# Email notification service

ht://Dig Copyright © 1995-2004 The ht://Dig Group
Please see the file COPYING for license information.

## Introduction

As any HTML author knows, information is only useful if it is valid. Unfortunately, a lot of information has an inherent expiration date. Things like meeting schedules, announcements of upcoming events, and pages with those annoying yellow 'NEW' images by certain links.

ht://Dig is a WWW index/search system developed at San Diego State University. Since this index system already scans all HTML documents, it was the logical choice to incorporate a reminder service into it.

ht://Dig can be told to remind you about an HTML page sometime in the future. The reminder/notification will come by email and will contain the URL to the page plus some other information.

## Use

ht://Dig detects special use of the <META> tag in HTML documents. The <META> tags should go between <HEAD> and </HEAD> of an HTML document.

Example:

> <HTML>
> <HEAD>
> <META NAME="htdig-email" CONTENT="pat.user@nowhere.net">
> <META NAME="htdig-email-subject" CONTENT="Reminder to update a page">
> <META NAME="htdig-notification-date" CONTENT="8/28/1995">
> <TITLE>Someone's homepage.</TITLE>
> </HEAD>
> <BODY>

> > Body of document

> </BODY>
> </HTML>

After 8/28/1995 pat.user@nowhere.net will get a mail message which will look something like this:

> From: ht://Dig email notification service
> Subject: WWW notification: Reminder to update a page
> To: pat.user@nowhere.net
> The following page was tagged to notify you after 8/28/1995.
> URL: http://www.sdsu.edu/~turtle/index.html
> Date: 8/28/1995
> Subject: Reminder to update a page

## Attributes

The special ht://Dig <META> tag attributes related to notification are:

- NAME="htdig-email" CONTENT="email address [, email address] ..."
- NAME="htdig-notification-date" CONTENT="earliest notification date"
- NAME="htdig-email-subject" CONTENT="notification message subject"

Descriptions of the values for the attributes:

htdig-email
  This is the email address the notification message should be sent to. Multiple email addresses can be given by separating them by commas. If no email address is given, no notification will be sent.
htdig-notification-date
  This is the date on or after which the notification should be sent. The format is simply month / day / year, or if the iso_8601 attribute is set, year - month - day. Make sure that the year has the century with it as well. This means that you should use 1995 instead of 95.
  The format of dates is actually a little more flexible than this. Any punctuation or white space can be used as separators, and if the year, month and date do not appear as expected in the order listed above, the notification service will try to make sense of the order used, if the date can be resolved unambiguously in another order. Using four-digit years avoids ambiguity between the year and the month or day. The format year - month - day is accepted without ambiguity when a four-digit year is used, whether the iso_8601 attribute is set or not. When the year is given after the month and day, the format is either day - month - year, if iso_8601 is true and the year has four digits, or month - day - year otherwise.
  If no date is given, no notification will be sent. If a date is given but is malformed, a notification of this error will be sent. For correct dates, a notification will be sent every time the system runs the notification service, on or after the date given. To end the notifications, you must update or remove the notification date in the document.
htdig-email-subject
  This specifies the subject the notification message. This is an optional attribute. Note that if you want to put spaces in the subject, you have to put double quotes (") around it.

There are a couple of other META attributes which are recognized. These can be found in the more general ht://Dig META tag documentation.

## Disclaimer

This service is a free service for all HTML maintainers whose documents are covered by the ht://Dig search system. If any of the attributes are improperly formatted, no notifications will be mailed. Email notification may not always occur on the date that you specified. We can only guarantee a notification of at most once a week.

Last modified: $Date: 2004/05/28 13:15:19 $