9. Infrastructure Architecture
While most of the software guidebook is focussed on the software itself, we do also need to consider the infrastructure because software architecture is about software and infrastructure.
Intent
This section is used to describe the physical/virtual hardware and networks on which the software will be deployed. Although, as a software architect, you may not be involved in designing the infrastructure, you do need to understand that it’s sufficient to enable you to satisfy your goals. The purpose of this section is to answer the following types of questions:
- Is there a clear physical architecture?
- What hardware (virtual or physical) does this include across all tiers?
- Does it cater for redundancy, failover and disaster recovery if applicable?
- Is it clear how the chosen hardware components have been sized and selected?
- If multiple servers and sites are used, what are the network links between them?
- Who is responsible for support and maintenance of the infrastructure?
- Are there central teams to look after common infrastructure (e.g. databases, message buses, application servers, networks, routers, switches, load balancers, reverse proxies, internet connections, etc)?
- Who owns the resources?
- Are there sufficient environments for development, testing, acceptance, pre-produc- tion, production, etc?
Structure
The main focus for this section is usually an infrastructure/network diagram showing the various hardware/network components and how they fit together, with a short narrative to accompany the diagram. If I’m working in a large organisation, there are usually infrastructure architects who look after the infrastructure architecture and create these diagrams for me. Sometimes this isn’t the case though and I will draw them myself.
Motivation
The motivation for writing this section is to force me (the software architect) to step outside of my comfort zone and think about the infrastructure architecture. If I don’t understand it, there’s a chance that the software architecture I’m creating won’t work or that the existing infrastructure won’t support what I’m trying to do.
Audience
The audience for this section is predominantly the technical people in the software develop- ment team along with others that may help deploy, support and operate the software system.
Required
Yes, an infrastructure architecture section should be included in all software guidebooks because it illustrates that the infrastructure is understood and has been considered.