Interface DataPlugin
In an OSGi environment such implementations should be registered at the OSGi
service registry specifying the list of root node URIs in a String
array or in case of a single value as String
in the
dataRootURIs
registration parameter.
When the first reference in a session is made to a node handled by this
plugin, the DmtAdmin calls one of the open...
methods to retrieve a
plugin session object for processing the request. The called method depends
on the lock type of the current session. In case of
openReadWriteSession(String[], DmtSession)
and
openAtomicSession(String[], DmtSession)
, the plugin may return
null
to indicate that the specified lock type is not supported. In
this case the DmtAdmin may call
openReadOnlySession(String[], DmtSession)
to start a read-only
plugin session, which can be used as long as there are no write operations on
the nodes handled by this plugin.
The sessionRoot
parameter of each method is a String array containing
the segments of the URI pointing to the root of the session. This is an
absolute path, so the first segment is always ".". Special
characters appear escaped in the segments.
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Field Summary
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Method Summary
Modifier and TypeMethodDescriptionopenAtomicSession
(String[] sessionRoot, DmtSession session) This method is called to signal the start of an atomic read-write session when the first reference is made within aDmtSession
to a node which is handled by this plugin.openReadOnlySession
(String[] sessionRoot, DmtSession session) This method is called to signal the start of a read-only session when the first reference is made within aDmtSession
to a node which is handled by this plugin.openReadWriteSession
(String[] sessionRoot, DmtSession session) This method is called to signal the start of a non-atomic read-write session when the first reference is made within aDmtSession
to a node which is handled by this plugin.
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Field Details
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MOUNT_POINTS
The string to be used as key for the mount points property when a DataPlugin is registered with mount points.- See Also:
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DATA_ROOT_URIS
The string to be used as key for the "dataRootURIs" property when an DataPlugin is registered.- Since:
- 2.0
- See Also:
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Method Details
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openReadOnlySession
ReadableDataSession openReadOnlySession(String[] sessionRoot, DmtSession session) throws DmtException This method is called to signal the start of a read-only session when the first reference is made within aDmtSession
to a node which is handled by this plugin. Session information is given as it is needed for sending alerts back from the plugin.The plugin can assume that there are no writing sessions open on any subtree that has any overlap with the subtree of this session.
- Parameters:
sessionRoot
- the path to the subtree which is accessed in the current session, must not benull
session
- the session from which this plugin instance is accessed, must not benull
- Returns:
- a plugin session capable of executing read operations
- Throws:
DmtException
- with the following possible error codes:NODE_NOT_FOUND
ifsessionRoot
points to a non-existing nodeCOMMAND_FAILED
if some unspecified error is encountered while attempting to complete the command
SecurityException
- if some underlying operation failed because of lack of permissions
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openReadWriteSession
ReadWriteDataSession openReadWriteSession(String[] sessionRoot, DmtSession session) throws DmtException This method is called to signal the start of a non-atomic read-write session when the first reference is made within aDmtSession
to a node which is handled by this plugin. Session information is given as it is needed for sending alerts back from the plugin.The plugin can assume that there are no other sessions open on any subtree that has any overlap with the subtree of this session.
- Parameters:
sessionRoot
- the path to the subtree which is locked in the current session, must not benull
session
- the session from which this plugin instance is accessed, must not benull
- Returns:
- a plugin session capable of executing read-write operations, or
null
if the plugin does not support non-atomic read-write sessions - Throws:
DmtException
- with the following possible error codes:NODE_NOT_FOUND
ifsessionRoot
points to a non-existing nodeCOMMAND_FAILED
if some unspecified error is encountered while attempting to complete the command
SecurityException
- if some underlying operation failed because of lack of permissions
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openAtomicSession
TransactionalDataSession openAtomicSession(String[] sessionRoot, DmtSession session) throws DmtException This method is called to signal the start of an atomic read-write session when the first reference is made within aDmtSession
to a node which is handled by this plugin. Session information is given as it is needed for sending alerts back from the plugin.The plugin can assume that there are no other sessions open on any subtree that has any overlap with the subtree of this session.
- Parameters:
sessionRoot
- the path to the subtree which is locked in the current session, must not benull
session
- the session from which this plugin instance is accessed, must not benull
- Returns:
- a plugin session capable of executing read-write operations in an
atomic block, or
null
if the plugin does not support atomic read-write sessions - Throws:
DmtException
- with the following possible error codes:NODE_NOT_FOUND
ifsessionRoot
points to a non-existing nodeCOMMAND_FAILED
if some unspecified error is encountered while attempting to complete the command
SecurityException
- if some underlying operation failed because of lack of permissions
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