The three common requirements that drive interoperability outlined in this chapter allow us to introduce two concepts that will help you select the correct technology for developing solutions. These technology options will make up Parts II and III of the book.
After working through the requirements, you might have guessed that the two interoperability concepts that can be derived from them are point-to-point interoperability and resource tier interoperability . Let's define these terms before we start looking at technical options.
Point-to-point interoperability covers the main points of connecting components discussed in this book. These points of interoperability are the .NET presentation tier to the J2EE business tier, the J2EE presentation tier to the .NET business tier, and the .NET business tier to the J2EE business tier and vice versa. These lines of connectivity are shown in Figure 2.11.
As you'll see when we start exploring the technical options for point-to- point interoperability in Part II, "Interoperability Technologies: Point to Point," the connectivity tends to be between two single points and, although it's not exclusively the case, it's often a synchronous call ”in other words, the calling component waits for a response from the other system. The point-to-point interoperability options we'll cover are .NET Remoting and XML Web services.
Resource tier interoperability covers the other connectivity points outlined in our requirements. These points connect the two platforms' business tiers to each of the resource tiers, as well as to the database, the message queue, and the broker, as shown in Figure 2.12.
When we cover the technical options for resource tier interoperability in Part III, "Interoperability Technologies: Resource Tier," these calls tend to be arbitrated (handled by the third party in the resource tier) and mostly asynchronous (meaning that data is sent to the resource tier without the expectation of an immediate reply). These options will include a shared database, message queue, and broker.