The purpose of the Shared Health Record software implementation is to provide a centralized repository for storing health data; with the goal of facilitating health information exchange among client systems. In line with the direction of the OpenHIE project, of which it is a part of, the OpenSHR does not aim to be a project specific implementation of a Shared Health Record, but rather it aims to provide a framework and several core software components that can be used to implement a specific SHR.

This document will focus on the high level architectural design for the OpenSHR. Please refer to this document for the OpenSHR requirements. The requirements themselves will be considered concluded within the scope of this document. For the Shared health Record component we have decided to make use of OpenMRS as the core technology to built off. The review process that we went through is described in in the tool recommendation document. This design document will describe the modifications needed to allow OpenMRS to be used as a SHR for OpenHIE.

To design a Shared health Record (SHR) around the OpenMRS platform, we will need to modify OpenMRS to be able to perform the functions of a SHR. Some of the key changes that we will need to make are as follows:

• Support the storage of unstructured data eg, documents such as CDA level 1 - 3
• Remove the user interface so the SHR can run as a headless service (separate the service layer from the UI layer)
• Add standards based interfaces to interact with the SHR eg, add endpoints for XDS.b + CDA or profiled HL7v2
• Add mechanisms for processing, storing and querying structured and unstructured data within OpenMRS
• Add hooks at various stages of data lifecycle for things like clinical decision support or data validation.
• Make sure everything can be mapped to as encounter-based domain model
• Allow the OpenMRS SHR to scale horizontally
• Modify the database for performance based on the SHR use case
• Modify required fields to suit a SHR

In the sections that follow we will explain these in more details and give a design of how these can be accomplished within OpenMRS.

Overview

The following diagram describes the overall architecture of the components that enable OpenMRS to act as a SHR.

In the initial version of the SHR we would like to be able to revive data in 2 different message formats:

1. CDA document
2. HL7 messages
   

We acknowledge that we would like to support CDA as the primary exchange format however we would also like to support a minimal set of HL7 v2 processing to allow legacy applications to send data in this format until such time as they are able to make use of CDA.

In this initial version we would also like to support 2 different interfaces on which the data can be received:

1. The XDS.b IHE profile - this would be the entry point for CDA documents and the primary standards based interface to receive clinical information.
2. A simple REST interface - this would be a simple entry point to receive HL7v2 or CDA documents on.

Basic architecture

The basic architecture for allowing OpenMRS to become a SHR is to provide a number of modules that expose the interfaces that we need of the SHR and allow us to process the message formats received and store these in the OpenMRS data model. Also, these module must allow data to be retrieved from OpenMRS and formatted in these standardised message formats in the case where data need to be queried by clients.

In order to do this we have 3 different types of modules:

1. Interface modules - these modules provide the service interfaces to send a receive information using a particular standardised interface.
2. Content handler module - this module forwards received data to the appropriate processing module so that it can be stored.
3. Processing modules - these modules provide functionality to interpret data in  particular format and store and retrieve this from OpenMRS's data model.

We also consider monitoring as a first class citizen and a module to monitor how the SHR is performing is required. All other module are expected to report monitoring data to this module.

Interface Modules

XDS.b interface module

This module provides an XBS.b interface into OpenMRS. It is expected to receive an type of document payloads over the XDS.b interface and pass those on to the content handler with the content type of the payload.

REST interface module

This module is expected to provide a RESTful interface for receiving and querying HL7 v2 messages as well as CDA documents. It will pass the received data on tot he content handler with the content type of the payload.

Content Handler Module

This module receives data from the interface handler along with the content type of that data. Using this information it is expected to forward data to the appropriate processing module that can handle that data. It is also required to have functionality to allow processing module to be able to register and de-register their interest to data of particular content types dynamically.

Processing Modules

CDA Processing module

The CDA processing module is expected to be able to process CDA documents and store these within OpenMRS's data model. It should also provide functions to retrieve information from OpenMRS and construct this as a CDA document as required.

HL7 v2 Processing module

The HL7 v2 processing module is expected to be able to process HL7 v2 message and store these within OpenMRS's data model. It should also provide functions to retrieve information from OpenMRS and construct this as a HL7 v2 messages as required.

Unstructured data processing module

The unstructured data processing module is expected to be able to process an other data that cannot be interpreted by any of the other processing modules. It is expected to be able to strore and retrieve data as-is in blob form. This module is useful for handling unstructured information such as images or pdf's but may be able to store any information that cannot be stored in another manner.

Metric and Monitoring Module

This module provides services to other modules that allow them to store specific metrics about the functions that they perform.

Additional OpenMRS Modifications

In addition to the creation of these modules there are some changes that we would like to make to OpenMRS itself:

• Remove the requirement to have to store patient names and dob as we would only want to store a patient identifier for a SHR
• Performs database modifications to improve performance for SHR functionality
• Add data lifecycle hooks for certain processes to hook into (for example clinical decision support functionality)
• Enable OpenMRS to be able to scale horizontally

Older notes:

Support unstructured data

Due to the need to manage document based (unstructured) data, we are interested in considering alternative methods other than just traditional RBDMS databases for the SHR.

Separate UI from service layer

TODO

Initial ideas:

OpenMRS already exists as two separate maven projects, one containing the view layer and one containing the service layer. Can OpenMRS already be deployed with just the service layer? We will need to check this with the OpenMRS devs.

Add standards-based interfaces

TODO

Initial ideas:

These could be added as modules, one per standard interface supported.

Process and store standards-based data

TODO

Initial ideas:

This logic could be stored in the module alongside the standard-based interface code.

Data lifecycle hooks

TODO

Initial ideas:

We could use hibernate interceptors or AOP to accomplish this.

Make sure everything can be mapped to as encounter-based domain model

TODO

Initial ideas:

TODO

Allow the OpenMRS SHR to scale horizontally

TODO

Initial ideas:

TODO

Modify the database for performance based on the SHR use case

TODO

Initial ideas:

TODO

NOTE :

If you're an OpenMRS developer who is new to OpenHIE, and want a quick refresher, or if if you're interested in reading up on these topics in depth, please refer to OpenMRS as the SHR design document : A quick introduction for OpenMRS developers