ToC+RI+Detailed+Component+Design

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=Transition of Care and Laboratory Results Interface Transformation Engine Conceptual Design=

Introduction
This document presents a conceptual design for a clinical data transformation subsystem to be used as part of the implementation of the Transition of Care (ToC) and Laboratory Results Interface (LRI) initiatives currently under development by the Standards and Interoperability Framework (the Framework) under the auspices of the Office of the National Coordinator for Health Information Technology (ONC) as part of the Nationwide Health Information Network (the Network).

This conceptual design is based upon the work of the Standards & Interoperability Framework’s Transitions of Care Work Group based at Transitions of Care (ToC) Initiative.

Use Cases
The following diagram summarizes initial transactions targeted for the ToC and LRI product initiatives. This is an abstract of the use case documentation presented at ToC Use Case & Requirements (UCR) WG.



Architecture
This design is based upon the software system architecture expressed at ToC RI Arch Overview



Separation of Concerns
This design takes account of the general design imperative to avoid entangling different concerns within a given component. In particular, the transformation subsystem is separated from the details of any particular business use case and from the specifics of the Reference Implementation architecture. This is done by designing a general-purpose transformation engine with no knowledge of nor dependencies on


 * Electronic Health Record (EHR) storage and retrieval methods,
 * details of data transport mechanisms, or
 * business processing other than data format transformations.

The design also separates the details of any particular data format from the mechanics of validating or transforming data. Whether the format represents one of the standards or an arbitrary format native to the hosting Health Information Organization (HIO), the mechanics of validating formatted data and transforming data in one format into its equivalent in another format are discrete from the details of the format being used. This separation is accomplished by designing the transformation subsystem to rely upon the Data Integration Reference Library (DIRL) to provide the machine-readable definitions of what constitutes a valid instance document in all formats known to the HIO.

Components
The **DIRL** corresponds to the Data Elements and Data Structural layers defined in the Transitions of Care Reference Implementation Architecture Description. It will be a product of the ongoing effort to standardize on a few universal document formats and to account for various proprietary and locally developed formats. The DIRL will provide XML Schema Documents (XSDs) and Extensible Stylesheet Language Transformations (XSLTs) specifying the standard eXtensible Markup Language (XML)-based document types, and other mechanisms as appropriate to cover non-XML-based document types.

The **transformation subsystem** corresponds to the Data Element Services layer of the architecture. The subsystem will use the resources provided by the DIRL to guide the parsing and validation of input data and the transformation and validation of output data. The subsystem is to be invoked by components of the Transitions of Care Orchestration layer.

The following diagram illustrates the transformation subsystem and its relationships to the DIRL and to a generic business use case controller (orchestration layer), which in reality could be for ToC, LRI, or another transaction type requiring data format transformation. The plan is to leverage existing open source products to provide the majority of the Enterprise Service Bus (ESB) and connector framework, so priority efforts can be focused on validators, transformer subsystem, and the DIRL.



Subsystem Details
The core of the transformation subsystem will comprise four types of components.


 * **Input parsers** will analyze input data into Clinical Information Model (CIM) document segments (data elements) and their relationships.
 * **Output generators** will encode CIM document segments and their relationships according to the specification governing the target data format.
 * **DIRL interfaces** will interact with the DIRL to retrieve and prepare the data format specifications for use.
 * A **conversion mapping agent** will use the parameters passed into the subsystem to orchestrate the functions of the other components to digest and validate the input data and to generate the required output data using the resources offered by the DIRL.

The following diagram illustrates the proposed component architecture for the transformer subsystem, along with a conceptual high-level document structure, which is intended to illustrate the potential structure of documents in support of ToC and LRI transactions as currently understood.

Prototyping and research is currently underway to confirm the viability of these models, along with an additional level of detailed design.



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