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if I dispose HttpClient instance in windows application, dose handshaking repeat again?



When you dispose of an HttpClient instance in your Windows Forms application, the TLS handshake does not repeat automatically when you create a new HttpClient. Let me explain why:




1- TLS Handshake:

  • During the initial creation of an HttpClient, a TLS handshake occurs when you make an HTTPS request.
  • The handshake establishes a secure connection between the client (your application) and the server (web API).
  • Part of this process involves verifying the server’s certificate and negotiating encryption parameters.

2- Connection Pooling:

  • .NET’s HttpClient uses connection pooling by default.
  • When you dispose of an HttpClient, the underlying connection is returned to the pool for reuse.
  • Subsequent requests using a new HttpClient instance can reuse an existing connection from the pool if available.

3- Reusing Existing Connections:

  • When you create a new HttpClient instance after disposing of the previous one, it can reuse an existing connection from the pool.
  • The existing connection already completed the TLS handshake during its initial creation.
  • Therefore, the handshake does not repeat for subsequent requests using the same connection.

4- Lifetime of HttpClient:

  • It’s generally recommended to reuse an HttpClient instance throughout your application’s lifetime.
  • Creating a new HttpClient for every request can lead to connection exhaustion and performance issues.
  • Dispose of the HttpClient only when your application shuts down or when you no longer need it.

5- Client Certificates and Handshake:

  • If you’re using a client certificate for two-way authentication, the client certificate is associated with the HttpClient instance.
  • When you create a new HttpClient, you need to set the client certificate again (if required).



In summary, disposing of an HttpClient does not trigger a new TLS handshake automatically. Reusing existing connections from the connection pool helps improve performance and avoids unnecessary handshakes.