Pull notifications are updates delivered to a computer or mobile device in response to a user or software-initiated poll of a remote server.
Generally, pull notifications are how noncritical updates and communications are delivered. Pull is the more traditional approach, in which a user or software client makes the initial request for info. The alternative, push notification (also called server push), is the delivery of content from a software application to a computing device without a specific request from the client. In push communications, a server sends a message about updates to the client, which has typically subscribed to updates in advance. The client may be built into the operating system, especially in the case of smartphones.
Pull notifications often rely on existing software installed on a computer or mobile device. For example, a base version of software, such as Skype, may be downloaded; the software then checks for updates. Requests for data followed by responses from servers make up the basis of network computing.