The first step for a solution architect is to understand the boundaries of the proposed solution. This is an important task as, with boundaries, the solution can be a moving target which is difficult to contain. Defining clear solution boundaries helps the delivery team focus on the right scope for the solution to be designed and developed.

The main input for this process of defining the boundaries of a solution would be the business requirements driving the solution. External dependencies such as external systems or processes which needs to be integrated with the solution also influences this process. These inputs help the architect define the context and scope for the solution. It also enables normalization of the solution by abstracting external work flows from the internal ones.

Let's take a simple example to understand this further. Consider the requirement to build a system for booking a movie ticket. Let's assume that the system is driven by a two step process:

1. Verify the availability of a seat.
2. Book the ticket.

Let's also assume that there are two separate services made available for us to consume the preceding mentioned actions. The solution boundaries of such a system would look like the ones illustrated as follows:

The box highlighted in green scopes the solution to be built and the other boxes are external systems which the solution is dependent on. This provides a clear understanding of the solution context to the application developers.