Problem Recently I came across a scenario at work where I had to deal with real time updates of payment status in mobile which involved an asynchronous chain of events in the backend. Mobile would call the backend to initiate a payment request, backend would do basic validation - initialize the payment and return a token to the UI. Actual payment involved multiple API calls to some of the internal systems as well as third party systems.

Why Some ISPs block TCP 22? Recently I got to know that some ISP indeed block any outbound traffic for port 22 (tcp) which is a standard port for ssh connections. (I came to know about this as I was being unable to log into one of the compute instances from my terminal via gcloud in gcp. I prefer terminal logins instead of browser as it’s simply 100 times easier to work with.

Playing with HTTP: Practical Notes and Examples HTTP is the foundation of the web, but it’s easy to overlook how it actually works. This post collects some hands-on notes, experiments, and practical tips for understanding HTTP, inspired by the excellent Udacity client-server communication course. Whether you’re a beginner or just want to refresh your basics, try these out yourself! Playing with HTTP: Practical Notes and Examples These are some hands-on notes and experiments from the excellent Udacity client-server communication course.