# Linking services

> What passes from one service to the other when you link them, how to link and unlink, and how to rename a received variable.

Source: https://docs.fransys.cloud/en/projets/relier-des-services/ Checked against the console on 2026-10-23.

## What a link carries

- **From a database to an application**: the database's connection variables (host, port, credentials).
- **From one application to another**: the variables the first one shares. To share a variable, tick **Expose to connected services** on that variable.

If neither service shares any variable, nothing passes: the console tells you before linking.

## Link two services

- **On the diagram**: drag a service's handle onto the other one, or click it to choose the service.
- **In the panel**: **Connections** tab, **Link to…**.
- **On a phone**: the **Link … to…** sheet.

A confirmation tells you what each service will receive. The link takes effect at the project's next deployment.

## Rename a received variable

In the panel of the receiving service, a received variable is marked **received from a connected service**. You can give it another name in this service; clear the field to go back to the original name.

This is how you link an application to two databases with the same engine: Fransys refuses to deploy while two received variables have the same name.

## Unlink

Hover over the link on the diagram, or go through the **Connections** tab, then **Unlink**. At the next deployment:
- the service that received the variables no longer gets them. If it uses them, it won't be able to start properly;
- a database's data stays intact;
- if you link these services again, the variables come back under their original names: renames are lost.

Nothing changes before the next deployment.