diff --git a/README.md b/README.md
index 604c204..8317553 100644
--- a/README.md
+++ b/README.md
@@ -4,8 +4,7 @@ The __CLDR__ package provides means to internationalize your application by leve
 data and conventions defined by the [Unicode Common Locale Data Repository](http://cldr.unicode.org/) (CLDR).
 
 The package targets the [CLDR version 26](http://cldr.unicode.org/index/downloads/cldr-26), from
-which data is retrieved when required. A stack of cache can be used to store and retrieve these
-data.
+which data is retrieved when required.
 
 
 
@@ -13,25 +12,28 @@ data.
 
 ## Instantiating the repository
 
-The CLDR is represented by a [Repository][] instance, from which you can access
-the available locales or supplemental data. When necessary, the repository fetches the required
-data through a provider. You can use the default provider, or define your own.
+The CLDR is represented by a [Repository][] instance, from which data is accessed. When required,
+data is retrieved through a provider, and in order to avoid hitting the web with every request,
+a stack of them is used.
 
-The following example demonstrates how such a repository is instantiated and how the
-available locales and supplemental data are accessed:
+The following example demonstrates how a repository can be instantiated with a nice stack of
+providers. One fetches the data from the web, the other from the filesystem, and the last one
+from the runtime memory:
 
 ```php
 <?php
 
 namespace ICanBoogie\CLDR;
 
-$provider = new Provider
-(
-	new RunTimeCache(new FileCache('/path/to/cached_repository')),
-	new Retriever
-);
-
+$provider = new RunTimeProvider(new FileProvider(new WebProvider, "/path/to/storage"));
 $repository = new Repository($provider);
+```
+
+The following example demonstrates how the repository can be used to access locales and
+supplemental data:
+
+```php
+<?php
 
 $english_locale = $repository->locales['en'];
 $french_locale = $repository->locales['fr'];
diff --git a/lib/FileCache.php b/lib/FileCache.php
deleted file mode 100644
index 90d9794..0000000
--- a/lib/FileCache.php
+++ /dev/null
@@ -1,67 +0,0 @@
-<?php
-
-/*
- * This file is part of the ICanBoogie package.
- *
- * (c) Olivier Laviale <olivier.laviale@gmail.com>
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace ICanBoogie\CLDR;
-
-/**
- * A cache that persists using files.
- *
- * <pre>
- * <?php
- *
- * use ICanBoogie\CLDR\FileCache;
- *
- * $cache = new FileCache('/path/to/cached_repository');
- * </pre>
- */
-class FileCache implements CacheInterface
-{
-	protected $root;
-
-	static private function path_to_key($path)
-	{
-		return str_replace('/', '--', $path);
-	}
-
-	public function __construct($root)
-	{
-		$this->root = rtrim($root, DIRECTORY_SEPARATOR) . DIRECTORY_SEPARATOR;
-	}
-
-	public function exists($path)
-	{
-		$key = self::path_to_key($path);
-		$filename = $this->root . $key;
-
-		return file_exists($filename);
-	}
-
-	public function retrieve($path)
-	{
-		$key = self::path_to_key($path);
-		$filename = $this->root . $key;
-
-		if (!file_exists($filename))
-		{
-			return;
-		}
-
-		return file_get_contents($filename);
-	}
-
-	public function store($path, $data)
-	{
-		$key = self::path_to_key($path);
-		$filename = $this->root . $key;
-
-		file_put_contents($filename, $data);
-	}
-}
diff --git a/lib/FileProvider.php b/lib/FileProvider.php
new file mode 100644
index 0000000..785c382
--- /dev/null
+++ b/lib/FileProvider.php
@@ -0,0 +1,104 @@
+<?php
+
+/*
+ * This file is part of the ICanBoogie package.
+ *
+ * (c) Olivier Laviale <olivier.laviale@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace ICanBoogie\CLDR;
+
+/**
+ * Provides CLDR data from the filesystem, and falls back to a specified provider when the data
+ * is not available.
+ */
+class FileProvider implements ProviderInterface, CacheInterface
+{
+	/**
+	 * Create a store key from a CLDR path.
+	 *
+	 * @param string $path A CLDR path.
+	 *
+	 * @return string A store key.
+	 */
+	static private function path_to_key($path)
+	{
+		return str_replace('/', '--', $path);
+	}
+
+	/**
+	 * The directory where files are stored.
+	 *
+	 * @var string
+	 */
+	protected $root;
+
+	/**
+	 * @var ProviderInterface
+	 */
+	protected $provider;
+
+	/**
+	 * @param ProviderInterface $provider Fallback provider.
+	 * @param string $directory Path to the directory where cached files are stored.
+	 */
+	public function __construct(ProviderInterface $provider, $directory)
+	{
+		$this->root = rtrim($directory, DIRECTORY_SEPARATOR) . DIRECTORY_SEPARATOR;
+		$this->provider = $provider;
+	}
+
+	public function exists($path)
+	{
+		$key = self::path_to_key($path);
+		$filename = $this->root . $key;
+
+		return file_exists($filename);
+	}
+
+	public function retrieve($path)
+	{
+		$key = self::path_to_key($path);
+		$filename = $this->root . $key;
+
+		if (!file_exists($filename))
+		{
+			return;
+		}
+
+		return json_decode(file_get_contents($filename), true);
+	}
+
+	public function store($path, $data)
+	{
+		$key = self::path_to_key($path);
+		$filename = $this->root . $key;
+
+		file_put_contents($filename, json_encode($data));
+	}
+
+	/**
+	 * The section path, following the pattern "<identity>/<section>".
+	 *
+	 * @param string $path
+	 *
+	 * @throws ResourceNotFound when the specified path does not exists on the CLDR source.
+	 *
+	 * @return string
+	 */
+	public function provide($path)
+	{
+		if ($this->exists($path))
+		{
+			return $this->retrieve($path);
+		}
+
+		$data = $this->provider->provide($path);
+		$this->store($path, $data);
+
+		return $data;
+	}
+}
diff --git a/lib/Locale.php b/lib/Locale.php
index 15fdb1f..26517ff 100644
--- a/lib/Locale.php
+++ b/lib/Locale.php
@@ -189,7 +189,7 @@ public function offsetGet($offset)
 				throw new OffsetNotDefined(array($offset, $this));
 			}
 
-			$data = $this->repository->provider->fetch("main/{$this->code}/{$offset}");
+			$data = $this->repository->fetch("main/{$this->code}/{$offset}");
 			$path = "main/{$this->code}/" . self::$available_sections[$offset];
 			$path_parts = explode('/', $path);
 
diff --git a/lib/Provider.php b/lib/Provider.php
deleted file mode 100644
index 861b1ce..0000000
--- a/lib/Provider.php
+++ /dev/null
@@ -1,59 +0,0 @@
-<?php
-
-/*
- * This file is part of the ICanBoogie package.
- *
- * (c) Olivier Laviale <olivier.laviale@gmail.com>
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace ICanBoogie\CLDR;
-
-/**
- * CLDR data provide.
- *
- * @package ICanBoogie\CLDR
- */
-class Provider
-{
-	protected $cache;
-	protected $retriever;
-
-	public function __construct(CacheInterface $cache, $retriever)
-	{
-		$this->cache = $cache;
-		$this->retriever = $retriever;
-	}
-
-	/**
-	 * Fetches the data available at the specified path.
-	 *
-	 * @param string $path
-	 *
-	 * @return array
-	 */
-	public function fetch($path)
-	{
-		$json = $this->cache->retrieve($path);
-
-		if (!$json)
-		{
-			$retriever = $this->retriever;
-			$json = $retriever($path);
-
-			if ($json)
-			{
-				$this->cache->store($path, $json);
-			}
-		}
-
-		return json_decode($json, true);
-	}
-
-	public function __invoke($path)
-	{
-		return $this->fetch($path);
-	}
-}
diff --git a/lib/ProviderInterface.php b/lib/ProviderInterface.php
new file mode 100644
index 0000000..896a4db
--- /dev/null
+++ b/lib/ProviderInterface.php
@@ -0,0 +1,31 @@
+<?php
+
+/*
+ * This file is part of the ICanBoogie package.
+ *
+ * (c) Olivier Laviale <olivier.laviale@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace ICanBoogie\CLDR;
+
+/**
+ * An interface for classes that can provide CLDR data.
+ *
+ * @package ICanBoogie\CLDR
+ */
+interface ProviderInterface
+{
+	/**
+	 * The section path, following the pattern "<identity>/<section>".
+	 *
+	 * @param string $path
+	 *
+	 * @throws ResourceNotFound when the specified path does not exists on the CLDR source.
+	 *
+	 * @return string
+	 */
+	public function provide($path);
+}
diff --git a/lib/Repository.php b/lib/Repository.php
index ef98c38..e2aff36 100644
--- a/lib/Repository.php
+++ b/lib/Repository.php
@@ -27,7 +27,7 @@
  * var_dump($repository->territories['FR']);
  * </pre>
  *
- * @property-read Provider $provider A CLDR provider.
+ * @property-read ProviderInterface $provider A CLDR provider.
  * @property-read LocaleCollection $locales Locale collection.
  * @property-read Supplemental $supplemental Representation of the "supplemental" section.
  * @property-read TerritoryCollection $territories Territory collection.
@@ -107,9 +107,9 @@ protected function get_currencies()
 	/**
 	 * Initializes the {@link $provider} property.
 	 *
-	 * @param Provider $provider
+	 * @param ProviderInterface $provider
 	 */
-	public function __construct(Provider $provider)
+	public function __construct(ProviderInterface $provider)
 	{
 		$this->provider = $provider;
 	}
@@ -129,7 +129,7 @@ public function __get($property)
 	/**
 	 * Fetches the data available at the specified path.
 	 *
-	 * Note: The method is forwarded to {@link Provider::fetch}.
+	 * Note: The method is forwarded to {@link Provider::provide}.
 	 *
 	 * @param string $path
 	 *
@@ -137,6 +137,6 @@ public function __get($property)
 	 */
 	public function fetch($path)
 	{
-		return $this->provider->fetch($path);
+		return $this->provider->provide($path);
 	}
 }
diff --git a/lib/RunTimeCache.php b/lib/RunTimeCache.php
deleted file mode 100644
index 033fb30..0000000
--- a/lib/RunTimeCache.php
+++ /dev/null
@@ -1,59 +0,0 @@
-<?php
-
-/*
- * This file is part of the ICanBoogie package.
- *
- * (c) Olivier Laviale <olivier.laviale@gmail.com>
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace ICanBoogie\CLDR;
-
-/**
- * A cache that only persists during the run time.
- *
- * This cache is meant to be used as a wrapper to more persistent cache:
- *
- * <pre>
- * <?php
- *
- * use ICanBoogie\CLDR\FileCache;
- * use ICanBoogie\CLDR\RunTimeCache;
- *
- * $cache = new RunTimeCache(new FileCache('/path/to/cached_repository'));
- * </pre>
- */
-class RunTimeCache implements CacheInterface
-{
-	private $cache = array();
-	private $static_cache;
-
-	public function __construct(CacheInterface $static_cache)
-	{
-		$this->static_cache = $static_cache;
-	}
-
-	public function exists($path)
-	{
-		return array_key_exists($path, $this->cache);
-	}
-
-	public function retrieve($path)
-	{
-		if (array_key_exists($path, $this->cache))
-		{
-			return $this->cache[$path];
-		}
-
-		return $this->cache[$path] = $this->static_cache->retrieve($path);
-	}
-
-	public function store($path, $data)
-	{
-		$this->cache[$path] = $data;
-
-		$this->static_cache->store($path, $data);
-	}
-}
diff --git a/lib/RunTimeProvider.php b/lib/RunTimeProvider.php
new file mode 100644
index 0000000..796d290
--- /dev/null
+++ b/lib/RunTimeProvider.php
@@ -0,0 +1,72 @@
+<?php
+
+/*
+ * This file is part of the ICanBoogie package.
+ *
+ * (c) Olivier Laviale <olivier.laviale@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace ICanBoogie\CLDR;
+
+/**
+ * Provides CLDR data from an array, and falls back to a specified provider when the data
+ * is not available.
+ */
+class RunTimeProvider implements ProviderInterface, CacheInterface
+{
+	private $store = array();
+	private $provider;
+
+	/**
+	 * @param ProviderInterface $provider Fallback provider.
+	 */
+	public function __construct(ProviderInterface $provider)
+	{
+		$this->provider = $provider;
+	}
+
+	public function exists($path)
+	{
+		return array_key_exists($path, $this->store);
+	}
+
+	public function retrieve($path)
+	{
+		if (!$this->exists($path))
+		{
+			return;
+		}
+
+		return $this->store[ $path ];
+	}
+
+	public function store($path, $data)
+	{
+		$this->store[$path] = $data;
+	}
+
+	/**
+	 * The section path, following the pattern "<identity>/<section>".
+	 *
+	 * @param string $path
+	 *
+	 * @throws ResourceNotFound when the specified path does not exists on the CLDR source.
+	 *
+	 * @return string
+	 */
+	public function provide($path)
+	{
+		if ($this->exists($path))
+		{
+			return $this->retrieve($path);
+		}
+
+		$data = $this->provider->provide($path);
+		$this->store($path, $data);
+
+		return $data;
+	}
+}
diff --git a/lib/Supplemental.php b/lib/Supplemental.php
index 90268e4..3cb069f 100644
--- a/lib/Supplemental.php
+++ b/lib/Supplemental.php
@@ -96,7 +96,7 @@ public function offsetGet($offset)
 				throw new OffsetNotDefined(array($offset, $this));
 			}
 
-			$data = $this->repository->provider->fetch("supplemental/{$offset}");
+			$data = $this->repository->fetch("supplemental/{$offset}");
 			$path = 'supplemental/' . self::$available_sections[$offset];
 			$path_parts = explode('/', $path);
 
diff --git a/lib/Retriever.php b/lib/WebProvider.php
similarity index 75%
rename from lib/Retriever.php
rename to lib/WebProvider.php
index 5dcab99..cb6b809 100644
--- a/lib/Retriever.php
+++ b/lib/WebProvider.php
@@ -14,21 +14,18 @@
 /**
  * Retrieves sections from the CLDR source.
  */
-class Retriever
+class WebProvider implements ProviderInterface
 {
-	protected $origin = 'http://www.unicode.org/repos/cldr-aux/json/26/';
+	protected $origin;
 
 	/**
-	 * Initializes the {@link $origin} property if the `$origin` param is specified.
+	 * Initializes the {@link $origin} property.
 	 *
 	 * @param string $origin
 	 */
-	public function __construct($origin=null)
+	public function __construct($origin="http://www.unicode.org/repos/cldr-aux/json/26/")
 	{
-		if ($origin)
-		{
-			$this->origin = $origin;
-		}
+		$this->origin = $origin;
 	}
 
 	/**
@@ -40,7 +37,7 @@ public function __construct($origin=null)
 	 *
 	 * @return string
 	 */
-	public function __invoke($path)
+	public function provide($path)
 	{
 		$ch = curl_init($this->origin . $path . '.json');
 
@@ -64,6 +61,6 @@ public function __invoke($path)
 			throw new ResourceNotFound($path);
 		}
 
-		return $rc;
+		return json_decode($rc, true);
 	}
 }
diff --git a/tests/FileProviderTest.php b/tests/FileProviderTest.php
new file mode 100644
index 0000000..61c2ab5
--- /dev/null
+++ b/tests/FileProviderTest.php
@@ -0,0 +1,52 @@
+<?php
+
+/*
+ * This file is part of the ICanBoogie package.
+ *
+ * (c) Olivier Laviale <olivier.laviale@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace ICanBoogie\CLDR;
+
+class FileProviderTest extends \PHPUnit_Framework_TestCase
+{
+	static private $directory;
+
+	static public function setupBeforeClass()
+	{
+		self::$directory = __DIR__ . DIRECTORY_SEPARATOR . 'repository' . DIRECTORY_SEPARATOR;
+	}
+
+	public function test_provider()
+	{
+		$path = 'some/path';
+		$root = self::$directory;
+
+		if (file_exists($root . 'some--path'))
+		{
+			unlink($root . 'some--path');
+		}
+
+		$expected = array('from http' => true );
+
+		$stub = $this->getMockBuilder('ICanBoogie\CLDR\WebProvider')
+			->getMock();
+
+		$stub
+			->expects($this->once())
+			->method('provide')
+			->willReturn($expected);
+
+		$provider = new FileProvider($stub, $root);
+
+		for ($i = 0 ; $i < 5 ; $i++)
+		{
+			$data = $provider->provide($path);
+			$this->assertSame($expected, $data);
+			$this->assertTrue($provider->exists($path));
+		}
+	}
+}
diff --git a/tests/ProviderTest.php b/tests/ProviderTest.php
deleted file mode 100644
index 49c8e56..0000000
--- a/tests/ProviderTest.php
+++ /dev/null
@@ -1,37 +0,0 @@
-<?php
-
-/*
- * This file is part of the ICanBoogie package.
- *
- * (c) Olivier Laviale <olivier.laviale@gmail.com>
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace ICanBoogie\CLDR;
-
-class ProviderTest extends \PHPUnit_Framework_TestCase
-{
-	static private $provider;
-
-	static public function setupBeforeClass()
-	{
-		self::$provider = new Provider(new RunTimeCache(new FileCache(__DIR__ . '/repository')), new Retriever);
-	}
-
-	public function test_sections()
-	{
-		$data = self::$provider->fetch('main/fr/ca-gregorian');
-
-		$this->assertInternalType('array', $data);
-		$this->assertArrayHasKey('main', $data);
-	}
-
-	public function test_supplement()
-	{
-		$data = self::$provider->fetch('supplemental/calendarPreferenceData');
-		$this->assertInternalType('array', $data);
-		$this->assertArrayHasKey('supplemental', $data);
-	}
-}
diff --git a/tests/RepositoryTest.php b/tests/RepositoryTest.php
index 21de0a9..88d370f 100644
--- a/tests/RepositoryTest.php
+++ b/tests/RepositoryTest.php
@@ -34,7 +34,7 @@ public function provide_test_properties_type()
 
 			array( 'currencies',   'ICanBoogie\CLDR\CurrencyCollection' ),
 			array( 'locales',      'ICanBoogie\CLDR\LocaleCollection' ),
-			array( 'provider',     'ICanBoogie\CLDR\Provider' ),
+			array( 'provider',     'ICanBoogie\CLDR\ProviderInterface' ),
 			array( 'supplemental', 'ICanBoogie\CLDR\Supplemental' ),
 			array( 'territories',  'ICanBoogie\CLDR\TerritoryCollection' ),
 
diff --git a/tests/RunTimeProviderTest.php b/tests/RunTimeProviderTest.php
new file mode 100644
index 0000000..560fdde
--- /dev/null
+++ b/tests/RunTimeProviderTest.php
@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * This file is part of the ICanBoogie package.
+ *
+ * (c) Olivier Laviale <olivier.laviale@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace ICanBoogie\CLDR;
+
+class RunTimeProviderTest extends \PHPUnit_Framework_TestCase
+{
+	public function test_provider()
+	{
+		$path = 'some/path';
+		$expected = array('from http' => true );
+
+		$stub = $this->getMockBuilder('ICanBoogie\CLDR\WebProvider')
+			->getMock();
+
+		$stub
+			->expects($this->once())
+			->method('provide')
+			->willReturn($expected);
+
+		$provider = new RunTimeProvider($stub);
+
+		for ($i = 0 ; $i < 5 ; $i++)
+		{
+			$data = $provider->provide($path);
+			$this->assertSame($expected, $data);
+			$this->assertTrue($provider->exists($path));
+		}
+	}
+}
diff --git a/tests/RetrieverTest.php b/tests/WebProviderTest.php
similarity index 59%
rename from tests/RetrieverTest.php
rename to tests/WebProviderTest.php
index 3d3f0f5..d5ae738 100644
--- a/tests/RetrieverTest.php
+++ b/tests/WebProviderTest.php
@@ -11,16 +11,14 @@
 
 namespace ICanBoogie\CLDR;
 
-class RetrieverTest extends \PHPUnit_Framework_TestCase
+class WebProviderTest extends \PHPUnit_Framework_TestCase
 {
-	public function test_retrieve_ok()
+	public function test_provide_ok()
 	{
-		$r = new Retriever;
+		$provider = new WebProvider;
 
-		$json = $r('main/fr/characters');
-		$this->assertStringStartsWith('{', $json);
-
-		$data = json_decode($json, true);
+		$data = $provider->provide('main/fr/characters');
+		$this->assertInternalType('array', $data);
 		$this->assertArrayHasKey('main', $data);
 	}
 
@@ -29,7 +27,8 @@ public function test_retrieve_ok()
 	 */
 	public function test_retrieve_failure()
 	{
-		$r = new Retriever;
-		$r('undefined_locale/characters');
+		$provider = new WebProvider;
+
+		$provider->provide('undefined_locale/characters');
 	}
 }
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 82ebd52..b4061b8 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -27,8 +27,7 @@ function get_repository()
 
 	if (!$repository)
 	{
-		$provider = new Provider(new RunTimeCache(new FileCache(__DIR__ . '/repository')), new Retriever);
-		$repository = new Repository($provider);
+		$repository = new Repository(new RunTimeProvider(new FileProvider(new WebProvider, __DIR__ . '/repository')));
 	}
 
 	return $repository;