Schema version information

Information on the version structure

All of the schema files released since 2007 have used a new versioning system. This is composed of two parts, Major and Minor.

Major

The major part of a version is contained in the namespace of each schema. This consists of the month and year the schema was first released. The format for the new URI for the namespace will be

http://www.openmicroscopy.org/Schemas/[NameSpaceTitle]/[YearAsFourDigits]-[MonthAsTwoDigits]

This means the June 2016 major release for the OME schema uses the namespace

http://www.openmicroscopy.org/Schemas/OME/2016-06/

and that the schema file will be located at

http://www.openmicroscopy.org/Schemas/OME/2016-006/ome.xsd

There will be a consultation period before each major release. Major releases may include breaking changes.

Minor

In the schema element of the XSD file, there is a version attribute:

<xsd:schema xmlns="http://www.openmicroscopy.org/Schemas/OME/2016-06"
    …
    version="1"
    … >

This is used to record the minor version number of the schema. This starts at 1 and counts up in integers (1, 2, 3 etc.) with each minor version.

A new minor version is used for small non-breaking changes. If a change is more significant, or would break application relying on the current schema, then it must be a major version.

Minor versions will be released as needed.

Examples and consequences

The relationship between a major and minor version has been set up as follows. Any file written by an application conforming to a major version, will always continue to be valid under any minor version update to the schema. The first releases to make use of the major and minor system were June 2007(Major) and September 2007(Minor). If microscope application X saves a file using the major June 2007 version of OME-XML, then that file can be read by any application that understands either the June 2007 major version or the September 2007 minor version. The main consequence of this approach is that file readers have to be kept up to date or have to be written in a way that allows some flexibility.

An example of a minor change is the serial number in the manufacture specification. In the June 2007 major version, a SerialNumber is required in ManafactSpec. It was decided to make this optional as it was not always available to a file writer. This is a minor change as the new file can still validate whether it is present or absent.

An example of a major change is the moving of ImageRef from the SPW.xsd file to the ome.xsd file. This change had been proposed as it is envisaged that in the future ImageRef will be used outside the Screen/Plate/Well model, so it belongs in the same namespace as Image. As any reference to SPW:ImageRef would then have to become OME:ImageRef, this causes validation errors in files following the June 2007 schema and is therefore a new major version.

Technical schema descriptions

Auto-generated documentation is available for each release of the schema, including information on each attribute and element. These are published as XSD files on the OME website. They are usually read by XML validators and parsers but are viewable as text files. Alternatively, you can browse the current version of the entire Schema online.

Transforms are available which convert between the the different versions of the schemas. They can be downloaded from:

http://www.openmicroscopy.org/Schemas/Transforms/