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Making Sense of APIs and the API Economy

API economy

This article introduces APIs, both old and new, with a particular focus on microservices that have become a key part of the API economy. So, what are APIs and how are they classified?

Classifying APIs by Type

Here’s a simple method of classification for APIs. First, there are the “older” types of APIs, which refers to APIs used for access methods and performance management. The Queued Sequential Access Method, (QSAM) was released in OS/360. It offered device independence to the extent that the same API calls (e.g., get and put) are used for different devices. The VSAM is in the same class as QSAM.

The Application Response Measurement (ARM) API is another older programming interface. ARM focuses on application response measurement and has the function “arm_init” which is used to define an application. This command must be made before any other ARM API calls related to that application (such as “arm_start” and “arm_end”) are initiated. This is a brief glimpse into its programming interface.

In addition to the older APIs, there are new APIs that have been around since the dawn of the web. Three examples of new APIs are those focused on data, monetization and microservice-type APIs.

Data access APIs are becoming common and are available on sites like that are supported by the U.S. Federal Government. Agriculture, climate, consumer and health are all examples of data sets available on Data is also available in many forms (like .xls and .tar) for both human viewing and program use. Financial APIs accept online and mobile payments. PayPal payments and Square online and in-person payments are examples of financial APIs.

Newly emerging application programs in the form of a microservice are the most important new type of API. These programs are created from a variety of API Management tools, some of which are automatically generated. This produces a new kind of application running on top of the legacy applications that are non-disruptive to the existing application.

Zooming in on Microservice APIs

Microservice APIs have dominated since the creation of cloud computing. M-type APIs are special a kind of small data program. These small data programs are grouped into applications. They’re created in an integrated development environment (IDE) and provide a connection between the legacy world (called the systems of record) and the new world of engagement of mobile devices. These microservice APIs are surrounded by support capabilities, including a management console, security, analytics and logging, all of which are used for governance. The most complete API management programs have a necessary full lifecycle approach because microservice APIs need to be handled as company assets.

There are two main perspectives when it comes to microservices. One view characterizes it as an architectural style while the other uses the term describe the data programs created with API management software products.

  1. An Architectural style: Initially, microservices was an architectural style used in different programming environments. Through adoption of the microservice architectural style, companies use several small modules, communicating using lightweight protocols that combine to provide an application for any company’s business needs.
  2. A kind of program: As API management products evolved, the automated outputs of their IDEs, small data programs, began to be called microservices. These data applications can stand on their own or be combined into applications by making important data and processes available in new ways without disrupting the system of record.

Joseph Gulla is the general manager and IT leader of Alazar Press, a publisher of award-winning children’s books. Joe is a frequent contributor to IBM Destination z (the community where all things mainframe converge) and writes weekly for the IT Trendz blog where he explores a wide range of topics that interconnect with IBM Z.

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Making Sense of APIs and the API Economy

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