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activity by change detection and notification vendors is minimal. No one vendor has successfully leveraged exclusive rights to change detection and notification technology through patents or other legal means. This has resulted in significant functional overlap between products and services.
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are designed to find web pages, CDN systems are designed to monitor changes to web pages. Before change detection and notification, it was necessary for users to manually check for web page changes, either by revisiting web sites or periodically searching again. Efficient and effective change
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Monitoring options vary by service or product and range from monitoring a single web page at a time to entire web sites. What is actually monitored also varies by service or product with the possibilities of monitoring text, links, documents, scripts, images or screen shots.
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Some web pages change regularly, due to the inclusion of adverts or feeds in the presented page. This can trigger false-positives in the change-detection, since users are often only interested in changes to the main content. Some approaches to mitigate this issue exist.
59:. Historically, change polling has been done either by a server which sent email notifications or a desktop program which audibly alerted the user to a change. Change alerting is also possible directly to mobile devices and through
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developed the first change detection and notification tool, known as Mind-it, which ran for six years. This spawned new services such as ChangeDetection (1999), ChangeDetect (2002),
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Content extraction. For popular sites, or sites running popular software, content may be actively separated from chaff by selecting a sub-tree of the DOM, for example using
127:, where the software which would normally run on a separate server runs on your own hardware locally, generally means that the software provides a miniature
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167:) and ignore changes below some threshold. The threshold may be set by the user, or estimated automatically by comparing some early versions of the page.
111:. Typically, an associated website with a configuration is managed by the user. Some services also have a mobile device application which connects to a
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Create a metric of difference between two versions of a page (calculated for example from change in total size, changes in HTML file, or changes in the
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detection and notification is hampered by the fact that most servers do not accurately track content changes through Last-Modified or
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23:) is the automatic detection of changes made to World Wide Web pages and notification to interested users by email or other means.
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Mallawaarachchi, Vijini; Meegahapola, Lakmal; Alwis, Roshan; Heshan, Eranga; Meedeniya, Dulani; Jayarathna, Sampath (2020-05-14).
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Chakravarthy, S.; Hara, S. C. H. (2006). "Automating Change
Detection and Notification of Web Pages (Invited Paper)".
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polls content, tracks changes and logs data. Client applications can be browser extensions, mobile apps or programs.
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web-server headers. In 2019 a comprehensive analysis regarding CDN systems was published.
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A relatively newer approach, which lays between server-based and client-based is to use
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Change detection and notification services can be categorized by the
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With the notable exception of Google's patent filings related to
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International
Journal of Computer Science and Mobile Computing
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they use. Three principal approaches can be distinguished:
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Change
Detection and Notification of Web Pages: A Survey
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Self-hosted website change detection and notification
281:"He created Google Alerts. Now he's an almond farmer"
51:(2003), and Versionista (2007) which was used by the
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to extract only the text the user is interested in.
67:and HTTP callbacks for application integration.
340:Shobhna, Bansal; Chadhaury, Manoj (June 2013).
131:with a browser interface instead of a classic
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115:and provides alerts to the mobile device.
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57:2008 United States presidential election
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174:. Another typical method is the use of
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256:"To the Wayback Machine, Sherman!"
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375:changedetection.io github
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366:8 September
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183:References
129:web server
361:2320-088X
265:9 January
43:In 1996,
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105:webhooks
65:webhooks
26:Whereas
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45:NetMind
39:History
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