During my work placement in a software development role at Ericsson, I have worked on a diverse range of software applications written in the Java pro- gramming language. These applications are utilised both within Ericsson, and by telecommunications network providers around the world, as part of a large software system responsible for the management of telecommunications network models. In this dissertation, I describe my work on two substantial software applications comprising part of this larger system, with a focus upon the software engineering techniques that were most relevant to my work. Numerous design patterns were implemented during my work on each of these projects. Accordingly, both theoretical and practical aspects of relevant design patterns are discussed in depth. Several other software engineering techniques - code refactoring, software testing, and code reviews - collectively facilitated the delivery of high quality code. These techniques are each discussed in the context of my project work. Having completed the two software projects described in this dissertation and witnessed their successful deployment, it is clear that each of the aforementioned software engineering techniques played an important role. Knowledge and application of these techniques accelerated the development of these projects, and minimised faults in the final delivered product.