SharePoint 2013 Search is highly complex. You have Content Sources and Result Sources. You have Result Sources, Result Types, Result Blocks and Result Sets--not to mention Query Rules and Query Builder. You see these everywhere, but defining them is not easy at all. It seems that Query Rules
are the fresh air of Search in 2013. You feel it, you need it, but it’s hard to touch it.
This is why I decided to create a big-picture view of SharePoint 2013 Search, which you can see in Figure 1. I'd like to emphasize that it may be complex, BUT the beauty of it is in this
complexity: You can build so much with Search!
Figure 1: The big picture of SharePoint 2013 Search
Well, what can you see on this big picture?
On the left side are the source systems, with all the data you can pull into SharePoint Search. The most important types of data sources are
SharePoint sites (of course), file shares and database content (through direct database access or Web Services), but you can also connect to Exchange Public
folders and web sites (for example, your company's public website). If you have some very specific system, you can also write or buy a third-party custom
connector (for example, to SAP).
You can connect these systems by creating Content Sources in SharePoint. I wrote a blog post How to Organize Content Sources a while ago. You can find some
best practices there.
Crawling is the process in which the Search Engine enumerates and gets the content from these systems. The crawled items will then be
indexed into the Local Search Index.
Based on the local index, you can create Result Sources. These can get the indexed items from one or more Content Sources, and you can also apply
some filters there. For example, a Result Source can be "Documents" from "everywhere", or "Old content" including everything that is older than 3 years.
Another way to pull content in to SharePoint Search is through federation: you can define Result Sources to use a remote index to provide the
results from. With this, you can provide results from huge web sites like MSDN or Financial Times, or from places that use different security options, etc.
You don't have to build the index as you use it from a remote location, but you need a live Internet connection; and there are other limitations, too.
Besides the content itself, you store a lot of metadata in the Local Search Index. you can use metadata in a lot of different ways. For example,
metadata be the basics for the Refiners; you can Sort the results by metadata; you can display metadata on the Result Set and/or on the Hover Panel, etc.
Don't forget: metadata is the glue of Search. Despite its a relatively small part of the picture above, metadata might be one of the most important
things in the full Search story!
are in the middle of the big picture, because as I said, they are everywhere. You can use them to transform a query, to change the ranking of the results, to display various Result Blocks (Oops, one more Search term here!), etc.
are basically where you display the results. They can use Query Rules, as well as various Result Sources. They can also display various metadata
(managed properties) from the Local Search Index. They also use Result Types to decide which item to display in what way. For example, a
Word document will be displayed differently than a Calendar item.
The Hover Panel appears when the user hovers the mouse over a result in the Result Set. The Hovel Panel is the flyout card with the document preview (if it's
available), with some metadata, and with some actions to take on the results (e.g., open the document, open its location, send it to someone, start a
workflow, etc.) Again, the Hover Panel is tied to Result Types; different types have different Hover Panels.
Once everything is put together, the results are ready to be displayed. The last question is, “How?” The answer is formulated in Display
Templates. They define the way the results are get displayed (by Result Type, of course), as well as how the Hover Panel will be displayed. Moreover, you
use Display Templates for the Refinement Panel.
The Big Picture
To make a long story short, this is the big picture of Search in SharePoint 2013. Of course, each of these pieces would be worth a separate blog post, or
sometimes even a separate book (like Query Rules, for example). I hope this helps you to understand how these pieces work together. Please let me know if it
makes sense, and if I should change or add anything. This is still evolving.