Technical Interoperability of Disparate Systems - An Electronic Health Record (EHR)-Centric System Implemented with a Service-Oriented Architecture

The independent organizations (a.k.a. silos) shown in Figure 1 typically implement their business processes on different computer systems (Unix, Windows, mainframes), on different platforms (J2EE, .NET) and with different vocabularies. Yet, they all need to communicate in a way that serves, in this case, a trauma victim at the time of his or her emergency, researchers who will later study cohorts of this trauma victim, and sundry others (most of whom are not shown in the simplified model).

This post will discuss an Electronic Health Record (EHR)-centric system implemented with a Service-Oriented Architecture (SOA) -- the business industry’s de facto standard for interoperability. The functions of this system are data collection, management and distribution for both the immediate situation and long term health care experiences.

I’ll address some of the challenges (and opportunities) of technical interoperability, holding off ‘til later posts any discussion of semantic interoperability.

Note: This rather lengthy post is not and is not meant to be a palimpsest on SOA. But, I have included a number of references (links to references) for anyone looking for a more detailed account of this topic.

Figure 1

Figure 2 shows a traditional implementation of the system shown in the use case drawn in Figure 1. When a change -- virtually any change -- is made in one part of this interconnected system, the overall system usually stops working, until system-wide adjustments are made. In short, the figure below shows a system that’s “hard wired.”

Note: For simplicity, these figures and this discussion omit a number of real-world details: for example, the voice communication often employed by police and EMS teams.

Figure 2

To remedy this problem, a new architecture, that of Service-Oriented Architecture (SOA), was devised. An SOA implementation of the system shown in the use case is outlined in Figure 3. At first glance, the SOA-based system might seem more complicated than the system shown in Figure 2. But, as the following discussion will attempt to show, it isn’t.

Figure 3

Note: The major part of this post will be based on a Web services implementation of SOA. However, before concluding this post, I’ll address the oft-heard view that SOA is now “dead.” SOA is indeed alive and kicking in many organizations.

The system in Figure 2, if fleshed out, would move toward becoming the fully connected system shown below (in practice, very few systems are fully connected). In such a system of computer applications, when one node is changed, all other nodes that connect to it would need a new interface to the changed node.

As shown, in a fully connected network with n nodes, there are n x (n-1) / 2 direct paths. That means 15 connections for 6 nodes, 45 connections for 10 nodes, etc.

In contrast, each node in the system in Figure 3 has only one connection – that to a bus, as represented in the figure below.



Service-Oriented Architecture

SOA relies on services exposing their functionality via interfaces that other applications and services can read to understand how to utilize those services.

This style of architecture promotes reuse at the macro (service) level rather than micro (classes) level. It can also simplify interconnection to – and usage of – existing IT (legacy) assets.

Designers can implement SOA using a wide range of technologies, including SOAP, REST, DCOM, CORBA, or Web Services. (I gave a brief overview of DCOM, CORBA and Web Services in my June 16 post and will discuss REST below.) The key is independent services with defined interfaces that can be called to perform their tasks in a standard way, without a service having foreknowledge of the calling application, and without the application having or needing knowledge of how the service actually performs its tasks.

Albeit in the distant past, I’ve used the Oracle SOA Suite to federate a unified system out of the disparate systems shown in the figures.

This suite, which includes JDeveloper, a robust Java IDE, is by no means the only solution; there are others, both proprietary and open source! For example,

Proprietary: http://i.zdnet.com/whitepapers/cape_clear_Principles_of_BPEL.pdf

Open source: http://orchestra.ow2.org/xwiki/bin/view/Main/

However, the Oracle SOA Suite is a complete set of service infrastructure components for creating, deploying, and managing services. It enables services to be created, managed, and orchestrated into composite applications and business processes. Additionally, you can adopt it incrementally on a project by project basis and still benefit from the common security, management, deployment architecture, and development tools that you get out of the box.

This Suite is a standards-based technology suite that consists of the following:

* Oracle BPEL Process Manager to orchestrate services into business processes
* ESB to connect existing IT systems and business partners as a set of services
* Oracle Business Rules for dynamic decisions at run time that can be managed by business users or business analysts
* Oracle Application Server Integration Business Activity Monitoring to monitor services and disparate events and provide real-time visibility into the state of the enterprise, business processes, people, and systems.
* Oracle Web Services Manager to secure and manage authentication, authorization, and encryption policies on services that is separate from your service logic
* UDDI registry to discover and manage the life cycle of Web services.
* Oracle Application Server that provides a complete Java 2, Enterprise Edition (J2EE) environment for your J2EE applications.

For an overview of the soon-to-be-released Version 11, see

http://www.oracle.com/technology/products/ias/bpel/techpreview/2008-05-01-whats-new-in-oracle-soa-suite-tp4.pdf

Business Process Execution Language (BPEL)

One of the key standards accelerating the adoption of SOA is Business Process Execution Language (BPEL) for Web Services. BPEL enables organizations to automate their business processes by orchestrating services (thus enabling developers to build end-to-end business processes spanning applications, systems, and people in a standard way). Existing functionality is exposed as services. New applications are composed using services. Services are reused across different applications. Services everywhere! For an account of Orchestration versus Choreography, see

http://www.oracle.com/technology/pub/articles/matjaz_bpel1.html

BPEL has emerged as the standard for process orchestration enabling you to build end-to-end business processes spanning applications, systems, and people in a standard way.

In the next figure, I show two pallets of drag-and-drop components available in version 10.3 of the SOA Suite for the development of a BPEL process. Version 11 will be availability shortly.

Introduction to the JDeveloper BPEL Designer

http://download-west.oracle.com/docs/cd/B31017_01/core.1013/b28938/design.htm#CHDIJCGH

Enterprise Service Bus

An Enterprise Service Bus (ESB) is an architectural pattern, not a software product. Different software products can form an ESB. In some cases, companies use multiple products in different areas, leveraging specific functionality to meet their unique requirements. These different products can be federated together as the realization of the ESB pattern.

In the next figure, I show two pallets of drag-and-drop components available in version 10.3 of the SOA Suite for the development of an ESB. As I mentioned earlier, Version 11 will be availability shortly.

Introduction to the JDeveloper ESB Designer

http://download-west.oracle.com/docs/cd/B31017_01/core.1013/b28938/design.htm#CHDIBCCC

Figure 3 introduced Business Activity Monitoring (BAM) and Business Rules to the architecture

Business Activity Monitoring – BAM satisfies a growing need to enable health care executives, and more specifically operations managers, to improve their decision-making processes by first getting a real time view of the business events occurring in their enterprise, and second using the derived intelligence to analyze and improve the efficiency of their business processes.

Understanding Business Activity Monitoring in Oracle SOA Suite
http://www.packtpub.com/article/business-activity-monitoring-in-oracle-soa-suite

Business Rules – Business Rules is one of the newer technologies (typically run from an application server) and is designed to make applications more agile. A business analyst can change business policies expressed as rules quickly and safely with little or no assistance from a programmer

Using Business Rules to Define Decision Points in Oracle SOA Suite

Part 1. http://www.packtpub.com/article/business-rules-define-decision-points-oracle-soa-suite-part1

Part 2. http://www.packtpub.com/article/business-rules-define-decision-points-oracle-soa-suite-part2

For detailed coverage of the Oracle Service Bus, BPEL Process Manager, Web Service Manager, Rules, Human Workflow, and Business Activity Monitoring. See

Oracle SOA Suite Developer's Guide
http://www.packtpub.com/developers-guide-for-oracle-soa-suite-10gr3/book

and

Getting Started With Oracle SOA Suite 11g R1 – A Hands-On Tutorial
http://www.packtpub.com/getting-started-with-oracle-soa-suite-11g-r1/book

When designing an SOA solution, it's not always clear whether you should use a Web services BPEL process or an ESB mediation flow (or both).

http://www.ibm.com/developerworks/websphere/library/techarticles/0803_fasbinder2/0803_fasbinder2.html

Building Event-Driven Architecture with an Enterprise Service Bus

http://www.oracle.com/technology/pub/articles/jellema-esb.html

Software frameworks

You should keep in mind that interoperability issues between platforms can arise when switching from one protocol to another and one software framework to another. Some examples include SOAP, REST, the .Net Framework, Enterprise Java Beans (EJB), and Java Messaging Service (JMS).

.Net Web services running over HTTP can be called in three different ways: HTTP GET operation, HTTP POST operation, and SOAP. The GET and POST operations are useful if you need to call a Web Service quickly and no SOAP client is readily available. You can use REST to perform GET, POST, PUT, and DELETE operations over the HTTP in a Perl script. In this script, you can specify SQL queries and simple message queues.

For a discussion of SOAP/REST in the .NET (Visual Studio 2008 SP1) ecosystem, see

http://www.pluralsight.com/community/blogs/scottallen/archive/2008/08/11/visual-studio-sp1-and-the-metification-of-rest.aspx

and

http://msdn.microsoft.com/en-us/library/dd203052.aspx

Often, services within an organization’s firewall are REST-based, while 3rd party partners use a mix of SOAP and HTTPS protocols to access their public services. By using REST for internal services, organizations are avoiding some of the overhead that the WS-* standards introduce.

If the SOAP client is available, here's how to make a simple choice between REST and SOAP. If the application is resource-based, choose REST. If the application is activity-based, opt for SOAP. Under REST, a client might request that several operations be performed on a series of resources over the HTTP. For SOAP-based requests, only one invoke operation is needed for each activity-oriented service that a client might request be performed.

REST requests do not depend on WSDL as SOAP requests do. Yet, REST and SOAP can co-exist as requests from a composite Web service application to an external Web service.

When to use REST based web services?

http://oracled.wordpress.com/2009/03/11/when-to-use-rest-based-web-services/

When Web services are outside the control of the organization (as in the figures at the top of this post), you need to ensure that they can interoperate externally with one another with respect to shared semantics and contractual obligations. Semantic misunderstandings and contractual loopholes contribute to interoperability problems between external enterprise Web services. Future posts will focus on these aspects of interoperability.

For presentations that includes the pros and cons of different protocols (SOAP and HTTP) and software frameworks (.NET and J2EE), see

http://www.esri.com/events/devsummit/pdfs/keynote_chappell.pdf

and

http://www.esri.com/events/devsummit/sessions/keynote.html

The oft-heard view that SOA is now “dead”

Once thought to be the savior of IT, SOA instead turned into a great failed experiment -- at least for many organizations. SOA was supposed to reduce costs and increase agility on a massive scale. In many situations, however, SOA has failed to deliver its promised benefits.

Yet, although SOA is understandably purported to be dead by many, the requirement for a service-oriented architecture is stronger than ever.

Adopting SOA (i.e., application re-architecture) requires disruption to the status quo. SOA is not simply a matter of deploying new technology and building service interfaces to existing applications; it requires redesign of the application portfolio. And it requires a massive shift in the way IT operates. The small select group of organizations that has seen spectacular gains from SOA did so by treating it as an agent of transformation. In each of these success stories, SOA was just one aspect of the transformation effort. And here’s the secret to success: SOA needs to be part of something bigger. If it isn’t, then you need to ask yourself why you’ve been doing it.

The latest shiny new technology will not make things better. Incremental integration projects will not lead to significantly reduced costs and increased agility. If you want spectacular gains, then you need to make a spectacular commitment to change.

Note: As of 2008, increasing numbers of third-party software companies offer software services for a fee. In the future, SOA systems may consist of such third-party services combined with others created in-house.

More on this can be found in “WOA: Putting the Web Back in Web Services.”

http://blogs.gartner.com/nick_gall/2008/11/19/woa-putting-the-web-back-in-web-services/

Also, here’s a link to one of my earlier articles on SOA

“The Economic, Cultural and Governance Issues of SOA”

http://www.cioupdate.com/reports/article.php/11050_3652091_1/The-Economic-Cultural-and-Governance-Issues-of-SOA.htm

Interoperability of Disparate Systems ...

A system that includes new and old technologies -- partially represented by the use case diagram shown below -- will be the subject of upcoming posts. Interoperability -- technical and semantic -- using open, standard protocols will be my focus.



{double click for larger view}

For anyone not familiar with use case diagrams, here's a link to an easy-to-follow introduction to using them and another link to the Wikipedia entry for use case diagrams.

The discussion of technical interoperability will include, but not be limited to, whether to employ Web services with BPEL or ESB (or both) and business activity monitoring (BAM) tools.

The discussion of semantic interoperability will include, but not be limited to, whether to employ HL7 version 3 messages or CDA documents (or both).

Other topics such as service level agreements (SLA), key performance indicators (KPI), telemetry, and telemedicine will be included.

Electronic Health Records (EHR) – Interoperability of Disparate Systems – Technical

As the title suggests, this post, the first in a series of continuations of my June 13 post, is about the technical aspects of interoperability. For your convenience, I’ve copied the figure below from the earlier post.




The word "interoperability" means different things to different people. To DBAs, for example, the ability of SQL Server, Oracle and DB2 to recognize each other’s commands is a sign of the interoperability of these databases. In the current post, however, I'll focus primarily on a distributed computing model that is capable of cross-platform and cross-programming language interoperability, Web services. In the process, I'll compare Web services with a couple of its predecessors, CORBA and DCOM, which are still being used widely.

Why CORBA and DCOM success is limited

Although CORBA and DCOM have been implemented on various platforms, the reality is that any solution built on these protocols will be dependent on a single vendor's implementation. Thus, if one were to develop a DCOM application, all participating nodes in the distributed application would have to be running a flavor of Windows. In the case of CORBA, every node in the application environment would need to run the same ORB product. Now there are cases where CORBA ORBs from different vendors do interoperate. However, that interoperability generally does not extend into higher-level services such as security and transaction management. Furthermore, any vendor specific optimizations would be lost in this situation.

Both these protocols depend on a closely administered environment. The odds of two random computers being able to successfully make DCOM or IIOP calls out of the box are fairly low. In addition, programmers must deal with protocol unique message format rules for data alignment and data types. DCOM and CORBA are both reasonable protocols for server-to-server communications. However, both they have severe weaknesses for client-to-server communications, especially when the client machines are scattered across the Internet.

CORBA overview

Common Object Requesting Broker Architecture (CORBA) provides standards-based infrastructure for interactions between distributed objects. It allows software components running on dissimilar hardware, hosted on different operating systems, and programmed in different programming languages to communicate, collaborate, and perform productive work over a network.

A CORBA system accomplishes this magical task by confining the interaction between objects to well-defined interfaces. To use the service of a distributed object, you must interact with it through the interface. How the interface is implemented -- or even where it is implemented -- is not known and doesn't have to be known by the client. The figure below illustrates the workings of a typical CORBA system.

Object interactions in CORBA




Achieving location transparency

In this figure, the client code makes use of a server object through its interface. In fact, the interface is implemented by a stub object that is local to the client. As far as the client can tell, it's only interacting with the local stub object. Under the hood, the stub object implements the same interface as the remote server object. When the client invokes methods on the interface, the stub object forwards the call to a CORBA component called the Object Request Broker (ORB). The calling code in the client does not have to know that the call is actually going through a stub.

DCOM overview

Distributed Component Object Model (DCOM) is a Microsoft proprietary technology for software components distributed across several networked computers to communicate with each other. However, it has been deprecated in favor of the Microsoft .NET Framework, which includes support for Web services.

Internet poses problems for CORBA and DCOM

DCOM was a major competitor to CORBA. Proponents of both of these technologies saw them as one day becoming the model for code and service-reuse over the Internet. However, the difficulties involved in getting either of these technologies to work over Internet firewalls, and on unknown and insecure machines, meant that normal HTTP requests in combination with web browsers won out over both of them.

Web services overview

Web services specifications such as SOAP, WSDL, and the WS-* family are currently the leading distributed computing standards for interfacing, interoperability, and quality of service policies. Web services are often called "CORBA for the Web" because of their many derivative concepts and ideas.

There are several ways to think about Web services when building applications. At the most basic level it is an advanced communications protocol family allowing applications to talk to each other. This level has progressed quite significantly over the past few years with many tools (e.g., Oracle’s JDeveloper and Microsoft's Visual Studio) that allow software developers to write interacting Web services and build complex applications. This level is often characterized by direct one-on-one interactions between services or relatively few services interacting with each other.

SOA overview

However, just using Web services as a communications protocol belies its true power, that of the service-oriented architecture (SOA). The SOA describes an entire system of services dynamically looking around for each other, getting together to perform some application, and recombining in many ways. This model encourages the reuse of technology and software that evolves the way applications are designed, developed and put to use. It brings the world of distributed computing to a closer reality. At this level software developers need to think of the SOA model and design their distributed application across the model. This level is characterized by the use of technologies to allow distributed communications of services such as the use of an Enterprise Service Bus (ESB), which is a common distribution network for services to work with. More on ESB in an upcoming post.

Finally, the highest level is to look at this SOA model and the many component services as building blocks that can be assembled in whole sections into full applications instead of the traditional method of writing line after line of code. By examining the connecting interfaces, we can build whole applications without ever really writing code. For that matter direct code may even get in the way since the services may be written in numerous different languages and platforms. The blocks can be put together into a workflow of operations that define how the application performs, and other tools can be used to monitor the effectives of the workflow at each service or group of services. At this level, developers can put away the use of regular programming languages and work in a Model-Driven Architecture that helps them to build applications more accurately to a design. More on workflow in an upcoming post.