This guide covers the most common communication protocols used in modern cloud-native architectures, compares their capabilities, and discusses when to use each. It also analyzes support and limitations within the context of AWS services like ALB, NLB, API Gateway, and more.

---

🔗 Protocols Covered

• REST (HTTP/1.1)
• gRPC (HTTP/2)
• GraphQL
• WebSockets
• Apache Kafka
• AWS EventBridge
• MQTT
• SOAP
• Thrift

---

🔄 Comparison of Protocols

Feature	REST	gRPC	GraphQL	WebSockets	Kafka/EventBridge	MQTT	SOAP	Thrift
Transport Protocol	HTTP/1.1	HTTP/2	HTTP/1.1	TCP (via HTTP)	TCP	TCP	HTTP/SMTP	TCP
Data Format	JSON	Protobuf	JSON	Custom/JSON	JSON/Avro/Proto	Binary	XML	Binary
Real-Time Support	❌ No	✅ Limited	❌ No	✅ Full	✅ Asynchronous	✅ Yes	❌ No	❌ No
Bi-directional Streaming	❌ No	✅ Yes	❌ No	✅ Yes	✅ Pub/Sub	✅ Yes	❌ No	❌ No
Browser Support	✅ Yes	❌ No	✅ Yes	✅ Yes	❌ No	❌ No	✅ Yes	❌ No
Human Readable	✅ Yes	❌ No	✅ Yes	✅ Mostly	❌ Usually not	❌ No	✅ Yes	❌ No
Performance	⚠️ Medium	✅ High	⚠️ Medium	✅ High	✅ High	✅ High	⚠️ Slow	✅ High
Schema-Based	❌ No	✅ Protobuf	✅ Schema	❌ No	✅ Schema Optional	✅ Yes	✅ WSDL	✅ IDL

---

✅ When to Use Which Protocol

🔵 REST (HTTP/1.1 + JSON)

• Use When: Building public APIs, needing browser compatibility, or ease of debugging.
• Pros: Ubiquitous, human-readable, stateless, supports caching.
• Cons: No streaming, verbose payloads.
• AWS Services: API Gateway (REST), ALB, Lambda integrations.

🔵 gRPC (HTTP/2 + Protobuf)

• Use When: Internal microservices, high-performance, low-latency needs.
• Pros: Binary format, streaming, code generation, compact.
• Cons: Not natively browser-compatible.
• AWS Services:
  • ✅ Supported via NLB for passthrough.
  • ⚠️ ALB does not support backend HTTP/2 (gRPC gets downgraded).
  • ✅ App Mesh + Envoy for gRPC proxying.

🔵 GraphQL

• Use When: Client-controlled queries, frontend flexibility.
• Pros: Single endpoint, declarative data needs.
• Cons: Complex server-side; caching is harder.
• AWS Services:
  • ✅ AWS AppSync (managed GraphQL layer).
  • ❌ Not supported directly in API Gateway.

🔵 WebSockets

• Use When: Real-time updates, chat, collaborative apps.
• Pros: Bi-directional, full-duplex.
• Cons: Stateful, harder to scale.
• AWS Services:
  • ✅ API Gateway (WebSocket APIs).
  • ✅ AWS AppSync (real-time GraphQL subscriptions).

🔵 Kafka / EventBridge

• Use When: Event-driven architecture, async comms, log ingestion.
• Pros: Decouples producers and consumers, scales well.
• Cons: Complex ops (Kafka); EventBridge has limits.
• AWS Services:
  • ✅ Amazon MSK (Kafka).
  • ✅ EventBridge (fully managed).

🔵 MQTT

• Use When: IoT devices, bandwidth-constrained environments.
• Pros: Lightweight, topic-based pub/sub.
• Cons: Requires MQTT broker, less tooling.
• AWS Services:
  • ✅ AWS IoT Core (native MQTT broker).

🔵 SOAP (XML-based)

• Use When: Enterprise integrations, legacy systems.
• Pros: Strong contract, security standards (WS-Security).
• Cons: Verbose XML, complex.
• AWS Services:
  • ✅ API Gateway (SOAP passthrough via HTTP).
  • ✅ Lambda (can host SOAP servers).

🔵 Apache Thrift

• Use When: Polyglot environments, fast RPC.
• Pros: Cross-language, compact.
• Cons: Requires Thrift IDL, harder to debug.
• AWS Services:
  • ✅ EC2/ECS/EKS custom apps.
  • ❌ Not natively integrated in managed services.

---

🧠 Summary Matrix: AWS Support

Protocol	Supported by ALB	Supported by NLB	API Gateway	AppSync	IoT Core	EventBridge
REST	✅ Yes	✅ Yes (TCP)	✅ Yes	❌ No	❌ No	✅ Yes
gRPC	⚠️ Partial	✅ Yes (Passthru)	❌ No	❌ No	❌ No	❌ No
GraphQL	✅ Yes (manual)	✅ Yes	❌ No	✅ Yes	❌ No	❌ No
WebSocket	❌ No	✅ Yes (manual)	✅ Yes	✅ Yes	❌ No	❌ No
Kafka	❌ No	✅ Yes (MSK)	❌ No	❌ No	❌ No	✅ Yes
MQTT	❌ No	✅ Yes (via IoT)	❌ No	❌ No	✅ Yes	❌ No
SOAP	✅ Yes	✅ Yes (TCP)	✅ (via passthrough)	❌ No	❌ No	❌ No
Thrift	❌ No	✅ Yes (custom)	❌ No	❌ No	❌ No	❌ No

---

📌 Final Thoughts

Choosing the right communication protocol is a balance of:

• Performance vs compatibility
• Streaming vs statelessness
• Human readability vs compactness
• Synchronous vs asynchronous
• Operational complexity vs AWS-managed offerings

Design your architecture by aligning the protocol’s strengths with your application’s needs — especially around real-time behavior, scale, client type (browser vs internal), and AWS service compatibility.