Top 5 Oracle Service Bus (OSB) Fundamental Interview Questions
Q1. What is OSB and why do we need OSB?
Ans – In simple terms, it is a middleware tool provided by Oracle. It stands for Oracle Service Bus. It is used to deliver low-cost, standards-based integration for mission-critical SOA environments where performance and scalability are important. It simply helps to transform a complex architecture into a simple one by connecting different applications and services.
Q2. What is Proxy Service?
Ans - A proxy service is a service which you can expose to the outside world. Instead of publishing the actual service to the real world, we can publish the proxy service with additional/optimized business logic.
A proxy service can call any other proxy service (PS), local proxy service (LPS), and business service (BS). It is often called over the HTTP protocol.
Q3. What is Business Service?
Ans – A business service represents the configuration required to connect to an external or backend service. It can use a WSDL or other service definitions, depending on the type of service.
A business service is normally not called directly from the outside world. It is generally called by a proxy service. It directly communicates with the backend/business application.
Q4. What is Local Proxy Service?
Ans – A local proxy service is treated as an internal service. It is not exposed to the outside world. It is normally used for internal processing, validation, or common business logic, and it is used internally between proxy services, local proxy services, and business services.
It is called over the "local" protocol. They do not have an endpoint which a consumer sitting outside the OSB can invoke.
In order to invoke an internal proxy service, the consumer will have to invoke an external proxy service, which in turn will route it to the internal service.
Q5. What is VETO pattern?
Ans – VETO stands for Validation, Enrich, Transform and Operate. A commonly used approach in ESB/OSB is the VETO pattern.
The "Validate" step is usually the first part of an ESB process. It checks whether the incoming message meets the required conditions. Validation can be performed at different layers depending on the integration design.
The "Enrich" step involves adding additional data to a message to make it more meaningful and useful to a target service or application.
The "Transform" step converts the message to a target format.
The "Operate" step is the invocation of the target service or an interaction with the target application.
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