Modeling imprecise requirements with XML

Abstract

Fuzzy theory is suitable to capture and analyze the informal requirements that are imprecise in nature, meanwhile, XML is emerging as one of the dominant data formats for data processing on the internet. In this paper, we have developed a fuzzy object-oriented modeling technique (FOOM) schema based on XML to model requirements specifications and incorporated the notion of stereotype to facilitate the modeling of imprecise requirements. FOOM schema is also transformed into a set of application programming interfaces (APIs) in an automatic manner. A schema graph is proposed to serve as an intermediate representation for the structure of FOOM schema to bridge the FOOM schema and APIs for both content validation and data access for the XML documents.

Introduction

One of the foci of the recent developments in object-oriented modeling (OOM) has been the extension of OOM to fuzzy logic to capture informal requirements that are imprecise in nature (see Ref. [10] for a survey on fuzzy object-oriented model). Meanwhile, XML is emerging as one of the dominant data formats for data processing on the Internet [20]. XML is rapidly establishing itself as the metagrammar for interorganizational communication and becoming increasingly urgent that requirements analysts, system designer and software developers be able to: (1) model the information represented in XML, and (2) describe the relationships between the XML and the systems to process it.

In this paper, we propose (an overview of our approach is depicted in Fig. 1):

• To define a fuzzy object-oriented modeling technique (FOOM) [11] schema for modeling the FOOM requirements specifications in XML format: as a continuation of our previous work in using fuzzy logic as a basis for formulating imprecise requirements [12], we have extended FOOM along two dimensions:

• To define the FOOM schema for constructing requirements specifications, and for validating the model: the FOOM schema is defined based on the key features described in FOOM, including fuzzy set, fuzzy attribute, fuzzy rule, and fuzzy association, by using the XML schema; and

• To incorporate the notion of stereotypes in FOOM to facilitate the modeling of imprecise requirement: we extend the FOOM by incorporating three kinds of stereotype: entity, control, and interface. In addition, we also add a new stereotype, fuzzy entity to better describe the semantics of imprecise requirements.

• To transform the FOOM schema into a set of application programming interfaces (APIs) for content validation and data access in an automatic manner: a schema graph is used to serve as an intermediate representation for the structure of FOOM schema to bridge the FOOM schema and APIs for both content validation and data access for an XML document. Through the APIs generated from the schema graph, the XML documents are parsed to perform the structure and content validation, and to access the data from an object tree. The object tree is a tree-like structure for an XML document as a result of the parsing. A top-level document instance is the root of the tree with zero or more element objects as its children. An element object is defined in a recursive manner with zero or more attributes and/or text elements. In an element object, there are two kinds of methods: get and set method (see Fig. 2). An object tree serves as an internal representation of an XML document. APIs can exploit the information in the object tree to perform the content validation and access the data of an XML document.

We chose the meeting schedule problem [23] as an example throughout this paper to illustrate the proposed approach.

The organization of this paper is as follow. We first introduce the background on XML and XML schema in Section 2. In Section 3, the mappings of FOOM to XML schema and to XML documents are discussed. Several kinds of fuzziness in fuzzy objects are identified, and an extension of FOOM with stereotypes is also described. In Section 4, we propose a schema graph as an intermediate representation for an XML schema, and algorithms for transforming the XML schema into a set of APIs especially for performing the structure and content validation and data access of XML documents. The implementation of FOOM prototype is briefly described in Section 5. Related works are discussed in Section 6, and concluding remarks are given in Section 7.