# Exporting and Exposing your Repository

When you build a digital repository with Tainacan, you gain the ability to show it to the world in many different ways thanks to the power and flexibility of WordPress.

But sometimes you don’t want just to have your collections browsable via web, you want to download a spreadsheet to work with or you want to make it available via APIs so it can be consumed by other applications or harvested by an aggregator. This page describe how Tainacan handle with these situations.

## Mapping

With Tainacan you have the possibility to map your collection structure to one or more known standards you may want to be compatible with. So even if you use a custom set of metadata to describe your collection, you may be compatible and interoperate with other repositories.

You do it by informing, for each metadatum you create, what is it relative in each format you want to map your collection to. You may say for example, that you "Name" Metadatum is the equivalent to the dc:Title attribute in Dublin Core and some another attribute in other format you choose.

Tainacan is shipped with some Mapping standards that implement popular metadata standards. And it will be easy to create new standards.  See more [details about mapping standards](mapping-standards.md). 

You can also use these mapping standards as a preset when you create a new Collection.

## Exporting

Exporting allows you to download the content of your repository to a file - or to multiple files. The format of the package you will download depends on the exporter you will use. Tainacan ships with a simple CSV exporter and a Tainacan-Package exporter, that allows you to export all the content of your collections, including the attachments, to import in another Tainacan instance.

Whatever exporter you choose to you use, you will be able to choose wether you want to download the collection as it is, which means, with the metadata the way the were created in Tainacan, or if you want to download it in a mapped version. For example, if you mapped your collection to Dublin Core, you can download a CSV file either in Dublin Core format or in the original format.

Tainacan makes it very easy to developers to create new exporters and publish them as plugins anyone can use.

## Exposing

Tainacan is powered with an API that allows other applications to search and consume the content of your repository. By default, this API serves the content in JSON format, preserving the metadata in the collections the way you created them.

In the same way you can choose the format of the file when you export your collection, one can choose the format he/she want to consume yout content in. This is what exposers are for.

Each exposer implements a different way of presenting your data in the API response, and may support one or many mappings. See more [details about exposers](exposers.md).

For example, the default JSON exposer supports any mapping and can serve your content exposing any metadata standard you mapped your content to. The decision is in the hands of the application that makes the request to your API.

On the other hand, OAI-PMH exposer only supports Dublin Core mapping and will always serve content this way.

Exposers are also really easy to develop and can be added to your Tainacan instance via plugins.

## Exposing API

Using exposing API is easy, need only to set some parameters to API call, for example to expose an Item with id 123 using XML format on site URI http://example.com, so we need to call API with this URI: http://example.com/wp-json/tainacan/v2/items/123 with this URI the Tainacan will return the Item 123 data, but with we send this parameter at body, exposer=xml, It will return a WordPress JSON with XML formatted in data propriety.
Example using WordPress rest server:

	$item_exposer_json = json_encode([
				'exposer'  => 'Xml',
				'mapper'  => 'Dublin Core',
			]);
			$request = new \WP_REST_Request('GET', '/wp-json/tainacan/v2/items/123' );
			$request->set_body($item_exposer_json);
			$response = $this->server->dispatch($request);


Or with we want only the XML data, without JSON respond  for example, we need only to put the expose parameter at URI, like:
http://example.com/wp-json/tainacan/v2/items/123?exposer=xml
Tainacan have support to metadata mapping, the parameter for using the mapper is  mapper=[mapper], so for our last example, if we want a CSV, using dublin-core mapper exposing the content at CSV format, not JSON:
http://example.com/wp-json/tainacan/v2/items/123?exposer=xml&mapper=dublin-core