Oracle Service Bus Interview Questions

1) Tell me about Oracle Service Bus?

Ans: Oracle Service Bus, an Enterprise Service Bus implementation, helps transform the architecture by establishing connections and interactions between the services and the applications. Oracle Service Bus was formerly called the Aqualogic Service Bus. Oracle Service Bus helps in managing the web services and delivers message brokering. In simple terms, Oracle Service Bus is implemented to achieve and maintain the routing and transformations of messages to enhance the application integration. Oracle Service Bus follows the SOA principles, which would help in connecting with the service consumers.

2) List out the different features of the Oracle Service Bus?

Ans: The Oracle Service bus is designed with many features involved in it. Some of them are listed below:

1.Enables location transparency
2.Provides service security
3.Implementation of Service level agreement
4.Handling of dynamic routing
5.Supports multi-protocol messaging
6.Enables message enrichment
7.Enables service orchestration
8.Enables message transformation

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3) What do you understand by the term Business service and proxy service? List out the differences between business service and proxy service?

Ans: Business service: The business service is identified as a service in Oracle Service Bus that is mainly used to connect to the target system. The primary responsibility of the business service is to fetch the data from any third-party network, database, or JMS and provide the data to the proxy service.

Proxy service:The proxy service is a service in Oracle Service bus identified to be exposed to the source system or any calling applications. In simple terms, the service will be provided to the source system.

4) Explain about the publish table and publish node in OSB?

Ans: Publish table: The publish table is used to publish an action or a message to zero or more statically provided services.

Publish Node: It helps identify the target service for a message and helps in configuring the message on how it is packed and sent to the service.

5) List out the various protocols that the Oracle Service Bus provides its extensive support to?

Ans: There are several protocols that the Oracle Service bus supports:

1.SOAP
2.EJB
3.Email
4.JMS
5.Tuxedo
6.Native MQ
7.SMTP/POP/IMAP
8.Native MQ
9.FTP
10.STFP
11.File

6) Briefly, explain about Split Join? Give a brief idea about the different types of Split joins?

Ans: Split Join: Split Join is a feature available in the Oracle Service Bus that allows parallel processing. This feature is developed to enhance the performance by processing the individual messages in a request concurrently. In simpler terms, the input messages are split into sub-messages, achieve the task, and send the response again to the destinations by aggregating the same. There are two different types of Split joins. They are:

1.Static Split Join: The static split join is used when we are aware of the number of services or operations to be performed at the design time. Static Join here is nothing but the constant services join.
2.Dynamic Split Join: The dynamic split join is used when we are not aware of the number of services or operations to be performed. Let's say an example like Shopping site. We are not mindful of the number of orders that we could get on a daily or weekly basis. In such cases, the dynamic split join would be the best option to be used.

7) What are the different types of pipelines available in Oracle Service Bus? Briefly explain about the Pipeline Error handler?

Ans: There are two different types of pipelines available in Oracle Service Bus. They are a Request and Response pipeline.

The pipeline error handler is responsible for handling the errors that arise in the request and response pipeline.

8) Briefly explain about message flow? Is it possible to delete the start node in the message flow?

Ans: The message flow in the Oracle service bus plays a crucial role in defining the request message flow from the start node to the route activity. Apart from the request flow, it also defines the response message flow from the route to the start node. It also includes other components like stages, branch nodes, route nodes, actions, pipeline pairs, etc. Start node is created or comes by default once the proxy service is created. A start node is required and included in every message flow. No, it is not possible to delete the start node in the message flow.

9) What do you know about the VETRO Concept?

Ans: VETRO in oracle Service Bus is named with a functionality assigned to each letter in it. VETRO means:

V - Visualization

E - Enrichment

T - Transform

R - Route

O - Operate

10) What do you understand by Content based routing in Oracle Service Bus?

Ans: Content-based routing in Oracle Service bus refers to routing based on the message content. If the routing of the request message to the different business services is done based on the Content of the message, then this type of routing is called Content-based routing.

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11) What do you understand by the term SLA Alert in Oracle Service Bus? Explain briefly about throttling in the Oracle service bus?

Ans: SLA Alert:  SLA here refers to the Service Level agreements or the contracts, which are the agreements signed between the service consumer and the service provider. The SLA alerts will arise when there is a violation in the guidelines to be followed, or simply if the service level agreements are violated.

Throttling: Throttling is a feature in Oracle Service Bus that helps process a certain set of messages at once. To perform such tasks, we need to set up some parameters in the oracle service bus.

12) How does file pooling work in OSB?What is Service pooling in OSB?

Ans: File pooling works in two different ways either by using OSB File protocol or File adapter. 

OSB File Protocol: The polling of the file is done using the file protocol in the proxy service.

File Adapter: File Adapter can be created using Jdeveloper and further imported to WSDL and XSD file into the Oracle Service Bus and generate the proxy service accordingly.

Service pooling: Service pooling refers to the process of grouping one or more services together. This is found to be beneficial when there is service down. If there is one service down, the other services will take up the request and perform the necessary operations required as per the request without any disturbance or interruption.

13) What do you understand by the message context?

Ans: A message context refers to the set of properties that hold and maintain the data and meta-data related to the message. All these properties are defined by the proxy service, which is implemented using Context variables. The message context is defined in XML schema format, which relates to a different property. The context variables are predefined, and others are user-defined. The message context is considered as the heart of the proxy service.

14) Without using the JCA adapters, is there any way to connect to the database?

Ans: Yes, there is a possibility to connect to the database without using the JCA adapters. It is possible by using a function called XQuery execute-SQL(). Instead of using the function, it is recommended to use JCA adapters.

15) Is it possible to use MDS in Oracle Service Bus? Can we use DVMs in Oracle Service Bus?

Ans: No, it is not possible to use MDS in Oracle Service Bus. No, we cannot use DVM's as well in Oracle Service Bus as it does not support.

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16) How does Security work in Oracle Service Bus? Can we use OWSM to secure OSB services?

Ans: Oracle Service Bus makes use of a framework called Weblogic Security Framework. Yes, we can use OWSM to secure the Oracle Service Bus services.

17) Do you know how the Java code is called from the Oracle service bus?

Ans: Oracle service bus makes use of the Java callout activity to call the Java code.

18) Briefly explain the differences between Oracle service bus and oracle SOA suite?

Ans: Oracle Service Bus: OSB refers to an Oracle service bus that is an integrated enterprise service bus that is specifically designed to perform multiple activities like virtualizing, integrating, and management of the services. 

Oracle SOA Suite: The oracle SOA Suite is the tool that is used for designing and running the business processes. It is considered a comprehensive suite of components for developing, securing, and monitoring service-oriented architecture (SOA). Service components (BPEL process, business rule, human task, spring, and mediator) are the building blocks that you use to construct an SOA composite application.

19) What do you understand by Service Result caching in Oracle Service Bus? How to perform Service Callout in Oracle Service Bus?

Ans: Service result caching: Service result caching is the option that is specifically used to improve the performance of the oracle service bus. The service result caching is used when there is a connection between the business service and the external service, which will further return a static response. With the use of the service result caching, it will consider the response from the cache, which will also improve the performance of the Oracle Service Bus.

The service callout can be performed on the Oracle Service bus by using the Service callout option inside the Oracle service bus to get the required data or the information.

20) Explain briefly about the customization file?

Ans: A customization file is used in the oracle service, a combination of XML files. It allows the users to open the file as required in any editor and substitute the required environment values. The customization file also helps in searching for the specific environment values in the oracle service bus console or the customization file and replacing them with the new values accordingly. Filter options are also available to search and filter based on the project or the variable type.

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21) Can you explain how to move the large file without reading in the Oracle Service Bus?

Ans: The move option is available in the Oracle SOA suite that helps in moving large files from one location to another. The oracle service bus does not have this option added to it. However, there is one other way to move the files on Oracle Service Bus. The content streaming option is used and available for the file protocol in the oracle service bus, helping to move the large files.

22) Explain the terms: Location transparency and OSB Service Orchestration?

Ans: Location transparency: Location transparency is the strategy that is defined to hide the physical location of the actual physical location of the service endpoints. All the service consumers should have a brief idea about the logical machine and port name for every service. This helps add and enhance flexibility, which will also include adding, moving, prioritizing and removing the service endpoints as and when required. This helps in avoiding the repetition of the compilation of the service consumed again and again.

OSB Service Orchestration: OSB service orchestration is the process that helps in combining the services to make new services. OSB service orchestration which is a light orchestration that could be either synchronous or asynchronous.

23) What do you understand by Message Enrichment?

Ans: Message enrichment is a feature in the Oracle Service bus that is designed to enrich the messages with the additional information required. Let's say an example of an invoice. If a customer sends an invoice to the health insurance company, the company can check and extend the invoices based on the decision system.

24) Is it required to create a session when we develop projects in Eclipse? Can we test the proxy service from Eclipse?

Ans: No, it is not required to create a session during the project development in Eclipse. The concept of creation of session would come into the picture when we deploy the project to the server from the Eclipse.

Yes, the proxy service can be tested from Eclipse. To perform the testing, you need to right click on the proxy service option, followed by Run As and run on the server.

25) Describe OSB's role as a Message Broker?

Ans: Message brokering is one of the essential components in the Oracle Service Bus that enables the Content-based routing via sending and receiving the messages and data transformation.

26) To transform from binary to XML or XML to binary format, what will we use in OSB?

Ans: MFL is used to transform from binary to XML or XML to a binary format that we will use in OSB.

27) Can multiple users work on an SB console at one time?

Ans: Yes, multiple users can work on the SB console at a time.The users could be the same or of different roles. This happens because sessions will be created for every user individually.

28) How to perform file listing in OSB?

Ans: The file listing can be performed in the Oracle Service Bus by creating a file adapter with file listing operation in Jdeveloper. 

29) Do we have a global variable in OSB (Can we access a variable that is defined in proxy service message flow from other proxy service message flow)?

Ans: No, there is no possibility to access the variable in proxy service message flow from other proxy service message flow.

30) What do you understand by the term stages in Oracle Service Bus?