In this section, we will explain the various design considerations that need to be kept in mind before choosing EDA patterns for architecture implementation. The main considerations are the following:

• Agility: Agility refers to the ability to cope with the rapid changes that happen in the environment. In the EDA pattern, components are loosely coupled. This ensures that changes that happen to one component do not affect the other components in the system. Hence, the degree of agility offered by the EDA pattern is high, making it an ideal choice for the design of systems that require continuous changes without any downtime.
• Ease of deployment: The EDA pattern components are loosely coupled in nature, which makes their deployment very easy. For solutions that require maximum ease of deployment, event broker topology is a better option than event mediator topology. This is due to the fact that in event mediator topology, there exists a relatively tight coupling between the event mediator and event processor.
• Testability: Unit testing of EDA pattern components is difficult because of the fact that it requires special test clients and test tools to generate events that are required for testing purposes.
• Performance: EDA has the capability to perform asynchronous operations in parallel, which provides very high performance for the architecture, irrespective of the time lag involved in queuing and dequeuing messages.
• Scalability: EDA offers a high level of scalability because of the highly decoupled nature of the components.
• Ease of development: Ease of development using this pattern is low because of the asynchronous nature of the pattern.

Though there are well-defined components for an EDA pattern, the implementation style of the pattern varies based on the type of system functionality and complexity. In the next section, we will learn about the various styles in which EDA patterns are implemented.