Host Datastore Browser APIs

The DatastoreBrowser managed object type provides access to the contents of one or more datastores.

The items in a datastore are files that contain configuration, virtual disk, and the other data associated with a virtual machine.

Although datastores may often be implemented using a traditional file system, a full interface to a file system is not provided here. Instead, specialized access for virtual machine files is provided. A datastore implementation may completely hide the file directory structure.

The intent is to provide functionality analogous to a file chooser in a user interface.

Files on datastores do not have independent permissions through this API. Instead, the permissions for all the files on a datastore derive from the datastore object itself. It is not possible to change individual file permissions as the user browsing the datastore may not necessarily be a recognized user from the point of view of the host changing the permission. This occurs if the user browsing the datastore is doing so through the VirtualCenter management server.

The DatastoreBrowser provides many ways to customize a search for files. A search can be customized by specifying the types of files to be searched, search criteria specific to a file type, and the amount of detail about each file. The most basic queries only use file details and are efficient with limited side effects. For these queries, file metadata details can be optionally retrieved, but the files themselves are opened and their contents examined. As a result, these files are not necessarily validated.

More complicated queries can be formed by specifying the specific types of files to be searched, the parameters to filter for each type, and the desired level of detail about each file. This method of searching for files is convenient because it allows additional data about the virtual machine component to be retrieved. In addition, certain validation checks can be performed on matched files as an inherent part of the details collection process. However, gathering extra details or the use of type specific filters can sometimes only be implemented by examining the contents of a file. As a result, the use of these conveniences comes with the cost of additional latency in the request and possible side effects on the system as a whole.

The DatastoreBrowser is referenced from various objects, including from Datastore, ComputeResource, HostSystem and VirtualMachine. Depending on which object is used, there are different requirements for the accessibility of the browsed datastore from the host (or hosts) associated with the object:

When referenced from the target Datastore, it needs to be accessible from at least one host on which the datastore is mounted. See accessible.
When referenced from a ComputeResource, the target datastore needs to be accessible from at least one host in the ComputeResource. See accessible.
When referenced from a HostSystem, the target datastore needs to be accessible from that host. See accessible.
When referenced from a VirtualMachine, the target datastore needs to be accessible from the host on which the virtual machine is registered. See accessible.