# Ground Link channel (IRPCGroundLink)

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)

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

The M-Files Ground Link channel: a long-lived two-way stream between a Ground Link proxy and the
M-Files Server that hosts the vault, typically in M-Files Cloud.

- **gRPC service:** `MFiles.IRPCGroundLink`
- **Book and level:** [Server integration API](https://developer.m-files.com/APIs/gRPC-API/integration/index.md), specialized
- **Methods:** 1
- **Proto file:** [`mfiles/IRPCGroundLink.proto`](https://developer.m-files.com/APIs/gRPC-API/downloads/proto/mfiles/IRPCGroundLink.proto)

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## Overview

**For M-Files components only.** M-Files Ground Link connects a vault, typically in M-Files Cloud,
to external repositories (connectors) that run on premises. The on-premises side, a Ground Link
proxy on an M-Files Server, opens the channel to the server that hosts the vault. Applications
should not call this service.

- **Who opens it and in which direction:** the Ground Link proxy calls
  [OpenGroundLinkChannel](https://developer.m-files.com/APIs/gRPC-API/Reference/MFiles.IRPCGroundLink/OpenGroundLinkChannel/index.md), a connection
  from the premises to the vault's server. Over the open stream each side can send calls and
  returns; typically the vault side calls the connector services on the premises.
- **What flows over it:** [GroundLinkMessage](https://developer.m-files.com/APIs/gRPC-API/Reference/MFiles.IRPCGroundLink/OpenGroundLinkChannel/index.md#request)s that wrap .NET
  remoting calls and their returns of the M-Files external connector framework. A response
  carries the `id` of its request. The server does not interpret the messages; it hands them to
  the vault's Ground Link application.
- **Authentication:** no M-Files session. The call metadata names the target vault and carries a
  secret that the vault's Ground Link application checks.
- **Lifetime:** the channel stays open until either side closes it. The server closes all channels
  of a vault when the vault stops accepting Ground Link connections, for example when it goes
  offline.

<a id="methods"></a>

## Methods

| Method | Summary | Facts |
|---|---|---|
| [OpenGroundLinkChannel](https://developer.m-files.com/APIs/gRPC-API/Reference/MFiles.IRPCGroundLink/OpenGroundLinkChannel/index.md) | Opens a bi-directional Ground Link channel between the client and server. | `internal: not for applications` `write` `no session` `client streaming` `server streaming` |