/// <summary>
/// Converts this Kafka message into a CloudEvent object.
/// </summary>
/// <param name="message">The Kafka message to convert. Must not be null.</param>
/// <param name="formatter">The event formatter to use to parse the CloudEvent. Must not be null.</param>
/// <param name="extensionAttributes">The extension attributes to use when parsing the CloudEvent. May be null.</param>
/// <returns>A reference to a validated CloudEvent instance.</returns>
public static CloudEvent ToCloudEvent(this Message <string, byte[]> message,
CloudEventFormatter formatter, IEnumerable <CloudEventAttribute> extensionAttributes)
{
Validation.CheckNotNull(message, nameof(message));
Validation.CheckNotNull(formatter, nameof(formatter));
if (!IsCloudEvent(message))
{
throw new InvalidOperationException();
}
var contentType = ExtractContentType(message);
CloudEvent cloudEvent;
// Structured mode
if (MimeUtilities.IsCloudEventsContentType(contentType))
{
cloudEvent = formatter.DecodeStructuredModeMessage(message.Value, new ContentType(contentType), extensionAttributes);
}
else
{
// Binary mode
if (!(GetHeaderValue(message, SpecVersionKafkaHeader) is byte[] versionIdBytes))
{
throw new ArgumentException("Request is not a CloudEvent");
}
string versionId = Encoding.UTF8.GetString(versionIdBytes);
CloudEventsSpecVersion version = CloudEventsSpecVersion.FromVersionId(versionId)
?? throw new ArgumentException($"Unknown CloudEvents spec version '{versionId}'", nameof(message));
cloudEvent = new CloudEvent(version, extensionAttributes)
{
DataContentType = contentType
};
foreach (var header in message.Headers.Where(h => h.Key.StartsWith(KafkaHeaderPrefix)))
{
var attributeName = header.Key.Substring(KafkaHeaderPrefix.Length).ToLowerInvariant();
if (attributeName == CloudEventsSpecVersion.SpecVersionAttribute.Name)
{
continue;
}
// TODO: Is this feasible?
var headerValue = header.GetValueBytes();
if (headerValue is null)
{
continue;
}
string attributeValue = Encoding.UTF8.GetString(headerValue);
cloudEvent.SetAttributeFromString(attributeName, attributeValue);
}
formatter.DecodeBinaryModeEventData(message.Value, cloudEvent);
}
InitPartitioningKey(message, cloudEvent);
return(Validation.CheckCloudEventArgument(cloudEvent, nameof(message)));
}
public void IsCloudEventsContentType(string contentType, bool expectedResult) => Assert.Equal(expectedResult, MimeUtilities.IsCloudEventsContentType(contentType));
private static bool HasCloudEventsContentType(HttpRequest request) => MimeUtilities.IsCloudEventsContentType(request?.ContentType);
// TODO: This would include "application/cloudeventsarerubbish" for example... private static bool HasCloudEventsContentType(HttpContent content) => MimeUtilities.IsCloudEventsContentType(content?.Headers?.ContentType?.MediaType);
// TODO: Avoid all the byte[] -> string conversions? If we didn't care about case-sensitivity, we could prepare byte arrays to perform comparisons with.
/// <summary>
/// Indicates whether this message holds a single CloudEvent.
/// </summary>
/// <remarks>
/// This method returns false for batch requests, as they need to be parsed differently.
/// </remarks>
/// <param name="message">The message to check for the presence of a CloudEvent. Must not be null.</param>
/// <returns>true, if the request is a CloudEvent</returns>
public static bool IsCloudEvent(this Message <string, byte[]> message) =>
GetHeaderValue(message, SpecVersionKafkaHeader) is object ||
MimeUtilities.IsCloudEventsContentType(ExtractContentType(message));
private static bool HasCloudEventsContentType(Message message, out string contentType)
{
contentType = message.Properties.ContentType?.ToString();
return(MimeUtilities.IsCloudEventsContentType(contentType));
}
