Thrift.Transport.TTransportException: Cannot write to null outputstream

Question

I'm doing some work with Cassandra and the Thrift libraries. I realize these are very early libraries and will (undoubtedly) change at some point.

I've been using the following link for help with setting up my C# code to write and read to and from my Cassandra server (which I have running in an Ubuntu Server instance in my local VirtualBox). I've confirmed that the trivial read / write functionality works.

Where I'm having a problem is executing the following method (which was generated for me using the thrift.definition file that came with Cassandra):

public void send_get_count(string keyspace, string key, ColumnParent column_parent, ConsistencyLevel consistency_level)

Here's my setup code:

TTransport _transport;
TProtocol _protocol;
Cassandra.Client _client;

public Test()
{
    _transport = new TSocket("192.168.56.101", 9160);
    _protocol = new TBinaryProtocol(_transport);
    _client = new Cassandra.Client(_protocol);
}

My calling code looks like so:

public void GetAllBlogEntries()
    {
        var timestamp = DateTime.Now.Millisecond;
        var keyspace = "Keyspace1";

        var utf8Encoding = System.Text.Encoding.UTF8;

        var columnParent = new ColumnParent() {Column_family = "BlogEntries"};
        var predicate = new SlicePredicate()
        {
            Slice_range = new SliceRange()
                          {
                              Start = new byte[0],
                              Finish = new byte[0],
                              Count = 10,
                              Reversed = false
                          }
        };

        var results = _client.get_range_slice(keyspace, columnParent, predicate, "", "", 5, ConsistencyLevel.ONE);

        foreach(var slice in results)
        {
            Console.WriteLine("Found Key: {0}", slice.Key);
            foreach(var resultColumn in slice.Columns)
            {
                var column = resultColumn.Column;
                Console.WriteLine("\tName: {0}, value: {1}",
                                  utf8Encoding.GetString(column.Name),
                                  utf8Encoding.GetString(column.Value));                        
            }
        }
    } 

The first line of this method is where I am getting my exception:

oprot_.WriteMessageBegin(new TMessage("get_count", TMessageType.Call, seqid_));

And here is the exception:

Thrift.Transport.TTransportException: Cannot write to null outputstream at Thrift.Transport.TStreamTransport.Write(Byte[] buf, Int32 off, Int32 len) at Thrift.Protocol.TBinaryProtocol.WriteI32(Int32 i32) at Thrift.Protocol.TBinaryProtocol.WriteMessageBegin(TMessage message) at Apache.Cassandra.Cassandra.Client.send_get_range_slice(String keyspace, ColumnParent column_parent, SlicePredicate predicate, String start_key, String finish_key, Int32 row_count, ConsistencyLevel consistency_level) in Cassandra.cs: line 341 at Apache.Cassandra.Cassandra.Client.get_range_slice(String keyspace, ColumnParent column_parent, SlicePredicate predicate, String start_key, String finish_key, Int32 row_count, ConsistencyLevel consistency_level) in Cassandra.cs: line 335 at CassandraDemo.Models.Test.GetAllBlogEntries() in Test.cs: line 212 at CassandraDemo.Tests.Models.TestTest.Test_GetAllBlogEntries_Success() in TestTest.cs: line 42

Any ideas?

Answer 1

You need to call Open() on the transport.