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Getting "I/O error occurred" when trying to connect to Denodo through ADO.Net

I am using the same code provided in the samples/vdp folder. I am able to connect to the Denodo DB through Sqlworkbench from my machine but not from the C# code. Please help. Below is the error stack: at Npgsql.NpgsqlState.<ProcessBackendResponses_Ver_3>d__a.MoveNext() at Npgsql.NpgsqlState.IterateThroughAllResponses(IEnumerable`1 ienum) at Npgsql.NpgsqlConnectedState.Startup(NpgsqlConnector context) at Npgsql.NpgsqlConnector.Open() at Npgsql.NpgsqlConnectorPool.GetPooledConnector(NpgsqlConnection Connection) at Npgsql.NpgsqlConnectorPool.RequestPooledConnectorInternal(NpgsqlConnection Connection) at Npgsql.NpgsqlConnectorPool.RequestPooledConnector(NpgsqlConnection Connection) at Npgsql.NpgsqlConnectorPool.RequestConnector(NpgsqlConnection Connection) at Npgsql.NpgsqlConnection.Open()
user
31-03-2021 08:27:39 -0400

1 Answer

Hi, In general, the error "I/O error occurred" occurs when a firewall is configured to close connection after a certain period of inactivity. If I face this issue, I would enable the "connection eviction" thread of that data source by following the steps provided in the [Recommended connection pool configuration settings for firewall enabled environments](https://community.denodo.com/docs/html/browse/latest/en//vdp/vql/generating_wrappers_and_data_sources/creating_data_sources/jdbc_data_sources#recommended-settings-of-the-connection-pool-in-environments-with-a-firewall) section of Virtual DataPort VQL Guide. By doing this, the connection pool will periodically execute the validation query, which will maintain the connections alive. For more information on accessing Virtual DataPort Server through ADO.Net, you could refer to the [Access Through an ADO.NET Data Provider](https://community.denodo.com/docs/html/browse/8.0/en//vdp/developer/access_through_an_ado.net_data_provider/access_through_an_ado.net_data_provider#access-through-an-ado-net-data-provider) section of Virtual DataPort Developer Guide. Hope this helps!
Denodo Team
05-04-2021 09:18:46 -0400
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