Overture Tool

Formal Modelling in VDM

Overture Tool

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Net Meeting 116

Date 9 September 2018, 00:00 CEST
Participants PGL, TO, PJ, NP, KP, MV, HM. Minutes by PJ.

Review Status of the Action List

See Net Meeting Actions

Overture Language Board Status

RC 44, “Total Functions” was discussed at today’s Language Board net meeting. A summary of the discussion is available here.

Status of VDMTools/Viennatalk Development


Status of the Overture Components

Issue 686 has been fixed.

In addition, some type-checker/interpreter issues have been reported recently. Nick will look into this when he returns to the UK.

vdm-mode.el NEW TOOL

vdm-mode.el is an Emacs package for writing VDM specifications using VDM-SL, VDM++ and VDM-RT. It currently supports the following features:

Release Planning


Next release of Overture, version 2.6.4, is due October 19.

Community Development

Overture Traffic

See download stats on the downloads page

Licensing of Overture source code

Based a recent email sent to the core mailing list by MV, there was a discussion about the best licensing strategy to use for Overture in the future. The problem is that GPL v3 might be too restrictive for our purposes: GPL v3 is quite specific about what you can do (and cannot do) when you build applications that include other code. For example, formally we cannot use libraries and plugins that are not compliant to GPLv3 in any applications built with Overture code. Furthermore, most of Eclipse is released under EPL (a weak copyleft license) that is NOT compatible with GPL.

We switched to GPLv3 roughly when we moved from sourceforge to Github with the argument that it would ensure that downstream users that either modify Overture or build tools on top of would be required to open source these changes or derived products. However, we never considered the Eclipse impact properly and ignored it, until it was spotted by a third party.

There are to ways to address this. Either we

The license change process is roughly as follows:

Based on the discussion, people seem to lean towards a more permissive license. Concretely, it was proposed to consider BSD two-clause and the impact that has on the community.

Publications Status and Plans

See Planned Publications.

Any Other Business