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tanszek:oktatas:iss_t:object_request_broker [2026/03/01 17:44] – [Object Request Broker (ORB)] kneheztanszek:oktatas:iss_t:object_request_broker [2026/03/01 17:58] (current) – [Object Request Broker (ORB)] knehez
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 Conceptually: Conceptually:
  
-Client -> ORB -> Remote Object +<mermaid> 
- +sequenceDiagram 
-Remote Object -> ORB -> Client+Client->>ORB: Method call 
 +ORB->>RemoteObject: Forward request 
 +RemoteObject-->>ORB: Return result 
 +ORB-->>Client: Return response 
 +</mermaid>
  
 The ORB handles all low-level details such as transport protocols and data encoding. The ORB handles all low-level details such as transport protocols and data encoding.
 +
 +----
 +
 +==== Distributed Objects Concept ====
 +
 +CORBA extends object-oriented principles to distributed environments.
 +
 +Remote objects:
 +
 +  * expose methods,
 +  * encapsulate data,
 +  * can be invoked across networks.
 +
 +Unlike REST (which is resource-based) or JSON-RPC (which is procedure-based), CORBA is object-based. Objects can share both state (data) and behavior (methods).
 +
 +This design reflects classic OOP thinking in distributed systems.
 +----
 +==== IDL – Interface Definition Language ====
 +
 +CORBA introduced a language-independent interface definition mechanism called IDL (Interface Definition Language).
 +
 +IDL allows developers to define object interfaces independently of programming languages.
 +
 +Example IDL:
 +
 +<sxh>
 +interface Calculator { 
 +   long add(in long a, in long b); 
 +}; 
 +</sxh>
 +
 +From this IDL definition, language-specific stubs and skeletons are generated automatically (e.g., for C++, Java, Python).
 +
 +This ensures:
 +
 +  * language interoperability
 +  * strict interface contracts
 +  * platform independence
 +
 +IDL was one of the early solutions to cross-language service integration.
 +
 +CORBA IDL supports interface inheritance, allowing one interface to extend another.
 +This enables the reuse of method definitions and supports polymorphism in distributed systems.
 +
 +Below is an example from a simplified employee management system.
 +
 +<sxh> 
 +module Company {
 +
 +interface Person {
 +   string getName();
 +   long getId();
 +};
 +
 +interface Employee : Person {
 +   double getSalary();
 +   void setSalary(in double newSalary);
 +};
 +
 +interface Manager : Employee {
 +   void addTeamMember(in Person p);
 +};
 +
 +};
 +</sxh>
 +
 +
 +----
 +==== Marshalling and Unmarshalling ====
 +
 +CORBA introduced standardized marshalling and unmarshalling mechanisms.
 +
 +This mechanism is essential in distributed systems because memory representations differ across:
 +
 +  * programming languages
 +  * operating systems
 +  * CPU architectures (32-bit vs 64-bit, little-endian vs big-endian)
 +  * Without marshalling, raw in-memory data could not be safely transmitted between heterogeneous systems.
 +
 +**Marshalling**:
 +converting objects or parameters into a platform-independent serialized format for transmission.
 +
 +**Unmarshalling**:
 +reconstructing the original objects from the serialized data on the receiving side.
 +
 +This ensures that data types remain consistent across systems, different hardware architectures can communicate, and programming language differences are abstracted.
 +----
 +
 +
 +==== Service Registry Concept ====
 +
 +CORBA introduced early ideas similar to a service registry.
 +
 +Objects could register themselves in a naming service, allowing clients to discover them dynamically.
 +
 +This resembles:
 +
 +  * modern service discovery systems (e.g., Consul, Eureka),
 +  * DNS-based service resolution,
 +  * microservice registries.
 +
 +Services were browsable in a uniform manner, which was advanced for its time.
 +
 +----
 +==== Known Implementations ====
 +
 +Well-known CORBA implementations include:
 +  * ORBix
 +  * VisiBroker
 +  * TAO
 +
 +Java-based CORBA implementations
 +  * Java RMI (conceptually related, though not CORBA-based)
 +
 +CORBA support has historically been included in enterprise application servers such as:
 +  * JBoss
 +  * IBM WebSphere
 +
 +Although less common today, CORBA is still present in:
 +  * banking systems,
 +  * telecommunications,
 +  * aerospace and defense systems,
 +  * legacy enterprise infrastructures.
 +
 +----
 +==== Why CORBA Declined ====
 +
 +Despite its strong architectural design, CORBA gradually declined due to:
 +
 +  * high complexity
 +  * steep learning curve
 +  * heavyweight configuration
 +  * firewall/NAT issues
 +  * verbose tooling
 +  * rise of simpler HTTP-based APIs (REST)
 +
 +Tutorial: https://medium.com/@diremund/understanding-corba-building-a-banking-system-with-java-47c67fc42a66
tanszek/oktatas/iss_t/object_request_broker.1772387043.txt.gz · Last modified: 2026/03/01 17:44 by knehez