I'm facing an issue that's beyond my Zend Framework knowledge, i hope you guys could help.
I have a old fully-functional system installed in my server (let's call it http://stable.server.com), which has a very old PHP version. I'm planning to upgrade my PHP version to the latest (and hopefully in a few months, to 7!) but my code uses a lot of deprecated functions and has some code that isn't valid for PHP 5.6 but it was for older versions. I've made a division of modules in order to migrate each module, test it and then upload it to a parallel server with the latest PHP version (let's call it http://updated.server.com). Of course each one has a different Zend installation, with the same version and configuration file.
Of course those modules has some communication between themselves, and I want to keep the change the most transparent for my users. So when I call from updated.server.com to stable.server.com and viceversa, my app asks me to login again. When I'm logged in the two systems, this communication goes straight, but I want to avoid the users to login again.
¿Any of you have made something like this? I'd like of course a secure way to avoid that login between systems, so nobody could mount a fake system and login from it.
Thank you all in advance.