Apama 10.3.1 | Apama Documentation | Developing Apama Applications | Developing Apama Applications in EPL | Using EPL Plug-ins | Using the MemoryStore | Exposing in-memory or persistent data to dashboards
 
Exposing in-memory or persistent data to dashboards
You can expose committed in-memory data or committed persistent data as DataViews for use by dashboards. Note, however that is not supported for distributed stores. The Schema event defines the following fields for this purpose:
*exposeMemoryView — When this field is true, the MemoryStore makes the rows in the in-memory table associated with this schema available to Apama's scenario service. That is, the MemoryStore creates DataViews that contain this data.
*exposePersistentView — When this field is true, the MemoryStore makes the rows in the on-disk table associated with this schema available to Apama's scenario service. That is, the MemoryStore creates DataViews that contain this data. You cannot expose a persistent view of a table in a correlator-persistent store.
*memoryViewDisplayName — Specifies the display name for the exposed DataView created from the in-memory table.
*memoryViewDescription — Specifies the description for the exposed DataView created from the in-memory table.
*persistentViewDisplayName — Specifies the display name for the exposed DataView created from the on-disk table.
*persistentViewDescription — Specifies the description for the exposed DataView created from the on-disk table.
The MemoryStore exposes in-memory changes after successfully committing them to the table. The MemoryStore exposes on-disk changes after the transaction that contains the changes is committed.
The exposeMemoryView and exposePersistentView fields have an impact on the time it takes to prepare a table for the first time. When a table is prepared the rows that are loaded from disk need to be reflected to the Scenario Service.
If you prepare the same table multiple times the display names and descriptions must match or the MemoryStore rejects the contradicting request.
When a display name or description field is blank (an empty string), the MemoryStore chooses the display name or the description for the exposed DataView. You can specify a non-empty string for one or more fields to override the default. Leave the display name and description fields blank when you are not exposing the corresponding DataView.
The fields of the exposed views are the same as those of the table, in the same order as they are defined in the table schema. The key is not part of the exposed views. Each row in the table forms a single exposed view.
See Making Application Data Available to Clients. See also Building and Using Apama Dashboards.

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