Despite the increasing maturity of model-driven software development (MDD), some research challenges remain open in the field of information systems (IS). For instance, there is a need to improve modelling techniques so that they cover several development stages in an integrated way, and they facilitate the transition from analysis to design. This paper presents Message Structures, a technique for the specification of communicative interactions between the IS and organisational actors. This technique can be used both in the analysis stage and in the design stage. During analysis, it allows abstracting from the technology that will support the IS, and to complement business process diagramming techniques with the specification of the communicational needs of the organisation. During design, Message Structures serves two purposes: (i) it allows to systematically derive a specification of the IS memory (e.g. a UML class diagram), (ii) and it allows to reason the user interface design using abstract patterns. This technique is part of Communication Analysis, a communication-oriented requirements engineering method, but it can be adopted in order to extend widely-used business process and functional requirements modelling techniques (e.g. BPMN, Use Cases). Moreover, the paper presents two tools that support Message Structures, one uses the Xtext technology, and the other uses the Eclipse Modelling Framework. Industrial experience has shown us that the technique can be adopted and applied in complex projects.