Moss information management policy customization (MOSS policm policies)

Moss introduces information management policies. By attaching some policies to the document library or list, you can implement some automated functions, such as automatically tagging documents, forcing document review, and enabling document expiration, even
Insert a barcode when the user prints the document.

Is it difficult? How is this useful feature implemented?

There are two types of information management policies: Real-Time and scheduled.

Real-time policies, such as mandatory review, are generally implemented using eventcycler. When a policy is added, the implementation class of the Policy automatically adds the corresponding content type.
A special eventaggreger.

A scheduled policy, such as an expiration Policy, is implemented through the WSS job. When a policy is added, the policy implementation class automatically adds a background scheduled operation.Program, Regularly poll the corresponding document library to detect
Whether the expiration condition is met. In addition to a scheduled job, the expiration policy adds an additional field and an eventvalidator to the document library. When a document is operated, eventvalidator operates on this field, it is convenient for the polling program to check whether the application has expired.

The policy can be expanded. See the followingArticle.
Http://www.sharepointblogs.com/tonstegeman/archive/2007/02/01/moss-custom-policies-part-1-creating-a-custom-information-management-policy.aspx
Http://www.sharepointblogs.com/tonstegeman/archive/2007/02/12/moss-custom-policies-part-2-creating-a-handler-to-submit-items-to-the-records-center.aspx
Http://www.sharepointblogs.com/tonstegeman/archive/2007/02/15/moss-custom-policies-part-3-implementing-the-custom-policy.aspx

The above article only describes how to implement a "synchronization policy". How can we implement a regular policy? Do we need a timer ourselves? It is not that easy to consider performance issues if you write your own data.
Fortunately, the expiration Policy of moss can be expanded. We can extend the "Action" after expiration, so that we can use the detection mechanism of the expiration policy to implement our own functions, for example, we can
Write an action class to save documents that have not been modified for more than a period of time to other places for archiving.
Refer to the following articles:
Adding a custom action to the moss expiration Policy:
Http://www.tonstegeman.com/Blog/Lists/Posts/Post.aspx? List = 70640fe5% 2d28d9% 2d464f % 2db1c9% 2d91e07c8f7e47 & id = 25