ejb-vs-cdi.json

{
  "id": 99,
  "slug": "ejb-vs-cdi",
  "title": "EJB versus CDI",
  "category": "enterprise",
  "difficulty": "intermediate",
  "jdkVersion": "11",
  "oldLabel": "Java EE",
  "modernLabel": "Jakarta EE 8+",
  "oldApproach": "EJB",
  "modernApproach": "CDI Bean",
  "oldCode": "@Stateless\npublic class OrderEJB {\n    @EJB\n    private InventoryEJB inventory;\n\n    public void placeOrder(Order order) {\n        // container-managed transaction\n        inventory.reserve(order.getItem());\n    }\n}",
  "modernCode": "@ApplicationScoped\npublic class OrderService {\n    @Inject\n    private InventoryService inventory;\n\n    @Transactional\n    public void placeOrder(Order order) {\n        inventory.reserve(order.getItem());\n    }\n}",
  "summary": "Replace heavyweight EJBs with lightweight CDI beans for dependency injection and transactions.",
  "explanation": "CDI (Contexts and Dependency Injection) provides the same dependency injection and transaction management as EJBs, but as plain Java classes with no container-specific interfaces or superclasses. Scopes like @ApplicationScoped and @RequestScoped control lifecycle, and @Transactional replaces mandatory EJB transaction semantics.",
  "whyModernWins": [
    {
      "icon": "🪶",
      "title": "Lightweight",
      "desc": "CDI beans are plain Java classes with no EJB-specific interfaces or descriptors."
    },
    {
      "icon": "💉",
      "title": "Unified injection",
      "desc": "@Inject works for every managed bean, JAX-RS resources, and Jakarta EE components alike."
    },
    {
      "icon": "🧪",
      "title": "Easy unit testing",
      "desc": "Plain classes without EJB proxy overhead are straightforward to instantiate and mock."
    }
  ],
  "support": {
    "state": "available",
    "description": "Widely available since Jakarta EE 8 / Java 11"
  },
  "prev": "enterprise/servlet-vs-jaxrs",
  "next": "enterprise/jdbc-vs-jpa",
  "related": [
    "enterprise/servlet-vs-jaxrs",
    "enterprise/jdbc-vs-jpa",
    "language/records-for-data-classes"
  ],
  "docs": [
    {
      "title": "Jakarta CDI Specification",
      "href": "https://jakarta.ee/specifications/cdi/"
    },
    {
      "title": "Jakarta Transactions — @Transactional",
      "href": "https://jakarta.ee/specifications/transactions/"
    }
  ]
}