Legacy System Integration with APIs

Why is legacy system integration such a hot topic? In 2019, more than 35% of people working with APIs were back-end developers. In comparison, less than 1% are busy with providing APIs. This requires a closer look!

I was surprised by these figures on Statista from a 2019 survey. More than 10.000 API developers, testers, and executives responded to the survey worldwide.

The need for Legacy System Integration and Core System Integration via APIs

Only a few companies in the survey are internet or cloud start-ups that built their core applications and systems by design, on, and with APIs from scratch. Over decades, companies of the so-called old economy invested in assets that we call legacy systems today: databases, business applications for ERP, SCM, CRM, etc. Many of these systems are still running core processes on mainframes or home-grown self-coded systems.

Today, they face legacy system integration challenges when they attempt to:

• Allow access for web-based and mobile technologies to data and information stored in legacy systems or databases and available digital services of core applications. To provide better services to customers that would love to get direct access via the web or mobile devices to such capabilities and assets has been a very important driver. Benefits could be access to information such as actual stock information, or up-to-the-minute prices. Logistics service providers, for example, publish consignment or tracking APIs to provide digital services for their customers.
• Manage the integration of cloud-based SaaS solutions to backend legacy systems. This can be a huge issue, as SaaS solutions have become widespread. Salesforce is an example of a SaaS solution, and it has more than 150,000 customers.
• Transform their SOA architecture into a WOA architecture. The W is for ‘Web’ and means that Rest APIs have proven to be more suitable to allow flexible and easy-to-handle integration for all relevant legacy systems and enterprise applications, on premises as well as for the ground-to-cloud use case.
• Comply with regulations such as PSD2 in financial services that require implementation of technical standards and interfaces. The objective of PSD2 is to open up and become accessible for others. Corporate customers have started to take advantage of this development and integrate their bank partners directly with their core system, so they can get real-time information such as status of their bank accounts.

What do all of these legacy system integration challenges have in common? The integration pattern required is based on APIs.

Why is legacy system integration the most significant role for developers working with APIs?

APIs are the most popular, and in many cases, the only integration style offered by modern public cloud platforms and SaaS applications, and are required for the integration of mobile devices. This also applies to many new regulation requirements or customer requests when it comes to the exposure of information, data and digital services to external parties.

However, legacy systems and most core applications don’t support such API-based integrations.

Although many companies hold assets like data and information and could provide valuable digital services, they cannot be entered via APIs because of their legacy system challenges.

As a result, many developers are busy integrating APIs with back-ends.

It’s likely that once developers get used to working with APIs (e.g. through uses cases like SaaS integration), they will use them for other internal integration scenarios as well. Then, with a new appreciation for the advantages over SOA-based approaches e.g. by using an enterprise service bus (ESB), these developers may eventually decide to change their architectural paradigm to target a web-based architecture built on APIs.

As a result, many developers are busy integrating APIs with back-ends.

It’s likely that once developers get used to working with APIs (e.g. through uses cases like SaaS integration), they will use them for other internal integration scenarios as well. Then, with a new appreciation for the advantages over SOA-based approaches e.g. by using an enterprise service bus (ESB), these developers may eventually decide to change their architectural paradigm to target a web-based architecture built on APIs.

The API journey often starts – or ends – with API integration

Legacy system integration with APIs is a huge effort – as the figures of the survey show. Developers are façading and setting up API proxies to create an API-accessible layer. However, providing access to the assets of the back-end via this layer is someone else’s job. Many companies are starting to code this part themselves – which requires a deep and detailed understanding of the integration technologies of each back-end, be it a legacy system or a core application. Once accomplished, the re-usability of the access to the respective back-ends is not necessarily given. This knowledge is hidden within each developer’s individual programming code and the experience exclusively belongs to the developer, driven by a single use case.

Unfortunately, companies will lose transparency and control over these integrations, which can be distressing to say the least, especially with respect to governance and security. In the event of a disruption, without the developer there is no one to identify the root cause and to analyze and resolve the issue.

We have also seen companies start their API journey by purchasing an API management platform. Very soon they realized that they still need to integrate the platform with their legacy systems. Even the most popular API management vendors lack the necessary functionalities and features required for integration. The reason for this? Integration has never been a part of their DNA because their roots are to serve purely API-driven infrastructures.

Hybrid integration platforms reduce the efforts of API integration

Many companies have found that to ignore API integration or to self-code will prevent scaling and fast execution of further requirements.

A simple analogy: When many people need to repeatedly climb up a mountain, it makes no sense for them to continue climbing up every single time – it makes sense to build a stairway.

This is the advantage of hybrid integration platforms. They come with a broad offering of pre-configured and ready-to-run adapters and connectors to integrate easily with all the typical legacy systems and applications used in back-end infrastructures. Combined on one unified platform with all features to support API management – API initiatives and projects will scale, speed of execution will rise, costs will be reduced and transparency of the complete process will improve.