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diff --git a/www/wiki/includes/externalstore/ExternalStore.php b/www/wiki/includes/externalstore/ExternalStore.php
new file mode 100644
index 00000000..de7d1a4c
--- /dev/null
+++ b/www/wiki/includes/externalstore/ExternalStore.php
@@ -0,0 +1,254 @@
+<?php
+/**
+ * @defgroup ExternalStorage ExternalStorage
+ */
+
+use MediaWiki\MediaWikiServices;
+
+/**
+ * Interface for data storage in external repositories.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Constructor class for key/value blob data kept in external repositories.
+ *
+ * Objects in external stores are defined by a special URL. The URL is of
+ * the form "<store protocol>://<location>/<object name>". The protocol is used
+ * to determine what ExternalStoreMedium class is used. The location identifies
+ * particular storage instances or database clusters for store class to use.
+ *
+ * When an object is inserted into a store, the calling code uses a partial URL of
+ * the form "<store protocol>://<location>" and receives the full object URL on success.
+ * This is useful since object names can be sequential IDs, UUIDs, or hashes.
+ * Callers are not responsible for unique name generation.
+ *
+ * External repositories might be populated by maintenance/async
+ * scripts, thus partial moving of data may be possible, as well
+ * as the possibility to have any storage format (i.e. for archives).
+ *
+ * @ingroup ExternalStorage
+ */
+class ExternalStore {
+	/**
+	 * Get an external store object of the given type, with the given parameters
+	 *
+	 * @param string $proto Type of external storage, should be a value in $wgExternalStores
+	 * @param array $params Associative array of ExternalStoreMedium parameters
+	 * @return ExternalStoreMedium|bool The store class or false on error
+	 */
+	public static function getStoreObject( $proto, array $params = [] ) {
+		return MediaWikiServices::getInstance()
+			->getExternalStoreFactory()
+			->getStoreObject( $proto, $params );
+	}
+
+	/**
+	 * Fetch data from given URL
+	 *
+	 * @param string $url The URL of the text to get
+	 * @param array $params Associative array of ExternalStoreMedium parameters
+	 * @return string|bool The text stored or false on error
+	 * @throws MWException
+	 */
+	public static function fetchFromURL( $url, array $params = [] ) {
+		$parts = explode( '://', $url, 2 );
+		if ( count( $parts ) != 2 ) {
+			return false; // invalid URL
+		}
+
+		list( $proto, $path ) = $parts;
+		if ( $path == '' ) { // bad URL
+			return false;
+		}
+
+		$store = self::getStoreObject( $proto, $params );
+		if ( $store === false ) {
+			return false;
+		}
+
+		return $store->fetchFromURL( $url );
+	}
+
+	/**
+	 * Fetch data from multiple URLs with a minimum of round trips
+	 *
+	 * @param array $urls The URLs of the text to get
+	 * @return array Map from url to its data.  Data is either string when found
+	 *     or false on failure.
+	 * @throws MWException
+	 */
+	public static function batchFetchFromURLs( array $urls ) {
+		$batches = [];
+		foreach ( $urls as $url ) {
+			$scheme = parse_url( $url, PHP_URL_SCHEME );
+			if ( $scheme ) {
+				$batches[$scheme][] = $url;
+			}
+		}
+		$retval = [];
+		foreach ( $batches as $proto => $batchedUrls ) {
+			$store = self::getStoreObject( $proto );
+			if ( $store === false ) {
+				continue;
+			}
+			$retval += $store->batchFetchFromURLs( $batchedUrls );
+		}
+		// invalid, not found, db dead, etc.
+		$missing = array_diff( $urls, array_keys( $retval ) );
+		if ( $missing ) {
+			foreach ( $missing as $url ) {
+				$retval[$url] = false;
+			}
+		}
+
+		return $retval;
+	}
+
+	/**
+	 * Store a data item to an external store, identified by a partial URL
+	 * The protocol part is used to identify the class, the rest is passed to the
+	 * class itself as a parameter.
+	 *
+	 * @param string $url A partial external store URL ("<store type>://<location>")
+	 * @param string $data
+	 * @param array $params Associative array of ExternalStoreMedium parameters
+	 * @return string|bool The URL of the stored data item, or false on error
+	 * @throws MWException
+	 */
+	public static function insert( $url, $data, array $params = [] ) {
+		$parts = explode( '://', $url, 2 );
+		if ( count( $parts ) != 2 ) {
+			return false; // invalid URL
+		}
+
+		list( $proto, $path ) = $parts;
+		if ( $path == '' ) { // bad URL
+			return false;
+		}
+
+		$store = self::getStoreObject( $proto, $params );
+		if ( $store === false ) {
+			return false;
+		} else {
+			return $store->store( $path, $data );
+		}
+	}
+
+	/**
+	 * Like insert() above, but does more of the work for us.
+	 * This function does not need a url param, it builds it by
+	 * itself. It also fails-over to the next possible clusters
+	 * provided by $wgDefaultExternalStore.
+	 *
+	 * @param string $data
+	 * @param array $params Map of ExternalStoreMedium::__construct context parameters
+	 * @return string|bool The URL of the stored data item, or false on error
+	 * @throws MWException
+	 */
+	public static function insertToDefault( $data, array $params = [] ) {
+		global $wgDefaultExternalStore;
+
+		return self::insertWithFallback( (array)$wgDefaultExternalStore, $data, $params );
+	}
+
+	/**
+	 * Like insert() above, but does more of the work for us.
+	 * This function does not need a url param, it builds it by
+	 * itself. It also fails-over to the next possible clusters
+	 * as provided in the first parameter.
+	 *
+	 * @param array $tryStores Refer to $wgDefaultExternalStore
+	 * @param string $data
+	 * @param array $params Map of ExternalStoreMedium::__construct context parameters
+	 * @return string|bool The URL of the stored data item, or false on error
+	 * @throws MWException
+	 */
+	public static function insertWithFallback( array $tryStores, $data, array $params = [] ) {
+		$error = false;
+		while ( count( $tryStores ) > 0 ) {
+			$index = mt_rand( 0, count( $tryStores ) - 1 );
+			$storeUrl = $tryStores[$index];
+			wfDebug( __METHOD__ . ": trying $storeUrl\n" );
+			list( $proto, $path ) = explode( '://', $storeUrl, 2 );
+			$store = self::getStoreObject( $proto, $params );
+			if ( $store === false ) {
+				throw new MWException( "Invalid external storage protocol - $storeUrl" );
+			}
+
+			try {
+				if ( $store->isReadOnly( $path ) ) {
+					$msg = 'read only';
+				} else {
+					$url = $store->store( $path, $data );
+					if ( strlen( $url ) ) {
+						return $url; // a store accepted the write; done!
+					}
+					$msg = 'operation failed';
+				}
+			} catch ( Exception $error ) {
+				$msg = 'caught exception';
+			}
+
+			unset( $tryStores[$index] ); // Don't try this one again!
+			$tryStores = array_values( $tryStores ); // Must have consecutive keys
+			wfDebugLog( 'ExternalStorage',
+				"Unable to store text to external storage $storeUrl ($msg)" );
+		}
+		// All stores failed
+		if ( $error ) {
+			throw $error; // rethrow the last error
+		} else {
+			throw new MWException( "Unable to store text to external storage" );
+		}
+	}
+
+	/**
+	 * @return bool Whether all the default insertion stores are marked as read-only
+	 * @since 1.31
+	 */
+	public static function defaultStoresAreReadOnly() {
+		global $wgDefaultExternalStore;
+
+		$tryStores = (array)$wgDefaultExternalStore;
+		if ( !$tryStores ) {
+			return false; // no stores exists which can be "read only"
+		}
+
+		foreach ( $tryStores as $storeUrl ) {
+			list( $proto, $path ) = explode( '://', $storeUrl, 2 );
+			$store = self::getStoreObject( $proto, [] );
+			if ( !$store->isReadOnly( $path ) ) {
+				return false; // at least one store is not read-only
+			}
+		}
+
+		return true; // all stores are read-only
+	}
+
+	/**
+	 * @param string $data
+	 * @param string $wiki
+	 * @return string|bool The URL of the stored data item, or false on error
+	 * @throws MWException
+	 */
+	public static function insertToForeignDefault( $data, $wiki ) {
+		return self::insertToDefault( $data, [ 'wiki' => $wiki ] );
+	}
+}
diff --git a/www/wiki/includes/externalstore/ExternalStoreDB.php b/www/wiki/includes/externalstore/ExternalStoreDB.php
new file mode 100644
index 00000000..22a2d2bc
--- /dev/null
+++ b/www/wiki/includes/externalstore/ExternalStoreDB.php
@@ -0,0 +1,335 @@
+<?php
+/**
+ * External storage in SQL database.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+use MediaWiki\MediaWikiServices;
+use Wikimedia\Rdbms\ILoadBalancer;
+use Wikimedia\Rdbms\IDatabase;
+use Wikimedia\Rdbms\DBConnRef;
+use Wikimedia\Rdbms\MaintainableDBConnRef;
+use Wikimedia\Rdbms\DatabaseDomain;
+
+/**
+ * DB accessible external objects.
+ *
+ * In this system, each store "location" maps to a database "cluster".
+ * The clusters must be defined in the normal LBFactory configuration.
+ *
+ * @ingroup ExternalStorage
+ */
+class ExternalStoreDB extends ExternalStoreMedium {
+	/**
+	 * The provided URL is in the form of DB://cluster/id
+	 * or DB://cluster/id/itemid for concatened storage.
+	 *
+	 * @param string $url
+	 * @return string|bool False if missing
+	 * @see ExternalStoreMedium::fetchFromURL()
+	 */
+	public function fetchFromURL( $url ) {
+		list( $cluster, $id, $itemID ) = $this->parseURL( $url );
+		$ret = $this->fetchBlob( $cluster, $id, $itemID );
+
+		if ( $itemID !== false && $ret !== false ) {
+			return $ret->getItem( $itemID );
+		}
+
+		return $ret;
+	}
+
+	/**
+	 * Fetch data from given external store URLs.
+	 * The provided URLs are in the form of DB://cluster/id
+	 * or DB://cluster/id/itemid for concatened storage.
+	 *
+	 * @param array $urls An array of external store URLs
+	 * @return array A map from url to stored content. Failed results
+	 *     are not represented.
+	 */
+	public function batchFetchFromURLs( array $urls ) {
+		$batched = $inverseUrlMap = [];
+		foreach ( $urls as $url ) {
+			list( $cluster, $id, $itemID ) = $this->parseURL( $url );
+			$batched[$cluster][$id][] = $itemID;
+			// false $itemID gets cast to int, but should be ok
+			// since we do === from the $itemID in $batched
+			$inverseUrlMap[$cluster][$id][$itemID] = $url;
+		}
+		$ret = [];
+		foreach ( $batched as $cluster => $batchByCluster ) {
+			$res = $this->batchFetchBlobs( $cluster, $batchByCluster );
+			/** @var HistoryBlob $blob */
+			foreach ( $res as $id => $blob ) {
+				foreach ( $batchByCluster[$id] as $itemID ) {
+					$url = $inverseUrlMap[$cluster][$id][$itemID];
+					if ( $itemID === false ) {
+						$ret[$url] = $blob;
+					} else {
+						$ret[$url] = $blob->getItem( $itemID );
+					}
+				}
+			}
+		}
+
+		return $ret;
+	}
+
+	public function store( $location, $data ) {
+		$dbw = $this->getMaster( $location );
+		$dbw->insert( $this->getTable( $dbw ),
+			[ 'blob_text' => $data ],
+			__METHOD__ );
+		$id = $dbw->insertId();
+		if ( !$id ) {
+			throw new MWException( __METHOD__ . ': no insert ID' );
+		}
+
+		return "DB://$location/$id";
+	}
+
+	public function isReadOnly( $location ) {
+		return ( $this->getLoadBalancer( $location )->getReadOnlyReason() !== false );
+	}
+
+	/**
+	 * Get a LoadBalancer for the specified cluster
+	 *
+	 * @param string $cluster Cluster name
+	 * @return ILoadBalancer
+	 */
+	private function getLoadBalancer( $cluster ) {
+		$lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
+		return $lbFactory->getExternalLB( $cluster );
+	}
+
+	/**
+	 * Get a replica DB connection for the specified cluster
+	 *
+	 * @param string $cluster Cluster name
+	 * @return DBConnRef
+	 */
+	public function getSlave( $cluster ) {
+		global $wgDefaultExternalStore;
+
+		$lb = $this->getLoadBalancer( $cluster );
+		$domainId = $this->getDomainId( $lb->getServerInfo( $lb->getWriterIndex() ) );
+
+		if ( !in_array( "DB://" . $cluster, (array)$wgDefaultExternalStore ) ) {
+			wfDebug( "read only external store\n" );
+			$lb->allowLagged( true );
+		} else {
+			wfDebug( "writable external store\n" );
+		}
+
+		$db = $lb->getConnectionRef( DB_REPLICA, [], $domainId );
+		$db->clearFlag( DBO_TRX ); // sanity
+
+		return $db;
+	}
+
+	/**
+	 * Get a master database connection for the specified cluster
+	 *
+	 * @param string $cluster Cluster name
+	 * @return MaintainableDBConnRef
+	 */
+	public function getMaster( $cluster ) {
+		$lb = $this->getLoadBalancer( $cluster );
+		$domainId = $this->getDomainId( $lb->getServerInfo( $lb->getWriterIndex() ) );
+
+		$db = $lb->getMaintenanceConnectionRef( DB_MASTER, [], $domainId );
+		$db->clearFlag( DBO_TRX ); // sanity
+
+		return $db;
+	}
+
+	/**
+	 * @param array $server Master DB server configuration array for LoadBalancer
+	 * @return string|bool Database domain ID or false
+	 */
+	private function getDomainId( array $server ) {
+		if ( isset( $this->params['wiki'] ) ) {
+			return $this->params['wiki']; // explicit domain
+		}
+
+		if ( isset( $server['dbname'] ) ) {
+			// T200471: for b/c, treat any "dbname" field as forcing which database to use.
+			// MediaWiki/LoadBalancer previously did not enforce any concept of a local DB
+			// domain, but rather assumed that the LB server configuration matched $wgDBname.
+			// This check is useful when the external storage DB for this cluster does not use
+			// the same name as the corresponding "main" DB(s) for wikis.
+			$domain = new DatabaseDomain(
+				$server['dbname'],
+				$server['schema'] ?? null,
+				$server['tablePrefix'] ?? ''
+			);
+
+			return $domain->getId();
+		}
+
+		return false; // local LB domain
+	}
+
+	/**
+	 * Get the 'blobs' table name for this database
+	 *
+	 * @param IDatabase $db
+	 * @return string Table name ('blobs' by default)
+	 */
+	public function getTable( $db ) {
+		$table = $db->getLBInfo( 'blobs table' );
+		if ( is_null( $table ) ) {
+			$table = 'blobs';
+		}
+
+		return $table;
+	}
+
+	/**
+	 * Fetch a blob item out of the database; a cache of the last-loaded
+	 * blob will be kept so that multiple loads out of a multi-item blob
+	 * can avoid redundant database access and decompression.
+	 * @param string $cluster
+	 * @param string $id
+	 * @param string $itemID
+	 * @return HistoryBlob|bool Returns false if missing
+	 */
+	private function fetchBlob( $cluster, $id, $itemID ) {
+		/**
+		 * One-step cache variable to hold base blobs; operations that
+		 * pull multiple revisions may often pull multiple times from
+		 * the same blob. By keeping the last-used one open, we avoid
+		 * redundant unserialization and decompression overhead.
+		 */
+		static $externalBlobCache = [];
+
+		$cacheID = ( $itemID === false ) ? "$cluster/$id" : "$cluster/$id/";
+		if ( isset( $externalBlobCache[$cacheID] ) ) {
+			wfDebugLog( 'ExternalStoreDB-cache',
+				"ExternalStoreDB::fetchBlob cache hit on $cacheID" );
+
+			return $externalBlobCache[$cacheID];
+		}
+
+		wfDebugLog( 'ExternalStoreDB-cache',
+			"ExternalStoreDB::fetchBlob cache miss on $cacheID" );
+
+		$dbr = $this->getSlave( $cluster );
+		$ret = $dbr->selectField( $this->getTable( $dbr ),
+			'blob_text', [ 'blob_id' => $id ], __METHOD__ );
+		if ( $ret === false ) {
+			wfDebugLog( 'ExternalStoreDB',
+				"ExternalStoreDB::fetchBlob master fallback on $cacheID" );
+			// Try the master
+			$dbw = $this->getMaster( $cluster );
+			$ret = $dbw->selectField( $this->getTable( $dbw ),
+				'blob_text', [ 'blob_id' => $id ], __METHOD__ );
+			if ( $ret === false ) {
+				wfDebugLog( 'ExternalStoreDB',
+					"ExternalStoreDB::fetchBlob master failed to find $cacheID" );
+			}
+		}
+		if ( $itemID !== false && $ret !== false ) {
+			// Unserialise object; caller extracts item
+			$ret = unserialize( $ret );
+		}
+
+		$externalBlobCache = [ $cacheID => $ret ];
+
+		return $ret;
+	}
+
+	/**
+	 * Fetch multiple blob items out of the database
+	 *
+	 * @param string $cluster A cluster name valid for use with LBFactory
+	 * @param array $ids A map from the blob_id's to look for to the requested itemIDs in the blobs
+	 * @return array A map from the blob_id's requested to their content.
+	 *   Unlocated ids are not represented
+	 */
+	private function batchFetchBlobs( $cluster, array $ids ) {
+		$dbr = $this->getSlave( $cluster );
+		$res = $dbr->select( $this->getTable( $dbr ),
+			[ 'blob_id', 'blob_text' ], [ 'blob_id' => array_keys( $ids ) ], __METHOD__ );
+		$ret = [];
+		if ( $res !== false ) {
+			$this->mergeBatchResult( $ret, $ids, $res );
+		}
+		if ( $ids ) {
+			wfDebugLog( __CLASS__, __METHOD__ .
+				" master fallback on '$cluster' for: " .
+				implode( ',', array_keys( $ids ) ) );
+			// Try the master
+			$dbw = $this->getMaster( $cluster );
+			$res = $dbw->select( $this->getTable( $dbr ),
+				[ 'blob_id', 'blob_text' ],
+				[ 'blob_id' => array_keys( $ids ) ],
+				__METHOD__ );
+			if ( $res === false ) {
+				wfDebugLog( __CLASS__, __METHOD__ . " master failed on '$cluster'" );
+			} else {
+				$this->mergeBatchResult( $ret, $ids, $res );
+			}
+		}
+		if ( $ids ) {
+			wfDebugLog( __CLASS__, __METHOD__ .
+				" master on '$cluster' failed locating items: " .
+				implode( ',', array_keys( $ids ) ) );
+		}
+
+		return $ret;
+	}
+
+	/**
+	 * Helper function for self::batchFetchBlobs for merging master/replica DB results
+	 * @param array &$ret Current self::batchFetchBlobs return value
+	 * @param array &$ids Map from blob_id to requested itemIDs
+	 * @param mixed $res DB result from Database::select
+	 */
+	private function mergeBatchResult( array &$ret, array &$ids, $res ) {
+		foreach ( $res as $row ) {
+			$id = $row->blob_id;
+			$itemIDs = $ids[$id];
+			unset( $ids[$id] ); // to track if everything is found
+			if ( count( $itemIDs ) === 1 && reset( $itemIDs ) === false ) {
+				// single result stored per blob
+				$ret[$id] = $row->blob_text;
+			} else {
+				// multi result stored per blob
+				$ret[$id] = unserialize( $row->blob_text );
+			}
+		}
+	}
+
+	/**
+	 * @param string $url
+	 * @return array
+	 */
+	protected function parseURL( $url ) {
+		$path = explode( '/', $url );
+
+		return [
+			$path[2], // cluster
+			$path[3], // id
+			isset( $path[4] ) ? $path[4] : false // itemID
+		];
+	}
+}
diff --git a/www/wiki/includes/externalstore/ExternalStoreFactory.php b/www/wiki/includes/externalstore/ExternalStoreFactory.php
new file mode 100644
index 00000000..940fb2e2
--- /dev/null
+++ b/www/wiki/includes/externalstore/ExternalStoreFactory.php
@@ -0,0 +1,42 @@
+<?php
+/**
+ * @defgroup ExternalStorage ExternalStorage
+ */
+
+/**
+ * @ingroup ExternalStorage
+ */
+class ExternalStoreFactory {
+
+	/**
+	 * @var array
+	 */
+	private $externalStores;
+
+	/**
+	 * @param array $externalStores See $wgExternalStores
+	 */
+	public function __construct( array $externalStores ) {
+		$this->externalStores = array_map( 'strtolower', $externalStores );
+	}
+
+	/**
+	 * Get an external store object of the given type, with the given parameters
+	 *
+	 * @param string $proto Type of external storage, should be a value in $wgExternalStores
+	 * @param array $params Associative array of ExternalStoreMedium parameters
+	 * @return ExternalStoreMedium|bool The store class or false on error
+	 */
+	public function getStoreObject( $proto, array $params = [] ) {
+		if ( !$this->externalStores || !in_array( strtolower( $proto ), $this->externalStores ) ) {
+			// Protocol not enabled
+			return false;
+		}
+
+		$class = 'ExternalStore' . ucfirst( $proto );
+
+		// Any custom modules should be added to $wgAutoLoadClasses for on-demand loading
+		return class_exists( $class ) ? new $class( $params ) : false;
+	}
+
+}
diff --git a/www/wiki/includes/externalstore/ExternalStoreHttp.php b/www/wiki/includes/externalstore/ExternalStoreHttp.php
new file mode 100644
index 00000000..879686f7
--- /dev/null
+++ b/www/wiki/includes/externalstore/ExternalStoreHttp.php
@@ -0,0 +1,41 @@
+<?php
+/**
+ * External storage using HTTP requests.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Example class for HTTP accessible external objects.
+ * Only supports reading, not storing.
+ *
+ * @ingroup ExternalStorage
+ */
+class ExternalStoreHttp extends ExternalStoreMedium {
+	public function fetchFromURL( $url ) {
+		return Http::get( $url, [], __METHOD__ );
+	}
+
+	public function store( $location, $data ) {
+		throw new MWException( "ExternalStoreHttp is read-only and does not support store()." );
+	}
+
+	public function isReadOnly( $location ) {
+		return true;
+	}
+}
diff --git a/www/wiki/includes/externalstore/ExternalStoreMedium.php b/www/wiki/includes/externalstore/ExternalStoreMedium.php
new file mode 100644
index 00000000..da7752b7
--- /dev/null
+++ b/www/wiki/includes/externalstore/ExternalStoreMedium.php
@@ -0,0 +1,91 @@
+<?php
+/**
+ * External storage in some particular medium.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup ExternalStorage
+ */
+
+/**
+ * Accessable external objects in a particular storage medium
+ *
+ * @ingroup ExternalStorage
+ * @since 1.21
+ */
+abstract class ExternalStoreMedium {
+	/** @var array */
+	protected $params = [];
+
+	/**
+	 * @param array $params Usage context options:
+	 *   - wiki: the domain ID of the wiki this is being used for [optional]
+	 */
+	public function __construct( array $params = [] ) {
+		$this->params = $params;
+	}
+
+	/**
+	 * Fetch data from given external store URL
+	 *
+	 * @param string $url An external store URL
+	 * @return string|bool The text stored or false on error
+	 * @throws MWException
+	 */
+	abstract public function fetchFromURL( $url );
+
+	/**
+	 * Fetch data from given external store URLs.
+	 *
+	 * @param array $urls A list of external store URLs
+	 * @return array Map from the url to the text stored. Unfound data is not represented
+	 */
+	public function batchFetchFromURLs( array $urls ) {
+		$retval = [];
+		foreach ( $urls as $url ) {
+			$data = $this->fetchFromURL( $url );
+			// Dont return when false to allow for simpler implementations.
+			// errored urls are handled in ExternalStore::batchFetchFromURLs
+			if ( $data !== false ) {
+				$retval[$url] = $data;
+			}
+		}
+
+		return $retval;
+	}
+
+	/**
+	 * Insert a data item into a given location
+	 *
+	 * @param string $location The location name
+	 * @param string $data The data item
+	 * @return string|bool The URL of the stored data item, or false on error
+	 * @throws MWException
+	 */
+	abstract public function store( $location, $data );
+
+	/**
+	 * Check if a given location is read-only
+	 *
+	 * @param string $location The location name
+	 * @return bool Whether this location is read-only
+	 * @since 1.31
+	 */
+	public function isReadOnly( $location ) {
+		return false;
+	}
+}
diff --git a/www/wiki/includes/externalstore/ExternalStoreMwstore.php b/www/wiki/includes/externalstore/ExternalStoreMwstore.php
new file mode 100644
index 00000000..5d7155e8
--- /dev/null
+++ b/www/wiki/includes/externalstore/ExternalStoreMwstore.php
@@ -0,0 +1,105 @@
+<?php
+/**
+ * External storage in a file backend.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * File backend accessible external objects.
+ *
+ * In this system, each store "location" maps to the name of a file backend.
+ * The file backends must be defined in $wgFileBackends and must be global
+ * and fully qualified with a global "wikiId" prefix in the configuration.
+ *
+ * @ingroup ExternalStorage
+ * @since 1.21
+ */
+class ExternalStoreMwstore extends ExternalStoreMedium {
+	/**
+	 * The URL returned is of the form of the form mwstore://backend/container/wiki/id
+	 *
+	 * @see ExternalStoreMedium::fetchFromURL()
+	 * @param string $url
+	 * @return bool
+	 */
+	public function fetchFromURL( $url ) {
+		$be = FileBackendGroup::singleton()->backendFromPath( $url );
+		if ( $be instanceof FileBackend ) {
+			// We don't need "latest" since objects are immutable and
+			// backends should at least have "read-after-create" consistency.
+			return $be->getFileContents( [ 'src' => $url ] );
+		}
+
+		return false;
+	}
+
+	/**
+	 * Fetch data from given external store URLs.
+	 * The URL returned is of the form of the form mwstore://backend/container/wiki/id
+	 *
+	 * @param array $urls An array of external store URLs
+	 * @return array A map from url to stored content. Failed results are not represented.
+	 */
+	public function batchFetchFromURLs( array $urls ) {
+		$pathsByBackend = [];
+		foreach ( $urls as $url ) {
+			$be = FileBackendGroup::singleton()->backendFromPath( $url );
+			if ( $be instanceof FileBackend ) {
+				$pathsByBackend[$be->getName()][] = $url;
+			}
+		}
+		$blobs = [];
+		foreach ( $pathsByBackend as $backendName => $paths ) {
+			$be = FileBackendGroup::singleton()->get( $backendName );
+			$blobs = $blobs + $be->getFileContentsMulti( [ 'srcs' => $paths ] );
+		}
+
+		return $blobs;
+	}
+
+	public function store( $backend, $data ) {
+		$be = FileBackendGroup::singleton()->get( $backend );
+		if ( $be instanceof FileBackend ) {
+			// Get three random base 36 characters to act as shard directories
+			$rand = Wikimedia\base_convert( mt_rand( 0, 46655 ), 10, 36, 3 );
+			// Make sure ID is roughly lexicographically increasing for performance
+			$id = str_pad( UIDGenerator::newTimestampedUID128( 32 ), 26, '0', STR_PAD_LEFT );
+			// Segregate items by wiki ID for the sake of bookkeeping
+			$wiki = isset( $this->params['wiki'] ) ? $this->params['wiki'] : wfWikiID();
+
+			$url = $be->getContainerStoragePath( 'data' ) . '/' . rawurlencode( $wiki );
+			$url .= ( $be instanceof FSFileBackend )
+				? "/{$rand[0]}/{$rand[1]}/{$rand[2]}/{$id}" // keep directories small
+				: "/{$rand[0]}/{$rand[1]}/{$id}"; // container sharding is only 2-levels
+
+			$be->prepare( [ 'dir' => dirname( $url ), 'noAccess' => 1, 'noListing' => 1 ] );
+			if ( $be->create( [ 'dst' => $url, 'content' => $data ] )->isOK() ) {
+				return $url;
+			}
+		}
+
+		return false;
+	}
+
+	public function isReadOnly( $backend ) {
+		$be = FileBackendGroup::singleton()->get( $backend );
+
+		return $be ? $be->isReadOnly() : false;
+	}
+}