NTiConnection Class.

Description.

The NTiConnection class represents the connection to the IBM i and implements the DbConnection class from the ADO.NET model (System.Data.Common namespace).

General considerations.

Connection Pool.

Starting with version 3.2.3, NTi implements a .NET-based connection pool, ensuring rigorous tracking of open connections and preventing the excessive creation of QZDASOINIT jobs.

Opening a connection to the IBM i involves several costly operations: IP resolution, TCP negotiation, authentication, and job creation on the IBM i. Repeating these operations for every request significantly impacts performance.

The NTi pooling mechanism works as follows:

• When a connection is requested, NTi first checks the pool for an available connection. If one is found, it is reused immediately; otherwise, a new connection is created and added to the pool.
• When the connection is no longer in use, it is returned to the pool instead of being closed.
• When the application stops or the pool is destroyed, all connections are properly closed.

Pooling is enabled by default starting with NTi 3.2.3. It can be disabled if manual control of connections is required.

💡 Observed benefits: response time reduced from 80ms to 6ms, delivering more than a 10x performance gain in some use cases (particularly with Entity Framework Core).

Multi-Factor Authentication (MFA)

MFA (Multi-Factor Authentication) is a security mechanism introduced by IBM in the latest IBM i releases (V7R6+). It's based on the generation of a one-time password (OTP) through a TOTP (Time-based One-Time Password) compatible application (e.g. Microsoft Authenticator).

When signing in, this code is required in addition to the regular password to strengthen access protection. Since version 4.4.0, NTi supports this mechanism and allows the OTP code to be provided in two ways:

• with a callback AdditionalFactorCallback, triggering an interactive user prompt.
• with the property AdditionalFactor, where the code is passed directly.

Reminder: Enabling MFA on IBM i (starting with V7R6).

1. System prerequisites:

• QSECURITY = 40 or 50
• QPWDLVL = 4

2. Enable MFA system-wide:

 CHGSECA ADLSGNFAC(*ENABLED)

💡 An IPL is required after this command to apply the changes.

3. Configure MFA per user:

From the user profile:

• Generate a TOTP key for the profile:

CHGTOTPKEY USRPRF() KEY(*GEN)

• Copy the key into the personal MFA application (e.g., Microsoft Authenticator) and securely store the recovery keys.
• Apply MFA to the user profile:

CHGUSRPRF USRPRF() AUTHMTH(*TOTP)

• Test the connection.

One instance = one TCP connection = one IBM i job.

Each instance of NTiConnection carries one TCP socket instance to connect to the IBM i. Thus there is a strong link between the instance, the connection and the IBM i job.

When an instance of NTiConnection is explicitly destroyed via .NET's Garbage Collector, the underlying TCP connection is instantly closed and destroyed in turn, causing the IBM i job to stop. This mechanism guarantees total user control of connections.

Connection string.

Like most database access providers, NTi uses a connection string to obtain IBM i connection information (user name, password, etc.). This connection string may contain sensitive information. There are a number of methods for securing the management of the connection string and configuration files.

Refer to the official .NET documentation and recommendations for their implementation.

ADO.NET implementation.

This class implements the usual methods and properties of the ADO.NET model for carrying out database access operations, in particular:

• Open()
• Close()
• CreateCommand()
• BeginTransaction()
• Commit()
• Rollback()

In this way, NTi integrates into any existing application developed with other vendors such as ODBC or OleDB drivers.

💡 Documentation for this default implementation can be found on any ADO.NET documentation, for example via the System.Data.Common namespace documentation .

Methods.

In addition to the functionality of the ADO.NET model, the NTiConnection class implements methods specific to the use of the IBM i, in particular for executing CL commands and calling RPG, CL... programs.

These specific methods are:

Properties.

The specific properties of the NTiConnection class allow you to define connection properties and access information about the state of the connection to the IBM i. To ensure compatibility with other providers' connection strings, some properties may correspond to several different keywords.