Trustworthy: j/xfs Introduction, 2nd part

As I discussed in the first part of the two-part series, the expansion of the Java platform's financial Services (J/XFS) is an international standard that can be used to define a clear interface for the many components that represent a piece of banking hardware. These components are called device services and can be plugged into the J/XFS system. The J/XFS environment, represented by the J/XFS kernel, treats device services as separate, internally variable parts.

In this article, you will learn a key part of the device services for developing banking under J/XFS. By the end of the discussion, you will understand:

Basic concepts and requirements for the development of equipment services under J/XFS

Reference implementation (J/XFS-oriented financial device interface) packages and documents are arranged

How FDI for J/XFS can support you when developing device services from the Java platform

If you haven't seen the first article in this series, I recommend that you read the first article before you start reading this article.

Development of equipment Services: Basic Concepts

The device service in J/XFS is a Java object that controls a particular hardware device. The application does not send messages directly to the device service object. Instead, they send an action request message to the J/XFS kernel, which ensures that the message reaches its destination in turn. As you can see from Figure 1, it is usually the kernel that invokes the method on the device service object.

Figure 1. J/XFS Device Service Message Flow: from application to hardware

The response is the same as the way it was sent back to the application. The device service object never sends messages directly to the application. Instead, the device service object sends the message to the kernel and the kernel sends the message to the appropriate receiver. Figure 2 illustrates how the device service reports to the application that the hardware has changed state.

Figure 2. J/XFS Device Service Message flow: from hardware to application

This system can be well served by the J/XFS device service developer. Because typically the device service object communicates with the J/XFS kernel, all you have to do is follow some basic concepts and implement the appropriate device service interface. In the following sections, I will outline the basic concepts that you must understand and follow when developing device services under J/XFS.