January 2020 Summaries

Webhooks and WebSub are both used for real-time updates but serve different purposes. Webhooks are user-defined Callback-URLs registered at a service provider's platform to receive information about events. They are generally used when there is one subscriber (company or a domain) that needs to be notified of events related to their business/domain playing out on different providers. Webhooks function in near real-time, are loosely coupled, and can handle downtime well. However, they can be difficult to debug and are susceptible to DDoS attacks. WebSub, on the other hand, is a network of Publishers, Subscribers, and Hubs that make it possible to share content over the internet securely. The Publisher is the content producer, the Subscriber the content consumer, and the Hub the content distributor. WebSub has an in-built security mechanism for sharing, accepting, and distributing content more securely between publishers and subscribers. It's ideal for broadcasting public information/data from a single publisher to millions of subscribers via hub. The choice between Webhooks and WebSub depends on the use case. Webhooks are better for event-driven notification systems where the consumer needs to be notified on every event occurrence with their account at the providers' platform. Examples include payment gateways, email providers, SMS & calling service provider, analytics platforms, and microservices. WebSub is better for use-cases such as broadcasting public information/data from a single publisher (or small number of publishers) to millions of subscribers via hub. It's ideal for platforms that frequently generate or update new content, like news aggregators, podcast networks, publishers, streaming services, etc.

Building real-time web or mobile applications requires careful selection of protocols to ensure efficient data delivery between servers and clients. MQTT (Message Queuing Telemetry Transport) and Server-Sent Events (SSE) are two protocols that serve different purposes in this context. MQTT, a bi-directional protocol, is ideal for IoT applications where devices require lightweight communication over unreliable networks, while SSE, a mono-directional protocol, is more suited for applications like real-time news services where information is pushed from the server to the client. MQTT relies on a broker to manage data exchange, supporting resource-constrained devices with its lightweight nature and Quality of Service (QoS) features, though it may have limitations concerning security and scaling. Conversely, SSE uses a simpler client-server model without brokers, synchronizing data over HTTP and offering built-in support for connection re-establishment, though it is limited to UTF-8 encoding and a specific number of open connections. Implementing these protocols in-house can present challenges, such as ensuring security and message delivery, prompting some developers to consider commercial solutions like Ably, which provides infrastructure and APIs for seamless integration of both MQTT and SSE.

In a recent IoT, WebHooks, Zapier masterclass hosted by Ably, the concept of 'Realtime' was introduced and explained. Realtime applications involve event-driven communication where entities are interested in being notified as soon as something occurs. These apps require low latency communication which traditional HTTP based communication cannot provide. Realtime protocols such as WebSockets, MQTT, and SSE allow for push-based communication, enabling server-initiated communications. The masterclass covered the development of a realtime voting app using Ably's API to facilitate communication between two separate entities or apps. The app was built with HTML, bootstrap, Fusioncharts, and hosted on Glitch. The next episode in the masterclass series will focus on IoT, WebHooks, Zapier, and other related topics.