Using Linguistic Knowledge to Classify Non-functional Requirements in SRS documents

Non-functional Requirements (NFRs) such as software quality attributes, software design constraints and software interface requirements hold crucial information about the constraints on the software system under development and its behavior. NFRs are subjective in nature and have a broad impact on the system as a whole. Being distinct from Functional Requirements (FR), NFRs are dealt with special attention, as they play an integral role during software modeling and development. However, since Software Requirements Specification (SRS) documents, in practice, are written in natural language, solely holding the perspectives of the clients, the documents end up with FR and NFR statements mixed together in the same paragraphs. It is, therefore, left upon the software analysts to classify and separate them manually. The research, presented in this paper, aims to automate the process of detecting NFR sentences by using a text classifier equipped with a part-of-speech (POS) tagger. The results reported in this paper outperform the recent work [6] in the field, and achieved a higher accuracy of 98.56% in the critical conditions of using 10-folds-cross-validation over the same data used by [6].The research reported in this paper is part of a larger project aimed at applying Natural Language Processing techniques in Software Requirements Engineering.