Frequently asked OSB Interview Questions And Answers
Latest OSB Interview Questions And Answers are as follows –
Q1. What is Oracle Service Bus (OSB)?
Ans: Oracle Service Bus allows you to manage Web services and deliver authentic message brokering through the configuration of proxy services in the Oracle Service Bus design-time environment. Oracle Service Bus manages the routing and transformation of messages in an enterprise system to promote seamless application integration.
Oracle Service Bus is a market-leading enterprise service bus built from the ground up for Service Oriented Architecture (SOA) life cycle management. It provides foundation capabilities for service discovery and intermediation, rapid service provisioning and deployment, and governance. This service-infrastructure software adheres to the SOA principles of building coarse-grained, loosely coupled, and standards-based services, creating a neutral container in which business functions may connect service consumers and back-end business services, regardless of the underlying infrastructure.
Q2. What are the key features of Oracle Service Bus or OSB?
- Supports Multiprotocol Messaging
- Enables Location Transparency
- Handles Dynamic Routing
- Enables Message Transformation
- Enables Service Orchestration
- Supports Message Enrichment
- Provides Service Security
- Implements Service Level Agreement
Q3. What are proxy services and business services in OSB?
Ans: The objective of OSB is to route messages between business services and service consumers through proxy services. Proxy services are generic intermediary web services that implement the mediation logic and are hosted locally on OSB. Proxy services route messages to business services and are exposed to service consumers.
Q4. What are the different types of Pipelines?
Ans: Request and Response Pipeline.
Q5. What are some of the major protocols that OSB supports?
- Native MQ
Q6. What is a Publish Table?
Ans: Use a publish table action to publish a message to Zero or more statically specified services.
Q7. What is a Publish Node?
Ans: Use a publish action to identify a statically specified target service for a message and to configure how the message is packaged and sent to that service
Q8. What are stages?
Ans: Stages are OSB Message Flow component to contain the actions
Q9. What is the message flow in Proxy Services?
Ans: Message flow in OSB is the most important part. It defines the request message flow from Start Node to Route activity and also defines the response message flow from Route to Start Node. It contains Pipeline Pairs, Branch Nodes, Route Nodes, Stages, Actions etc.
Q10. How we can connect to the Database from OSB?
Ans: We need to first create one JCA based DB adapter to connect to the database. Then we need to create that JCA based Business Service. We need to call that Business Service to perform database operations.
Q11. What is SLA alert in OSB?
Ans: A service-level agreement (SLA) is a contract between a service provider and a service consumer. In OSB monitoring framework we have SLA alerts that come into the picture when there is a violation of service level agreements.
Q12. What is Pipeline Error Handler?
Ans: Pipeline Error Handlers are used to handle the errors that occurred in the Request or Response Pipeline.
Q13. Explain OSB Service Orchestration?
Ans: Combining existing services to make new services
This is light orchestration as compared to the BPEL orchestration in SOA which may be Synchronous/Asynchronous
But in OSB 11g, it is stateless
There are limitations with OSB 11g as compared to the BPEL/SOA which could be used for maintaining states for hours/days as per our business needs
Q14. What is WSDL? Explain the steps to import WSDL.
Ans: A WSDL defines the public contract (interface specification) between a client and a service, whether the service is a proxy service or a business service. It is the formal description of a Web service. A WSDL is used to describe what a Web service´s interface is, where it resides, and how to invoke it. You create the WSDL resource first since subsequent service registration tasks depend on it. The WSDL is subsequently used to register the business service with the proxy service.
Q15. How to poll file in OSB?
Ans: The proxy service should be using file transport, and also define the required components like File Mask, Polling Interval, Read Limit, Post Read Action etc.
Q16. What is Alert Destination?
Ans: Alert Destination resources capture a list of recipients that can receive alert notifications from the Oracle Service Bus. They are used by Alert actions configured in the message flow, and by SLA alert rules. An Alert destination could include one or more of the following types of destinations: Reporting Datastream, SNMP trap, E-mail, JMS queue, or JMS topic. In the case of E-mail and JMS destinations, a destination resource could include a list of E-mail addresses or JMS URIs, respectively. Alert Destinations can be re-used across alert configurations for services.
Q17. Differentiate OSB and mediator.
Ans: Mediator is an internal component part of SCA. Mediator has the below functionality.
Cross Referencing(XREF): referencing key and fields from seperate systems by means of storing a mapping table.
Domain value Maps(DVM)
Schema Validation : Validate XML Payloads
OSB is a fully fledged standalone stateless ESB.
The main difference is mediator is intra-composite mediation while OSB is inter-composite mediation.
Q18. What is throttling in OSB.
Ans: Throttling is part of endpoint management where we can specify the number of parallel threads the endpoint can have.
Q19. What is split join and types of Split Join?
Ans: Split Join is OSB feature that is used to split input messages and process them with various business logic. There are two types
Static Split Join: Split into a fixed number of branches at the design time.
Dynamic split joins: the split is created dynamically based on the conditions defined during the design time.
Q20. What is Message Context?
Ans: All messages sent to and received by the proxy service are defined internally in the proxy service by a set of properties that holds the message data and meta-data related to that message. This set of properties is known as the Message Context (context) and is implemented using Context Variables. It is defined by an XML schema. Each Context Variable relates to a different property. Some Context Variables are predefined and others are user defined. The heart of the proxy service is the Message context. For a complete description of the Message Context and context variables used in the message flow.
Q21. Where does the Service Bus fit in the SOA landscape?
Significance of OSB in an SOA Landscape
- Oracle Service Bus is at the heart of Oracle’s comprehensive business integration solution and belongs to the Oracle Messaging product line
- Oracle Service Bus is primarily targeted for managing different types of services, and providing traditional message brokering across heterogeneous IT environments
- The lightweight, stateless, high-performance architecture of Oracle Service Bus and its converged intelligent message mediation and service life cycle management capabilities, make it an ideal core component of distributed services networks
- It is designed to fit into the broader IT Service-Oriented Architecture (SOA) landscape as a distributed service management intermediary and can be integrated with other Oracle business process management solutions in distributed heterogeneous deployments
Q22. How does a Service Bus facilitate a loosely coupled architecture?
Described solely by its interface contract and behavioral attributes (i.e. hides its implementation and facilitates loose-coupling)
Loose Coupling of Services:
Loose coupling is achieved through abstracting and resolving the differences between two or more systems in order to facilitate a seamless integration
An ESB/OSB provides or helps to mediate the differences along the following lines:
- Transport Protocol
- Interaction Pattern (message exchange pattern)
- Shape (Interface / Schema)
- Security Paradigm
More definition for loose coupling of services:
Oracle Service Bus establish loose coupling between service clients and business services
OSB maintains the central point security and monitoring
Oracle Service bus is an intermediary that processes incoming service request messages, determines routing logic, and transforms these messages for compatibility with other service consumers
It receives messages through a transport protocol such as HTTP(S), JMS, File, and FTP, and sends messages through the same or a different transport protocol
SOA is a kind of architecture that uses services as building blocks to facilitate enterprise integration and component reuse through loose coupling
Q23. Describe OSB’s role as a Message Broker?
- A message broker is an architectural pattern for message validation, message transformation and message routing
- It mediates communication amongst applications, minimizing the mutual awareness that applications should have of each other in order to be able to exchange messages, effectively implementing decoupling
OSB Message broker:
- Decoupling (via interfaces)
- Routing: provides routing to the correct service instance according to technical or functional data to take into account the partitioning of the components business applications
- Message transformation and enrichment
- Service composition/aggregation
- Light orchestration (stateless)
- Version management
- Protocol break
- Message validation
- Error handling
- Content Control
- Schema Validation
Q24. What are some of the major protocols that OSB supports?
- Native MQ
Q25. What is meant by Location Transparency?
A service bus is used for endpoint virtualization
In 11g stack, Oracle Service Bus (OSB) is the primary service bus
So, we can expose proxy service at OSB t0 outside world and in exposed OSB proxy message flow, route the incoming request to any business service on the basis of routing logic
Note: alternatively, use Mediator in SOA 11g to expose service and use mediator routing logic to route to actual service
OSB Location Transparency:
- OSB creates “Location Transparency” through isolation of consumers from service providers and acts as a proxy layer to transport the message
- OSB can be used to isolate service location changes
Q26. What is Message Enrichment?
Getting additional information from the existing service using Service Callout option
And then adding/inserting this additional information (required) into an incoming message/request XML before it route to the service endpoint
In OSB 11g, it is Business Service
Sometimes, you may have legacy application coded in core Java or EJB, and then at times you may need Java Callout
Q27. Explain OSB Service Orchestration?
Combining existing services to make new services.
This is light orchestration as compared to the BPEL orchestration in SOA which may be Synchronous/Asynchronous
But in OSB 11g, it is stateless
There are limitations with OSB 11g as compared to the BPEL/SOA which could be used for maintaining states for hours/days as per our business needs.
Q28. What is throttling in OSB?
Throttling, which lets you control the amount of message traffic to a business service, helps improve performance and stability by preventing message overload on high-traffic business services.
Throttling means we want to process certain messages in one time, then we need to set some parameters in OSB to do the required task.
Q29. What is Service pooling in OSB?
In OSB we can group together more than one service so that whenever one service goes down, request will route to next available service and end user can continue his work without any interruption.
Q.30 What is Customization File?
Customization files are XML files and you can open these files in any editor and substitute the required environment values.
In addition, you can search for specific environment values (that are not complex XML types) in Oracle Service Bus Console or in a customization file and replace them with the new values. You can fine-tune the scope of the search by filtering these environment values based on variable type or project.
Q31. What is Proxy Service?
It is a service in OSB which is exposed to source system or calling applications or services. Proxy services are Oracle Service Bus definitions of intermediary Web services that Oracle Service Bus implements locally on WebLogic Server.
Q32. What is Business Service?
It is a service in OSB that is used to connect to target system.. Business services are Oracle Service Bus definitions of the enterprise services that exchange messages during business processes
Q33. What does it mean by VETRO concept?
VETRO stands for
V – Virtualisation
E – Enrichment
T – Transform
R – Route
O – Operate
Q34. How to call Java code from OSB?
By using Java callout activity.
Q35. What is Service Result caching in OSB?
Service Result Caching is one of the options that you can use when you want to improve Oracle Service Bus performance. Service Result caching is used when we have business service which connects to external service which returns somewhat static response. So by using Service Result Caching we don’t hit external service for same request instead it will take the response from cache which improve the OSB performance
Q36. When we invoke proxy 2 from proxy 1 then which protocol we need use?
When there is internal proxy call in OSB then we use “local” transport instead of HTTP.
Q37. What is content based routing in OSB?
When we route the request message to different business services based on request message content, that is called content based routing.
Q38. What are different options available in OSB to read flat file?
We can read flat files in two different ways.
Using Message Format Language (MFL): We can MFL in OSB to read flat files.
File Adapter: Create file adapter which read flat file in Jdeveloper, copy JCA, WSDL & XSD file of file adapter in OSB and create proxy service which will read that flat file.
Q39. What is SLA alert in OSB?
A service-level agreement (SLA) is a contract between a service provider and a service consumer. In OSB monitoring framework we have SLA alerts which come into picture when there is violation of service level agreements.
Q40. How to move large file without reading it in OSB?
In Oracle SOA Suite we use “Move” opeartion to move large files from one location to another. But in Oracle Service Bus we don’t have that option available. But we can use Content Streaming option available for file protocol in OSB to move large files.
Q41. By how many ways we can do OSB development?
We can do development in OSB by two ways. Either we can use Eclipse which is IDE tool for OSB or we can use SB console for the development.
Q42. Will you prefer Eclipse or SB console for OSB development?
It is simple to work with SB console as compared to eclipse, so during initial phase we can opt for SB console and later go for eclipse. When we work at enterprise level, Eclipse is always recommended.
Q43. Do we need to create a session when we develop projects in Eclipse?
No, we need not to create a session when we develop projects in Eclipse, session will only come into picture when we deploy the project to server from eclipse.
Q44. Can multiple users work on SB console at one time?
Yes, multiple users with different user roles can work on SB console at same time as session will be created for each users individually.
Q45. What is Dynamic Routing action?
This action is used when we need to route the message to business service dynamically that means at design time we don’t know to which business service we have to route the message and that is determined at run time.
Q46. Which action we use to throw fault/error in message flow?
We use “raise-error” action to throw business fault in message flow.
Q47. What is reply action?
It specify that immediate reply is sent to invoker.
Q48. What actions we use for OSB reporting?
We use Alert, Log and Report for OSB reporting.
Q49. What is Oracle Service Bus Console?
Oracle Service Bus Console is a Web services management dashboard that allows you to monitor Web services and servers and perform service management tasks. The console enables you to perform operational tasks such as configuring proxy and business services, setting up security, managing resources, and capturing data for tracking or regulatory auditing. It provides views to monitor the current state and health of the Oracle Service Bus environment by displaying detailed statistics about servers, services, and alerts. The Oracle Service Bus Console also enables you to respond rapidly and effectively to changes in your service-oriented environment.
Q50. How Throttling is implemented in OSB?
In memory, the queue is used to store messages temporarily. Business service will throttle messages going to the backend and depending on the configuration of business service, will keep messages over the specified limit in an in-memory queue(up to a specified no of max messages) to ensure that backend is not overloaded.
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