/// <summary>
/// Executes the specified BRE policy using zero or more facts.
/// </summary>
/// <typeparam name="T">The type of the result expected from the BRE policy.</typeparam>
/// <param name="policyName">The name of the BRE policy that needs to be invoked.</param>
/// <param name="facts">Zero or more facts that will be submitted to the policy for evaluation.</param>
/// <returns>The instance of an object carrying the result of policy execution, or null reference if the policy was not fired successfully.</returns>
public T ExecutePolicy <T>(string policyName, params object[] facts) where T : class, new()
{
Guard.ArgumentNotNullOrEmptyString(policyName, "policyName");
var callToken = TraceManager.WorkerRoleComponent.TraceIn(policyName);
try
{
RulesEngineRequest request = new RulesEngineRequest(policyName);
request.AddFacts(new T());
if (facts != null)
{
request.AddFacts(facts);
}
using (var rulesEngineClient = new ReliableServiceBusClient <IOnPremiseRulesEngineServiceChannel>(roleConfigExtension.OnPremiseRelayTwoWayEndpoint, roleConfigExtension.CommunicationRetryPolicy))
{
RulesEngineResponse response = rulesEngineClient.RetryPolicy.ExecuteAction <RulesEngineResponse>(() =>
{
return(rulesEngineClient.Client.ExecutePolicy(request));
});
if (response.Success)
{
return((from fact in response.Facts where fact.GetType() == typeof(T) select fact).FirstOrDefault() as T);
}
else
{
return(default(T));
}
}
}
catch (Exception ex)
{
// Report on any exceptions and return the default value of T, do not re-throw the exception to the caller.
TraceManager.WorkerRoleComponent.TraceError(ex);
return(default(T));
}
finally
{
TraceManager.WorkerRoleComponent.TraceOut(callToken);
}
}
/// <summary>
/// Synchronously executes the task using the specified <see cref="RuntimeTaskExecutionContext"/> execution context object.
/// </summary>
/// <param name="context">The execution context.</param>
public override void Run(RuntimeTaskExecutionContext context)
{
Guard.ArgumentNotNull(context, "context");
Guard.ArgumentNotNull(context.Message, "context.Message");
var callToken = TraceManager.PipelineComponent.TraceIn();
Stream messageDataStream = null;
IEnumerable <object> facts = null;
string policyName = PolicyName, ctxPropName = null, ctxPropNamespace = null;
Version policyVersion = PolicyVersion;
RulesEngineRequest request = null;
bool responseRequired = true;
try
{
XmlReaderSettings readerSettings = new XmlReaderSettings()
{
CloseInput = false, CheckCharacters = false, IgnoreComments = true, IgnoreProcessingInstructions = true, IgnoreWhitespace = true, ValidationType = ValidationType.None
};
if (context.Message.BodyPart != null)
{
messageDataStream = BizTalkUtility.EnsureSeekableStream(context.Message, context.PipelineContext);
if (messageDataStream != null)
{
using (XmlReader messageDataReader = XmlReader.Create(messageDataStream, readerSettings))
{
// Navigate through the XML reader until we find an element with the expected name and namespace.
while (!messageDataReader.EOF && messageDataReader.Name != WellKnownContractMember.MessageParameters.Request && messageDataReader.NamespaceURI != WellKnownNamespace.DataContracts.General)
{
messageDataReader.Read();
}
// Element was found, let's perform de-serialization from XML into a RulesEngineRequest object.
if (!messageDataReader.EOF)
{
DataContractSerializer serializer = new DataContractSerializer(typeof(RulesEngineRequest));
request = serializer.ReadObject(messageDataReader, false) as RulesEngineRequest;
if (request != null)
{
policyName = request.PolicyName;
policyVersion = request.PolicyVersion;
facts = request.Facts;
}
}
}
}
}
// Check if the policy name was supplied when this component was instantiated or retrieved from a request message.
if (!String.IsNullOrEmpty(policyName))
{
// If policy version is not specified, use the latest deployed version.
PolicyExecutionInfo policyExecInfo = policyVersion != null ? new PolicyExecutionInfo(policyName, policyVersion) : new PolicyExecutionInfo(policyName);
// Use all context properties as parameters when invoking a policy.
for (int i = 0; i < context.Message.Context.CountProperties; i++)
{
ctxPropName = null;
ctxPropNamespace = null;
object ctxPropValue = context.Message.Context.ReadAt(i, out ctxPropName, out ctxPropNamespace);
policyExecInfo.AddParameter(String.Format("{0}#{1}", ctxPropNamespace, ctxPropName), ctxPropValue);
}
// If we still haven't determined what facts should be passed to the policy, let's use the request message as a single fact.
if (null == facts)
{
if (messageDataStream != null)
{
// Unwind the data stream back to the beginning.
messageDataStream.Seek(0, SeekOrigin.Begin);
// Read the entire message into a BRE-compliant type XML document.
using (XmlReader messageDataReader = XmlReader.Create(messageDataStream, readerSettings))
{
facts = new object[] { new TypedXmlDocument(Resources.DefaultTypedXmlDocumentTypeName, messageDataReader) };
responseRequired = false;
}
}
}
// Execute a BRE policy.
PolicyExecutionResult policyExecResult = PolicyHelper.Execute(policyExecInfo, facts);
// CHeck if we need to return a response. We don't need to reply back if we are not handling ExecutePolicy request message.
if (responseRequired)
{
// Construct a response message.
RulesEngineResponse response = new RulesEngineResponse(policyExecResult.PolicyName, policyExecResult.PolicyVersion, policyExecResult.Success);
// Add all facts that were being used when invoking the policy.
response.AddFacts(facts);
// Create a response message.
IBaseMessagePart responsePart = BizTalkUtility.CreateResponsePart(context.PipelineContext.GetMessageFactory(), context.Message);
XmlWriterSettings settings = new XmlWriterSettings();
// Initialize a new stream that will hold the response message payload.
MemoryStream dataStream = new MemoryStream();
context.PipelineContext.ResourceTracker.AddResource(dataStream);
settings.CloseOutput = false;
settings.CheckCharacters = false;
settings.ConformanceLevel = ConformanceLevel.Fragment;
settings.NamespaceHandling = NamespaceHandling.OmitDuplicates;
using (XmlWriter responseWriter = XmlWriter.Create(dataStream, settings))
{
responseWriter.WriteResponseStartElement("r", WellKnownContractMember.MethodNames.ExecutePolicy, WellKnownNamespace.ServiceContracts.General);
DataContractSerializer dcSerializer = new DataContractSerializer(typeof(RulesEngineResponse), String.Concat(WellKnownContractMember.MethodNames.ExecutePolicy, WellKnownContractMember.ResultMethodSuffix), WellKnownNamespace.ServiceContracts.General);
dcSerializer.WriteObject(responseWriter, response);
responseWriter.WriteEndElement();
responseWriter.Flush();
}
dataStream.Seek(0, SeekOrigin.Begin);
responsePart.Data = dataStream;
}
else
{
if (facts != null)
{
TypedXmlDocument xmlDoc = facts.Where((item) => { return(item.GetType() == typeof(TypedXmlDocument)); }).FirstOrDefault() as TypedXmlDocument;
if (xmlDoc != null)
{
// Initialize a new stream that will hold the response message payload.
MemoryStream dataStream = new MemoryStream();
context.PipelineContext.ResourceTracker.AddResource(dataStream);
XmlWriterSettings settings = new XmlWriterSettings
{
CloseOutput = false,
CheckCharacters = false,
ConformanceLevel = ConformanceLevel.Fragment,
NamespaceHandling = NamespaceHandling.OmitDuplicates
};
using (XmlWriter dataWriter = XmlWriter.Create(dataStream, settings))
{
xmlDoc.Document.WriteContentTo(dataWriter);
dataWriter.Flush();
}
dataStream.Seek(0, SeekOrigin.Begin);
context.Message.BodyPart.Data = dataStream;
}
}
}
}
else
{
throw new ApplicationException(String.Format(CultureInfo.InvariantCulture, ExceptionMessages.PolicyNameNotSpecified));
}
}
finally
{
if (messageDataStream != null && messageDataStream.CanSeek && messageDataStream.Position > 0)
{
messageDataStream.Seek(0, SeekOrigin.Begin);
}
TraceManager.PipelineComponent.TraceOut(callToken);
}
}
