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Content authors should not have to concern themselves with validating every link that they include in their content pages.
The Link Checker runs automatically assist content authors with their links including:
Validating links as they are added to content
Showing a list of all external links in the content
Performing link transformations
The Link Checker has a number of configuration options such as defining the validation internal, allowing certain links or link patters to be omitted from validation, and rewriting link rewriting rules.
Last Status - The last HTML status code returned when the Link Checked last checked the external link
Last Available - Time since the link was last available to the Link Checker
Last Accessed - time since the page with the external link was last accessed in the authoring interface
You can manipulate the content of the window, by using the two buttons at the top of the list of links:
Refresh - To refresh the content of the list
Check - To check an individual external link selected in the list
How the External Link Checker Works
Though easy to use, the External Link Checker relies on a number of services and understanding how they work helps you understand how to configure the Link Checker to meet your needs.
Whenever a content author saves any link to a page, an event handler is triggered.
The event handler traverse all content under /content and checks for new or updated links and adds them to a cache for the Link Checker.
The Day CQ Link Checker Service then executes on a regular schedule to check the entries in the cache for valid syntax.
The syntax-validated links then appear in the External Link Checker window. However they will be in a Pending state.
The Day CQ Link Checker Task then executes on a regular basis to validate the links by making a GET call.
The Day CQ Link Checker Task then updates the entries in the External Link Checker window with the results of the GET calls.
Configuring the Link Checker
The Link Checker is available automatically out-of-the-box in AEM. However there are a number of OSGi configurations that can be modified to change its behavior:
Day CQ Link Checker Info Storage Service - This service defines the size of the Link Checker cache in the repository.
Day CQ Link Checker Service - This service performs asynchronous checking of the syntax of external links. You can define the check period and which types of links are skipped by the checker among other options.
Day CQ Link Checker Task - This service performs the GET validation of external links. It allows separate definitions of intervals to check bad and good links among other options.
Day CQ Link Checker Transformer - Allows for converting links based on a user-defined rule set.