gRPC, GraphQL and Alternative API Styles in ASP.NET Core

Introduction

ShopNest public partners use REST; internal services use gRPC; mobile apps may prefer GraphQL (Hot Chocolate) — choose the right protocol per client.

After this article you will

• Compare REST vs gRPC vs GraphQL honestly
• Add Hot Chocolate GraphQL endpoint
• GraphQL queries, mutations, subscriptions
• OData for rich REST querying
• Multi-protocol gateway pattern

Prerequisites

• Article 71 — Blazor Complete Guide
• Articles 1–64 ShopNest foundations (MVC, EF Core, API, auth, deploy)

Architecture & design

// Hot Chocolate — Program.cs
builder.Services.AddGraphQLServer()
    .AddQueryType<Query>()
    .AddMutationType<Mutation>()
    .AddSubscriptionType<Subscription>();

Hands-on build guide — ShopNest Multi-Protocol API Gateway

1. GraphQL /graphql endpoint for products + categories.
2. gRPC InventoryService from Article 53 side-by-side.
3. YARP gateway routes /api → REST, /graphql → GraphQL.

Common pitfalls

• GraphQL N+1 queries — use DataLoader.
• Exposing GraphQL without auth — depth/complexity limits required.

Interview & portfolio questions

Q: When GraphQL?
A: Many clients need different field sets — one endpoint, client specifies shape.

Summary

• Not every API must be REST — match protocol to client
• ShopNest uses REST public + gRPC internal
• GraphQL optional for mobile flexibility

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