To accept a server's self-signed SSL certificate in a Java client, you can create a custom javax.net.ssl.X509TrustManager and use it to override the default trust manager.
There are several possible reasons why cURL is returning a 0 length response when trying to connect to an HTTPS site.
To get file_get_contents() to work with HTTPS, you may need to make sure that PHP has been compiled with the OpenSSL extension.
To send an HTTPS POST request using PHP, you can use the curl extension.
To perform HTTPS client certificate authentication in Java, you can use the HttpsURLConnection class and the SSLSocketFactory class.
To set up SSL on a local XAMPP/Apache server, you will need to generate a self-signed certificate, configure the Apache server to use the certificate, and then access the server using https.
To trust all certificates when using the Apache HttpClient library to make HTTPS requests, you can create a custom X509TrustManager implementation that trusts all certificates and use it to create an SSLContext with a custom TrustStrategy.