} // end AvroEncode
/// <summary>
/// Make a copy of an object as an Avro GenericRecord
/// </summary>
/// <param name="obj">Original object</param>
/// <param name="ktype">An associated KineticaType object that
/// describes the original object.</param>
/// <returns>GenericRecord object which is a copy of the specified object</returns>
private Avro.Generic.GenericRecord MakeGenericRecord(object obj, KineticaType ktype)
{
// Get the schema
var schema = KineticaData.SchemaFromType(obj.GetType(), ktype);
// Create a new GenericRecord for this schema
var recordToSend = new Avro.Generic.GenericRecord(schema);
// Copy each field from obj to recordToSend
foreach (var field in schema.Fields)
{
var property = obj.GetType()
.GetProperties()
.FirstOrDefault(prop => prop.Name.ToLowerInvariant() == field.Name.ToLowerInvariant());
if (property == null)
{
continue;
}
recordToSend.Add(field.Name, property.GetValue(obj, null));
}
// Return the newly created object
return(recordToSend);
}
} // lookupKineticaType()
/// <summary>
/// Encode specified object using Avro
/// </summary>
/// <param name="obj">Object to encode</param>
/// <returns>Byte array of binary Avro-encoded data</returns>
internal byte[] AvroEncode(object obj)
{
// Create a stream that will allow us to view the underlying memory
using (var ms = new MemoryStream())
{
// Write the object to the memory stream
// If obj is an ISpecificRecord, this is more efficient
if (obj is Avro.Specific.ISpecificRecord)
{
var schema = (obj as Avro.Specific.ISpecificRecord).Schema;
Avro.Specific.SpecificDefaultWriter writer = new Avro.Specific.SpecificDefaultWriter(schema);
writer.Write(schema, obj, new BinaryEncoder(ms));
}
else // Not an ISpecificRecord - this way is less efficient
{
// Get the KineticaType associated with the object to be encoded
Type obj_type = obj.GetType();
KineticaType ktype = lookupKineticaType(obj_type);
if (ktype == null)
{
throw new KineticaException("No known KineticaType associated with the given object. " +
"Need a known KineticaType to encode the object.");
}
// Make a copy of the object to send as a GenericRecord, then write that to the memory stream
var schema = KineticaData.SchemaFromType(obj.GetType(), ktype);
var recordToSend = MakeGenericRecord(obj, ktype);
var writer = new Avro.Generic.DefaultWriter(schema);
writer.Write(schema, recordToSend, new BinaryEncoder(ms));
}
// Get the memory from the stream
return(ms.ToArray());
}
} // end AvroEncode
} // end AvroDecode<T>
/// <summary>
/// Decode binary Avro data from a stream into an object
/// </summary>
/// <typeparam name="T">Type of expected object</typeparam>
/// <param name="stream">Stream to read for object data</param>
/// <returns>New object</returns>
private T AvroDecode <T>(Stream stream) where T : Avro.Specific.ISpecificRecord, new()
{
// T obj = new T(); // Activator.CreateInstance<T>();
var schema = KineticaData.SchemaFromType(typeof(T), null);
var reader = new Avro.Specific.SpecificReader <T>(schema, schema);
return(reader.Read(default(T), new BinaryDecoder(stream)));
}
/// <summary>
/// Decode binary Avro data into an object.
/// </summary>
/// <typeparam name="T">Type of expected object</typeparam>
/// <param name="bytes">Binary Avro data</param>
/// <param name="ktype">An optional KineticaType object to help in decoding the object.</param>
/// <returns>New object</returns>
private T AvroDecode <T>(byte[] bytes, KineticaType ktype = null) where T : new()
{
// Get the schema
var schema = KineticaData.SchemaFromType(typeof(T), ktype);
// Create a stream to read the binary data
using (var ms = new MemoryStream(bytes))
{
// Create a new object to return
T obj = new T();
if (obj is Avro.Specific.ISpecificRecord)
{
var reader = new Avro.Specific.SpecificDefaultReader(schema, schema);
reader.Read(obj, new BinaryDecoder(ms));
}
else
{
// Not ISpecificRecord, so first read into a new GenericRecord
var reader = new Avro.Generic.DefaultReader(schema, schema);
Avro.Generic.GenericRecord recordToReceive = new Avro.Generic.GenericRecord(schema);
reader.Read(recordToReceive, new BinaryDecoder(ms));
// Now, copy all the fields from the GenericRecord to obj
foreach (var field in schema.Fields)
{
var property = obj.GetType()
.GetProperties()
.FirstOrDefault(prop => prop.Name.ToLowerInvariant() == field.Name.ToLowerInvariant());
if (property == null)
{
continue;
}
object val;
// Try to get the property
if (recordToReceive.TryGetValue(field.Name, out val))
{
// If successful, write the property to obj
property.SetValue(obj, val);
}
} // end foreach
} // end if-else
// Return the new object
return(obj);
} // end using
} // end AvroDecode<T>
