Monitoring current SSAS acitivities

A question DBA's are always interested in is: who is connected to my database and what are they doing? For SSAS 2008 there are some Dynamic Management Views (DMV) to answer this question(s) (and many others). The query:

SELECT TABLE_NAME
  FROM $system.dbschema_tables
 WHERE TABLE_SCHEMA = '$SYSTEM'
   AND LEFT(TABLE_NAME,8) = 'DISCOVER'
 ORDER BY table_name

provides the following list of tables (I added links to and descriptions from the documentation; some of the linked pages are not very extensive):

- DISCOVER_COMMAND_OBJECTS: Provides resource usage and activity information about the objects in use by the referenced command.
- DISCOVER_COMMANDS: Provides resource usage and activity information about the currently executing or last executed commands in the opened connections on the server.
- DISCOVER_CONNECTIONS: Provides resource usage and activity information about the currently opened connections on the server.
- DISCOVER_DB_CONNECTIONS: Provides resource usage and activity information about the currently opened connections from the server to a database.
- DISCOVER_DIMENSION_STAT: This schema rowset returns statistics on the specified dimension.
- DISCOVER_ENUMERATORS: Returns a list of names, data types, and enumeration values of enumerators supported by the Microsoft XML for Analysis (XMLA) provider for a specific data source.
- DISCOVER_INSTANCES: Describes the instances on the server.
- DISCOVER_JOBS: Provides information about the active jobs executing on the server.
- DISCOVER_KEYWORDS: Returns information about keywords reserved by the Microsoft XML for Analysis (XMLA) provider.
- DISCOVER_LITERALS: Returns information about literals, including data types and values, supported by the Microsoft XML for Analysis (XMLA) provider.
- DISCOVER_LOCKS: Provides information about the current standing locks on the server.
- DISCOVER_MASTER_KEY: This schema rowset returns the server's master encryption key (the key that is used by the server to encrypt sensitive data on disk).
- DISCOVER_MEMORYGRANT: This rowset returns a list of internal memory quota grants that are taken by jobs that are currently running on the server.
- DISCOVER_MEMORYUSAGE: This schema rowset returns the DISCOVER_MEMORYUSAGE statistics for various objects allocated by the server.
- DISCOVER_OBJECT_ACTIVITY: This schema rowset provides resource usage per object since the start of the service. Some further information on this view can be found in Vidas Matelis' Blog.
- DISCOVER_OBJECT_MEMORY_USAGE: Provides information about memory resources used by objects.
- DISCOVER_PARTITION_DIMENSION_STAT: This schema rowset returns statistics on the dimension associated with a partition.
- DISCOVER_PARTITION_STAT: This schema rowset returns statistics on aggregations in a particular partition.
- DISCOVER_PERFORMANCE_COUNTERS: This schema rowset returns the value of one or more specified performance counters.
- DISCOVER_PROPERTIES: Returns a list of information and values about the standard and provider-specific properties that are supported by the Microsoft XML for Analysis (XMLA) provider for the specified data source.
- DISCOVER_SCHEMA_ROWSETS: Returns the names, restrictions, description, and other information for all enumeration values and any additional provider-specific enumeration values supported by the Microsoft XML for Analysis (XMLA) provider.
- DISCOVER_SESSIONS: Provides resource usage and activity information about the currently opened sessions on the server.
- DISCOVER_TRACE_COLUMNS: This schema rowset contains the DISCOVER_TRACE_COLUMNS schema rowset.
- DISCOVER_TRACE_DEFINITION_PROVIDERINFO: This schema rowset returns basic information about the trace provider, such as its name and description.
- DISCOVER_TRACE_EVENT_CATEGORIES: This schema rowset contains the DISCOVER_TRACE_EVENT_CATEGORIES schema rowset.
- DISCOVER_TRACES: This schema rowset contains the DISCOVER_TRACES schema rowset.
- DISCOVER_TRANSACTIONS: This schema rowset returns the current set of pending transactions on the system.

Some of these views have to be queried with the function SYSTEMRESTRICTSCHEMA to query restricted schema rowsets - you find some examples for the use of this function in Vidas Matelis' Blog.

To answer the initial question - who is on my db? - you could use the (simple) query

SELECT *
  FROM $system.DISCOVER_SESSIONS

Another option to get these information is to use the small GUI-application Activity Viewer (download from codeplex).