如何使用 LDAP/OID 连接字符串通过 C# 连接到 Oracle

Question

I have two questions regarding connecting to an Oracle database using C#.NET.

My program references Oracle.DataAccess.dll (version 2.122.19.1) in my Oracle 19c client 64-bit folder.

I have a using statement:

using Oracle.DataAccess.Client;

and this code to connect:

string connectionString = "Data Source=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=myserver.sys.mycompany.com)(PORT=1521)))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=mydb.mycompany.com)));User Id=MyLanId;Password=MyPasswors;Validate Connection=True;"

using (OracleConnection connection = new OracleConnection(connectionString))
{
    connection.Open();
}

Question #1:

How do I create an OID connection string that does not specify the DB name but instead queries the LDAP for the detail server/port info that is hardcoded in my TNS-less connection string above?

For example, in a Java program, we connect like this.

base.oracle.db.url=jdbc:oracle:thin:@ldap://oid.gtm.internal.mycompany.com:3060/dbname,cn=OracleContext,dc=mycompany,dc=com

What would the .NET equivalent be?

Question Number #2:

When I compile my C# program I selected "Any CPU" yet my program only works when I reference the 64-bit Oracle.DataAccess.dll. Is this because my PATh variable mentions my 64-bit oracle client folder before my 32-bit folder (I have both)? Right now, my PATH variable is way over the max length of 2048 and I cannot change it without making it shorter and I'm not sure what to delete.

Answer 1

I found this SO post,

How do I query LDAP from C# to resolve Oracle TNS hostname while using managed ODP.NET?

Instead of just passing in a connection string that points to an LDAP server, I can do an LDAP query to get the db descriptor to build the connection string.

It's a 2 step process, so I probably want to cache the connection string once I build it. I normally count on connection pooling and "close" connections when I am done with them but this two step process seems like I have to manually add some caching of the connection string to avoid the overhead of hitting LDAP multiple times.

Is there a better way?

    string directoryServer = "oid.gtm.internal.mycompany.com:3060";
    string defaultAdminContext = "cn=OracleContext,dc=mycompany,dc=com";
    string serviceName = "mydb";
    string userId = "mylanid";
    string password = "mypwd";

    using (IDbConnection connection = GetConnection(directoryServer, defaultAdminContext, serviceName, userId, password))
    {
        connection.Open();

        connection.Close();
    }
    
private static IDbConnection GetConnection(string directoryServer, string defaultAdminContext,
                                           string serviceName, string userId, string password)
{
    string descriptor = ConnectionDescriptor(directoryServer, defaultAdminContext, serviceName);
    // Connect to Oracle
    string connectionString = $"user id={userId};password={password};data source={descriptor}";
    OracleConnection con = new OracleConnection(connectionString);
    return con;
}

private static string ConnectionDescriptor(string directoryServer, string defaultAdminContext,
    string serviceName)
{
    string ldapAdress = $"LDAP://{directoryServer}/{defaultAdminContext}";
    string query = $"(&(objectclass=orclNetService)(cn={serviceName}))";
    string orclnetdescstring = "orclnetdescstring";

    DirectoryEntry directoryEntry = new DirectoryEntry(ldapAdress, null, null, AuthenticationTypes.Anonymous);
    DirectorySearcher directorySearcher = new DirectorySearcher(directoryEntry, query, new[] { orclnetdescstring },
        SearchScope.Subtree);

    SearchResult searchResult = directorySearcher.FindOne();
    byte[] value = searchResult.Properties[orclnetdescstring][0] as byte[];

    if (value != null)
    {
        string descriptor = Encoding.Default.GetString(value);
        return descriptor;
    }

    throw new Exception("Error querying LDAP");
}

Answer 2

Once you created oracle connection successfully

OracleConnection con = new OracleConnection(connectionString);

How to get data from it with a sql:

string strSQL="select * from users";

I use the following codes and no data return

  con.Open();
  OleDbDataAdapter oDA = new OleDbDataAdapter(strSQL, con);
  DataSet ds = new DataSet();
  oDA.Fill(ds);
  con.Close();

Please advise.