This style of plug-ins have been deprecated in BASE 3.3 and replaced by an extension point. See Section 27.8.14, “Login manager” for more information. Backwards compatibility is supported via a wrapper class that is automatically enabled if the auth.driver property is set.
BASE has support for storing files in two locations, the primary storage and
the secondary storage. The primary storage is always disk-based and must be
accessible by the BASE server as a path on the file system. The path to the
primary storage is configured by the userfiles
setting in the
base.config
file. The primary storage is internal to
the core. Client applications don't get access to read or manipulate the
files directly from the file system.
The secondary storage can be anything that can store files. It could, for example, be another directory, a remote FTP server, or a tape based archiving system. A file located in the secondary storage is not accessible by the core, client applications or plug-ins. The secondary storage can only be accessed by the secondary storage controller. The core (and client) applications uses flags on the file items to handle the interaction with the secondary storage.
Each file has an action attribute which default's to
File.Action.NOTHING
. It can take two other values:
File.Action.MOVE_TO_SECONDARY
File.Action.MOVE_TO_PRIMARY
All files with the action attribute set to MOVE_TO_SECONDARY
should be moved to the secondary storage by the controller, and all files
with the action attribute set to MOVE_TO_PRIMARY
should be
brought back to primary storage.
The moving of files between primary and secondary storage doesn't happen
immediately. It is up to the server administrator to configure how often and
at what times the controller should check for files that should be moved.
This is configured by the secondary.storage.interval
and secondary.storage.time
settings in the
base.config
file.
All you have to do to create a secondary storage controller is to
create a class that implements the
net.sf.basedb.core.SecondaryStorageController
interface. In your
base.config
file you then specify the
class name in the secondary.storage.driver
setting and its
initialisation parameters in the secondary.storage.init
setting.
Your class must have a public no-argument constructor. The BASE application will create only one instance of the class for lifetime of the BASE server. Here are the methods that you must implement:
public void init(String settings);
This method is called just after the object has been created with its argument
taken from the secondary.storage.init
setting in your
base.config
file. This method is only called once for
an object.
public void run();
This method is called whenever the core thinks it is time to do some
management of the secondary storage. How often the run()
method is called is controlled by the secondary.storage.interval
and secondary.storage.time
settings in the
base.config
file.
When this method is called the controller should:
Move all files which has action=MOVE_TO_SECONDARY
to
the secondary storage. When the file has been moved call
File.setLocation(Location.SECONDARY)
to tell the
core that the file is now in the secondary storage. You should also call
File.setAction(File.Action.NOTHING)
to reset the
action attribute.
Restore all files which has action=MOVE_TO_PRIMARY
.
The core will set the location attribute automatically, but you should
call File.setAction(File.Action.NOTHING)
to reset
the action attribute.
Delete all files from the secondary storage that are not present
in the database with location=Location.SECONDARY
.
This includes files which has been deleted and files that have been
moved offline or re-uploaded.
As a final act the method should send a message to each user owning files that has been moved from one location to the other. The message should include a list of files that has been moved to the secondary storage and a list of files moved from the secondary storage and a list of files that has been deleted due to some of the reasons above.
public void close()();
This method is called when the server is closing down. After this the object is never used again.
The configuration settings for the secondary storage controller is located in the
base.config
file. Here is an overview of the settings.
For more information read Appendix B, base.config reference.
The class name of the secondary storage plug-in.
Initialisation parameters sent to the plug-in by calling the
init()
method.
Interval in seconds between each execution of the secondary storage controller plug-in.
Time points during the day when the secondary storage controller plugin should be executed.
The BASE web client has integrated support for unpacking of
compressed files. See Section 7.2.1, “Upload a new file”.
Behind the scenes, this support is provided by plug-ins. The standard
BASE distribution comes with support for ZIP files
(net.sf.basedb.plugins.ZipFileUnpacker
)
and TAR files (
net.sf.basedb.plugins.TarFileUnpacker
).
To add support for additional compressed formats you have to create a plug-in that
implements the net.sf.basedb.util.zip.FileUnpacker
interface. The best way to do this is to extend the
net.sf.basedb.util.zip.AbstractFileUnpacker
which
implements all methods in the
Plugin
and
InteractivePlugin
interfaces. This leaves
you with the actual unpacking of the files as the only thing to implement.
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No support for configurations |
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The integrated upload in the web interface only works with plug-ins that does not require a configuration to run. |
Methods in the FileUnpacker
interface
public String getFormatName();
Return a short string naming the file format. For example:
ZIP files
or TAR files
.
public Set<String> getExtensions();
Return a set of strings with the file extensions that
are most commonly used with the compressed file format.
For example: [zip, jar]
. Do not include
the dot in the extensions. The web client and the
AbstractFlatFileUnpacker.isInContext()
method
will use this information to automatically guess which plug-in to
use for unpacking the files.
public Set<String> getMimeTypes();
Return a set of string with the MIME types that commonly used with
the compressed file format. For example:
[application/zip, application/java-archive]
.
This information is used by the
AbstractFlatFileUnpacker.isInContext()
method to automatically guess which plug-in to use for unpacking
the files.
public int unpack(DbControl dc,
Directory dir,
InputStream in,
File sourceFile,
boolean overwrite,
AbsoluteProgressReporter progress)
throws IOException, BaseException;
Unpack the files and store them in the BASE file system.
Do not close()
or
commit()
the
DbControl
passed to this method.
This is done automatically by the
AbstractFileUnpacker
or by the web client.
The dir
parameter is the root directory where
the unpacked files should be placed. If the compressed file
contains subdirectories the plug-in must create those subdirectories
unless they already exists.
If the overwrite
parameter is
FALSE
no existing file should be overwritten
unless the file is OFFLINE
or marked as
removed (do not forget to clear the removed attribute).
The in
parameter is the stream
containing the compressed data. The stream may come
directly from the web upload or from an existing
file in the BASE file system.
The sourceFile
parameter is the file
item representing the compressed file. This item may already be in
the database, or a new item that may or may not be saved in the database
at the end of the transaction. The information in this parameter
can be used to discover the options for file type, character set, MIME
type, etc. that was selected by the user in the upload dialog.
The PackUtil
has a useful method that can be used for copying information.
The progress
parameter, if not
null
, should be used to report the
progress back to the calling code. The plug-in should count
the number of bytes read from the in
stream. If it is not possible by other means the stream can
be wrapped by a net.sf.basedb.util.InputStreamTracker
object which has a
getNumRead()
method.
When the compressed file is uncompressed during the file upload from the web interface, the call sequence to the plug-in is slightly altered from the standard call sequence described in the section called “Executing a job”.
After the plug-in instance has been created, the
Plugin.init()
method is called with null
values for both the configuration
and job
parameters.
Then, the unpack()
method is called. The
Plugin.run()
method is never called in this case.
BASE has support for compressing and downloading a set of selected files and/or
directories. This functionality is provided by a plug-in, the
PackedFileExporter
. This plug-in doesn't do the actual
packing itself. This is delegated to classes implementing the
net.sf.basedb.util.zip.FilePacker
interface.
BASE ships with a number of packing methods, including ZIP and TAR. To
add support for other methods you have to provide an implementation
of the FilePacker
interface. Then, create a new configuration for the
PackedFileExporter
and enter the name of your class in the configuration wizard.
The FilePacker
interface is not a regular
plug-in interface (ie. it is not a subinterface to
Plugin
). This means that you don't have to
mess with configuration or job parameters. Another difference is that your
class must be installed in Tomcat's classpath (ie. in one of the
WEB-INF/classes
or WEB-INF/lib
folders).
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This may be converted to an extension point in the future |
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There are certain plans to convert the packing mechanism to an extension point in the future. The main reason is easier installation since code doesn't have to be installed in the WEB-INF/lib or WEB-INF/classes directory. See ticket #1600: Convert file packing plug-in system to an extension point for more information. |
Methods in the FilePacker
interface
public String getDescription();
Return a short description the file format that is suitable for use
in dropdown lists in client applications. For example:
Zip-archive (.zip)
or TAR-archive (.tar)
.
public String getFileExtension();
Return the default file extension of the packed format. The returned
value should not include the dot. For example:
zip
or tar
.
public String getMimeType();
Return the standard MIME type of the packed file format.
For example:
application/zip
or application/x-tar
.
public void setOutputStream(OutputStream out)
throws IOException;
Sets the outputstream that the packer should write the packed files to.
public void pack(String entryName,
InputStream in,
long size,
long lastModified)
throws IOException;
Add another file or directory to the packed file. The
entryName
is the name of the new entry, including
path information. The in
is the stream to read
the file data from. If in
is null
then the entry denotes a directory. The size
parameter
gives the size in bytes of the file (zero for empty files or directories).
The lastModified
is that time the file was last modified or 0 if not known.
public void close()
throws IOException;
Finish the packing. The packer should release any resources, flush
all data and close all output streams, including the out
stream
set in the setOutputStream
method.