Real-time client-server push strategies: specification and evaluation

Abstract

The widespread use of networked environments and the recent availabilityof high network bandwidthshas rekindled interest in the area of automatic data refresh/update mechanisms. In many application areas, the updated information has a limited period of usefulness. Therefore, the development of systems and protocols that can handle such update tasks within predefined deadlines is required. In this paper, we propose and evaluate two real-time update-propagation mechanisms in a client-server environment. The main idea is the transport of update transactions to the location of the cached data rather than the updated data itself. Unlike current push mechanisms, the propagation of update transactions to client sites is neither periodic nor mandatory. Instead, it is based on client-specific criteria which depend on the contents of the database object being updated. We examine real-time push scheduling issues using the popular client-server database model as our underlying framework and carry out a performance scalability study under varying system configurations.

PushNotify: Push server application

“…Push (also called server push) [5] describes a style of Internet-based communication where the request for a given transaction is initiated by the publisher or central server and a client might subscribe to various information "channels". Whenever a new content is available on one of those channels, the server would push that information out to the user [1]. Push server has to be intelligent enough so that it can analyze subscriptions, mobile devices usage pattern and browser statistics, to offer appropriately grained information.…”

“…This makes push system bi-directional in nature. PushNotify follows a scheme [1] in which whenever there is an update at a client, it is first sent to the server and then server evaluates that update, to know whether to which channel it belongs because a client may have subscribed to many channels. Data set of interest by clients is specified using a logical predicates that are specified using URI(uniform resource identifier) encoding [15].…”

Declarative Push on Web

“…In reality, the information push is emulated using information pull by polling at constant time intervals or keeping the connection open until next update is available. Some research-oriented push systems (Kanitkar and Delis, 1998) and (Xin et al, 2005) and push-pull combinations (Deolasee et al, 2001) are introduced in the literature, but they are not widely adopted.…”