Having recently re-read Alistair Cockburn’s book on Agile Software Development, I thought I’d repeat some of the concepts that he describes and try to expand on how those may apply to the development of Enterprise-level software, compared to Application-level software.

There is a very interesting section describing concepts for the design of a methodology for software development. Within this, the choice of a suitable approach is based on a range of criteria, including the following:

  • Methodology Size – the number of control elements in the approach
  • Ceremony – a level of precision and tolerance applied by the approach; greater ceremony corresponds to tighter controls
  • Methodology Weight – the product of size and ceremony, for comparison purposes
  • Problem Size – the number of elements in the problem domain and their inherent cross-complexity
  • Project Size – the number of people whose efforts need to be coordinated
  • System Criticality – the importance of the system, or the level of damage that may by caused by any undetected faults; Alistair uses a scale as follows: loss of comfort, loss of discretionary money, loss of irreplaceable money, loss of life

Other criteria listed in his book are precision, accuracy, relevance, tolerance, visibility, scale and stability. This last one is to determine how likely things are to change, explained with a suitable statement (‘if I were to ask the same questions today and in two weeks, how likely would I be to get the same answers?’)

Those I have included in a bullet list above are perhaps most useful to classify the different types of methodologies, with the others being useful to expand on the detail of any particular approach.

The most commonly-used Agile methodologies, such as XP and Scrum, are inherently lightweight, having minimal control elements and low ceremony, with them being most suited to smaller problems and projects.

Alistair includes an interesting table showing how projects can be characterised by communication load, criticality and priorities. Discussions can then position which type of methodology should, or should not, be used for a project under consideration. Those projects with smaller teams, changing requirements, flexibility in delivery, low risk and small scale are seen at one end of the scale, whilst massive programmes and projects needing strict controls against high risk (financial or life implications) will appear at the upper end of the scale.

In many cases, development of a new piece of standalone application software can benefit from the advantages of an Agile methodology. In this, early visibility of functional software is really useful, allowing changing ideas of the purpose and features of the application to be changed as development progresses. That has to be the true home of Agile software development, backed-up by approaches such as Test-Driven Development to improve the quality of software from ‘day one’.

However, it would seem that for the development of multiple integrated applications in an Enterprise software architecture, this is not going to be the best approach to take. For enterprise-level systems, the requirements are dictated by the business and not just by a set of end users as for an individual application. Up-front work is required to ensure that the overall architecture and requirements are understood, and that planning allows for dependencies between systems to be addressed during the longer software development lifecycle that will be involved. This does not remove the need for good measures of progress and assurances of quality, which can be seen from an Agile approach, but the scale of the project must be borne in mind.

It is for this reason that project management disciplines such as Prince2, and quality control standards such as ISO-9001 have been defined. These are often maligned as being overly heavyweight, but the reaction to use lightweight approaches instead does not often resolve the problems of poor software development and delivery. A lot of failed projects are hampered by understanding of requirements, communication difficulties and false reports of progress. Agile doesn’t fix that on a large scale, although that is essentially what it does address on smaller projects.

Stepping aside from the Agile/non-Agile thoughts, I would tender that for Enterprise-level programmes, the risks of failure are perhaps equal to that of smaller and mid-sized projects, in percentage terms. However, if those odds result in an overrun or under-delivery, then the sheer scale of an enterprise software project will mean that the costs incurred are much higher, the failings more visible, with the lack of delivery being more meaningful to a larger area of the business.

Given these (personal) views, it would seem that there is more risk is using lightweight methodologies for Enterprise-level software development as a whole, whilst still permitting their use within a programme for clearly-scoped or isolated areas of functionality. Would you seriously want to consider an informal approach to developing the software applications that are supposed to drive through large-scale business change in your enterprise? Would you not want to know what you are aiming to deliver before committing to developing chunks of that software?

Another consideration is that, if you wish to move on your whole software architecture to a new platform of integrated components, such as for many SOA initiatives, perhaps the stronger thoughts should go into a phased approach. Doing ‘big bang’ software development and delivery is always an all-or-nothing commitment. Instead, aim to develop and deliver incremental functionality, integrating new with old as you go. This may seem more expensive, due to the extra integration overhead, but this allows better management of costs, reduced risks and also – as for Agile approaches – allows you to use that software from each project phase in live operation if you wish.

To sum up, I feel that software development should indeed be performed in an ‘agile’ approach regardless of scale, but that when looking to delivery Enteprise-level solutions, there is a need for Enterprise-level methodologies and programme management, which is not what gets offered by Agile approaches. I also feel that this is just what Alistair Cockburn presses for in his book; he is an Agile proponent, but he clearly recognises the need for scale to be an input to the choice of approach taken to software delivery.