Difference between revisions of "API:EPrints/Storage"

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==NAME==
 
==NAME==
 
'''EPrints::Storage''' - store and retrieve objects in the storage engine
 
'''EPrints::Storage''' - store and retrieve objects in the storage engine
  
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<!-- Pod2Wiki=head_synopsis -->
 
==SYNOPSIS==
 
==SYNOPSIS==
  my $store = $repository-&gt;storage();
+
<source lang="perl">my $store = $repository->storage();
 
+
 
  $store-&gt;store(
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$store->store(
    $fileobj,   # file object
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$fileobj, # file object
    "diddle.pdf", # filename
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"diddle.pdf", # filename
    $fh       # file handle
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$fh # file handle
  );
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);</source>
 
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<!-- Pod2Wiki=head_description -->
 
<!-- Pod2Wiki=head_description -->
 
==DESCRIPTION==
 
==DESCRIPTION==
 
This module is the storage control layer which uses [[API:EPrints/Plugin/Storage|EPrints::Plugin::Storage]] plugins to support various storage back-ends. It enables the storage, retrieval and deletion of data streams. The maximum size of a stream is dependent on the back-end storage mechanism.
 
This module is the storage control layer which uses [[API:EPrints/Plugin/Storage|EPrints::Plugin::Storage]] plugins to support various storage back-ends. It enables the storage, retrieval and deletion of data streams. The maximum size of a stream is dependent on the back-end storage mechanism.
  
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<!-- Pod2Wiki=head_methods -->
 
==METHODS==
 
==METHODS==
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===new===
<!-- Edit below this comment -->
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 +
<source lang="perl">$store = EPrints::Storage->new( $repository )
  
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</source>
</div>
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===new===
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+
$store = EPrints::Storage-&gt;new( $repository )
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Create a new storage object for $repository. Should not be used directly, see [[API:EPrints/Session|EPrints::Session]].
 
Create a new storage object for $repository. Should not be used directly, see [[API:EPrints/Session|EPrints::Session]].
  
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===store===
 
===store===
  
$len = $store-&gt;store( $fileobj, CODEREF )
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<source lang="perl">$len = $store->store( $fileobj, CODEREF [, $offset ] )
Read from and store all data from CODEREF for $fileobj. The '''filesize''' field in $fileobj must be set at the expected number of bytes to read from CODEREF.
+
  
Returns undef if the file couldn't be stored, otherwise the number of bytes read.
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</source>
 +
Read from and store all data from CODEREF for $fileobj.
 +
 
 +
Behaviour is undefined if an attempt is made to write beyond $fileobj's '''filesize'''.
 +
 
 +
Returns undef if the file couldn't be stored, otherwise the number of bytes actually written.
  
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<!-- Pod2Wiki=head_retrieve -->
<!-- Pod2Wiki=item_retrieve -->
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===retrieve===
 
===retrieve===
  
$success = $store-&gt;retrieve( $fileobj, $offset, $n, CALLBACK )
+
<source lang="perl">$success = $store->retrieve( $fileobj, $offset, $n, CALLBACK )
 +
 
 +
</source>
 
Retrieve the contents of the $fileobj starting at $offset for $n bytes.
 
Retrieve the contents of the $fileobj starting at $offset for $n bytes.
  
 
CALLBACK = $rc = &amp;f( BUFFER )
 
CALLBACK = $rc = &amp;f( BUFFER )
  
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<!-- Pod2Wiki=head_delete -->
<!-- Pod2Wiki=item_delete -->
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===delete===
 
===delete===
  
$success = $store-&gt;delete( $fileobj )
+
<source lang="perl">$success = $store->delete( $fileobj )
 +
 
 +
</source>
 
Delete all object copies stored for $fileobj.
 
Delete all object copies stored for $fileobj.
  
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<!-- Pod2Wiki=head_delete_copy -->
<!-- Pod2Wiki=item_delete_copy -->
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===delete_copy===
 
===delete_copy===
  
$ok = $store-&gt;delete_copy( $plugin, $fileobj )
+
<source lang="perl">$ok = $store->delete_copy( $plugin, $fileobj )
 +
 
 +
</source>
 
Delete the copy of this file stored in $plugin.
 
Delete the copy of this file stored in $plugin.
  
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<!-- Pod2Wiki=head_get_local_copy -->
<!-- Pod2Wiki=item_get_local_copy -->
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===get_local_copy===
 
===get_local_copy===
  
$filename = $store-&gt;get_local_copy( $fileobj )
+
<source lang="perl">$fh = $store->get_local_copy( $fileobj )
Return the name of a local copy of the file.
+
  
Will retrieve and cache the remote object using {{API:PodLink|file=File/Temp|package_name=File::Temp|section=|text=File::Temp}} if necessary.
+
</source>
 +
Return a local copy of the file. Potentially expensive if the file has to be retrieved.
 +
 
 +
Stringifying $fh will give the full path to the local file, which may be useful for calling external tools (see {{API:PodLink|file=File/Temp|package_name=File::Temp|section=|text=File::Temp}}).
  
 
Returns undef if retrieval failed.
 
Returns undef if retrieval failed.
  
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<!-- Pod2Wiki=item_get_remote_copy -->
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===get_remote_copy===
 
===get_remote_copy===
  
$url = $store-&gt;get_remote_copy( $fileobj )
+
<source lang="perl">$url = $store->get_remote_copy( $fileobj )
 +
 
 +
</source>
 
Returns a URL from which this file can be accessed.
 
Returns a URL from which this file can be accessed.
  
 
Returns undef if this file is not available via another service.
 
Returns undef if this file is not available via another service.
  
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<!-- Pod2Wiki=head_get_plugins -->
<!-- Pod2Wiki=item_get_plugins -->
+
 
===get_plugins===
 
===get_plugins===
  
@plugins = $store-&gt;get_plugins( $fileobj )
+
<source lang="perl">@plugins = $store->get_plugins( $fileobj )
 +
 
 +
</source>
 
Returns the [[API:EPrints/Plugin/Storage|EPrints::Plugin::Storage]] plugin(s) to use for $fileobj. If more than one plugin is returned they should be used in turn until one succeeds.
 
Returns the [[API:EPrints/Plugin/Storage|EPrints::Plugin::Storage]] plugin(s) to use for $fileobj. If more than one plugin is returned they should be used in turn until one succeeds.
  
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<!-- Pod2Wiki=head_copy -->
<!-- Pod2Wiki=item_copy -->
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===copy===
 
===copy===
  
$ok = $store-&gt;copy( $plugin, $fileobj )
+
<source lang="perl">$ok = $store->copy( $plugin, $fileobj )
 +
 
 +
</source>
 
Copy the contents of $fileobj into another storage $plugin.
 
Copy the contents of $fileobj into another storage $plugin.
  
 
Returns 1 on success, 0 on failure and -1 if a copy already exists in $plugin.
 
Returns 1 on success, 0 on failure and -1 if a copy already exists in $plugin.
  
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<!-- Pod2Wiki=head_open_write -->
<!-- Pod2Wiki=item_open_write -->
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===open_write===
 
===open_write===
  
$ok = $storage-&gt;open_write( $fileobj )
+
<source lang="perl">$ok = $storage->open_write( $fileobj [, $offset ] )
Start a write session for $fileobj. $fileobj must have at least the "filesize" property set (which is the number of bytes that will be written).
+
 
 +
</source>
 +
Start a write session for $fileobj. $fileobj must have at least the "filesize" property set (which is the total number of bytes that will be written).
  
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 
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<!-- Pod2Wiki=head_write -->
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===write===
 
===write===
  
$ok = $storage-&gt;write( $fileobj, $buffer )
+
<source lang="perl">$ok = $storage->write( $fileobj, $buffer )
Write $buffer to the storage plugin(s).
+
 
 +
</source>
 +
Write $buffer to the storage plugin(s), starting from the previously written data.
  
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 
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<!-- Pod2Wiki=head_close_write -->
<!-- Pod2Wiki=item_close_write -->
+
 
===close_write===
 
===close_write===
  
$ok = $storage-&gt;close_write( $fileobj );
+
<source lang="perl">$ok = $storage->close_write( $fileobj );
 +
 
 +
</source>
 
Finish writing to the storage plugin(s) for $fileobj.
 
Finish writing to the storage plugin(s) for $fileobj.
  
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 
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<!-- Pod2Wiki=head_copyright -->
 
==COPYRIGHT==
 
==COPYRIGHT==
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #ccepadding: 0em 1em 0em 1em; font-size: 80%; '>
+
Copyright 2000-2011 University of Southampton.
<span style='display:none'>User Comments</span>
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 +
This file is part of EPrints http://www.eprints.org/.
 +
 
 +
EPrints is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
 +
 
 +
EPrints is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
 +
 
 +
You should have received a copy of the GNU Lesser General Public License along with EPrints.  If not, see http://www.gnu.org/licenses/.
 +
 
 
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Revision as of 09:56, 22 January 2013

EPrints 3 Reference: Directory Structure - Metadata Fields - Repository Configuration - XML Config Files - XML Export Format - EPrints data structure - Core API - Data Objects


API: Core API

Latest Source Code (3.3, 3.2) | Revision Log | Before editing this page please read Pod2Wiki


Warning The interface for this module has not been finalised and may change in the future.

NAME

EPrints::Storage - store and retrieve objects in the storage engine


SYNOPSIS

my $store = $repository->storage();
 
$store->store(
	$fileobj,		# file object
	"diddle.pdf",	# filename
	$fh				# file handle
);


DESCRIPTION

This module is the storage control layer which uses EPrints::Plugin::Storage plugins to support various storage back-ends. It enables the storage, retrieval and deletion of data streams. The maximum size of a stream is dependent on the back-end storage mechanism.


METHODS

new

$store = EPrints::Storage->new( $repository )

Create a new storage object for $repository. Should not be used directly, see EPrints::Session.


store

$len = $store->store( $fileobj, CODEREF [, $offset ] )

Read from and store all data from CODEREF for $fileobj.

Behaviour is undefined if an attempt is made to write beyond $fileobj's filesize.

Returns undef if the file couldn't be stored, otherwise the number of bytes actually written.


retrieve

$success = $store->retrieve( $fileobj, $offset, $n, CALLBACK )

Retrieve the contents of the $fileobj starting at $offset for $n bytes.

CALLBACK = $rc = &f( BUFFER )


delete

$success = $store->delete( $fileobj )

Delete all object copies stored for $fileobj.


delete_copy

$ok = $store->delete_copy( $plugin, $fileobj )

Delete the copy of this file stored in $plugin.


get_local_copy

$fh = $store->get_local_copy( $fileobj )

Return a local copy of the file. Potentially expensive if the file has to be retrieved.

Stringifying $fh will give the full path to the local file, which may be useful for calling external tools (see File::Temp).

Returns undef if retrieval failed.


get_remote_copy

$url = $store->get_remote_copy( $fileobj )

Returns a URL from which this file can be accessed.

Returns undef if this file is not available via another service.


get_plugins

@plugins = $store->get_plugins( $fileobj )

Returns the EPrints::Plugin::Storage plugin(s) to use for $fileobj. If more than one plugin is returned they should be used in turn until one succeeds.


copy

$ok = $store->copy( $plugin, $fileobj )

Copy the contents of $fileobj into another storage $plugin.

Returns 1 on success, 0 on failure and -1 if a copy already exists in $plugin.


open_write

$ok = $storage->open_write( $fileobj [, $offset ] )

Start a write session for $fileobj. $fileobj must have at least the "filesize" property set (which is the total number of bytes that will be written).


write

$ok = $storage->write( $fileobj, $buffer )

Write $buffer to the storage plugin(s), starting from the previously written data.


close_write

$ok = $storage->close_write( $fileobj );

Finish writing to the storage plugin(s) for $fileobj.


COPYRIGHT

Copyright 2000-2011 University of Southampton.

This file is part of EPrints http://www.eprints.org/.

EPrints is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

EPrints is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with EPrints. If not, see http://www.gnu.org/licenses/.