Microsoft embraced metadata in
SharePoint 2007; SharePoint 2003 incorporated “categories” for list
data, but this was very different from deserving the title of metadata.
SharePoint 2007 introduced the concept of the content type, which is a
grouping of related attributes that describe a piece of content.
SharePoint 2007 managed content types at the
site collection level and enabled site collection administrators to
create new content types in the Content Type Gallery, for use in the
site collection hierarchy. Site owners of subsites in the hierarchy
could elect to use content types defined at parent sites or the
top-level site collection, or they could define new ones for their site
and subsites. Content types also make inheritance possible, so site
owners could inherit from a site collection content type and add
additional attributes for the specific site instance.
The Managed Metadata Service—introduced
with SharePoint 2010—provides a central hub in a SharePoint farm for
management of metadata across site collections and web applications in
the farm. Centralizing metadata in this fashion releases content owners
from the shackles of the site collection, and it allows for content
types shared across multiple site collections—very useful if the
enterprise site consists of multiple site collections, as it should
according to best practices for content distribution.
Before I dig into the specific details of the
Managed Metadata Service, I will review the principal metadata
components in SharePoint: site columns and content types.
Site Columns
SharePoint maintains a list of site columns,
which represent attributes for metadata. If you have created a custom
list, or looked at an existing list defined in SharePoint, then you
will have seen the site columns in action as the “columns or fields” of
the list.
For example, a list of contacts in a site
maintains names and addresses of project members. The list retains the
first name, last name, street address, city, state, ZIP code, and DOB
of the contact. Each of these attributes exists as site columns in
SharePoint, and when applied to a list definition they constitute the columns or fields of the list.
Site columns have attributes of their own: title, description, and type. Table 1 lists the various types of site columns in SharePoint.
Table 1. Column Types in SharePoint
| Single line of text |
String of text up to a maximum of 255 characters. |
| Multiple lines of text |
Multiple lines of text; content owners specify how many lines to show in edit forms. |
| Choice |
Single choice of fixed values; choices are defined with the site column and displayed as radio buttons or drop-down list. |
| Number |
Floating-point number. |
| Currency |
Two-decimal place number with currency symbol. |
| Date and Time |
Date, Time, or both. |
| Lookup |
Single or multiple-choice lookup of value from another list in the
collection (at or below the location of the site column in the
hierarchy). |
| Yes/No |
Boolean value, shown as a check box in edit forms. |
| Person or Group |
Selection of people or groups from user credential store (Active Directory or other user store, such as LDAP). |
| Hyperlink or Picture |
Either a link to another location or link to an image to display; the content owner chooses at site column creation. |
| Calculated |
Site column value calculated from formula (Excel-like) from other columns in the list row. |
| Full HTML (Publishing) |
HTML field available with the Publishing feature. Allows rich text or full HTML markup. |
| Image (Publishing) |
Image-only field available with the Publishing feature. |
| Hyperlink (Publishing) |
Hyperlink-only field available with the Publishing feature. |
| Summary Links (Publishing) |
Allows collection of hyperlinks by the end user. When this column
is added to a page layout and publishing page content type, page
editors may add links to show as a collection on the page. |
| Rich Media (Publishing) |
Inclusion of movie, audio, and image media on Publishing pages. |
| External Data |
Single or multiple-choice lookup of value from an external list or content type. |
| Managed Metadata |
These columns surface terms from a term set in the Managed Metadata
Service Term Store . |
The following steps show how to access the Site Column Gallery in a site collection, and how to add a new column for use in the site collection:
- Click the gear icon.
- Click the Site Settings menu item.
- From the Site Settings page, in the Galleries section, click the Site Columns link.
- SharePoint displays the Site Column Gallery, like that in Figure 1.
The page in Figure 1
shows a list of the site column names, the type, and the location. If
you access the Site Column Gallery from a subsite, the location values
show where the site column resides in the hierarchy.
- Click the Birthday column.
- SharePoint displays the edit screen as in Figure 2.
Here you may change the column name, contained
group, description, and whether existing list columns based on this
column will update with changes. To change the column type you have no
choice but to create a new column, as follows:
- Navigate back to the Site Column Gallery, showing the list of site columns.
- Click the Create link.
- SharePoint shows a new edit form to populate with site column properties.
- Change the type to Person or Group.
- Wait for the page to post back and then scroll to the bottom.
- See the options to allow selection of people only, people and groups or a SharePoint Security Group to limit choice of person.
- Complete all mandatory properties on this page and then click OK to create the new site column.
Note The
page posts back automatically when you select different site column
types, because different types warrant additional properties.
