stream analytics 'Invalid Avro Format, drop invalid record.' - serialization

Question

I am trying to serialize my C# classes to 'Avro' using 'Microsoft Avro Library' and sending it to event hub. However when I am trying to read the data thru stream analytics it gives this error at the logs 'Invalid Avro Format, drop invalid record'
More details..
using reflection method as shown in https://azure.microsoft.com/en-in/documentation/articles/hdinsight-dotnet-avro-serialization/ to serialize to avro format and sending it to event hub
//Create a new AvroSerializer instance and specify a custom serialization strategy AvroDataContractResolver
//for serializing only properties attributed with DataContract/DateMember
var avroSerializer = AvroSerializer.Create<SensorData>();
//Create a memory stream buffer
using (var buffer = new MemoryStream())
{
//Create a data set by using sample class and struct
var expected = new SensorData { Value = new byte[] { 1, 2, 3, 4, 5 }, Position = new Location { Room = 243, Floor = 1 } };
//Serialize the data to the specified stream
avroSerializer.Serialize(buffer, expected);
var bytes = buffer.ToArray();
var data = new EventData(bytes) {PartitionKey = "deviceId"};
// send to event hub client
eventHubClient.Send(data);
}
Events are published fine to event hubs. I have created a worker role that can consume these events and can able to deserialize them.
However when I set this event hub as input to my stream analytics and setting the event serialization format as 'avro' it gives below errors..
Message: Invalid Avro Format, drop invalid record.
Message: IncorrectSerializationFormat errors are occuring too rapidly.
They are being suppressed temporarily
I guess I have to include Avro Schema as well. Can anyone please guide me a correct way to serialize a C# class to 'avro' so stream analytics could understand it?
Thanks for your time.

Answer 1

You will have to include the schema. Below is an example of how you can send events along with Schema. This uses an AvroContainer.
var eventHubClient = EventHubClient.CreateFromConnectionString("ReplaceConnectionString","ReplaceEventHubPath");
int numberOfEvents = 10;
using (var memoryStream = new MemoryStream())
using (var avroWriter = AvroContainer.CreateWriter<SensorData>(memoryStream, Codec.Null))
using (var sqWriter = new SequentialWriter<SensorData>(avroWriter, numberOfEvents))
{
Enumerable.Range(0, numberOfEvents)
.Select(i => new SensorData() { Id = "DeviceId", Value = i })
.ToList()
.ForEach(data => sqWriter.Write(data));
memoryStream.Seek(0, SeekOrigin.Begin);
var eventData = new EventData(memoryStream.ToArray());
eventHubClient.Send(eventData);
}