Interoperability is about the ability of one application to work with others through a standard format or protocol. Often, an application needs to communicate with the various upstream systems to consume data and downstream systems to supply data, so it is essential to establish that communication seamlessly.

For example, an e-commerce application needs to work with other applications in the supply chain management ecosystem. This includes enterprise resource planning applications to keep a record of all transactions, transportation life cycle management, shipping companies, order management, warehouse management, and labor management, and so on.

All applications should be able to exchange data seamlessly to achieve an end-to-end feature from customer order to delivery. You will encounter similar use cases everywhere, whether it is a healthcare application, manufacturing application, or telecom application.

A solution architect needs to consider application interoperability during design by identifying and working with various system dependencies. An interoperable application saves lots of costs as it depends on systems that can communicate in the same format without any data messaging effort. Each industry has its standard size for data exchange that it needs to understand and adhere to.

In general, for software design, the architect may choose a popular format such as JSON or XML between different applications so that they can communicate with each other. In modern RESTful API design and microservice architecture, both formats are supported out of the box.

System portability allows your application to work across different environments without the need for any changes or with minimal changes. Any software application must work across various operating systems and hardware to achieve higher usability. Since technology changes rapidly, you will often see that a new version of a software language, development platform, or operating system is released. Today, mobile applications are an integral part of any system design, and your mobile apps need to be compatible with major mobile operating systems platforms such as iOS, Android, and Windows.

During design, the solution architect needs to choose a technology that can achieve the desired portability of the application; for example, if you are aiming to deploy your application across different operating systems. Programming languages such as Java may be the better choice as it is often supported by all operating systems, and your application will work on a different platform without needing to be ported across. For mobile applications, an architect may choose a JavaScript-based language such as React Native, which can provide cross-platform mobile app development.

Interoperability enriches system extensibility, and portability increases the usability of an application. Both are critical attributes of an architecture design and may add additional exponential costs if they're not addressed during solution design. A solution architect needs to carefully consider both aspects as per industry requirements and system dependencies.