Microsoft Sharepoint Products and Technologies Resource Kit eBook

Chapter 21: The Architecture of the Gatherer 593
Your users will need to be educated about this process because it can be a bit
confusing. For example, let’s assume one of your users creates a search query to
look for the word “SharePoint” on the MSDN (Microsoft Solutions Developer Network)
library site. After executing the search, your user selects the Alert Me feature
and then selects To Be Notified Immediately.
Now, your user believes that he will be notified as soon as there is a change in
content in the online MSDN library concerning the word “SharePoint.” But this is not
the case. The gatherer does not place hooks in the content source so that the user
is automatically notified on the fly. Instead, the user’s configuration really results in
the user being notified within 5 minutes after the PQS plug-in becomes aware that
there has been a change in the MSDN Library that matches the user’s alert rule.
If you are crawling this site on a nightly basis, the user will not be notified until
after the next crawl.
Now, refer to the “Frequency of Updates” section later in this chapter. You’ll
notice that an incremental crawl is executed on all portal content every 10 minutes
by default. So, every 10 minutes, new or modified portal content is sent through the
PQS plug-in, thereby delivering faster notifications to your users than content that is
crawled only once per day. Therefore, if you crawl content incrementally on a onceper-day
schedule, which is quite common for many content sources, the effect is
that the user is really notified on a daily basis, not an immediate basis, as the user
interface (UI) would indicate.
Therefore, a best practice is as follows:
■ If you need fast notifications on content in the portal site, do nothing, as this is
accomplished by default.
■ If you need fast notifications on content outside the portal site, you’ll need to
match your crawling schedule with the notification schedule.
■ Determine the crawling schedule for your content sources by first determining
the frequency at which users need to be notified of new content in that content
source.
AutoCat Plug-In
The Auto Categorization (AutoCat) plug-in is the component that makes the Topic
Assistant feature possible. This feature is used to automatically categorize content
external to the portal site and assign it to the Topic area in accordance with how you
have trained the Assistant.
Building the Catalogs
Once the data stream has passed through the plug-ins, the data is then placed in one
of two areas. First, the metadata for the documents, including the exact URLs to each
document, are placed in the SPS.EDB file. The actual content of the documents is
first written to word lists in RAM, very quickly written to shadow indexes on disk,
and then merged into a Master Index on a nightly basis.