Compatibility and contract versions

Every YTCC version knows the versions of the formats and databases it can work with. These numbers are called contract versions. When a project, a database or a backup comes from another YTCC version, YTCC compares its version with its own and either uses it, upgrades it or refuses it. For where YTCC shows its own version, see Which version you are reading.

Where to read the versions

• Settings › About on the home page lists Product version, Installation and the contract versions: Control API, Configuration schema, Project registry schema, History schema, Project format, Page format, Driver API and Messaging API. When the components of the installation report different versions, it shows Component versions do not match and the names of the versions concerned. The same About window opens in the screen editor, on the runtime screen and in the configuration editor; it also lists the versions of the components and has Copy information (see Application settings).
• scada-manager version prints the product version, the installation, the control API and the contract versions.
• scada-manager version --json prints the same as JSON, with the fields product_version, install_id, control_api, install_dir, contracts and projects. install_id and install_dir are null for a standalone installation. projects lists each project with slug, db_name and hist_db_name.

Contract versions

The values are those of the version these docs describe.

Contract	In About	Value	What it versions
config_schema	Configuration schema	77	The project database: drivers, devices, signals, alarms, areas and zones
registry_schema	Project registry schema	7	The registry database that lists the projects of an installation
hist_schema	History schema	1.0	The history database of a project
project_format	Project format	1	The project file with the pages, symbols, popups and layouts
page_format	Page format	1	Each page in the project file
format_version	—	1	Project backups and project packages
control_api	Control API	1	The control interface of scada-manager
driver_api	Driver API	1	The interface between YTCC and its drivers
nats_api	Messaging API	1	The messages between the YTCC services

Which version opens what

Project database and registry

The programs and the database must have the same schema version. Connecting never upgrades a database.

The database is	What happens	What to do
Older than the programs	The configuration editor shows Project database is incompatible with this version with the command to run; the project's drivers do not start.	The setup program upgrades the databases when it upgrades YTCC. Otherwise stop the project and use Upgrade… on the home page, or run scada-manager migrate <project>, or scada-manager migrate --registry for the registry. See Databases and schema upgrade.
Newer than the programs	The same message, with update all YTCC programs together.	Use the YTCC version that upgraded the database.

After migrate, older YTCC versions can no longer use the database. Take a backup before you upgrade; see Upgrade to a new version and roll back.

History database

The history database is	What happens
Same major version, older minor version	The history writer upgrades it itself.
Same major version, newer minor version	The history writer keeps writing; the columns that the newer version added stay empty.
Different major version	The history writer does not start, does not change the database and is not restarted. Use the YTCC version that wrote this history.

migrate does not change history databases.

Project and page files

The file is	What happens
Older, or without a format version	It opens normally. On the first save, YTCC keeps a copy of the old project file in the project's backup folder and then saves it in the current format.
Newer, but marked as readable by this version	It opens, but saving is refused: This project was saved with a newer YTCC version; update to save it.
Newer and not readable by this version	It does not open: This project was saved with a newer YTCC version; update to open it.
A page in a newer page format	The page opens read-only: This page was saved with a newer YTCC version and is read-only here. Update YTCC to edit it. When the whole project is saved, the page is written back unchanged.

Backups and project packages

This applies to scada-manager import and to the Import project window of the home page.

The backup or package is	What happens
Made by the same or an older version	It is imported. An older database inside it is restored and then upgraded to the current schema; the Import project window shows upgraded to {0} on import.
Made by a newer version	The Import project window shows newer than this server and The package was made with a newer YTCC version than this server; update YTCC first, and the import is refused.
Of a newer format_version, or with a newer database schema	The import is refused. Update YTCC first.

See Backup and restore.

One project, one version

A project runs in one YTCC version at a time. Starting it in a second version opens Project is running in another version; see Start, stop and restart a project.