Push technology is a type of communication that takes place over the Internet when data is pushed from a server to a client without the client requesting it.
Most push technologies must be authorized or subscribed too. Once a user has subscribed, the relevant content is delivered as soon as it is available without waiting for a request from the receiver. Push technology is differentiated from pull technology based on whether it is the receiver (client) or the sender (server) that initiates the transaction. If the server initiates the transfer and sends information to the client without receiving a request, the process is implementing push technology. If the client, whether a browser, web application, or smartphone application, requests the information from the server before the server sends it, the process is implementing pull technology.
Push technologies are used to deliver content to various types of applications and devices.
- Websites employ push technology to continually update content in real-time, such as a breaking news ticker on a news website.
- Web applications often use push technology to notify users of new content, such as a tab that appears on a social media site indicating that new posts are available.
- Computer, tablet, and smartphone applications often use push technology to deliver notifications letting the user know as soon as new content is available.
Frequently Asked Questions
What are some examples of push technologies?
The most prevalent use of push technology today is for app notifications on smartphones. When you install a new application, such as the Facebook app, you can choose whether or not to receive notifications. If you do opt to receive notifications, you have just subscribed to a push technology.
Other examples of push technology include email delivered using SMTP, instant messaging applications, some online auction websites which push updated bid price information in real-time, and some sports websites which may push the score of a game to a browser or web application in real-time.
It's also true, that not everything that might initially look like push technology actually is. For example, while some sports sites use push technology, others may simply automatically refresh the page at regular intervals in order to pull down updated score information from the server. In addition, RSS feeds are actually checked at regular intervals by RSS readers which pull in new content and aren't pushed by from the feed to the reader.
Is email delivered using push or pull technology?
Email is an interesting case of a service that is often delivered using a combination of both push and pull technologies. SMTP, the protocol used to send mail from a client application to a mail server, and the protocol used to move messages between mail servers, is a push technology. POP Server (POP3) and IMAP, the protocols used to transfer email from a mail server to an email client, are pull technologies.
If you use webmail, or an integrated mail system, such as Microsoft Exchange and Outlook, your email is delivered using push technology. However, if you use an email client to check email on a separate mail server, such as having your Gmail delivered to a desktop application like Outlook, then you are actually using pull technology, and the application polls the server for new email periodically.