Web Services

Some of the current interfaces in health care, particularly financial interfaces, are still batch oriented. The majority of clinical system interfaces are point-to-point, using HL7 version 2-formatted messages. These are difficult to implement and maintain because the HL7 version 2 standard specifies format, but not the semantics of the data put into formatted areas. As a result, every interface in unique and it is sometimes impossible to overcome semantic differences in the meaning of data items as they exist in disparate systems.

HL7 version 3 specifications are based on the HL7 RIM object model and specify structure, semantics, and constraints on data to improve system interoperability. The HL7 standard also specifies XML implementations useful for processing transactions on the Web. The concept of HL7 EHR services that could be used generi-cally for any EHR to access data in any other EHR is in the early stages of analysis and design. It is, however, fundamental to true interoperability of clinical systems and medical devices and would facilitate tight coupling of systems via Web transactions (phase 3 in Fig. 8.6).

Full specification of HL7 version 3 Web services would streamline implementations of PSPAT by allowing the PSPAT workflow engine to more easily orchestrate behaviors across disparate health care systems

Fig. 8.6 Improved enterprise integration leads to enhanced interoperability, more access to critical functionality, lower implementation and maintenance costs, plug and play architectures, and more flexible and intelligent systems [21, 33]

and medical devices. Early work is underway jointly by HL7 and the Object Management Group [27], and a software factory implementation using the latest Visual Studio tooling has been specified by Microsoft [2].

The highest stage of interoperability (phase 5 in Fig. 8.6) would allow agents to implement goal-seeking behavior based on collaborative orchestration of higher-level services provided by one or more workflow engines [21]. These will be essential to future military systems now being prototyped using autonomous robots as surgeons [12].

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