How DataBrowser Works

DataBrowser interacts with vFabric GemFire both as a GemFire client and as an RMI client of the AdminAgent.

Discovery

As an RMI client, DataBrowser uses JMX to get information about the data regions in the distributed system and the servers on which they are located. This information is displayed on the left side of the Main Window, where the data regions are displayed in a hierarchical tree, with child data regions displayed as sub-nodes of their parent data region. The lower pane on the left shows the list of cache servers on which the region selected in the upper list is located.

Query Execution

A region must be selected to execute a query specified in the Query Pane. You may also select a cache server on which the query will be executed. If no cache server is selected, then the first one listed in the Member Pane is chosen for the execution of the query. DataBrowser does not prevent execution of complex queries, such as those creating a join across regions, on a cache server that does not contain the regions. In this case an error message, sent by query engine on the server is displayed.

DataBrowser creates a connection pool to a cache server the first time a query is executed on it. This pool uses the default settings specified by GemFire. This connection pool is maintained until the DataBrowser application is shut down, or the DataBrowser received a notification that the member is no longer present in the distributed system either because it has left or crashed. Though only a single ad-hoc query can be executed at a time, multiple CQs may be executed simultaneously. If these queries are being executed on the same cache server, then multiple connections to the cache server are automatically created.

DataBrowser uses the default settings of connection pools. These settings allow it to start with a single connection and allow for unbounded number of connections in pool. The DataBrowser maintains a connection pool per cache server, with a single connection in the pool. There is no fail-over to another cache server in case a connection is lost. If a query is being currently executed on a cache server that leaves, an error is returned in the UI.

Security

DataBrowser supports the GemFire security mechanism. It attempts to execute a query without presenting any security credentials to the cache server. If the distributed system is security enabled, then the DataBrowser received a security exception. It handles this by presenting a popup dialog populated with the name of the security plugin jar and properties specified in the Preferences dialog. The user may modify these if needed, or simply click the OK button to have the DataBrowser use the default jar and the properties. Currently DataBrowser does not provide mechanism that filters the list of regions and cache servers displayed based on the security credentials.
Note: For details on GemFire security, see the vFabric GemFire User's Guide.

Connection by DataBrowser to GemFire Distributed System

For details on client connection pools, see the client/server topology information in the vFabric GemFire User’s Guide.