> For the complete documentation index, see [llms.txt](https://docs.filecoin.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.filecoin.io/getting-started/how-retrieval-works/serving-retrievals.md).

# Serving retrievals

### The indexer

When a storage deal is originally made, the client can opt to make the data publicly discoverable. If this is the case, the storage provider must publish an advertisement of the storage deal to the Interplanetary Network Indexer (IPNI). IPNI maps a CID to a storage provider (SP). This mapping allows clients to query the IPNI to discover where content is on Filecoin.

The IPNI also tracks which data transfer protocols you can use to retrieve specific CIDs. Currently, Filecoin SPs have the ability to serve retrievals over Graphsync, Bitswap, and HTTP. This is dependent on the SP setup.

### Retrieval process

If a client wants to retrieve publicly available data from the Filecoin network, then they generally follow this process.

#### Query the IPNI

Before the client can submit a retrieval deal to a storage provider, they first need to find which providers hold the data. To do this, the client sends a query to the Interplanetary Network Indexer.

#### Select a provider

Assuming the IPNI returns more than one storage provider, the client can select which provider they’d like to deal with. Here, they will also get additional details (if needed) based on the retrieval protocol they want to retrieve the content over.

#### Initiate retrieval

The client then attempts to retrieve the data from the SP over Bitswap, Graphsync, or HTTP. Note that currently, clients can only get full-piece retrievals using HTTP.

#### Finalize the retrieval

Once the client has received the last chunk of data, the connection is closed.

### Implementation paths

Different retrieval workflows use different tools:

| Workflow                                                | Maintained path                                                                                                                                                                                                                            |
| ------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Serving PDP retrievals as a storage provider            | Use [Curio](https://curiostorage.org/) for PDP retrievals.                                                                                                                                                                                 |
| Serving PoRep retrievals as a storage provider          | Use [Boost](https://boost.filecoin.io/) to serve retrievals. Boost supports Graphsync retrievals by default, and storage providers can run [`booster-http`](https://boost.filecoin.io/http-retrieval) for HTTP retrievals when configured. |
| Retrieving data as a client                             | Use [Lassie](https://github.com/filecoin-project/lassie) to fetch content from Filecoin and IPFS using the best available retrieval path.                                                                                                  |
| Retrieving application data with Filecoin Onchain Cloud | See the [Filecoin Onchain Cloud retrieval docs](https://docs.filecoin.cloud/core-concepts/retrieval/) for maintained Synapse SDK retrieval flows.                                                                                          |

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