DCAR – Participants and roles

DCAR Participants

DCAR participants can be divided into two groups: stakeholders from the company and the evaluation team.

Company stakeholders

In order to make the DCAR as efficient as possible, we recommend the following stakeholders to be present:

  • The architect of the system
  • A project manager or representative of the business and customer perspective
  • Domain experts (optional)

The architect of the system is obligatory. If multiple architects were in charge of designing the system, at least one or two of them must attend who know the system and its objectives very well.

As described below, one essential step of DCAR is a presentation of the architecture by the architect. This presentation, and a subsequent interview are used to complete the list of architectural decisions assessed during the review.

Additionally to the architect, DCAR requires the presence of at least one representative of the management and customer perspective. This person presents the business model of the project and elaborates on the main business drivers. This is necessary, because DCAR aims at holistically capturing potential forces that influenced the architecture decisions made. Optimally, this participant is present during the whole DCAR session. S/he can act as a catalyst for stimulating the information exchange between the technical stakeholders and the review team.

Furthermore, domain experts, as optional DCAR participants, can provide additional insights in the domain’s problem and solution spaces.

Evaluation Team

The evaluation team is familiar with the review procedure and has experience in designing software architectures. They do not necessarily need experience in the domain of the evaluated system, although this is clearly a benefit. Ideally, the members of the review team are independent from the project’s company, because this allows for a more objective view on the system. However, if this is not feasible, for instance because of confidentiality issues, the reviewers can be company internals who have not had any responsibilities in the project under review.

The following list shows the different roles of the DCAR evaluation team; they will be explained in detail below:

  • Review leader
  • (Architecture) decision scribe
  • Minute writer
  • Questioner

Roles in the DCAR method can be assumed by the same person. That way, DCAR can be implemented with less effort. The minimum number of persons required for the evaluation team is two. In this case, one person takes the roles review leader and questioner, and a second person can be the decision scribe and minute writer.  However, three or four people are the optimum number of reviewers. In that case, different persons take the review leader, decision scribe, and minute writer roles. The questioner role can be combined with any other role.

The review leader is responsible for preparing the review. He gathers the evaluation team and acts as contact person for the company. The review leader furthermore negotiates the evaluation schedule and the scope of the review. During the DCAR, he opens the session and acts as a review chair. As such, he makes sure that the evaluation remains on schedule and focuses on the DCAR steps.

The decision scribe captures potential architecture decisions and forces on the fly, during the presentations held by the architects and the management representative. He constructs a graphical decision relationship diagram, which is incrementally refined during the whole review session. The decision diagram primarily serves two purposes: on the one hand it allows the review team to keep an overview over the important decisions and their interrelationships, during the review session. On the other hand, it is used to establish a feedback loop, i.e. it is presented to the company stakeholders during the review session to make sure that the review team understood the decisions well. An elaborate description of decision relationship diagrams and their construction can be found here.

The minute writer keeps track of all discussions held. It is his special responsibility to note down all forces that potentially impacted the architecture decisions made. The minute writer has an active role during the review. He asks questions for clarification and tries to elicit additional forces that did not come up during the initial presentations. Typically, in the analysis phase, the minute writer additionally acts as a questioner.

The minute writer also supports the company stakeholders during the decision documentation phase (see Step 6 below) to document decisions, especially if the stakeholders are not familiar with the concept of decisions and forces. After the review, the minute writer and decision scribe compose a comprehensive documentation of the architecture decisions elicited and discussed during the review session. This documentation is part of the final report.

It is in the questioners’ responsibility to question and challenge the decisions made by the architect. However, unlike other architecture evaluation methods, in which the architecture is under scrutiny, DCAR aims at supporting architects in identifying risks and issues, but also to raise confidence in non-critical decisions.

The minute writer keeps track of all discussions held. It is his special responsibility to note down all forces that potentially impacted the architecture decisions made. The minute writer has an active role during the review. He asks questions for clarification and tries to elicit additional forces that did not come up during the initial presentations. Typically, in the analysis phase, the minute writer additionally acts as a questioner.

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