1 XML Web Services Practical Implementations Bob Steemson Product Architect iSOFT plc

2 THE HEALTH iNNOVATOR Introduction i.Express Systems Integration (ESI) i.Express CHI Interface National Programme for Information Technology Questions

3 THE HEALTH iNNOVATOR i.Express Systems Integration Modern external interface to i.Express Based on XML and Web Services Builds on existing i.Express business objects and Systems Integration Toolkit (SIT) Allow services to be added incrementally Flexible configuration (based on XML)

4 THE HEALTH iNNOVATOR Support for Trigger Messages “Pull” service available now “Push” service under development (v12) Two possible data formats –Current data at the time of requesting –Before and after images of data at the time of event –Both utilise same code as related enquiry services

5 THE HEALTH iNNOVATOR Web Server(IIS) Request Handlers Express Systems Integration Architecture Database VB Objects ASP Pages Browser (IE5.5) ESI Frame work Request Handlers Request Handlers SOAP 3 rd Party Application Trigger Log Log Handler

6 THE HEALTH iNNOVATOR ESI Architecture ESI Framework –Single Entry Point passing credentials, target account, interface name and request type –Input and output data transmitted as XML –Security, Validation, Transformations, Lookups, Exceptions –Dynamically Configured using XML Files Request Handlers –Called from framework using exposed interfaces –Tightly coupled to Express Business Objects –Handlers can call other services internally –New services added as required –Special handler for trigger log messages ESI Unit Test Suite –Tests all ESI services with a single report produced –Tests configured using XML files

7 THE HEALTH iNNOVATOR Schemas Services use proprietary (iSOFT) schemas –Aligns services to the Express data set –Avoids issues with reference files and coded fields Similar to NHSiS Schemas –Can use XSLT to match NHSiS schemas exactly Many services are already available Further services are being developed as required –i.Express v12 will integrate iSOFT Clinical Manager

8 THE HEALTH iNNOVATOR Tools Used Developed using Visual Basic 6 –MSXML v4 (Validating Parser, DOM, XSLT) –MS SOAP Toolkit v2 (ISAPI, WSDL, test clients) ESI Web Services –Configuration held as XML documents Interactive Test Program –Load a request document from disk –Edit request document if necessary –Call service and display response Integrated Test suite –Tests defined as XML documents –Tests may be constructed from sub-tests

9 THE HEALTH iNNOVATOR What would I change? Pass request and response documents as DOM elements rather than strings Further separate security credentials from other parameters Develop a GUI configuration utility

10 THE HEALTH iNNOVATOR i.Express CHI Interface Web Service client to access external Web Service Web Service proxy accessed from ASP pages Maintains configuration and logon state information on host database Automatically logs on as required

11 THE HEALTH iNNOVATOR i.Express CHI Interface Architecture ASP Page Configuration “Factory” Creates Configuration & State Information Reads Request Message Writes Configuration Objects Creates CHI Proxy Response Message Reads SOAP Toolkit CHI Service NHS Net

12 THE HEALTH iNNOVATOR Tools Used Developed using Visual Basic 6 and ASP –MSXML v4 (Validating Parser, DOM, XSLT) –MS SOAP Toolkit v3 (SOAP client) Uses XSLT to convert from and to external XML –Simplifies serialisation and deserialisation Simple Emulator for test purposes –Written using VB6 and MS SOAP Toolkit –.NET wrapper to solve namespace issues Database components written in Data/Basic Configuration using ASP pages

13 THE HEALTH iNNOVATOR What would I change? Should have tested over HTTPS in-house –Everything worked, except that the server certificate was loaded in the wrong store –Difficult to diagnose on-site Emulator was a bit too simple –Namespaces issue was only apparent late in development

14 THE HEALTH iNNOVATOR National Program for IT - Requirements Interfaces to existing laboratory application Connect to integration hub using web services Supports HL7 v3 (XML) messaging Applications use “flat file” interface Needed yesterday!

15 THE HEALTH iNNOVATOR National Programme for IT - Solution.NET Web service to accept request from hub with HL7 message and write details as flat file.NET NT service to monitor for flat file, convert data to HL7 results message and pass to hub web service Make use of.NET XML Support where possible –Automatic creation of classes from XSD Schema –Object serialisation and de-serialisation using XmlSerializer class –Builds on ideas developed for CHI Interface

16 THE HEALTH iNNOVATOR Laboratory System Wrappers Integration Hub.NET Web Service.NET NT Service Order File Results File Laboratory System XML Order SOAP Flat File Order Writes Flat File Order Reads Flat File Results Writes Flat File Results Reads XML Results SOAP

17 THE HEALTH iNNOVATOR Development – Order Message Start with HL7 v3 message specified by NHS IA Create XSL to extract relevant data into a flatter XML document with no namespaces Create an XSD schema to describe XSL output XSD.EXE creates C# message classes from the XSD Write additional C# code: –Apply XSLT to input document –Use XmlSerializer to read transformed XML into message –Extract data from message objects and write to flat file

18 THE HEALTH iNNOVATOR Development – Results Message Create XSD schema for flatter XML document with results data Create XSL to transform this into HL7 v3 format specified by NHS IA XSD.EXE creates C# message classes from the XSD Write C# code –Read data and initialise message objects –Use XmlSerializer to serialise these as XML –Apply XSLT to generate HL7 v3 output

19 THE HEALTH iNNOVATOR Tools Used Visual Studio.NET 2003 –C# programming language - could have used VB.NET –Standard web service support –Standard web services client –XSD.EXE to generate message classes –Standard XML support classes including XmlSerializer XSLT Used to transform to and from HL7 v3 –Internal “flatter” XML that can be automatically serialised and deserialised

20 THE HEALTH iNNOVATOR Summary Three different implementations of web services Show both server and client ends Both VB6 and.NET (C#) development ESI – designed for future extensibility CHI Interface – limited scope to handle small number of request types NPfIT – rapid development requirements

21 THE HEALTH iNNOVATOR Questions Contact Details