API management design patterns for Digital Transformation

Digital Transformation (DT) has become the buzz word in the tech industry these days. The meaning of DT can be interpreted in different ways at different places. But simply it is the digitization of your business assets with the increased usage of technology. If that definition is not simple enough, you can think of an example like moving your physical file/folder based documents to computers and make them accessible instantly rather than browsing through 1000s of files stacked in your office. In a large enterprise, this will go to the levels where every asset in the business (from people to vehicles to securtiy cameras) becomes a digital asset and instantly reachable as well as authorized.

Once you have your assets in digitized format, it is quintissential to expose that digital information to various systems (internal as well as external) through properly managed interfaces. Application Programming Interface (API) s are the de facto standard of exposing your business functionalities to internal and external consumers. It is evident that your DT story will not be completed without having a proper API management platform in place.

Microservices Architecture (MSA) has evovled from being a theory in the Martin Fowler’s website to a go-to technology to implement REST services for your organization when achieving the DT. Most of the developers in the enterprise are moving towards MSA when writing business logic to implement back end core services. But in reality, there are so many other systems which are coming as Commercial Off The Shelf (COTS) offerrings which does not fit into microservices landscape natively.

With these basic requirements and unavoidable circustances within your organization’s IT eco system, how are you going to implement an efficient API management strategy? This will be the burning problem in most enterprises and I will touching up on possible solution patterns to address this problem.

API management for green field MSA

If your organization is just a startup and you don’t want to use high cost COTS software in your IT eco system, you can start off the things with full MSA. These kind of organizations are called as green field eco systems where you have the complete control of what needs to be developed and how those services are going to be developed. Once you have your back end core services written as microservices, you can decide on exposing them as APIs through proper API management platform.

Pattern 1 - Central API manager to manage all your micro services

As depicted in the below figure, this design pattern can be applied for a green field MSA where microservices discovery, authentication and management can be delegated to the central API management layer. There is a message broker for asynchronous inter-service communication.

Figure 1: Central API management in a green field MSA

Pattern 2 - Service mesh pattern with side car (micro gateway)

This pattern also applies to a green field MSA where all the back end systems are implemented as microservices. But this pattern can also be applied for scenarios where you have both microservices as well as monolithic (COTS) applications with slight modifications.

Figure 2: API management with service mesh and side car (micro gateway)

API management for practical enterprise architcture

As mentioned at the beginning of this post, most of the real world enterprises use COTS software as well as various cloud services to fullfill their day to day business requirements. In such an environment, if you are implementing a MSA, you need to accept that existing systems are there to stay for a long time and MSA should be able to live along with those systems.

Pattern 3: API management for modern hybrid eco system

This design pattern is mostly suited for enterprises which has COTS systems as well as MSA. This pattern is easy to implement and has been identified as the common pattern to apply on hybrid microservices eco system.

Figure 3: API management for modern enterprise

The same pattern can be applied for any enterprise which do not have any micro services but only traditional monolithic applications as back end services. In such scenarios, micro services will be replaced by monolithic web applications.