Health Information Resources formerly National Library for Health

EA TECHNICAL

NLH Enterprise Architecture: technical details

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What is a Service Oriented Architecture (SOA)?

The NLH enterprise architecture is based on the concept of Service Oriented Architecture (SOA), and web services. SOA is an architectural design style, whose goal is to reduce software barriers, and ensure interfaces allow different software services to interact effectively.

In terms of a software interface, a generic interface allows a descriptive, restrictive message to be sent to the service provider that is understood by the service provider. For example, SOAP Web services have messages that must be carried by the Simple Object Access Protocol (SOAP), and the description of the service must be described in the WSDLanguage (WSDL).

Key elements of the NLH enterprise architecture

There are three main types of information

• Framework (business process) models (points to Framework
• Abstract services
• Service bindings

The NLH enterprise architecture will consist of a set of "framework models" based around the core library business processes. The initial priorities of the NLH are:

• discovery to delivery
• identity and access management
• collections architecture frameworks

The Discovery to delivery business process. This is the key process in which the end user enters the system; surveys, discovers and obtains details of the required resource, and then requests the identified item, which is then delivered. An example would be an end user who enters a suite of bibliographic databases, surveys through searching the most appropriate database and discovers a relevant article. The user is then able to obtain information on the most appropriate copy of the article, which is then requested through linking to an ILL request form, and the user's local library then delivers a photocopy.

The Identity and access management process, describes how users identify themselves to the library service and how permission to access resources will be resolved.

The Collections architecture process, describes a logical, ie virtual, aggregation of documents, independent of source, which is available to an interface. A collection may consist of for example, systematic reviews, medicines information, information for patients, a collection of quality assessed journals, or community of practice reviewed collection of knowledge feeds.

Abstract services

Underpinning the delivery of the NLH enterprise architecture frameworks will be a set of components or "abstract services" which are used to deliver the business process described above.

The discovery to delivery framework will include the following abstract services which will support:

• Enter - entering the environment
• Survey - surveying the information landscape
• Discover - discovery of resources
• Detail - the selection of location and summary details
• Request - requesting of the resource
• Delivery - delivery of the requested resource

Identity management & Authentication (Enter). This abstract service determines whether the user "entering" the business process has the appropriate rights to use it, by providing a user registration and login service.

User preferences (Enter). This abstract service provides information about the identified preferences or profile of the user and their institutions so that choices can be presented.

Service Registry (Survey, All). This service provides metadata descriptions about business services and the content of available collections.

Terminology (Survey, Discover). This service provides the terminology related services, such as mapping a term from one controlled vocabulary to another, used to drive the search/browse interfaces.

Search/browse (Discover). This service accepts structured queries on collections and allows users to navigate the results.

Alert / current awareness service (Discover). This service provides information about alerts, feeds and updates on new resources.

Identifier Resolution (Detail). This "resolver service" takes Uniform Resource Identifiers (URIs) and returns information about the physical address and location of the resource. An NHS addressing framework is needed to ensure every information object in the NHS has an URI which is independent of the particular technology that is currently deployed.

Link Resolution (Detail, Deliver). This OpenURLs (Uniform Resource Locations) resolver accepts an item, encoded in the form of an openURL, and provides the end user with a set of links to delivery services to establish the most appropriate copy for delivery.

Document delivery (Deliver). This service allows the user to select the most appropriate copy, and select the preferred available delivery source. 

Metadata Scheme Registry (Discover). Provides information about the metadata schemas in use by other services to assist with disclosure and discovery.

This diagram indicates how the abstract services can be deployed as a "shared infrastructure" or "common information spine" that support end user interfaces, commercial indexers /aggregators and content providers.

A coherent and integrated user journey is desired. What the user sees as a web page and how results are  presented, will be separate from content and services, and owned and built by the NHS. Increasingly, the NHS will not want to purchase content locked into any single portal.