JCR or RDBMS

This paper compares java content repositories (JCR) and relational database management systems (RDBMS). The choice between these technologies is often made arbitrarily. The aim is to clarify why this choice should be discussed, when one technology should be selected instead of an other and how the selected technology should be used. Four levels (Data model, Specification, Project, Product) are analyzed to show the impact of this choice on different scopes. Follow a discussion on the best choice depending on the context. This defines the foundations of a decision framework. Day Software AG (Day) led the development of a JAVA specification which defines a uniform application programming interface (API) to manage content. This specification is called content repository API for java (JCR) and is part of the java community process. Implementations of this specification are actually provided by well known companies such as Oracle, Day or Alfresco. JCR implementations are often used to build high level content management systems and collaborative applications. Day also provides an open source implementation of the specification which is called Jackrabbit and which is used as a shell for some of its products. This diploma thesis takes place in this context. Day wants to clarify some points which relate to the data model promoted by their specification. The basic idea is to compare their approach to managing content with the approach promoted by competitors at different levels. The following sections will clarify the approach adopted to do this and give an overview of the content developed in this report. As explained, the purpose is to locate JCR in the database world. This work will be done by comparing the relational model and the model promoted by JCR. The relational model defined by Codd in the 70's is actually the most widely used data model. The unstructured or semi-structured model subtended by the JCR specification encounter a growing success in the content management area. These two models will be described and analyzed in this report. Each data model supports a philosophy, to structure and access data. On the one hand, the success of the relational model comes in large part from the facilities which are offered to describe clear data structures. On the other hand, the success of the JCR specification relates essentially to the facilities which are offered to express flexible data structures. These aspects show us that the discussion takes place at the same level. …