Installing apps
Once an app has been published, it can be discovered and installed by a user who has administrator
permissions in the current site. If you navigate to the Site Content
page within a site and click the tile with the caption add an app, you will be redirected to the main page for installing apps named addanapp.aspx.
This page displays apps that have been published to the app catalog
site. Remember that an Office 365 tenancy has a single app catalog
site, but on-premises farms have an app catalog site per web
application. Therefore, you will not see apps that have been published
to an app catalog site in a different web application.
A user requires administrator permissions within a site to install
an app. If you are logged on with a user account that does not have
administrator permissions within the current site, you will not be able
to see apps that have been published in the app catalog site. This is
true even when your user account has been granted permissions on the
app catalog site itself.
Once you locate an app that you want to install, you can simply
click its tile to install it. The app installation process typically
prompts you to verify whether you trust the app. A page appears that
displays a list of the permissions that the app is requesting along
with a button to grant or deny the apps permission request. You must
grant all permissions that the app has requested to continue with the
installation process. There is no ability to grant one requested
permission to an app while denying another; granting permissions to an
app during installation is always an all-or-nothing proposition.
After the app has been installed, you will see a tile for it on the Site Content page. This tile represents the app
launcher that a user can click to be redirected to the app’s start
page. The app title also displays an ellipse to access a fly-out menu
for app management, as illustrated in Figure 6.
Some apps require an app web. When this is the case, the
app web is created as a child site under the current site where the app
has been installed. If the app contains host feature elements such as
client web parts and UI custom actions, these user interface extensions
will be made available in the host site, as well.
Installing apps at tenancy scope
You have seen that the app catalog site provides a place where you
can upload apps in order to publish them. Once an app has been
published in the app catalog site, a user within the same Office 365
tenancy or within the same on-premises web application can discover the
app and install it at site scope. However, the functionality of an app
catalog site goes one step further: it plays a central role in installing apps at tenancy level.
You install an app at tenancy scope by installing
it in an app catalog site. Just as with a site-scoped installation, you
must first publish the app by uploading it to the Apps for SharePoint document library in the app catalog site. After publishing
the app, you should be able to locate it on the Add An App page of the
app catalog site and install it just as you would install an app in any
other type of site. However, things are a bit different after the app
has been installed in an app catalog site. More specifically, the app
provides different options in the fly-out menu that is available on the
Site Content page, as shown in Figure 7.
As you can see in Figure 7, an app that has been installed in an app catalog site has a Deployment menu command that is not available in any other type of site. When you click the Deployment
menu command, you are redirected to a page on which you can configure
the app so that you can make it available to users in other sites.
You have several options when you configure an app in an app catalog
site to make it available in other sites. One option is to make the app
available to all sites within the scope of the app catalog site. Or,
you can be more selective and just make the app available in sites that
were created by using a specific site template or sites created under a
specific managed path. There is even an option to add the URLs of site
collections one-by-one if you need fine-grained control.
After you configure the criteria for a tenancy-scoped app
installation to indicate the sites in which it can be used, you will
find that the app does not appear in those sites instantly. That’s
because the SharePoint host environment relies on a timer job to push
the required app metadata from the app catalog site to all the other
sites. By default, this timer job is configured to run once every five
minutes. During your testing you can speed things up by navigating to
the Central Administration site and locating the timer job definition named App
Installation Service. The page for this timer job definition provides a
Run Now button that you can click to run it on demand.
