Mutyam's Oracle Fusion Middleware Blog: Oracle Service Bus Interview Questions with Answers

Part - I

1. To connect to source system which service we will use?

Ans: We will use Proxy service to connect to Source system.

2. To connect to target system which service we will use?

Ans: We will use Business service to connect to target system.

3. What is Business Service?

Ans: It is a service in OSB which is used to connect to target system.

4. What is Message Flow?

Ans: Message flow is there in proxy service, we do all types of transformation, routing and other processing message flow only.

5. Do we have global variable in OSB (Can we access variable which is defined in proxy service message flow from other proxy service message flow)?

Ans: No, we can't access variable in proxy service message flow from other proxy service message flow.

6. Can we use direct bindings to call SOA composites?

Ans: Yes, we can direct binding-bindings to call SOA composites along with SOAP bindings.

7. Where the file will go if there is any error while polling the file?

Ans: During configuring file or ftp protocol in OSB, we need to specify error directory, so you can see file to that directory if file polling failed.

8. Why we use Split-Joins in OSB?

Ans: In short - For parallel processing. (Split-Joins let you send message invocations in parallel (in addition to sequentially) and to aggregate the responses.)

Oracle Service Bus's Split-Join feature lets you split a service payload, such as an order, into individual messages for concurrent processing. Concurrent processing, as opposed to sequential processing, greatly improves service performance. Split-Join achieves this task by splitting an input message payload into sub messages (split), routing them concurrently to their destinations, and aggregating the responses into one overall return message (join). This process of payload splitting and response aggregation is called a Split-Join pattern.

9. Types of Split-Joins?

Ans: Static and dynamic.

Static Spilt-Join: The static Split-Join branches from the main execution thread of an OSB message flow by splitting a payload into a fixed number of new branches according to the configuration of the Split-Join. At design time you determine the number and variety of services to be invoked.
Dynamic Spilt-Join: The dynamic Split-Join branches from the main execution thread of an OSB message flow by dynamically creating new branches according to the contents of the incoming payload. The dynamic Split-Join uses conditional logic to determine the number of branches to create. All requests are handled simultaneously, and the responses are aggregated into a single reply.

10. How to call Java code from OSB?

Ans: By using Java callout activity.

11. Can we use more than one route node in message flow?

Ans: No, we can't we use more than one route node in proxy service message flow.

12. When we call asynchronous service from OSB then how to get response back from that asynchronous service to OSB?

Ans: Design the proxy service which in turn calls business service which in turn calls asynchronous service. In the message flow of this proxy change the message header to below.

You need to specify ReplyTo value so that asynchronous service response came to CallSyncCompositeProxy proxy service.