Requirements management using SysML

Revision as of 20:10, 28 February 2019

Abstract

Every project involves ... highly interdependent requirements describing the relationships and constraints of the elements that make up the project. Managing the complexity of these requirements is crucial for projects success. Object-oriented modeling languages such as SysML provides a generic framework to construct so called models of engineering projects. These models make for a tool to comprehend complexity, thereby supporting the project manager to comply with quality, reduce risk, and be responsive to change in requirements. These strong abilities arises from the nature of object oriented modeling, instead of archiving requirements in large amounts of text-documents, a model is build in a computer program that captures the multi-dimensional relationships between requirements across components, use cases, system level functioning, and performance. This enables is traceability, ie. a way to trace down individual elements impact on other elements, from mikro to makro level. This ability is particularly important for projects mangaers, who cannot comprehend every little detail in a project, instead they must understand the overall system dynamics, that focuses on the relationships of the elements. In this article, a brief introduction to SysML and requirements management will be introduced laying the basis for further discussion about how it affects the project manager particular in regards to harnessing complexity, reducing risk, and communicating effectively.

Introduction

PMBOK describes a project as “ “.Any engineering project involves delivering --- within a agreed time frame, at a certain cost and to an agreed quality.

To talk about what quaility a delivery must perform, a clear non ambiguity specification must be made. This requirements specification specifies what exactly should be delivered, but also functions as a baseline to evaluate whether the delivery is as the client ordered, in other words if the project comply with defined quality.

If the project does not live up to quality it may in worst case be ... by the client, or closed down before time, in this way ....more and less related to risk assume that.

Maintaining and making this specefication is a non trivial endeavor, as requirements is a wide term that can involve everything from functional or non function, to busiensss, and transitistiong requiremetns, and use case requirements. Therefore they must be organized in an intelligent way that deem them useful through the life cycle of the project. One way to order them, proposed by the PMBOK, is through a requireents tracebility matrix (RTM). This matrix relates requirement on one axis with several .... business objectives on another. kilde: 5.2.3 CoLLeCT reQuIreMenTS: ouTPuTS

It can be argued that the RTM approach has some limitations rooted in its lack of capabilities to present mulitiple relations between objects at different abstration levels.

bare intro til requiremetns, og risk

Her skal der stå noget pmbok elller Prince om requriment g Irak. Hvornår og hvad gør de Find gradins objectives

Document-based or model-based

The document-based-approach:

In most organisations the approach to managing requirements is the so called document based approach; here requirements are categorised in a hieratic specification tree, and documented as text files. Part from being a rigorous proces that can be difficult to maintain, this approach has a fundamental flaw the deeply affects management decision making on a broad level. The problem with the document-based-approach arises as it can not depict the complex reality of the relations between components. Instead the relations are depicted in a framing decided by the system engineer responsible for designing and maintaining the system. The drives a range of issues related to managements decision making, as certain perspectives of the system are not visble: making for traceability issues I.e. when tracing a customer requirements all the way down to the rationale behind decisions of low system level components This in turn makes it difficult to asses change impact in projects, and delivering with the right quality, .. leading to reduced quality and higher uncertainty.... The complexity and probability of damage drastically increases with the size of projects and width of program, as more complicated networks of relation arises between technology, stakeholders...

Instead the Project management office should shift the requirements management approach to a model-based approach. In a model-based-approach, ....... OOSEM object-oriented systems engeneering method. The products of the model-based approach depicts the messy structures ... with fewer.. as requiremetns can be inherited and derived from eachother.

A good mental model for understanding the dynamics of the model-based system is picturing a mountain. The mountain itself is the model "object" with all its different trees, animals, snow. The different view that can be extracted from the model to understand to system is then photographs of the moutain from different lokations. Two photos may show partly similar elements, but they will depict different truths about the moutain itself.

Quick overview/introduction of SysML

SysML is a visual modeling language developed by the Object Mangagement Group (OMG), as a profile/flavour/extension to the UML from software development.

SysML defines nine views/blocks to make a model, these are These are the different views that help us understand the complexity. When learning about SysML for the first time, it can be .. to start with the SysML Lite version, so we will do that here.

billede a model

Affecting project and program management

The SysML approach contribute in variety of ways to simplify and give powerfull insights.

It makes it the trade-off analysis more clear, thereby making it easier to take the right decesions

Implementing SysML

Before deciding to implement SysML in a project or program, the project mangement office has to asses whether the right ressources in terms of time/knpwledge are present for .. as well as understanding..... læs øverst i bog efter forklaring

Limitations

Increased complexity, for small projects. Requireme that all people are in and understand,

References

150211142014_2_Friedentahl_-_A_Practical_Guide_to_SysML_2nd

PMBOK 5.2.3.1 reQuIreMenTS doCuMenTaTIon