
= Application Perspective Monitoring
:description: Overview of application perspective monitoring in {page-component-title} to view availability of remote services from another service.

Application Perspective Monitoring in {page-component-title} lets you see the availability of a remote service.
For example, the service may be hosted in Houston, but accessed in Seattle from your central location in New York.
If a service outage occurs, understanding the perspective from which the outage was monitored can make troubleshooting easier.

Application Perspective Monitoring uses the Minion infrastructure to monitor a service's availability from different perspectives.
When a service is not responsive, an outage is generated with the corresponding perspective information.

.Application Perspective Monitoring diagram
image::application-perspective-monitoring/apm-operation.png["Network diagram illustrating how Application Perspective Monitoring monitors remote services", 700]

NOTE: Use the `perspective-only` flag in the package definition to define packages that will be used only for Application Perspective Monitoring.

== Configuration

Application Perspective Monitoring requires at least one {page-component-title} Minion on your network (see xref:deployment:minion/install.adoc[]).

To configure Application Perspective Monitoring, you must first create an application and associate a set of services and perspectives from which to monitor them:

. Log in to the {page-component-title} web UI.
. Click menu:Distributed Monitoring[Manage Applications] in the side menu.
. Or, click menu:Administration[Configure OpenNMS] in the side menu, then click *Manage Applications*.
. Specify a name for the application and click *Add New Application*.
. Click the *Edit* symbol beside your new application.
** Select the services that you want to monitor from the *Available Services* list, and click *Add >>* to add them to the application.
** Select the perspective locations from which to monitor the specified services from the *Available Locations* list, and click *Add >>* to add them to the application.

.Example application configuration
image::application-perspective-monitoring/configure-app.png["Example of a configured application, including services and locations for perspective monitoring", 800]

After you configure the application, Minions at the specified perspective locations start to monitor the application's associated services.
The figure below shows an HTTP outage detected from all perspective locations, and by pollerd:

.HTTP outage detected by Application Perspective Monitoring
image::application-perspective-monitoring/perspective-outages.png["Outages list displaying five perspectives of an HTTP outage"]

The Perspective column shows the perspective location from which a Minion detected the outage.
If the column is empty, it indicates that the normal process detected the outage: either {page-component-title} detected it in the default location, or a Minion detected it in the corresponding node's location.
