This API depends on the card terminal used, but supplies generic functions that allow communication with memory cards and processor cards. This API is a low level interface to the reader. But still used because it complies with the ISO7816 standards and have a simple programming logic resembling assembly. You just send code byes along with the data packets and receive the response.
PC/SC Workgroup is responsible for the development of the PC/SC Specifications. Under Windows, MacOS and Linux corresponding APIs could be found. Under Linux, pcsc-lite suit could be downloaded from http://www.linuxnet.com.
OpenCard Framework, OCF, is an object-oriented framework for smart card communications. OCF uses Java's inter-operability between environments to deploy architecture and APIs for application developers and service providers.
GlobalPlatform was formed in 1999 by organizations those were interested in issuing multiple application smart cards. The major goal of GlobalPlatform is to define the specifications and infrastructure for multi-application smart cards.
As you could understand from above, the standardization period of smart cards is not finished. The demand on smart cards is growing on the basis of end-user and developer. In my opinion, if you are a developer or in a decision making position, you should carefully analyse all the standards as well as the companies manufacturing smart cards. As a developers point of view, in the near future I think, Java will evaluate itself as the standard because of portability and cross-platform uses in spite of its slowness and fast evolution.