XmlHttpRequestProcessorBuilder Class

The request-processing functionality of XmlHttpRequestProcessor is defined by the processing components it uses internally. To create an XmlHttpRequestProcessor with default out-of-the-box functionality, simply create an instance of this builder class and call Build. Or you can customize the the request-processing functionality by setting custom processing components before calling Build()...

Providing custom processing components

There are two main ways that you might want to provide custom processing components:

First, you might want to provide a component that you have created or downloaded. For example, here's how to create an XmlHttpRequestProcessor with a custom IHttpRequestDispatcher called customHttpRequestDispatcher (which we're assuming you have already created):

XmlHttpRequestProcessor.Builder builder =
        new XmlHttpRequestProcessor.Builder(accountKey, securityKey);
builder.SetHttpRequestDispatcher(customHttpRequestDispatcher);
IRequestProcessor processor = builder.Build();

Dim builder As New XmlHttpRequestProcessor.Builder(accountKey, securityKey)
builder.SetHttpRequestDispatcher(customHttpRequestDispatcher)
Dim processor As IRequestProcessor = builder.Build()

You might also want to wrap, or decorate, the default implementation of a component, adding a little extra functionality. Here's an example that logs the XML of the requests that are sent to the API:

static class LoggingRequestToXml : IRequestToXml {
    private readonly IRequestToXml wrappedRequestToXml;
    internal LoggingRequestToXml(IRequestToXml requestToXmlToWrap) {
        this.wrappedRequestToXml = requestToXmlToWrap;
    }
    private void Log(string s) {
        // Logging code would need to go here.
    }
    public string GetXml(Request request) {
        string xml = wrappedRequestToXml.GetXml(request);
        Log(xml);
        return xml;
    }
}

XmlHttpRequestProcessor.Builder builder =
        new XmlHttpRequestProcessor.Builder(accountKey, securityKey);
builder.SetRequestToXml(new LoggingRequestToXml(builder.GetRequestToXml()));
IRequestProcessor processor = builder.Build();

Class LoggingRequestToXml : Implements IRequestToXml
    Private ReadOnly wrappedRequestToXml As IRequestToXml
    Sub New(requestToXmlToWrap As IRequestToXml)
        wrappedRequestToXml = requestToXmlToWrap
    End Sub
    Private Sub Log(s As String)
        ' Logging code would need to go here.
    End Sub
    Function GetXml(request As Request) As String Implements IRequestToXml.GetXml
        Dim xml As String = wrappedRequestToXml.GetXml(request)
        Log(xml)
        Return xml
    End Function
End Class

Dim builder As New XmlHttpRequestProcessor.Builder(accountKey, securityKey)
builder.SetRequestToXml(New LoggingRequestToXml(builder.GetRequestToXml()))
Dim processor As IRequestProcessor = builder.Build()

The processing process

If, for whatever reason, you're providing customized processing components, it's important to understand how these components are used in Process(Request). Here's a step-by-step explanation:

1. The IRequestToXml component turns the Request into an XML string.
2. The IEndpointGetter component provides the endpoint URL that the XML request should be sent to.
3. A RequestSecurityInfo object is created using:
   • The endpoint URL.
   • The AccountKey.
   • A request timestamp fetched from the IUtcTimestampFactory component and formatted using the IDateTimeFormatter component.
   • A random string created by the IRandomFactory component.
4. The IXmlRequestWrapper component takes the request XML from step 1 and adds in the security info from step 3 to make a complete XML request.
5. The IStringToBytes component turns the complete XML into a byte array.
6. The ISigner component uses the SecurityKey (a representation of which it holds internally) to create a Signature of the request-XML byte array, so that its integrity can be checked on the API servers. Note that the security key itself is not sent over the wire, only a signature created using that key.
7. The IBytesToEncodedString component turns both the XML byte array and the signature byte array into EncodedString objects that each contain an encoded string version of the byte array (that can easily be sent over HTTP) and a code name to indicate the encoding used.
8. An HttpRequestData object is created to store the request parameters that should be sent over HTTP to the endpoint URL:
   • The request_encoding parameter holds the Encoding of the string-encoded request XML byte array.
   • The signature_encoding parameter holds the Encoding of the string-encoded signature byte array.
   • The signature_method parameter holds the name of the algorithm used to create the signature.
   • The encoded_request parameter holds the string-encoded request XML.
   • The encoded_signature parameter holds the string-encoded signature.
9. The IHttpRequestDispatcher component POSTs the parameters from the HttpRequestData to the endpoint URL, and returns a stream containing the XML response.
10. The IResponseParser component parses the XML response into a Response object - the end result of the processing.

Reference