Task: Outline the Architecture |  |
Outline the architecture through analysis of the architecturally significant requirements and identification of architectural constraints, decisions and objectives.
Disciplines: Architecture
Purpose
To provide sufficient guidance and direction for the team to begin or continue evolving the architecture.
Relationships
Roles | Primary Performer: Architect | Additional Performers: Analyst Developer Project Manager Stakeholder
Inputs | Mandatory: Glossary Use-Case Model Vision | Optional: Architecture Notebook Supporting Requirements Specification Use Case
Outputs | Architecture Notebook
Main Description
This task focuses on identifying the architectural goals for an iteration that will guide development and testing. It relies on gathering experience gained in similar systems or problem domains to constrain and focus the architecture so that effort is not wasted in re-inventing architecture.
Steps
Identify architectural goals
Work with the team, especially the Stakeholder and Analyst, to describe the remaining goals for the architecture and identify which ones are appropriate to address for this iteration. Examine the product Vision and requirements. These goals will prioritize and guide the approach to important technical decisions. It will be important to regularly review the status of these goals throughout the project to make sure that they are still valid and that the system is on track to deliver them.
Identify architecturally significant requirements
Identify which of the current requirements are architecturally significant. Explore and refine those that must be implemented in order to realize the architectural goals for the current iteration. See Concept: Architecturally Significant Requirements and Guideline: Determine Architecturally Significant Requirements for more information. Reference the architecturally significant requirements in the Architecture Notebook after they are identified. It will be important to review this list regularly in line with changes to requirements to make sure that they are still valid.
Identify constraints on the architecture
List any constraints on the architecture and any trade-offs between competing requirements and resources. Decide how the architecture will meet these issues. Justify each of the decisions made and capture this information. Regularly review the list of constraints to make sure that they are still valid and that no new ones have appeared.
Survey, assess and select available assets
Identify assets from other areas that may be reused in the current architecture. These could include: Architectural frameworks Architectural mechanisms Architectural decisions Constraints Applications Components COTS software
Define approach for structuring the system
Decide how to structure the software, both in logical and physical terms. As a minimum, decide on: How to partition the software when managing development (the use of layering as a partitioning strategy, for example). How the software will be composed at run time. For each software partition, briefly describe Their name and purpose. Their relationships to other partitions. These decisions will form the basis for structuring the Design and the Build.
Define approach for deploying the system
Outline how the software will deploy over the nodes on the network. Work with stakeholders such as network support and deployment teams to ensure that the proposed approach is a good fit for the wider technical environment.
Identify architectural mechanisms
Make a list of the technical services that the system needs to provide and capture some basic information about each item on the list. It's generally a good idea to make an initial list of all the mechanisms required for the project and then prioritize the development of those that need to be delivered to achieve the goals of the current iteration. See Concept: Architectural Mechanism to understand what architecture mechanisms are and how to describe them. See Guideline: Architectural Mechanisms to understand how to develop them. See Guideline: Outline the Architecture for perspectives and issues to consider when defining the architecture.
Identify key abstractions
Identify the key abstractions that the system needs to handle. These can usually be found by looking for nouns that the requirements emphasize or repeat, because they help identify what is important to the business. The Glossary is also a useful source for key abstractions as it is itself a list of business nouns. Not all nouns will be key abstractions in the system though, so work with the Analyst and Stakeholder as they will have knowledge and materials that are relevant to this step.
Verify architectural consistency
The Architect works with the Developer and Project Manager to verify that the architecture is consistent with the requirements; and that the descriptions of the architecture are complete, meaningful, and clear.
Capture architectural decisions
Capture important decisions about the architecture for future reference. Consider using the templates provided for the Architecture Notebook. Developers in particular should clearly understand the current state of the architecture each iteration before developing the architecture.
Key Considerations
This task is most beneficial when developing new and unprecedented systems. In systems where there is already a well-defined architecture, this task might be omitted, or performed quickly as a review of the existing architecture. It is critical that this task is performed collaboratively with active involvement of other team members and project stakeholders so that consensus and common understanding is reached. It is particularly vital for the architect to involve the developer(s) throughout this task. The architecture effort is about providing leadership and coordination of the technical work rather than putting in a solo performance.
More Information
Concepts | Architecturally Significant Requirements Architectural Mechanism Software Architecture
Guidelines | Outline the Architecture Layering Determine Architecturally Significant Requirements
This program and the accompanying materials are made available under the Eclipse Public License v1.0 which accompanies this distribution. OpenUP Copyright.