Change Detection and Notification of Webpages: A Survey <s> Change Detection & Notification Systems <s> An end block adapted for use on a kiln car includes a refractory body having a transverse projection at a front end and a transverse recess at a rear end. The recess is dimensioned to receive therewithin a projection on the front end of another block with a loose fit therebetween. A sealing layer of resilient refractory material may be disposed within the recess for contact with the front end projection of another block. <s> BIB001 </s> Change Detection and Notification of Webpages: A Survey <s> Change Detection & Notification Systems <s> Web pages at present have become dynamic and frequently changing, compared to the past where web pages contained static content which did not change often. People have the need to keep track of web pages which are of interest to them, using bookmarks in the web browser and continuously keep track of them in order to get the updates. Tracking changes which occur in these bookmarked web pages and getting updates has become a significant challenge in the current context. Hence there is a need for better and convenient methods to keep track of web pages. Many researches and implementations have been carried out in order to increase the efficiency of change detection of web pages and related algorithms. In this paper, we discuss the architectural aspects of change detection systems and introduce an optimized change detection solution including a web service, browser plugin and an email notification service. Consequently, this research will pave the way for a novel research area to explore. <s> BIB002
"Change Detection & Notification (CDN) systems" BIB002 automatically detect changes made to pages in the web and notifies about the change/s to interested parties. The significant difference between search engines and CDN systems is that search engines are developed for searching webpages whereas CDN systems are developed for monitoring changes that occur in webpages. In theory, most of the search engines also have an underlying change detection mechanism to determine which sites to crawl and keep their search results up-to-date [Googlebot 2013 ]. The use of CDN systems allows to reduce the browsing time and facilitates users with the ability to check for changes in webpages BIB001 ]. CDN systems emerged in the WWW with the introduction of "Mind-it" (currently discontinued) [netmind mindit 2018] , the first CDN tool which was developed by NetMind in 1996. Since then, several services were introduced such as "ChangeDetection" (introduced in 1999, now known as "Visualping" [VisualPing.io 2013]), "ChangeDetect" [ChangeDetect.com 2002] (introduced in 2002), "Google Alerts" [Google Alerts 2003 ] (introduced in 2003 , "Follow That Page" [Follow That Page 2008] and "Wachete" [Wachete.com 2014] . CDN systems have evolved throughout the past few decades, with improvements in detection rates, efficient crawling mechanisms and user-friendly notification techniques. CDN systems available at present have become easier to use and are more flexible to incorporate user requirements. Majority of the currently available CDN systems provide various monitoring options including the following [Wachete.com 2014] [VisualPing.io 2013]. (1) Multiple webpage monitoring: multiple parts of a webpage, an entire webpage, multiple webpages or an entire website. (2) Content to monitor: text, images, links, documents (PDF, DOC, DOCX). (3) Threshold of changes: percentage of changes occurring in a given webpage. (4) Frequency of monitoring: hourly, daily, weekly, monthly or on demand monitoring. (5) Frequency of notification: twice a day, once a day, once a week or as changes occur.