public void Save(Activity activity)
{
var preparedAppendDesc = session.Prepare(AppendActivityStreamQueryTemplateDesc);
var preparedAppendAsc = session.Prepare(AppendActivityStreamQueryTemplateAsc);
byte[] data = SerializeActivity(activity);
session
.Execute(preparedAppendDesc
.Bind(Convert.ToBase64String(activity.StreamId), activity.Timestamp, data));
session
.Execute(preparedAppendAsc
.Bind(Convert.ToBase64String(activity.StreamId), activity.Timestamp, data));
}