API economy at present revolves around API hosting and management. The pre-requisite for API management, obviously, is to have APIs (Application Programming Interface) on the existing/new systems within the businesses. It is imperative to arrive at a methodology for designing, developing or extracting; and exposing such APIs around existing legacy systems. Extraction of APIs (API-fication) can be direct: a completely new application or platform leverages the legacy application for supplying to the APIs; and indirect: the legacy application hosts the API within itself.
How to qualify legacy activities
A legacy application is functionality-oriented, it does not necessarily have an API system around it. The most challenging activity to get APIs out of it is qualification of the functions, starting with categorization of activities:
The categorization needs definitions of complexity levels that are useful in downstream activities of estimations, scheduling and implementation of APIs.
How to rank legacy activities
Upon identification of the functions (activities), the next logical step is to rank them using specific parameters. Since the API ecosystem is pivotal for developers, these rankings orient towards developer benefits:
By design, this ranking mechanism has ‘financial viability’ as the key consideration, to address ‘alternate revenue streams’. The manifestation of financial viability are API-fication scoring models (See figure 1, 2 & 3). The modeller is customizable.
Figure 1: API-fication scoring parameters for business
Figure 2: API-fication scoring parameters for developers
Figure 3: General API-fication scoring parameters
Peeling the layers of legacy software
Peeling legacy applications based on architecture tiers offer potential methods for APIs.
The API-fication Scoring Model would contain parameters to evaluate these methods for optimum design and efforts.
When conceiving APIs, additional parameters of design and extraction (Decorators) qualify the APIs and deal with scalability and ability to document – apart from standards such as Swagger. The main decorators are:
Decorators enhance API consumption, enterprise management and usage, thereby improving financial viability.
A methodology brings consistency in considering the actions, associated templates, algorithms and tools in performing the API roll-out. Figure 4 represents the methodology steps and details.
Figure 4: Methodology for API extraction
A legacy application, with its dependencies and complexities, needs different evaluations to extract APIs out of it. There are direct or indirect ways of creating APIs and it is important to qualify (that includes rankings, financial viabilities and design qualifications) and a methodology to manage lifecycle activities of APIs. These aspects have to be optimally leveraged to transform a legacy application to the world of APIs.
Praveen Kodikkambrath Practice Director & Principal Architect - Microsoft Practice, Business Application Services, Wipro- Praveen has 19+ years of experience in development, consulting, delivery, sales and pre-sales, CxO and analyst interactions, innovation and marketing.
His area of expertise is Application Estate Transformation that includes Cloud and digital initiatives. He has built transformation services to scale, including management of services and strategy, customer accounts, solutions development, delivery and management of associated people structures.
He has pioneered a productized solution that addresses all transformation requirements across Microsoft technologies (Azure, Office365, BizTalk, Dynamic).