and Public Key Infrastructure (PKI) will meet the core need of being able to securely send a message between identified, authorised parties. Web services When we connect one computer to another we “tell” it to “ask” the other for something. This request and response scenario isn’t necessarily kicked off by direct user command. Many computers are programmed to automatically connect to others and get or send information when specified events occur. When computers connect to each other they are networked. There are many ways of networking computers, and the most successful network (in terms of scalability, reliability, geographical coverage and sheer weight of numbers) is the Internet. The Internet is so successful because it is based on a very simple set of rules that any computer (no matter how weak it is or what operating system it uses) can easily implement. This simplicity comes with a price, but it also comes with many advantages and those advantages are slowly being worked out and exploited. The most important example is, of course, the World Wide Web. Just like the simple rules underlying the Internet, the web has its own set of very simple rules for computers networked to the Internet to transmit and store information. Web services is the term given to a collection of data formatting and Internet standards that together enable computers on the Internet to interact with each other (i.e. independent of direct human input). Some of these standards have been around for 20 years or more, some for only 10 years. Only this century has web services started to make an impact on the computing world, and increasingly it’s becoming an unstoppable force for solving data sharing problems. It has succeeded where other methods have failed. The web service standards aren’t all that mysterious. In fact, you probably use them every day. When you browse a web page, your computer is using an address (i.e. “http:// something.something.something/something_else) to connect to a computer somewhere and ask it for the information that it has stored at that address (i.e. a web page). Pretty much the same thing happens with web services. The address follows the same pattern (once again, it starts with “http://”). Only instead of a web page with text and images, the computer that is requesting information will receive text structured in a special way that it can “understand” and act upon. Some mock-up web services code is shown in Figure 1. NEHTA has chosen web services because it enables the interoperability that is so essential for e-Health. Moreover, it is flexible enough to cope with our current situation, an interim stage, and the final push towards full interoperability. NEHTA’s ultimate vision is for every health provider (from GP or specialist clinic to a large regional health service) to be able to directly connect with each other and exchange information. Health providers only need an Internet connection and NEHTA compliant software. PKI Secure messaging systems need to establish a user’s credentials (for identification and authorisation) and be able to audit the message. Web services technology by itself cannot perform these functions, and this is where PKI enters the picture. PKI works by providing all participating users a public and a private key to authenticate details. A full explanation of PKI is beyond the scope of this article, suffice to say that PKI requires a central body — currently Medicare Australia — to manage the issuing of public and private keys and for users to secure their private key and keep their details current. NEHTA have selected PKI for their solution because it is the only method in existence that can both prove identity and guarantee the integrity and provenance of a message. NEHTA is currently working with Medicare Australia to develop a certification body and structure (called NASH - National Figure 1 - A mockup of how a computer service might request another service and receive a response using web services. REQUEST

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