* finished refactoring of attribute handling code, especially the

  merging of attributes, such that all tests are passed
* tested and finished implementation of group support in slxconfig
* added new class AttributeRoster which keeps track of the known
  attributes (the ones provided by the openslx core and any other
  ones that may have been added by some plugin).
* added new option --list-attributes to slxconfig which shows information
  about all known attributes


git-svn-id: http://svn.openslx.org/svn/openslx/trunk@1444 95ad53e4-c205-0410-b2fa-d234c58c8868

5 files changed, 650 insertions, 669 deletions

diff --git a/config-db/OpenSLX/AttributeRoster.pm b/config-db/OpenSLX/AttributeRoster.pm
new file mode 100644
index 00000000..46b90f74
--- /dev/null
+++ b/config-db/OpenSLX/AttributeRoster.pm
@@ -0,0 +1,126 @@
+# Copyright (c) 2006, 2007 - OpenSLX GmbH
+#
+# This program is free software distributed under the GPL version 2.
+# See http://openslx.org/COPYING
+#
+# If you have any feedback please consult http://openslx.org/feedback and
+# send your suggestions, praise, or complaints to feedback@openslx.org
+#
+# General information about OpenSLX can be found at http://openslx.org/
+# -----------------------------------------------------------------------------
+# AttributeRoster.pm
+#	- provides information about all available attributes
+# -----------------------------------------------------------------------------
+package OpenSLX::AttributeRoster;
+
+use strict;
+use warnings;
+
+our (@ISA, @EXPORT, $VERSION);
+
+use Exporter;
+$VERSION = 0.2;
+@ISA = qw(Exporter);
+
+@EXPORT = qw(
+	$%AttributeInfo
+);
+
+use OpenSLX::Basics;
+
+################################################################################
+###
+### Load the available AttrInfo-modules and build a hash containing info about
+### all known attributes from the data contained in those modules.
+###
+################################################################################
+
+my %AttributeInfo = ();
+
+my $libPath = "$openslxConfig{'base-path'}/lib";
+foreach my $module (glob("$libPath/OpenSLX/AttrInfo/*.pm")) {
+	next if $module !~ m{/([^/]+)\.pm$};
+	my $class = "OpenSLX::AttrInfo::$1";
+	vlog(2, "loading attr-info from module '$module'");
+	my $instance = instantiateClass($class);
+	my $attrInfo = $instance->AttrInfo();
+	foreach my $attr (keys %$attrInfo) {
+		$AttributeInfo{$attr} = $attrInfo->{$attr};
+	}
+}
+
+=item C<getAttrInfo()>
+
+Returns info about all attributes.
+
+=over
+
+=item Return Value
+
+An hash-ref with info about all known attributes.
+
+=back
+
+=cut
+
+sub getAttrInfo
+{
+	my $class = shift;
+	my $name  = shift;
+
+	if (defined $name) {
+		my $attrInfo = $AttributeInfo{$name};
+		return if !defined $attrInfo;
+		return { $name => $AttributeInfo{$name} };
+	}
+
+	return \%AttributeInfo;
+}
+
+=item C<getSystemAttrs()>
+
+Returns the attribute names that apply to systems.
+
+=over
+
+=item Return Value
+
+An array of attribute names.
+
+=back
+
+=cut
+
+sub getSystemAttrs
+{
+	my $class = shift;
+
+	return 
+		grep { $AttributeInfo{$_}->{"applies_to_systems"} }
+		keys %AttributeInfo
+}
+
+=item C<getClientAttrs()>
+
+Returns the attribute names that apply to clients.
+
+=over
+
+=item Return Value
+
+An array of attribute names.
+
+=back
+
+=cut
+
+sub getClientAttrs
+{
+	my $class = shift;
+
+	return 
+		grep { $AttributeInfo{$_}->{"applies_to_clients"} }
+		keys %AttributeInfo
+}
+
+1;
diff --git a/config-db/OpenSLX/ConfigDB.pm b/config-db/OpenSLX/ConfigDB.pm
index 289f6f7f..8269ec0c 100644
--- a/config-db/OpenSLX/ConfigDB.pm
+++ b/config-db/OpenSLX/ConfigDB.pm
@@ -16,6 +16,8 @@ use warnings;
 our (@ISA, @EXPORT_OK, %EXPORT_TAGS, $VERSION);
 $VERSION = 1;    # API-version
 
+use Storable qw(dclone);
+
 use Exporter;
 @ISA = qw(Exporter);
 
@@ -81,7 +83,7 @@ to filtering (with boolean operators and hierarchical expressions)].
 =cut
 
 my @supportExports = qw(
-  isAttribute mergeAttributes pushAttributes
+  mergeAttributes pushAttributes
   externalIDForSystem externalIDForClient externalConfigNameForClient
   externalAttrName generatePlaceholderFor
 );
@@ -112,6 +114,7 @@ sub new
 	my $class = shift;
 
 	my $self = {
+		'db-schema' => OpenSLX::DBSchema->new,
 	};
 
 	return bless $self, $class;
@@ -182,7 +185,7 @@ sub connect		## no critic (ProhibitBuiltinHomonyms)
 	$self->{'db-type'} = $dbType;
 	$self->{'meta-db'} = $metaDB;
 
-	$self->_checkAndUpgradeDBSchemaIfNecessary($metaDB);
+	$self->{'db-schema'}->checkAndUpgradeDBSchemaIfNecessary($metaDB);
 
 	return 1;
 }
@@ -281,55 +284,7 @@ sub getColumnsOfTable
 	my $self      = shift;
 	my $tableName = shift;
 
-	return	
-		map { (/^(\w+)\W/) ? $1 : $_; } 
-		@{$DbSchema->{tables}->{$tableName}->{cols}};
-}
-
-=item C<getKnownSystemAttrs()>
-
-Returns the attribute names that apply to systems.
-
-=over
-
-=item Return Value
-
-An array of attribute names.
-
-=back
-
-=cut
-
-sub getKnownSystemAttrs
-{
-	my $self = shift;
-
-	return 
-		grep { $AttributeInfo{$_}->{"applies_to_systems"} }
-		keys %AttributeInfo
-}
-
-=item C<getKnownClientAttrs()>
-
-Returns the attribute names that apply to clients.
-
-=over
-
-=item Return Value
-
-An array of attribute names.
-
-=back
-
-=cut
-
-sub getKnownClientAttrs
-{
-	my $self = shift;
-
-	return 
-		grep { $AttributeInfo{$_}->{"applies_to_clients"} }
-		keys %AttributeInfo
+	return $self->{'db-schema'}->getColumnsOfTable($tableName);
 }
 
 =item C<fetchVendorOSByFilter([%$filter], [$resultCols])>
@@ -1243,10 +1198,12 @@ The IDs of the new system(s), C<undef> if the creation failed.
 
 sub addSystem
 {
-	my $self    = shift;
-	my $valRows = _aref(shift);
+	my $self      = shift;
+	my $inValRows = _aref(shift);
 
-	_checkCols($valRows, 'system', qw(name export_id));
+	_checkCols($inValRows, 'system', qw(name export_id));
+
+	my ($valRows, $attrValRows) = _cloneAndUnhingeAttrs($inValRows);
 
 	foreach my $valRow (@$valRows) {
 		if (!$valRow->{kernel}) {
@@ -1264,7 +1221,7 @@ sub addSystem
 		}
 	}
 
-	return $self->{'meta-db'}->addSystem($valRows);
+	return $self->{'meta-db'}->addSystem($valRows, $attrValRows);
 }
 
 =item C<removeSystem(@$systemIDs)>
@@ -1324,48 +1281,50 @@ sub changeSystem
 {
 	my $self      = shift;
 	my $systemIDs = _aref(shift);
-	my $valRows   = _aref(shift);
+	my $inValRows = _aref(shift);
 
-	return $self->{'meta-db'}->changeSystem($systemIDs, $valRows);
-}
+	my ($valRows, $attrValRows) = _cloneAndUnhingeAttrs($inValRows);
 
-=item C<setSystemAttr($systemID, $attrName, $attrValue)>
-
-Sets a value for an attribute of the given system. If the system already
-has a value for this attribute, it will be overwritten.
-
-=over
-
-=item Param C<systemID>
-
-The ID of the system whose attribute shall be changed.
-
-=item Param C<attrName>
-
-The name of the attribute to change.
-
-=item Param C<attrValue>
-
-The new value for the attribute.
-
-=item Return Value
-
-C<1> if the attribute could be set, C<undef> if not.
-
-=back
-
-=cut
-
-sub setSystemAttr
-{
-	my $self      = shift;
-	my $systemID  = shift;
-	my $attrName  = shift;
-	my $attrValue = shift;
-
-	return $self->{'meta-db'}->setSystemAttr($systemID, $attrName, $attrValue);
+	return $self->{'meta-db'}->changeSystem($systemIDs, $valRows, $attrValRows);
 }
 
+#=item C<setSystemAttr($systemID, $attrName, $attrValue)>
+#
+#Sets a value for an attribute of the given system. If the system already
+#has a value for this attribute, it will be overwritten.
+#
+#=over
+#
+#=item Param C<systemID>
+#
+#The ID of the system whose attribute shall be changed.
+#
+#=item Param C<attrName>
+#
+#The name of the attribute to change.
+#
+#=item Param C<attrValue>
+#
+#The new value for the attribute.
+#
+#=item Return Value
+#
+#C<1> if the attribute could be set, C<undef> if not.
+#
+#=back
+#
+#=cut
+#
+#sub setSystemAttr
+#{
+#	my $self      = shift;
+#	my $systemID  = shift;
+#	my $attrName  = shift;
+#	my $attrValue = shift;
+#
+#	return $self->{'meta-db'}->setSystemAttr($systemID, $attrName, $attrValue);
+#}
+
 =item C<setClientIDsOfSystem($systemID, @$clientIDs)>
 
 Specifies all clients that should offer the given system for booting.
@@ -1608,10 +1567,12 @@ The IDs of the new client(s), C<undef> if the creation failed.
 
 sub addClient
 {
-	my $self    = shift;
-	my $valRows = _aref(shift);
+	my $self      = shift;
+	my $inValRows = _aref(shift);
+
+	_checkCols($inValRows, 'client', qw(name mac));
 
-	_checkCols($valRows, 'client', qw(name mac));
+	my ($valRows, $attrValRows) = _cloneAndUnhingeAttrs($inValRows);
 
 	foreach my $valRow (@$valRows) {
 		if (!$valRow->{boot_type}) {
@@ -1619,7 +1580,7 @@ sub addClient
 		}
 	}
 
-	return $self->{'meta-db'}->addClient($valRows);
+	return $self->{'meta-db'}->addClient($valRows, $attrValRows);
 }
 
 =item C<removeClient(@$clientIDs)>
@@ -1679,48 +1640,50 @@ sub changeClient
 {
 	my $self      = shift;
 	my $clientIDs = _aref(shift);
-	my $valRows   = _aref(shift);
-
-	return $self->{'meta-db'}->changeClient($clientIDs, $valRows);
-}
-
-=item C<setClientAttr($clientID, $attrName, $attrValue)>
-
-Sets a value for an attribute of the given client. If the client already
-has a value for this attribute, it will be overwritten.
-
-=over
-
-=item Param C<clientID>
-
-The ID of the client whose attribute shall be changed.
-
-=item Param C<attrName>
-
-The name of the attribute to change.
-
-=item Param C<attrValue>
-
-The new value for the attribute.
-
-=item Return Value
-
-C<1> if the attribute could be set, C<undef> if not.
-
-=back
-
-=cut
+	my $inValRows = _aref(shift);
 
-sub setClientAttr
-{
-	my $self      = shift;
-	my $clientID  = shift;
-	my $attrName  = shift;
-	my $attrValue = shift;
+	my ($valRows, $attrValRows) = _cloneAndUnhingeAttrs($inValRows);
 
-	return $self->{'meta-db'}->setClientAttr($clientID, $attrName, $attrValue);
+	return $self->{'meta-db'}->changeClient($clientIDs, $valRows, $attrValRows);
 }
 
+#=item C<setClientAttr($clientID, $attrName, $attrValue)>
+#
+#Sets a value for an attribute of the given client. If the client already
+#has a value for this attribute, it will be overwritten.
+#
+#=over
+#
+#=item Param C<clientID>
+#
+#The ID of the client whose attribute shall be changed.
+#
+#=item Param C<attrName>
+#
+#The name of the attribute to change.
+#
+#=item Param C<attrValue>
+#
+#The new value for the attribute.
+#
+#=item Return Value
+#
+#C<1> if the attribute could be set, C<undef> if not.
+#
+#=back
+#
+#=cut
+#
+#sub setClientAttr
+#{
+#	my $self      = shift;
+#	my $clientID  = shift;
+#	my $attrName  = shift;
+#	my $attrValue = shift;
+#
+#	return $self->{'meta-db'}->setClientAttr($clientID, $attrName, $attrValue);
+#}
+
 =item C<setSystemIDsOfClient($clientID, @$systemIDs)>
 
 Specifies all systems that should be offered for booting by the given client.
@@ -1957,17 +1920,19 @@ The IDs of the new group(s), C<undef> if the creation failed.
 
 sub addGroup
 {
-	my $self    = shift;
-	my $valRows = _aref(shift);
+	my $self      = shift;
+	my $inValRows = _aref(shift);
+
+	_checkCols($inValRows, 'group', qw(name));
 
-	_checkCols($valRows, 'group', qw(name));
+	my ($valRows, $attrValRows) = _cloneAndUnhingeAttrs($inValRows);
 
 	foreach my $valRow (@$valRows) {
 		if (!defined $valRow->{priority}) {
 			$valRow->{priority} = '50';
 		}
 	}
-	return $self->{'meta-db'}->addGroup($valRows);
+	return $self->{'meta-db'}->addGroup($valRows, $attrValRows);
 }
 
 =item C<removeGroup(@$groupIDs)>
@@ -2001,42 +1966,42 @@ sub removeGroup
 	return $self->{'meta-db'}->removeGroup($groupIDs);
 }
 
-=item C<setGroupAttr($groupID, $attrName, $attrValue)>
-
-Sets a value for an attribute of the given group. If the group already
-has a value for this attribute, it will be overwritten.
-
-=over
-
-=item Param C<groupID>
-
-The ID of the group whose attribute shall be changed.
-
-=item Param C<attrName>
-
-The name of the attribute to change.
-
-=item Param C<attrValue>
-
-The new value for the attribute.
-
-=item Return Value
-
-C<1> if the attribute could be set, C<undef> if not.
-
-=back
-
-=cut
-
-sub setGroupAttr
-{
-	my $self      = shift;
-	my $groupID  = shift;
-	my $attrName  = shift;
-	my $attrValue = shift;
-
-	return $self->{'meta-db'}->setGroupAttr($groupID, $attrName, $attrValue);
-}
+#=item C<setGroupAttr($groupID, $attrName, $attrValue)>
+#
+#Sets a value for an attribute of the given group. If the group already
+#has a value for this attribute, it will be overwritten.
+#
+#=over
+#
+#=item Param C<groupID>
+#
+#The ID of the group whose attribute shall be changed.
+#
+#=item Param C<attrName>
+#
+#The name of the attribute to change.
+#
+#=item Param C<attrValue>
+#
+#The new value for the attribute.
+#
+#=item Return Value
+#
+#C<1> if the attribute could be set, C<undef> if not.
+#
+#=back
+#
+#=cut
+#
+#sub setGroupAttr
+#{
+#	my $self      = shift;
+#	my $groupID  = shift;
+#	my $attrName  = shift;
+#	my $attrValue = shift;
+#
+#	return $self->{'meta-db'}->setGroupAttr($groupID, $attrName, $attrValue);
+#}
 
 =item C<changeGroup(@$groupIDs, @$valRows)>
 
@@ -2062,11 +2027,13 @@ C<1> if the group(s) could be changed, C<undef> if not.
 
 sub changeGroup
 {
-	my $self     = shift;
-	my $groupIDs = _aref(shift);
-	my $valRows  = _aref(shift);
+	my $self      = shift;
+	my $groupIDs  = _aref(shift);
+	my $inValRows = _aref(shift);
 
-	return $self->{'meta-db'}->changeGroup($groupIDs, $valRows);
+	my ($valRows, $attrValRows) = _cloneAndUnhingeAttrs($inValRows);
+
+	return $self->{'meta-db'}->changeGroup($groupIDs, $valRows, $attrValRows);
 }
 
 =item C<setClientIDsOfGroup($groupID, @$clientIDs)>
@@ -2525,7 +2492,7 @@ sub aggregatedSystemFileInfoFor
 	my $self   = shift;
 	my $system = shift;
 
-	my $info = {%$system};
+	my $info = dclone($system);
 
 	my $export = $self->fetchExportByID($system->{export_id});
 	if (!defined $export) {
@@ -2586,32 +2553,6 @@ sub aggregatedSystemFileInfoFor
 
 =over
 
-=item C<isAttribute($key)>
-
-Returns whether or not the given key is an exportable attribute.
-
-=over
-
-=item Param C<system>
-
-The key to check.
-
-=item Return Value
-
-1 if the given key is indeed an attribute (currently, this means that
-it starts with 'attr_'), 0 if not.
-
-=back
-
-=cut
-
-sub isAttribute
-{
-	my $key = shift;
-
-	return $key =~ m[^attr_];
-}
-
 =item C<mergeAttributes($target, $source)>
 
 Copies all attributes from source that are unset in target over (source extends target).
@@ -2648,7 +2589,7 @@ sub mergeAttributes
 		my $sourceVal = $sourceAttrs->{$key};
 		my $targetVal = $targetAttrs->{$key};
 		if (defined $sourceVal && !defined $targetVal) {
-			vlog(0, _tr("merging %s (val=%s)", $key, $sourceVal));
+			vlog(3, _tr("merging %s (val=%s)", $key, $sourceVal));
 			$targetAttrs->{$key} = $sourceVal;
 		}
 	}
@@ -2851,51 +2792,6 @@ sub generatePlaceholderFor
 ################################################################################
 ### private stuff
 ################################################################################
-sub _checkAndUpgradeDBSchemaIfNecessary
-{
-	my $self   = shift;
-	my $metaDB = shift;
-
-	vlog(2, "trying to determine schema version...");
-	my $currVersion = $metaDB->schemaFetchDBVersion();
-	if (!defined $currVersion) {
-		# that's bad, someone has messed with our DB: there is a
-		# database, but the 'meta'-table is empty. 
-		# There might still be data in the other tables, but we have no way to 
-		# find out which schema version they're in. So it's safer to give up.
-		croak _tr('Could not determine schema version of database');
-	}
-
-	if ($currVersion == 0) {
-		vlog(1, _tr('Creating DB (schema version: %s)', $DbSchema->{version}));
-		foreach my $tableName (keys %{$DbSchema->{tables}}) {
-			# create table (optionally inserting default values, too)
-			$metaDB->schemaAddTable(
-				$tableName,
-				$DbSchema->{tables}->{$tableName}->{cols},
-				$DbSchema->{tables}->{$tableName}->{vals}
-			);
-		}
-		$metaDB->schemaSetDBVersion($DbSchema->{version});
-		vlog(1, _tr('DB has been created successfully'));
-	} elsif ($currVersion < $DbSchema->{version}) {
-		vlog(
-			1,
-			_tr(
-				'Our schema-version is %s, DB is %s, upgrading DB...',
-				$DbSchema->{version}, $currVersion
-			)
-		);
-		$metaDB->schemaUpgradeDBFrom($currVersion);
-		$metaDB->schemaSetDBVersion($DbSchema->{version});
-		vlog(1, _tr('upgrade done'));
-	} else {
-		vlog(1, _tr('DB matches current schema version (%s)', $currVersion));
-	}
-
-	return 1;
-}
-
 sub _aref
 {    # transparently converts the given reference to an array-ref
 	my $ref = shift;
@@ -2927,4 +2823,20 @@ sub _checkCols
 	return 1;
 }
 
+sub _cloneAndUnhingeAttrs
+{
+	my $inValRows = shift;
+
+	# clone data and unhinge attrs
+	my (@valRows, @attrValRows);
+	foreach my $inValRow (@$inValRows) {
+		push @attrValRows, $inValRow->{attrs};
+		my $valRow = dclone($inValRow);
+		delete $valRow->{attrs};
+		push @valRows, $valRow;
+	}
+
+	return (\@valRows, \@attrValRows);
+}
+
 1;
diff --git a/config-db/OpenSLX/Export/DHCP/ISC.pm b/config-db/OpenSLX/ConfigExport/DHCP/ISC.pm
index 2e7aa01b..e3dd0738 100644
--- a/config-db/OpenSLX/Export/DHCP/ISC.pm
+++ b/config-db/OpenSLX/ConfigExport/DHCP/ISC.pm
@@ -11,7 +11,7 @@
 # ISC.pm
 #	- provides ISC-specific implementation of DHCP export.
 # -----------------------------------------------------------------------------
-package OpenSLX::Export::DHCP::ISC;
+package OpenSLX::ConfigExport::DHCP::ISC;
 
 use strict;
 use warnings;
diff --git a/config-db/OpenSLX/DBSchema.pm b/config-db/OpenSLX/DBSchema.pm
index 801f50a9..cd92c07e 100644
--- a/config-db/OpenSLX/DBSchema.pm
+++ b/config-db/OpenSLX/DBSchema.pm
@@ -16,25 +16,8 @@ package OpenSLX::DBSchema;
 use strict;
 use warnings;
 
-our (@ISA, @EXPORT, $VERSION);
-
-use Exporter;
-$VERSION = 0.2;
-@ISA = qw(Exporter);
-
-@EXPORT = qw(
-	$DbSchema %DbSchemaHistory %AttributeInfo
-);
-
-our ($DbSchema, %DbSchemaHistory, %AttributeInfo);
-
-
 use OpenSLX::Basics;
 
-use POSIX qw(locale_h);
-my $lang = setlocale(LC_MESSAGES);
-my $country = $lang =~ m[^\w\w_(\w\w)] ? lc($1) : 'us';
-
 ################################################################################
 ### DB-schema definition
 ### 	This hash-ref describes the current OpenSLX configuration database 
@@ -51,7 +34,13 @@ my $country = $lang =~ m[^\w\w_(\w\w)] ? lc($1) : 'us';
 ### 		fk		=> foreign key (integer)
 ################################################################################
 
-$DbSchema = {
+use POSIX qw(locale_h);
+my $lang = setlocale(LC_MESSAGES);
+my $country = $lang =~ m[^\w\w_(\w\w)] ? lc($1) : 'us';
+
+my $VERSION = 0.2;
+
+my $DbSchema = {
 	'version' => $VERSION,
 	'tables' => {
 		'client' => {
@@ -170,7 +159,7 @@ $DbSchema = {
 			],
 			'vals' => [
 				{
-					'schema_version' => $DbSchema->{'version'},
+					'schema_version' => $VERSION,
 				},
 			],
 		},
@@ -213,16 +202,6 @@ $DbSchema = {
 				# attributes of default system
 				{
 					'system_id' => 0,
-					'name' => 'automnt_dir',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
-					'name' => 'automnt_src',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
 					'name' => 'country',
 					'value' => "$country",
 				},
@@ -233,21 +212,6 @@ $DbSchema = {
 				},
 				{
 					'system_id' => 0,
-					'name' => 'hw_graphic',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
-					'name' => 'hw_monitor',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
-					'name' => 'hw_mouse',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
 					'name' => 'late_dm',
 					'value' => 'no',
 				},
@@ -258,52 +222,12 @@ $DbSchema = {
 				},
 				{
 					'system_id' => 0,
-					'name' => 'nis_domain',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
-					'name' => 'nis_servers',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
-					'name' => 'ramfs_fsmods',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
-					'name' => 'ramfs_miscmods',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
 					'name' => 'ramfs_nicmods',
 					'value' 
 						=> 'forcedeth e1000 e100 tg3 via-rhine r8169 pcnet32',
 				},
 				{
 					'system_id' => 0,
-					'name' => 'ramfs_screen',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
-					'name' => 'sane_scanner',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
-					'name' => 'scratch',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
-					'name' => 'slxgrp',
-					'value' => '',
-				},
-				{
-					'system_id' => 0,
 					'name' => 'start_alsasound',
 					'value' => 'yes',
 				},
@@ -409,23 +333,301 @@ $DbSchema = {
 
 ################################################################################
 ###
-### Load the available AttrInfo-modules and build a hash containing info about
-### all known attributes from the data contained in those modules.
+### standard methods
+###
+################################################################################
+sub new
+{
+	my $class = shift;
+
+	my $self = {
+	};
+
+	return bless $self, $class;
+}
+
+sub checkAndUpgradeDBSchemaIfNecessary
+{
+	my $self   = shift;
+	my $metaDB = shift;
+
+	vlog(2, "trying to determine schema version...");
+	my $currVersion = $metaDB->schemaFetchDBVersion();
+	if (!defined $currVersion) {
+		# that's bad, someone has messed with our DB: there is a
+		# database, but the 'meta'-table is empty. 
+		# There might still be data in the other tables, but we have no way to 
+		# find out which schema version they're in. So it's safer to give up.
+		croak _tr('Could not determine schema version of database');
+	}
+
+	if ($currVersion == 0) {
+		vlog(1, _tr('Creating DB (schema version: %s)', $DbSchema->{version}));
+		foreach my $tableName (keys %{$DbSchema->{tables}}) {
+			# create table (optionally inserting default values, too)
+			$metaDB->schemaAddTable(
+				$tableName,
+				$DbSchema->{tables}->{$tableName}->{cols},
+				$DbSchema->{tables}->{$tableName}->{vals}
+			);
+		}
+		$metaDB->schemaSetDBVersion($DbSchema->{version});
+		vlog(1, _tr('DB has been created successfully'));
+	} elsif ($currVersion < $DbSchema->{version}) {
+		vlog(
+			1,
+			_tr(
+				'Our schema-version is %s, DB is %s, upgrading DB...',
+				$DbSchema->{version}, $currVersion
+			)
+		);
+		$self->_schemaUpgradeDBFrom($metaDB, $currVersion);
+		$metaDB->schemaSetDBVersion($DbSchema->{version});
+		vlog(1, _tr('upgrade done'));
+	} else {
+		vlog(1, _tr('DB matches current schema version (%s)', $currVersion));
+	}
+
+	return 1;
+}
+
+sub getColumnsOfTable
+{
+	my $self      = shift;
+	my $tableName = shift;
+
+	return	
+		map { (/^(\w+)\W/) ? $1 : $_; } 
+		@{$DbSchema->{tables}->{$tableName}->{cols}};
+}
+
+################################################################################
+###
+### methods for upgrading the DB schema
 ###
 ################################################################################
+sub _schemaUpgradeDBFrom
+{
+	my $self        = shift;
+	my $metaDB      = shift;
+	my $currVersion = shift;
 
-%AttributeInfo = ();
+	$self->_upgradeDBTo0_2($metaDB) if $currVersion < 0.2;
+
+	return 1;
+}
 
-my $libPath = "$openslxConfig{'base-path'}/lib";
-foreach my $module (glob("$libPath/OpenSLX/AttrInfo/*.pm")) {
-	next if $module !~ m{/([^/]+)\.pm$};
-	my $class = "OpenSLX::AttrInfo::$1";
-	vlog(2, "loading attr-info from module '$module'");
-	my $instance = instantiateClass($class);
-	my $attrInfo = $instance->AttrInfo();
-	foreach my $attr (keys %$attrInfo) {
-		$AttributeInfo{$attr} = $attrInfo->{$attr};
+sub _upgradeDBTo0_2
+{
+	my $self   = shift;
+	my $metaDB = shift;
+
+	# move attributes into separate tables ...
+	#
+	# ... system attributes ...
+	$metaDB->schemaAddTable(
+		'system_attr', 
+		[
+			'id:pk',
+			'system_id:fk',
+			'name:s.128',
+			'value:s.255',
+		]
+	);
+	foreach my $system ($metaDB->fetchSystemByFilter()) {
+		my %attrs;
+		foreach my $key (keys %$system) {
+			next if substr($key, 0, 5) ne 'attr_';
+			my $attrValue = $system->{$key} || '';
+			next if $system->{id} > 0 && !length($attrValue);
+			my $newAttrName = substr($key, 5);
+			$attrs{$newAttrName} = $attrValue;
+		}
+		$metaDB->setSystemAttrs($system->{id}, \%attrs);
+	}
+	$metaDB->schemaDropColumns(
+		'system',
+		[
+			'attr_automnt_dir',
+			'attr_automnt_src',
+			'attr_country',
+			'attr_dm_allow_shutdown',
+			'attr_hw_graphic',
+			'attr_hw_monitor',
+			'attr_hw_mouse',
+			'attr_late_dm',
+			'attr_netbios_workgroup',
+			'attr_nis_domain',
+			'attr_nis_servers',
+			'attr_ramfs_fsmods',
+			'attr_ramfs_miscmods',
+			'attr_ramfs_nicmods',
+			'attr_ramfs_screen',
+			'attr_sane_scanner',
+			'attr_scratch',
+			'attr_slxgrp',
+			'attr_start_alsasound',
+			'attr_start_atd',
+			'attr_start_cron',
+			'attr_start_dreshal',
+			'attr_start_ntp',
+			'attr_start_nfsv4',
+			'attr_start_printer',
+			'attr_start_samba',
+			'attr_start_snmp',
+			'attr_start_sshd',
+			'attr_start_syslog',
+			'attr_start_x',
+			'attr_start_xdmcp',
+			'attr_tex_enable',
+			'attr_timezone',
+			'attr_tvout',
+			'attr_vmware',
+		],
+		[
+			'id:pk',
+			'export_id:fk',
+			'name:s.64',
+			'label:s.64',
+			'kernel:s.128',
+			'kernel_params:s.512',
+			'hidden:b',
+			'comment:s.1024',
+		]
+	);
+	#
+	# ... client attributes ...
+	$metaDB->schemaAddTable(
+		'client_attr',
+		[
+			'id:pk',
+			'client_id:fk',
+			'name:s.128',
+			'value:s.255',
+		]
+	);
+	foreach my $client ($metaDB->fetchClientByFilter()) {
+		my %attrs;
+		foreach my $key (keys %$client) {
+			next if substr($key, 0, 5) ne 'attr_';
+			my $attrValue = $client->{$key} || '';
+			next if !length($attrValue);
+			my $newAttrName = substr($key, 5);
+			$attrs{$newAttrName} = $attrValue;
+		}
+		$metaDB->setClientAttrs($client->{id}, \%attrs);
 	}
+	$metaDB->schemaDropColumns(
+		'client',
+		[
+			'attr_automnt_dir',
+			'attr_automnt_src',
+			'attr_country',
+			'attr_dm_allow_shutdown',
+			'attr_hw_graphic',
+			'attr_hw_monitor',
+			'attr_hw_mouse',
+			'attr_late_dm',
+			'attr_netbios_workgroup',
+			'attr_nis_domain',
+			'attr_nis_servers',
+			'attr_sane_scanner',
+			'attr_scratch',
+			'attr_slxgrp',
+			'attr_start_alsasound',
+			'attr_start_atd',
+			'attr_start_cron',
+			'attr_start_dreshal',
+			'attr_start_ntp',
+			'attr_start_nfsv4',
+			'attr_start_printer',
+			'attr_start_samba',
+			'attr_start_snmp',
+			'attr_start_sshd',
+			'attr_start_syslog',
+			'attr_start_x',
+			'attr_start_xdmcp',
+			'attr_tex_enable',
+			'attr_timezone',
+			'attr_tvout',
+			'attr_vmware',
+		],
+		[
+			'id:pk',
+			'name:s.128',
+			'mac:s.20',
+			'boot_type:s.20',
+			'unbootable:b',
+			'kernel_params:s.128',
+			'comment:s.1024',
+		]
+	);
+	#
+	# ... group attributes ...
+	$metaDB->schemaAddTable(
+		'group_attr',
+		[
+			'id:pk',
+			'group_id:fk',
+			'name:s.128',
+			'value:s.255',
+		]
+	);
+	foreach my $group ($metaDB->fetchGroupByFilter()) {
+		my %attrs;
+		foreach my $key (keys %$group) {
+			next if substr($key, 0, 5) ne 'attr_';
+			my $attrValue = $group->{$key} || '';
+			next if !length($attrValue);
+			my $newAttrName = substr($key, 5);
+			$attrs{$newAttrName} = $attrValue;
+		}
+		$metaDB->setGroupAttrs($group->{id}, \%attrs);
+	}
+	$metaDB->schemaDropColumns(
+		'groups',
+		[
+			'attr_automnt_dir',
+			'attr_automnt_src',
+			'attr_country',
+			'attr_dm_allow_shutdown',
+			'attr_hw_graphic',
+			'attr_hw_monitor',
+			'attr_hw_mouse',
+			'attr_late_dm',
+			'attr_netbios_workgroup',
+			'attr_nis_domain',
+			'attr_nis_servers',
+			'attr_sane_scanner',
+			'attr_scratch',
+			'attr_slxgrp',
+			'attr_start_alsasound',
+			'attr_start_atd',
+			'attr_start_cron',
+			'attr_start_dreshal',
+			'attr_start_ntp',
+			'attr_start_nfsv4',
+			'attr_start_printer',
+			'attr_start_samba',
+			'attr_start_snmp',
+			'attr_start_sshd',
+			'attr_start_syslog',
+			'attr_start_x',
+			'attr_start_xdmcp',
+			'attr_tex_enable',
+			'attr_timezone',
+			'attr_tvout',
+			'attr_vmware',
+		],
+		[
+			'id:pk',
+			'name:s.128',
+			'priority:i',
+			'comment:s.1024',
+		]
+	);
+
+	return 1;
 }
 
 1;
diff --git a/config-db/OpenSLX/MetaDB/DBI.pm b/config-db/OpenSLX/MetaDB/DBI.pm
index 98754777..a6d2eef0 100644
--- a/config-db/OpenSLX/MetaDB/DBI.pm
+++ b/config-db/OpenSLX/MetaDB/DBI.pm
@@ -713,24 +713,16 @@ sub changeGlobalInfo
 
 sub addSystem
 {
-	my $self    = shift;
-	my $valRows = shift;
-
-	# separate the attribute hashes ...
-	my @attrValRows 
-		=	map {
-				my $attrs = $_->{attrs};
-				delete $_->{attrs};
-				$attrs;
-			}
-			@$valRows;
+	my $self        = shift;
+	my $valRows     = shift;
+	my $attrValRows = shift;
 
 	# ... store the systems to get the IDs ...
 	my @systemIDs = $self->_doInsert('system', $valRows);
 
 	# ... finally store the individual attribute sets
 	foreach my $id (@systemIDs) {
-		my $attrs = shift @attrValRows;
+		my $attrs = shift @$attrValRows;
 		next if !defined $attrs;
 		return if !$self->setSystemAttrs($id, $attrs);
 	}
@@ -751,17 +743,11 @@ sub changeSystem
 	my $self      = shift;
 	my $systemIDs = shift;
 	my $valRows   = shift;
+	my $attrValRows = shift;
 
-	# separate the attribute hashes and store them individually
-	my @attrValRows 
-		=	map {
-				my $attrs = $_->{attrs};
-				delete $_->{attrs};
-				$attrs;
-			}
-			@$valRows;
+	# store the attribute hashes individually
 	foreach my $id (@$systemIDs) {
-		my $attrs = shift @attrValRows;
+		my $attrs = shift @$attrValRows;
 		next if !defined $attrs;
 		return if !$self->setSystemAttrs($id, $attrs);
 	}
@@ -776,20 +762,21 @@ sub setSystemAttrs
 	my $systemID = shift;
 	my $attrs    = shift;
 
-	# we take the simple path and remove all attributes ...
+	# for now we take the simple path and remove all attributes ...
 	return if !$self->_doDelete('system_attr', [ $systemID ], 'system_id');
 
 	# ... and (re-)insert the given ones
-	foreach my $key (keys %$attrs) {
-		return if !$self->_doInsert(
-			'system_attr', [ {
-				system_id => $systemID,
-				name      => $key,
-				value     => $attrs->{$key},
-			} ]
-		);
-	}
-	return 1;
+	my @attrData 
+		=	map {
+				{
+					system_id => $systemID,
+					name      => $_,
+					value     => $attrs->{$_},
+				}			
+			}
+			grep { defined $attrs->{$_} }
+			keys %$attrs;
+	return $self->_doInsert('system_attr', [ @attrData ]);
 }
 
 sub setClientIDsOfSystem
@@ -822,22 +809,14 @@ sub addClient
 {
 	my $self    = shift;
 	my $valRows = shift;
-
-	# separate the attribute hashes ...
-	my @attrValRows 
-		=	map {
-				my $attrs = $_->{attrs};
-				delete $_->{attrs};
-				$attrs;
-			}
-			@$valRows;
+	my $attrValRows = shift;
 
 	# ... store the clients to get the IDs ...
 	my @clientIDs = $self->_doInsert('client', $valRows);
 
 	# ... finally store the individual attribute sets
 	foreach my $id (@clientIDs) {
-		my $attrs = shift @attrValRows;
+		my $attrs = shift @$attrValRows;
 		next if !defined $attrs;
 		return if !$self->setClientAttrs($id, $attrs);
 	}
@@ -855,20 +834,14 @@ sub removeClient
 
 sub changeClient
 {
-	my $self      = shift;
-	my $clientIDs = shift;
-	my $valRows   = shift;
+	my $self        = shift;
+	my $clientIDs   = shift;
+	my $valRows     = shift;
+	my $attrValRows = shift;
 
-	# separate the attribute hashes and store them individually
-	my @attrValRows 
-		=	map {
-				my $attrs = $_->{attrs};
-				delete $_->{attrs};
-				$attrs;
-			}
-			@$valRows;
+	# store the attribute hashes individually
 	foreach my $id (@$clientIDs) {
-		my $attrs = shift @attrValRows;
+		my $attrs = shift @$attrValRows;
 		next if !defined $attrs;
 		return if !$self->setClientAttrs($id, $attrs);
 	}
@@ -883,19 +856,21 @@ sub setClientAttrs
 	my $clientID = shift;
 	my $attrs    = shift;
 
-	# we take the simple path and remove all attributes ...
+	# for now we take the simple path and remove all attributes ...
 	return if !$self->_doDelete('client_attr', [ $clientID ], 'client_id');
 
 	# ... and (re-)insert the given ones
-	foreach my $key (keys %$attrs) {
-		return if !$self->_doInsert(
-			'client_attr', [ {
-				client_id => $clientID,
-				name      => $key,
-				value     => $attrs->{$key},
-			} ]
-		);
-	}
+	my @attrData 
+		=	map {
+				{
+					client_id => $clientID,
+					name      => $_,
+					value     => $attrs->{$_},
+				}			
+			}
+			grep { defined $attrs->{$_} }
+			keys %$attrs;
+	return $self->_doInsert('client_attr', [ @attrData ]);
 	return 1;
 }
 
@@ -927,24 +902,16 @@ sub setGroupIDsOfClient
 
 sub addGroup
 {
-	my $self    = shift;
-	my $valRows = shift;
-
-	# separate the attribute hashes ...
-	my @attrValRows 
-		=	map {
-				my $attrs = $_->{attrs};
-				delete $_->{attrs};
-				$attrs;
-			}
-			@$valRows;
+	my $self        = shift;
+	my $valRows     = shift;
+	my $attrValRows = shift;
 
 	# ... store the groups to get the IDs ...
 	my @groupIDs = $self->_doInsert('groups', $valRows);
 
 	# ... finally store the individual attribute sets
 	foreach my $id (@groupIDs) {
-		my $attrs = shift @attrValRows;
+		my $attrs = shift @$attrValRows;
 		next if !defined $attrs;
 		return if !$self->setGroupAttrs($id, $attrs);
 	}
@@ -962,20 +929,14 @@ sub removeGroup
 
 sub changeGroup
 {
-	my $self     = shift;
-	my $groupIDs = shift;
-	my $valRows  = shift;
+	my $self        = shift;
+	my $groupIDs    = shift;
+	my $valRows     = shift;
+	my $attrValRows = shift;
 
-	# separate the attribute hashes and store them individually
-	my @attrValRows 
-		=	map {
-				my $attrs = $_->{attrs};
-				delete $_->{attrs};
-				$attrs;
-			}
-			@$valRows;
+	# store the attribute hashes individually
 	foreach my $id (@$groupIDs) {
-		my $attrs = shift @attrValRows;
+		my $attrs = shift @$attrValRows;
 		next if !defined $attrs;
 		return if !$self->setGroupAttrs($id, $attrs);
 	}
@@ -990,19 +951,21 @@ sub setGroupAttrs
 	my $groupID = shift;
 	my $attrs   = shift;
 
-	# we take the simple path and remove all attributes ...
+	# for now we take the simple path and remove all attributes ...
 	return if !$self->_doDelete('group_attr', [ $groupID ], 'group_id');
 
 	# ... and (re-)insert the given ones
-	foreach my $key (keys %$attrs) {
-		return if !$self->_doInsert(
-			'group_attr', [ {
-				group_id => $groupID,
-				name      => $key,
-				value     => $attrs->{$key},
-			} ]
-		);
-	}
+	my @attrData 
+		=	map {
+				{
+					group_id => $groupID,
+					name     => $_,
+					value    => $attrs->{$_},
+				}			
+			}
+			grep { defined $attrs->{$_} }
+			keys %$attrs;
+	return $self->_doInsert('group_attr', [ @attrData ]);
 	return 1;
 }
 
@@ -1089,16 +1052,6 @@ sub schemaFetchDBVersion
 	return $row->{schema_version};
 }
 
-sub schemaUpgradeDBFrom
-{
-	my $self        = shift;
-	my $currVersion = shift;
-
-	$self->_upgradeDBTo0_2() if $currVersion < 0.2;
-
-	return 1;
-}
-
 sub schemaSetDBVersion
 {
 	my $self      = shift;
@@ -1317,218 +1270,6 @@ sub schemaChangeColumns
 	return;
 }
 
-sub _upgradeDBTo0_2
-{
-	my $self = shift;
-
-	# move attributes into separate tables ...
-	#
-	# ... system attributes ...
-	$self->schemaAddTable(
-		'system_attr', 
-		[
-			'id:pk',
-			'system_id:fk',
-			'name:s.128',
-			'value:s.255',
-		]
-	);
-	foreach my $system ($self->fetchSystemByFilter()) {
-		my %attrs;
-		foreach my $key (keys %$system) {
-			next if substr($key, 0, 5) ne 'attr_';
-			my $attrValue = $system->{$key} || '';
-			next if $system->{id} > 0 && !length($attrValue);
-			my $newAttrName = substr($key, 5);
-			$attrs{$newAttrName} = $attrValue;
-		}
-		$self->setSystemAttrs($system->{id}, \%attrs);
-	}
-	$self->schemaDropColumns(
-		'system',
-		[
-			'attr_automnt_dir',
-			'attr_automnt_src',
-			'attr_country',
-			'attr_dm_allow_shutdown',
-			'attr_hw_graphic',
-			'attr_hw_monitor',
-			'attr_hw_mouse',
-			'attr_late_dm',
-			'attr_netbios_workgroup',
-			'attr_nis_domain',
-			'attr_nis_servers',
-			'attr_ramfs_fsmods',
-			'attr_ramfs_miscmods',
-			'attr_ramfs_nicmods',
-			'attr_ramfs_screen',
-			'attr_sane_scanner',
-			'attr_scratch',
-			'attr_slxgrp',
-			'attr_start_alsasound',
-			'attr_start_atd',
-			'attr_start_cron',
-			'attr_start_dreshal',
-			'attr_start_ntp',
-			'attr_start_nfsv4',
-			'attr_start_printer',
-			'attr_start_samba',
-			'attr_start_snmp',
-			'attr_start_sshd',
-			'attr_start_syslog',
-			'attr_start_x',
-			'attr_start_xdmcp',
-			'attr_tex_enable',
-			'attr_timezone',
-			'attr_tvout',
-			'attr_vmware',
-		],
-		[
-			'id:pk',
-			'export_id:fk',
-			'name:s.64',
-			'label:s.64',
-			'kernel:s.128',
-			'kernel_params:s.512',
-			'hidden:b',
-			'comment:s.1024',
-		]
-	);
-	#
-	# ... client attributes ...
-	$self->schemaAddTable(
-		'client_attr',
-		[
-			'id:pk',
-			'client_id:fk',
-			'name:s.128',
-			'value:s.255',
-		]
-	);
-	foreach my $client ($self->fetchClientByFilter()) {
-		my %attrs;
-		foreach my $key (keys %$client) {
-			next if substr($key, 0, 5) ne 'attr_';
-			my $attrValue = $client->{$key} || '';
-			next if !length($attrValue);
-			my $newAttrName = substr($key, 5);
-			$attrs{$newAttrName} = $attrValue;
-		}
-		$self->setClientAttrs($client->{id}, \%attrs);
-	}
-	$self->schemaDropColumns(
-		'client',
-		[
-			'attr_automnt_dir',
-			'attr_automnt_src',
-			'attr_country',
-			'attr_dm_allow_shutdown',
-			'attr_hw_graphic',
-			'attr_hw_monitor',
-			'attr_hw_mouse',
-			'attr_late_dm',
-			'attr_netbios_workgroup',
-			'attr_nis_domain',
-			'attr_nis_servers',
-			'attr_sane_scanner',
-			'attr_scratch',
-			'attr_slxgrp',
-			'attr_start_alsasound',
-			'attr_start_atd',
-			'attr_start_cron',
-			'attr_start_dreshal',
-			'attr_start_ntp',
-			'attr_start_nfsv4',
-			'attr_start_printer',
-			'attr_start_samba',
-			'attr_start_snmp',
-			'attr_start_sshd',
-			'attr_start_syslog',
-			'attr_start_x',
-			'attr_start_xdmcp',
-			'attr_tex_enable',
-			'attr_timezone',
-			'attr_tvout',
-			'attr_vmware',
-		],
-		[
-			'id:pk',
-			'name:s.128',
-			'mac:s.20',
-			'boot_type:s.20',
-			'unbootable:b',
-			'kernel_params:s.128',
-			'comment:s.1024',
-		]
-	);
-	#
-	# ... group attributes ...
-	$self->schemaAddTable(
-		'group_attr',
-		[
-			'id:pk',
-			'group_id:fk',
-			'name:s.128',
-			'value:s.255',
-		]
-	);
-	foreach my $group ($self->fetchGroupByFilter()) {
-		my %attrs;
-		foreach my $key (keys %$group) {
-			next if substr($key, 0, 5) ne 'attr_';
-			my $attrValue = $group->{$key} || '';
-			next if !length($attrValue);
-			my $newAttrName = substr($key, 5);
-			$attrs{$newAttrName} = $attrValue;
-		}
-		$self->setGroupAttrs($group->{id}, \%attrs);
-	}
-	$self->schemaDropColumns(
-		'groups',
-		[
-			'attr_automnt_dir',
-			'attr_automnt_src',
-			'attr_country',
-			'attr_dm_allow_shutdown',
-			'attr_hw_graphic',
-			'attr_hw_monitor',
-			'attr_hw_mouse',
-			'attr_late_dm',
-			'attr_netbios_workgroup',
-			'attr_nis_domain',
-			'attr_nis_servers',
-			'attr_sane_scanner',
-			'attr_scratch',
-			'attr_slxgrp',
-			'attr_start_alsasound',
-			'attr_start_atd',
-			'attr_start_cron',
-			'attr_start_dreshal',
-			'attr_start_ntp',
-			'attr_start_nfsv4',
-			'attr_start_printer',
-			'attr_start_samba',
-			'attr_start_snmp',
-			'attr_start_sshd',
-			'attr_start_syslog',
-			'attr_start_x',
-			'attr_start_xdmcp',
-			'attr_tex_enable',
-			'attr_timezone',
-			'attr_tvout',
-			'attr_vmware',
-		],
-		[
-			'id:pk',
-			'name:s.128',
-			'priority:i',
-			'comment:s.1024',
-		]
-	);
-
-	return 1;
-}
-
 1;
 
 =head1 NAME