HL7 over HTTP

[HiraveBapu]

i am looking to accept HL7 messages over HTTP (WebAPI server) in .NET. any suggestions ? currently i am testing with sending HL7 over HTTP from hapiTestPanel to my .NET webApi application. Currently webapi application failed to accept messages or test panel failed to send over HTTP. Any suggestions ?

[nzcoward]

I know this is late... however, you can use the Hapi suggested spec for HL7 over HTTP with the correct header. I am including my solution - it's generic, so you'll need to have the correct handlers in the API server for each version, but it gets the IMessages into your controllers:

First you will need a MediaTypeFormatter:

    public class Hl7MediaTypeFormatter : MediaTypeFormatter
    {
        private static readonly Type _supportedType = typeof(IMessage);

        public Hl7MediaTypeFormatter()
        {
            SupportedMediaTypes.Add(new MediaTypeHeaderValue("x-application/hl7-v2+er7"));
        }

        public override async Task<object> ReadFromStreamAsync(Type type, Stream readStream, HttpContent content, IFormatterLogger formatterLogger)
        {
            if (readStream.Length == 0)
                return null;

            var parser = new PipeParser();

            var streamReader = new StreamReader(readStream);
            var messageContent = await streamReader.ReadToEndAsync();

            return parser.Parse(messageContent);
        }

        public override async Task WriteToStreamAsync(Type type, object value, Stream writeStream, HttpContent content, TransportContext transportContext)
        {
            var parser = new PipeParser();
            var encodedHl7 = parser.Encode((IMessage)value).Trim();

            var streamWriter = new StreamWriter(writeStream);
            await streamWriter.WriteAsync(encodedHl7);
            await streamWriter.FlushAsync();
        }

        public override bool CanReadType(Type type)
        {
            return _supportedType.IsAssignableFrom(type);
        }

        public override bool CanWriteType(Type type)
        {
            return _supportedType.IsAssignableFrom(type);
        }
    }

If you are using the WebApiConfig template, you add the MediaTypeFormatter for the config:

    public static void Register(HttpConfiguration config)
    {
            // Web API configuration and services

            // Web API routes
            config.MapHttpAttributeRoutes();

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );

            config.Formatters.Add(new Hl7MediaTypeFormatter());
    }

Then you can have your controller accept IMessage parameters in its actions:

    public class MyController : ApiController
    {
        public IMessage Post([FromBody] IMessage message)
        {
                //... do something with your message
        }
    }

All you need to do is ensure that your HTTP headers in the request have the Content Type of x-application/hl7-v2+er7.

[yoliva]

We used the approach suggested in hapi-hl7overhttp in our asp.net core project and works great. take a look at their specification.