Use cases are commonly used as notation for capturing functional requirements through scenarios. The problem is that there is no universal notation for use case contents which is capable of accommodating all the needs of software project participants. Business analysts and stakeholders need understandability and informality, while for architects and designers, precision and unambiguity are the most crucial features. In this paper we propose a metamodel and concrete syntax for three complementary representations of use case scenarios. These representations present the same information, but put emphasis on different aspects of it thus accommodating for different readers. This metamodel utilises the idea of separation of requirements as such from their representations as well as the idea of clear distinction between description of the system's behaviour and of the problem domain.

Creation of an unambiguous requirements specification with precise domain vocabulary is crucial for capturing the essence of any software system, either when developing a new system or when recovering knowledge from a legacy one. Software specifications usually maintain noun notions and include them in central vocabularies. Verb or adjective phrases are easily forgotten and their definitions buried inside imprecise paragraphs of text. This paper proposes a model-based language for comprehensive treatment of domain knowledge, expressed through constrained natural language phrases that are grouped by nouns and include verbs, adjectives and prepositions. In this language, vocabularies can be formulated to describe behavioural characteristics of a given problem domain. What is important, these characteristics can be linked from within other specifications similarly to a wiki. The application logic can be formulated through sequences of imperative subject-predicate sentences containing only links to the phrases in the vocabulary. The paper presents an advanced tooling framework to capture application logic specifications making them available for automated transformations down to code. The tools were validated through a controlled experiment.

A case-based approach allows reuse without the usual and significant effort for making software explicitly reusable. We even support such reuse for only partially developed requirements, since it allows reuse already without the need to develop a "complete" specification first. The solution information (models and code) of (one of) the most similar problems can then be taken for reuse and adapted to the newly specified requirements. And even the specification of these new requirements can be facilitated, since the retrieved software case contains related requirements, which may be reused as well.

Use cases are used in many methodologies to drive the software engineering process. Though, their transition to code was usually a mostly manual process. In the context of MDD, use cases gain attention as first-class artifacts with representation notations allowing for automatic transformations to analysis and design models. The paper concentrates on an important problem of constructing transformations that cater for use case relationships. It presents a notation that unifies the ambiguous "include" and "extend", and allows for representing them within textual use case scenarios. This notation, equipped with runtime semantics, is used to construct a direct transformation into working code. The code is placed within method bodies of the Controller/Presenter and View layers within the MVC/MVP framework. Based on this transformation, an agile use-case-driven development process is possible.

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