# IRPCIndexingDataSource.DownloadFile_ReadBlockForFIX

Location: [gRPC API](https://developer.m-files.com/APIs/gRPC-API/index.md) > [Server integration API](https://developer.m-files.com/APIs/gRPC-API/integration/index.md) > [Indexing data source](https://developer.m-files.com/APIs/gRPC-API/Reference/MFiles.IRPCIndexingDataSource/index.md)

HTML version: https://developer.m-files.com/APIs/gRPC-API/Reference/MFiles.IRPCIndexingDataSource/DownloadFile_ReadBlockForFIX/

Badges: `Server integration API / specialized` `internal: not for applications` `write` `session`

Gets a specific block from a file from the server for file data indexing.

- **Service:** [Indexing data source](https://developer.m-files.com/APIs/gRPC-API/Reference/MFiles.IRPCIndexingDataSource/index.md) `MFiles.IRPCIndexingDataSource`
- **gRPC method:** `/MFiles.IRPCIndexingDataSource/DownloadFile_ReadBlockForFIX`
- **HTTP (mf-http-grpc):** `POST /grpc/v1/download-file_-read-block-for-fix`
- **Request:** [`DownloadFile_ReadBlockForFIXRequest`](https://developer.m-files.com/APIs/gRPC-API/Reference/MFiles.IRPCIndexingDataSource/DownloadFile_ReadBlockForFIX/index.md#request)
- **Response:** [`DownloadFile_ReadBlockForFIXResponse`](https://developer.m-files.com/APIs/gRPC-API/Reference/MFiles.IRPCIndexingDataSource/DownloadFile_ReadBlockForFIX/index.md#response)
- **Book and level:** Server integration API, specialized
- **Kind:** write
- **Session:** Required: the session ID from LogIn in the mfiles-session-id-bin metadata.
- **Idempotent:** no
- **Returns metadata structure version:** no
- **Streaming:** none (unary)

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## Remarks

**For M-Files components only.** Search indexers call it to read a block of a file opened with
[DownloadFile_BeginForFIX](https://developer.m-files.com/APIs/gRPC-API/Reference/MFiles.IRPCIndexingDataSource/DownloadFile_BeginForFIX/index.md).
Applications should not call it.
- Requires a vault session with the vault rights `see_all_objects` and `see_deleted_objects`.

<a id="request"></a>

## Request: DownloadFile_ReadBlockForFIXRequest

> Nested message fields are expanded to depth 3; follow a type link for deeper levels and for the type's own page.

| Field | Type | Description |
|---|---|---|
| `download_id` | `int32` | Download session identifier. |
| `block_size` | `uint32` | The number of bytes wanted. |
| `offset` | `int64` | The offset to start reading from. |

<a id="response"></a>

## Response: DownloadFile_ReadBlockForFIXResponse

> Nested message fields are expanded to depth 3; follow a type link for deeper levels and for the type's own page.

| Field | Type | Description |
|---|---|---|
| `data` | `bytes` | Block data. |

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## Related methods

- [DownloadFile_BeginForFIX](https://developer.m-files.com/APIs/gRPC-API/Reference/MFiles.IRPCIndexingDataSource/DownloadFile_BeginForFIX/index.md): Begins downloading a file for file data indexing.
- [DownloadFile_EndForFIX](https://developer.m-files.com/APIs/gRPC-API/Reference/MFiles.IRPCIndexingDataSource/DownloadFile_EndForFIX/index.md): Ends downloading a file for file data indexing.