LESSON 3: Setting an expiration time
LESSON 3: Setting an expiration time
This tutorial explains how to add an expiration time to a Web Slice.
Expiration is appropriate if the content in the Web Slice may not be relevant after a certain date and time. For example, the ticket auction ends at a certain time, after which the auction will close and there will not be any more updates.
An expiration time is expressed with the following attributes:
- class="endtime" - Signifies that this is an expiration element.
- title="__UTC_Format__" - The title attribute contains the expiration date and time in Universal Time Code (UTC) format.
Example:
The following is an example of the hAtom abbr design pattern used to encode the expiration date and time.
<abbr class="endtime" title="2008-04-29T17:50:00-08:00"></abbr>
UTC time is expressed in relation to Greenwich Mean Time (GMT). If today was March 5, 2008 at 5:35 p.m. in Las Vegas, then that could be expressed as "2008-03-05T17:35:00-08:00." The time is written in 24 hour time and the -08:00 indicates that the time zone is eight hours behind GMT.
Exercise #3:
Add an expiration time to the ticket auction Web Slice
A few things to remember:
- Select an expiration time very close to now so that you can view the Web Slice before and after it expires.
- The title of a Web Slice that is about to expire turns bold and italic, as shown below.
- Once the content has expired, the Web Slice title turns grey. Users can still click through to the Web page where the Web Slice originated.
Quick Review
- Use the abbr design pattern to add an expiration date to your Web Slice.
- Express the date and time in UTC format.
Check your work
Confirm that your expiration value was correctly added to the Web Slice by viewing the feed source.
- Open your Feeds list in the Favorites Center (Ctrl+J).
- Click the feed with the title of your Web Slice.
- Right-click on the feed reader page, and select View source from the option menu.
- Search for a tag called mon:expiration. If you don't see this tag, then your expiration value was not accepted.
If you are having any trouble, you can view the example implementation in Source Listing #3.
More Lessons
Go forward to LESSON 4: Setting a time-to-live (TTL) value
Go back to LESSON 2: Adding visible content to your Web Slice