Cassandra is a distributed storage system that can spread over thousands of nodes and store terabytes of structured data. Cassandra was developed at Facebook to solve performance issues during searches in Facebook Inbox. Cassandra can provide a highly available service without a single point of failure. Cassandra borrows some of its architecture choices from Google’s BigTable1 1: Bigtable: A Distributed Storage System for Structured Data and Amazon’s Dynamo2 2: Dynamo: Amazon’s Highly Available Key-value Store.

Last week, while reading the book Designing data-intensive applications, I came across the term “Gossip Protocols.” The title was quite intriguing; hence I search for it on Google. It turns out that it is a communication protocol. It is sometimes also called the “Epidemic Protocol.” We are facing an ongoing pandemic called COVID-19. The term “Epidemic Protocol” caught my attention, and I started wondering how the knowledge of epidemics is going to be useful in computer systems.

It has been three months since 2020 started. I was not able to keep up with my yearly habit of posting year reviews due to some reasons. One primary reason behind my negligence is my disinterest in writing on this blog. I felt that it was because the old layout of this blog had been too recurrent for me. So, I decided to fix that issue before thinking about writing.

Before I start, here is some technical information about my website - Hosted on Gitlab and usage its CD for automatic deployment, which is triggered on a git commit. The domain name registrar is GoDaddy. Let’s Encrypt as the TLS certificate provider for my domain name. Let’s Encrypt provides certificates for 90 days only, so I was forced to set up the certbot every three months, then generate the certificate and manually deploy the certificates to GitLab.

Recently, I am experimenting with Web Application Firewalls a lot. ModSecurity is one of them. It is the most famous and useful open-source Web Application Firewall (WAF) in existence. It is supported by various web servers such as Apache, Nginx, and IIS. The job of ModSecurity is to sit in front of the application web server and check the incoming requests and outgoing responses to filter out malicious content. It does so by the use of powerful and complex regular expressions.