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:: com :: sun :: star :: embed ::

service Storage
Description
This is a service that allows to get access to a package using storage hierarchy.

A root storage should be retrieved by using StorageFactory service. Substorages are created through XStorage interface of a parent storage.


Included Services - Summary
BaseStorage

This service describes the base functionality of storages. (details)

Exported Interfaces - Summary
XTransactedObject

allows to commit or revert changes that were done for the storage. (details)

XTransactionBroadcaster

allows to track storage's transaction state.

XEncryptionProtectedSource

allows to set password to a root storage. (details)

Properties' Summary
string
MediaType
allows to get and set the media type of the storage.  
string
Version
[ OPTIONAL ]
allows to get and set the version of the format related to the MediaType.  
[ readonly ] boolean
MediaTypeFallbackIsUsed
allows to detect whether mediatype is detected by using fallback approach.  
[ readonly ] boolean
IsRoot
allows to detect whether the storage is a root one.  
[ readonly ] boolean
RepairPackage
[ OPTIONAL ]
allows to detect whether storage is open in "repair package" mode or not.  
[ readonly ] boolean
HasEncryptedEntries
[ OPTIONAL ]
allows to detect if the storage contains encrypted entries.  
[ readonly ] boolean
HasNonEncryptedEntries
[ OPTIONAL ]
allows to detect if the storage contains nonencrypted entries.  
Included Services - Details
BaseStorage
Description
This service describes the base functionality of storages.

Please see below the description of additional requirements for the package storage implementation.

interface ::com::sun::star::lang::XComponent

A root storage is created by StorageFactory and is controlled by refcounting. In case refcounting is decreased to zero the storage will be disposed automatically. It is still strongly recommended that a root storage is disposed explicitly since in garbage collector based languages the refcounting can be decreased too late and resources locked by the storage will not be freed until then.

A substorage is created by XStorage interface of storage. Each time a substorage is opened it is locked ( in case it is opened in readonly mode it is locked for writing, in case it is opened in read-write mode it is locked for reading and writing ) until it is disposed. The lifetime of substorage is also controlled by refcounting but because of mentioned garbage collection specific it is strongly recommended to dispose substorages explicitly.

In case a storage object is disposed all the elements ( substorages and substreams ) retrieved from the object are disposed. If the storage was opened in read-write mode all noncommited changes will be lost.

interface XStorage
XStorage::openStreamElement

This method returns StorageStream service implementation.

If the child stream is an encrypted one a corect common storage password should be set through XEncryptionProtectedSource interface to this storage or to a one of storages in parent hierarchy. In case the password is not set or is a wrong one an exception will be thrown.

XStorage::openEncryptedStreamElement
This method allows to specify reading password for the stream explicitly. The password will be used to read the stream. It is possible to specify a new password for stream storing through XEncryptionProtectedSource interface. In case a new password is not specified an old one will be used for storing.
XStorage::openStorageElement
This method returns Storage service implementation.
XStorage::cloneStreamElement

This method returns StorageStream service implementation.

The latest flashed version of the stream will be used. The stream can be flashed explicitly by XOutputStream::flush call.

A storage flashes on commit all the child streams it owns. So in case after the stream is changed neither the storage was commited nor the stream was flushed explicitly, the changes will not appear in the new created stream. This method allows to retrieve copy of a child stream even in case it is already opened for writing.

If the child stream is an encrypted one a corect common storage password should be set through XEncryptionProtectedSource interface to this storage or to a one of storages in parent hierarchy. In case the password is not set or is a wrong one an exception will be thrown.

XStorage::cloneEncryptedStreamElement

This method returns StorageStream service implementation.

The latest flashed version of the stream will be used. The stream can be flashed explicitly by XOutputStream::flush call.

A storage flashes on commit all the child streams it owns. So in case after the stream is changed neither the storage was commited nor the stream was flushed explicitly, the changes will not appear in the new created stream. This method allows to retrieve copy of a child stream even in case it is already opened for writing.

XStorage::copyLastCommitTo
This method gets Storage service implementation and fills it in with the latest commited version of this storage. So in case the storage was not commited after it was changed, the changes will not appear in the new created storage.
XStorage::copyStorageElementLastCommitTo

This method gets Storage service implementation and fills it in with the contents of the requested substorage. The latest commited version of child storage will be used. So in case the child storage was not commited after it was changed, the changes will not appear in the new created storage.

This method allows to retrieve copy of a child storage even in case it is already opened for writing.

XStorage::removeStorageElement
If the element is opened the removing will fail.
property URL
If the storage is created based on url this property allows to retrieve it.
Exported Interfaces - Details
XTransactedObject
Description
allows to commit or revert changes that were done for the storage.

If a storage is commited all changes made to it will be integrated to it's parent storage. This is recursive process, so the last commited storage should be the root one. For the package based storages commit of a root storage also means flashing to the related medium. If a storage is not commited, no changes for it or it's child elements will be stored.

XTransactionBroadcaster
Description
allows to track storage's transaction state.
XEncryptionProtectedSource
Usage Restrictions
optional
Description
allows to set password to a root storage.

This interface can be supported by a storage to allow to set a common storage password. This password is used as default password to decrypt all encrypted streams and to encrypt streams that are marked to use common storage password on storing. Specifying of the password for a storage allows to use it for the whole subtree. Of course substorage can allow to overwrite the common storage password for own subtree.

Properties' Details
MediaType
string MediaType;
Description
allows to get and set the media type of the storage.
Version
string Version;
Usage Restrictions
optional
Description
allows to get and set the version of the format related to the MediaType.
MediaTypeFallbackIsUsed
[ readonly ] boolean MediaTypeFallbackIsUsed;
Description
allows to detect whether mediatype is detected by using fallback approach.

Can be set to true if the mediatype can not be detected in standard way, but there is a fallback solution allows to do it.

Usually means that the document validity is questionable, although the package itself is not corrupted. The decision about document validity in this case is in application hands. It is up to user of the storage to deside whether he accepts the fallback approach for an implementation of this service, outputs a warning or an error.

IsRoot
[ readonly ] boolean IsRoot;
Description
allows to detect whether the storage is a root one.
RepairPackage
[ readonly ] boolean RepairPackage;
Usage Restrictions
optional
Description
allows to detect whether storage is open in "repair package" mode or not.
HasEncryptedEntries
[ readonly ] boolean HasEncryptedEntries;
Usage Restrictions
optional
Description
allows to detect if the storage contains encrypted entries.

In case it is set to true the storage itself and/or a tree of substorages contain encrypted streams. Usually in case this property is supported the implementation supports XEncryptionProtectedSource interface.

HasNonEncryptedEntries
[ readonly ] boolean HasNonEncryptedEntries;
Usage Restrictions
optional
Description
allows to detect if the storage contains nonencrypted entries.

In case it is set to true the storage itself and/or a tree of substorages contains nonencrypted streams. Usually in case this property is supported the implementation supports XEncryptionProtectedSource interface.


 
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