executes long-running operations independent of the main Microsoft Dynamics CRM system process. This results in improved overall system performance and improved scalability.The asynchronous service features a managed queue for the execution of asynchronous registered plug-ins, workflows, and operations such as bulk mail, bulk import, and campaign activity propagation. These operations are registered with the asynchronous service and executed later when the service processes its queue. All workflows are executed by the asynchronous service.In This SectionAsynchronous Service ArchitectureRead an overview of the asynchronous service architecture and how it integrates into the Microsoft Dynamics CRM platform.Stopping and Starting the Asynchronous ServiceLearn how to stop and re-start the service.System Job and Bulk Operation Entity ModelsFind information about the system job and bulk operation entities and their related classes.Supported Entities for Asynchronous OperationsLists the entities can be used with the asynchronous service.Recurrence Pattern in Asynchronous Job ExecutionDescribes how to set the recurrence pattern for an asynchronous job.Dependency and Execution OrderDiscover how to run time dependencies and the order of execution between asynchronous operations.Operation StatesRead an overview of the various states that an asynchronous operation can be in and the well defined path from one state to another.Bulk OperationsFind general information on the bulk operations supported by the asynchronous service.Deletion ServiceDescribes how entities are deleted from the database.Related SectionsPlug-insDocuments the plug-in model that can be used to implement custom business logic that is executed in response to a Microsoft Dynamics CRM event.WorkflowsDescribes how to create custom workflow components and workflow activities.Data ManagementProvides information about the entities used for operations such as duplicate data detection, bulk delete, data migration, and data import.© 2010 Microsoft Corporation. All rights reserved. 




Asynchronous communication

For other uses, see Asynchrony.In telecommunications, asynchronous communication is transmission of data, generally without the use of an external clock signal, where data can be transmitted intermittently rather than in a steady stream.[1] Any timing required to recover data from the communication symbols is encoded within the symbols. A notable exception is the RS-232 port, and some derivatives, which are asynchronous, but still have an external clock signal available, although not commonly used. The most significant aspect of asynchronous communications is that data is not transmitted at regular intervals, thus making possible variable bit rate, and that the transmitter and receiver clock generators do not have to be exactly synchronized all the time.

Physical layerEdit

Main article: Asynchronous serial communicationIn asynchronous serial communication the physical protocol layer, the data blocks are code words of a certainword length, for example octets (bytes) or ASCII characters, delimited by start bits and stop bits. A variable length space can be inserted between the code words. No bit synchronization signal is required. This is sometimes called character oriented communication. Examples are the RS-232C serial standard, and MNP2 and V.2modems and older.

Data link layer and higherEdit

Asynchronous communication at the data link layer or higher protocol layers is known as statistical multiplexingor packet mode communication, for example asynchronous transfer mode (ATM). In this case the asynchronously transferred blocks are called data packets, for example ATM cells. The opposite is circuit switched communication, which provides constant bit rate, for example ISDN and SONET/SDH.The packets may be encapsulated in a data frame, with a frame synchronization bit sequence indicating the start of the frame, and sometimes also a bit synchronization bit sequence, typically 01010101, for identification of the bit transition times. Note that at the physical layer, this is considered as synchronous serial communication. Examples of packet mode data link protocols that can be/are transferred using synchronous serial communication are the HDLC, Ethernet, PPP and USB protocols.

Application layerEdit

An asynchronous communication service or application does not require a constant bit rate.[citation needed]Examples are file transfer, email and the World Wide Web. An example of the opposite, a synchronous communication service, is realtime streaming media, for example IP telephony, IP-TV and video conferencing.

Electronically mediated communicationEdit

Electronically mediated communication is often asynchronous in that the participants do not communicate concurrently. Examples include email and bulletin board systems, where participants send or post messages at different times. The term acquired currency in online learning, where exchanges between teachers and students are often asynchronous instead of synchronous (that is, simultaneous), as they would be in face-to-face or telephone conversations.

See alsoEdit

Synchronization in telecommunicationsAsynchronous serial communicationAsynchronous systemAsynchronous transfer mode (ATM)Asynchronous circuitAsynchronyAnisochronousBaud ratePlesiochronousPlesiochronous Digital Hierarchy (PDH)

References

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