Originally published on September 9, 2009 and updated on July 6, 2023.

Introduction to Design Patterns: Provider and Strategy

As software developers, we often come across recurring solutions to common problems, known as design patterns. These patterns provide us with a shared language, making our communications more efficient and precise. In this realm of patterns, two that often come up for discussion are the “Provider Model” and the “Strategy” pattern. At first glance, they seem distinctly different, but are they really?

Exploring the Provider Model Pattern

To understand this, let’s start by dissecting the Provider Model pattern. According to the technical documentation on Microsoft’s Developer Network (MSDN), the Provider Model pattern is characterized by its role as a functionality provider for an API. It acts as a contractual binding between the API and the Business Logic/Data Abstraction Layer. Put simply, the Provider is an implementation of the API that operates independently from the API itself.

Illustrating the Provider Model: The ‘Whidbey Membership’ Feature

To illustrate this, let’s take a look at the ‘Whidbey Membership’ feature. This feature contains a static method called Membership.ValidateUser(). However, this method does not embed any business logic. Instead, it forwards the call to a configured provider. It then becomes the responsibility of the provider class to implement the method and call whatever Business Logic Layer (BLL) or Data Access Layer (DAL) is necessary.

Something like this:

Understanding the Strategy Pattern

On the surface, this concept seems innovative and efficient. We’re presented with an abstract API, and all that’s required of us is to create a concrete implementation of it. This allows the calling code to use our implementation. However, there’s a twist that often gets overlooked.

Comparing Strategy and Provider Model Patterns

To bring this twist to light, we need to delve into the Strategy pattern. The Strategy pattern is particularly useful in scenarios where it is necessary to dynamically swap the algorithms used in an application. The pattern provides a means to define a family of algorithms, encapsulate each one as an object, and make them interchangeable. This allows the algorithms to vary independently from the clients that use them.

Emphasizing the Role of Design Patterns in Application Design

When we closely compare the Strategy pattern and the Provider Model pattern, the similarities are striking. The Strategy pattern explicitly talks about using interfaces, and the Provider Model pattern uses abstract classes, but fundamentally, they are the same. Both patterns have an interface which is then implemented by any number of providers that can be interchanged as needed.

The Importance of Design Patterns in Software Development

The key takeaway here is that design patterns are not something we construct our applications around. They are existing solutions that we observe and incorporate after they have been implemented in an application. As developers, we need to strive to describe what we have using the patterns that already exist. This is crucial because if we fail to recognize and reuse existing patterns, we risk losing the main purpose of having patterns in the first place. That purpose being: to allow software engineers to communicate design without having to specify everything in painstaking detail.

I hope this discussion has clarified the Provider Model pattern, and shed light on its relationship with the Strategy pattern. In the ever-evolving field of software development, understanding and utilizing such design patterns is key to efficient and effective communication, as well as robust application design.​ Have you used the Provider Model or Strategy patterns in your projects? What has been your experience? 

If you’re interested in exploring more about design patterns or other aspects of software development, feel free to check out our other blog posts. Stay tuned for more insights and discussions on the latest trends and topics in software design and development.