# websockets

# WebSockets Study Guide

---

# What is a WebSocket?

A WebSocket is:

# a persistent real-time communication connection between two systems.

Unlike normal REST APIs:

* the connection stays open
* both systems can send data anytime

---

# Simple Explanation

# REST API

Client asks for information repeatedly.

Example:

```text id="ws1"
"Any new messages?"
"Any new messages?"
"Any new messages?"
```

---

# WebSocket

Connection stays open continuously.

Server pushes updates instantly:

```text id="ws2"
"New message received"
```

without client repeatedly asking.

---

# Why WebSockets Exist

WebSockets enable:

# real-time communication

Examples:

* live chat
* agent status updates
* notifications
* voice/video signaling
* stock market feeds
* multiplayer gaming

---

# Common WebSocket Use Cases

| Use Case              | Example                      |
| --------------------- | ---------------------------- |
| Live Chat             | Customer-agent messaging     |
| Agent Presence        | Agent online/offline updates |
| Notifications         | Real-time alerts             |
| Voice/Video Apps      | Session signaling            |
| Monitoring Dashboards | Live metrics                 |
| Collaboration Tools   | Real-time updates            |

---

# How WebSockets Work

# Step 1 — Client Connects

Example:

```text id="ws3"
Browser → WebSocket Server
```

---

# Step 2 — Connection Upgraded

Initial connection starts using HTTP/HTTPS.

Then upgraded to:

# WebSocket protocol

---

# Step 3 — Persistent Connection Established

Connection remains:

# continuously open

Both sides can send data anytime.

---

# WebSocket Communication Flow

```text id="ws4"
Client ↔ WebSocket Server
```

Bidirectional communication.

---

# REST API vs WebSocket

| REST API                  | WebSocket             |
| ------------------------- | --------------------- |
| Request/response          | Persistent connection |
| Stateless                 | Stateful              |
| Client initiates requests | Both sides send data  |
| Polling often required    | Real-time updates     |
| Short-lived connection    | Long-lived connection |

---

# Simple Analogy

# REST API

Like sending emails:

* request
* response
* connection closes

---

# WebSocket

Like phone call:

* connection stays active
* both sides talk anytime

---

# Example WebSocket Flow

```text id="ws5"
Customer sends message
      ↓
Agent instantly receives message
      ↓
Agent replies immediately
      ↓
Customer sees reply in real time
```

No repeated API polling needed.

---

# WebSocket URLs

Instead of:

```text id="ws6"
https://
```

WebSockets use:

```text id="ws7"
ws://
```

Secure WebSockets:

```text id="ws8"
wss://
```

---

# Secure WebSockets

# WSS = WebSocket Secure

Equivalent of:

# HTTPS for WebSockets

Uses:

* TLS encryption
* secure communication

VERY important in:

* banking
* enterprise platforms
* customer interactions

---

# Why WebSockets Matter In Glia

Glia heavily relies on:

* real-time chat
* live agent updates
* voice interactions
* customer engagement

WebSockets are commonly used for:

* live interaction synchronization
* agent presence
* messaging
* session updates

---

# WebSockets vs Webhooks

| WebSocket               | Webhook                     |
| ----------------------- | --------------------------- |
| Persistent connection   | One-time event notification |
| Real-time bidirectional | Event-based push            |
| Both sides communicate  | Source system pushes        |
| Continuous session      | Stateless notification      |

---

# WebSockets vs REST APIs

| REST API                     | WebSocket                 |
| ---------------------------- | ------------------------- |
| Request/response             | Continuous communication  |
| Polling required for updates | Instant updates           |
| Better for CRUD operations   | Better for real-time apps |

CRUD:

* Create
* Read
* Update
* Delete

---

# Common WebSocket Troubleshooting

# Problem 1 — Connection Fails

Possible causes:

* firewall blocking
* proxy issues
* incorrect endpoint
* TLS/certificate issue

---

# Problem 2 — Connection Drops

Possible causes:

* timeout
* network instability
* load balancer session timeout

---

# Problem 3 — TLS/WSS Failure

Symptoms:

* secure connection rejected
* certificate errors

Check:

* TLS certificates
* HTTPS/WSS configuration

---

# Problem 4 — Authentication Failure

Some WebSockets require:

* bearer token
* session authentication
* OAuth validation

Result:
connection rejected.

---

# Problem 5 — High Latency

Symptoms:

* delayed chat messages
* slow updates

Possible causes:

* network congestion
* overloaded server
* scaling issues

---

# WebSocket Troubleshooting Flow

# Step 1 — Validate Endpoint

Check:

```text id="ws9"
ws://
```

or:

```text id="ws10"
wss://
```

---

# Step 2 — Validate Connectivity

Check:

* firewall
* proxy
* load balancer
* port access

---

# Step 3 — Validate Authentication

Check:

* bearer token
* OAuth session
* API credentials

---

# Step 4 — Validate TLS/WSS

Check:

* certificate validity
* TLS compatibility
* HTTPS/WSS support

---

# Step 5 — Review Logs

Check:

* WebSocket handshake logs
* disconnect reasons
* timeout events
* session logs

---

# Common Interview Questions

# “What is a WebSocket?”

Good Answer:

> “A WebSocket is a persistent bidirectional communication protocol that enables real-time data exchange between systems over a continuously open connection.”

---

# “Difference between REST API and WebSocket?”

Good Answer:

> “REST APIs use a request/response model with short-lived connections, while WebSockets maintain a persistent connection that supports real-time bidirectional communication.”

---

# “Why use WebSockets?”

Good Answer:

> “WebSockets are ideal for real-time applications such as live chat, notifications, voice signaling, and agent presence updates because they eliminate the need for continuous polling.”

---

# “Difference between WebSocket and webhook?”

Good Answer:

> “WebSockets maintain a persistent real-time communication session, while webhooks are one-time event notifications triggered when specific events occur.”

---

# “How would you troubleshoot WebSocket issues?”

Good Answer:

> “I would validate endpoint connectivity, verify firewall and proxy access, confirm authentication and TLS configuration, review handshake and disconnect logs, and isolate any network or session timeout issues.”

---

# Important Security Concepts

Secure WebSockets should use:

# WSS (WebSocket Secure)

This provides:

* TLS encryption
* secure communication
* token protection

---

# Easy Memory Trick

# REST API = Request/Response

# Webhook = Event Notification

# WebSocket = Live Continuous Conversation

---

# Important Terms To Know

| Term                  | Meaning                         |
| --------------------- | ------------------------------- |
| WebSocket             | Persistent real-time connection |
| WSS                   | Secure WebSocket                |
| Bidirectional         | Both sides communicate          |
| Persistent Connection | Connection remains open         |
| Polling               | Repeated API requests           |
| Real-Time             | Instant communication           |
| Handshake             | Initial connection setup        |
| Stateful              | Maintains session state         |