Arabic Bulgarian Chinese Croatian Czech Danish Dutch English Estonian Finnish French German Greek Hebrew Hindi Hungarian Icelandic Indonesian Italian Japanese Korean Latvian Lithuanian Malagasy Norwegian Persian Polish Portuguese Romanian Russian Serbian Slovak Slovenian Spanish Swedish Thai Turkish Vietnamese
Arabic Bulgarian Chinese Croatian Czech Danish Dutch English Estonian Finnish French German Greek Hebrew Hindi Hungarian Icelandic Indonesian Italian Japanese Korean Latvian Lithuanian Malagasy Norwegian Persian Polish Portuguese Romanian Russian Serbian Slovak Slovenian Spanish Swedish Thai Turkish Vietnamese

definition - push technology

definition of Wikipedia

   Advertizing ▼

analogical dictionary


Push technology


Push, or server push, describes a style of Internet-based communication where the request for a given transaction is initiated by the publisher or central server. It is contrasted with pull, where the request for the transmission of information is initiated by the receiver or client.


  General use

Push services are often based on information preferences expressed in advance. This is called a publish/subscribe model. A client might "subscribe" to various information "channels". Whenever new content is available on one of those channels, the server would push that information out to the user.

Synchronous conferencing and instant messaging are typical examples of push services. Chat messages and sometimes files are pushed to the user as soon as they are received by the messaging service. Both decentralised peer-to-peer programs (such as WASTE) and centralised programs (such as IRC or XMPP) allow pushing files, which means the sender initiates the data transfer rather than the recipient.

Email may also be a push system: the SMTP protocol is a push protocol (see Push e-mail). However, the last step —from mail server to desktop computer— typically uses a pull protocol like POP3 or IMAP. Modern e-mail clients make this step seem instantaneous by repeatedly polling the mail server, frequently checking it for new mail. The IMAP protocol includes the IDLE command, which allows the server to tell the client when new messages arrive. The original BlackBerry was the first popular example of push code for email in a wireless context.[citation needed]

Another popular type of Internet push code was PointCast Network, which gained popularity in the 1990s. It delivered news and stock market data. Both Netscape and Microsoft integrated it into their software at the height of the browser wars, but it later faded away and was replaced in the 2000s with RSS (a pull code).

Other uses are push enabled web applications including market data distribution (stock tickers), online chat/messaging systems (webchat), auctions, online betting and gaming, sport results, monitoring consoles and sensor network monitoring.


  HTTP server push

HTTP server push (also known as HTTP streaming) is a mechanism for sending data from a web server to a web browser. HTTP server push can be achieved through several mechanisms.

Generally the web server does not terminate a connection after response data has been served to a client. The web server leaves the connection open so that if an event is received, it can immediately be sent to one or multiple clients. Otherwise the data would have to be queued until the client's next request is received. Most web servers offer this functionality via CGI (e.g. Non-Parsed Headers scripts on Apache).

Another mechanism is related to a special MIME type called multipart/x-mixed-replace, which was introduced by Netscape in 1995. Web browsers would interpret this as a document changing whenever the server felt like pushing a new version to the client.[1] It is still supported by Firefox, Opera and Safari today, but ignored by Internet Explorer.[2] It can be applied to HTML documents, and also for streaming images in webcam applications.

The WHATWG Web Applications 1.0 proposal[3] included a mechanism to push content to the client. On September 1, 2006, the Opera web browser implemented this new experimental coding in a feature called "Server-Sent Events".[4][5] It is now being standardized as part of HTML5.[6] Another related part of HTML5 is the WebSockets API, which allows a web server and client to communicate over a full-duplex TCP connection.


In this technique, the server takes advantage of persistent HTTP connections and leaves the response perpetually "open" (i.e. it never terminates the response), effectively fooling the browser into continuing in "loading" mode after the initial page load would normally be complete. The server then periodically sends snippets of JavaScript to update the content of the page, thereby achieving push capability. By using this technique the client doesn't need Java applets or other plug-ins to keep an open connection to the server. The clients will be automatically notified by new events, pushed by the server.[7][8] One serious drawback to this method, however, is the lack of control the server has over the browser timing out. A page refresh is always necessary if a timeout occurs on the browser end.

  Long polling

Long polling is a variation of the traditional polling technique and allows emulation of an information push from a server to a client. With long polling, the client requests information from the server in a similar way to a normal poll. However, if the server does not have any information available for the client, instead of sending an empty response, the server holds the request and waits for some information to be available. Once the information becomes available (or after a suitable timeout), a complete response is sent to the client. The client will normally then immediately re-request information from the server, so that the server will almost always have an available waiting request that it can use to deliver data in response to an event. In a web/AJAX context, long polling is also known as Comet programming.

Long polling is itself not a true push, but can be used under circumstances where a real push is not possible, and offers many of the same benefits in terms of rapid delivery. For example, BOSH is a popular long polling alternative to TCP, used when TCP is difficult or impossible (e.g. in a web browser).[9]

  Flash XMLSocket relays

This technique, used by Cbox and other chat applications, makes use of the XMLSocket object in a single-pixel Adobe Flash movie. Under the control of JavaScript, the client establishes a TCP connection to a unidirectional relay on the server. The relay server does not read anything from this socket; instead it immediately sends the client a unique identifier. Next, the client makes an HTTP request to the web server, including with it this identifier. The web application can then push messages addressed to the client to a local interface of the relay server, which relays them over the Flash socket. The advantage of this approach is that it appreciates the natural read-write asymmetry that is typical of many web applications, including chat, and as a consequence it offers high efficiency. Since it does not accept data on outgoing sockets, the relay server does not need to poll outgoing TCP connections at all, making it possible to hold open tens of thousands of concurrent connections. In this model, the limit to scale is the TCP stack of the underlying server operating system.

  Other coding

The term Comet has been used to describe push technologies applied to Ajax web applications. It is used as an umbrella term for a combination of web technologies such as HTTP server push and long polling (see above).

XMPP is often used for push applications as well, especially the PubSub extensions. Apple uses this code for its iCloud push support.

BOSH is a long-lived HTTP technique used in XMPP, but that can be used on the web. The specification (XEP-0124: Bidirectional-streams Over Synchronous HTTP (BOSH)) reads: This specification defines a transport protocol that emulates the semantics of a long-lived, bidirectional TCP connection between two entities (such as a client and a server) by efficiently using multiple synchronous HTTP request/response pairs without requiring the use of frequent polling or chunked responses.

  See also


  1. ^ CGI Programming on the World Wide Web O'Reilly book explaining how to use Netscape server-push
  2. ^ Server-Push Documents (HTML & XHTML: The Definitive Guide) O'Reilly book explaining server-push
  3. ^ "Web Applications 1.0 specification". http://www.whatwg.org/specs/web-apps/current-work/#scs-server-sent. 
  4. ^ "Event Streaming to Web Browsers". 2006-09-01. http://my.opera.com/WebApplications/blog/show.dml/438711. Retrieved 2007-03-23. 
  5. ^ "Opera takes the lead with AJAX support among browsers: More efficient streaming". 2006-09-01. http://operawatch.com/news/2006/09/opera-takes-the-lead-with-ajax-support-among-browsers-more-efficient-streaming.html. Retrieved 2007-03-23. 
  6. ^ Server-Sent Events
  7. ^ Pushlets introduction
  8. ^ JavaWorld article about pushlets
  9. ^ "XEP-0124: Bidirectional-streams Over Synchronous HTTP (BOSH)". http://xmpp.org/extensions/xep-0124.html#intro. Retrieved 2012-06-26. 

  External links


   Advertizing ▼


All translations of push technology

sensagent's content

  • definitions
  • synonyms
  • antonyms
  • encyclopedia

Dictionary and translator for handheld

⇨ New : sensagent is now available on your handheld

   Advertising ▼

sensagent's office

Shortkey or widget. Free.

Windows Shortkey: sensagent. Free.

Vista Widget : sensagent. Free.

Webmaster Solution


A windows (pop-into) of information (full-content of Sensagent) triggered by double-clicking any word on your webpage. Give contextual explanation and translation from your sites !

Try here  or   get the code


With a SensagentBox, visitors to your site can access reliable information on over 5 million pages provided by Sensagent.com. Choose the design that fits your site.

Business solution

Improve your site content

Add new content to your site from Sensagent by XML.

Crawl products or adds

Get XML access to reach the best products.

Index images and define metadata

Get XML access to fix the meaning of your metadata.

Please, email us to describe your idea.


The English word games are:
○   Anagrams
○   Wildcard, crossword
○   Lettris
○   Boggle.


Lettris is a curious tetris-clone game where all the bricks have the same square shape but different content. Each square carries a letter. To make squares disappear and save space for other squares you have to assemble English words (left, right, up, down) from the falling squares.


Boggle gives you 3 minutes to find as many words (3 letters or more) as you can in a grid of 16 letters. You can also try the grid of 16 letters. Letters must be adjacent and longer words score better. See if you can get into the grid Hall of Fame !

English dictionary
Main references

Most English definitions are provided by WordNet .
English thesaurus is mainly derived from The Integral Dictionary (TID).
English Encyclopedia is licensed by Wikipedia (GNU).


The wordgames anagrams, crossword, Lettris and Boggle are provided by Memodata.
The web service Alexandria is granted from Memodata for the Ebay search.
The SensagentBox are offered by sensAgent.


Change the target language to find translations.
Tips: browse the semantic fields (see From ideas to words) in two languages to learn more.

last searches on the dictionary :

2895 online visitors

computed in 0.124s

I would like to report:
section :
a spelling or a grammatical mistake
an offensive content(racist, pornographic, injurious, etc.)
a copyright violation
an error
a missing statement
please precise:



Company informations

My account



   Advertising ▼

Vintage P Telephone Lucent Technologies Trimline - push-button White (9.99 USD)

Commercial use of this term

Push Up Balconette Cacique Lane Bryant Plus Size Bra Air Pad Technology New NWT (21.75 USD)

Commercial use of this term

Troy Technologies 90105 Wheelchair Push Handle Extensions NIB (50.0 USD)

Commercial use of this term

CARLING TECHNOLOGIES 172 Miniature Push Button Switch,15A @ 125V (7.0 USD)

Commercial use of this term

Antique-Crank-Vintage Crosley Wall Phone with Push Button Technology Black (65.23 USD)

Commercial use of this term

Crosley CR55-BC Wall Phone with Push Button Technology (Brushed Chrome) (58.95 USD)

Commercial use of this term

Copperbite 1/2-inch Copper Copper Coupling Easy Push-fit Technology 10169900 (12.72 USD)

Commercial use of this term

Supply Stop Valve Push On 1/4" Comp Accor Technology Cpvc Fittings PO5-3R (13.88 USD)

Commercial use of this term

Push In Tube Elbow Connector 1/4" Od Watts Water Technologies 17146502 (8.49 USD)

Commercial use of this term

Push In Tube Tee 1/4" Od Watts Water Technologies Brass Push-Fit Fittings - Tees (10.04 USD)

Commercial use of this term

Crosley 1950's Retro Vintage Payphone Wall Phone Push Button Technology (Black) (111.61 USD)

Commercial use of this term

Quick Connect Tee 1/2" Watts Water Technologies Brass Push-Fit Fittings - Tees (13.98 USD)

Commercial use of this term

SAFETY TECHNOLOGY INTERNATIONAL SS-2105EX Emergency Exit Push Button, Green (37.9 USD)

Commercial use of this term

Push In Tube Male Elbow 1/4" Od Watts Water Technologies 17146922 048643219489 (7.77 USD)

Commercial use of this term

NEW Crosley 1950's Classic Payphone with Push Button Technology Telephone, Pink (87.87 USD)

Commercial use of this term


Commercial use of this term

Copperbite 1/2-inch Tee Easy Push-fit Technology Dimensional Standards (17.37 USD)

Commercial use of this term


Commercial use of this term

Tectite Series 2-inch Copper Male Elbow Easy Push-fit Technology 10177351 (12.5 USD)

Commercial use of this term