25+ LATEST Interview Questions & Answers [ SOA ] -2020 | ACTE
SOA Interview Questions and Answers

25+ LATEST Interview Questions & Answers [ SOA ]

Last updated on 03rd Jul 2020, Blog, Interview Questions

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SOA stands for Service Oriented Architecture. If you are preparing for SOA interview, the following SOA interview questions and answers can be very useful to you. Basically, these SOA interview questions and answers cover basic concepts of SOA like services in SOA, characteristics and principles of services in SOA, loose coupling of services, contract, address and bindings in SOA, main benefits of SOA to the business and IT, difference between services and components in SOA, requirement of SOA to the business, pitfalls of SOA etc. Let’s have a look:

1. What is a Service in SOA?

Ans:

 In the real world, a service is what we pay for and we get the intended service: 

  1. Example 1 (from Real World): You go to a restaurant and order food: Your order first goes to the counter and then it goes to the kitchen where the food is prepared and finally the waiter serves the food.
  • So in order to order an item from a restaurant you need three logical departments / services to work together (counter, kitchen, and waiter).
  • In the same manner in software world, these services are termed as business services. 
  1. Example 2 (from Software World): You go to Amazon to order a book. Different services like payment gateway, stock system, and delivery system come together to achieve your task. 
  • All the services are self contained and logical. They are like black boxes. In short we do not need to understand the internal details of how the business service works. For the external world it’s just a black box which takes messages and serves accordingly. For instance the ‘payment gateway’ business service takes the message ‘check credit’ and gives out output: does the customer have credit or not. For the ‘order system’ business service ‘payment gateway’ service is a black box.

2. What are the main characteristics of services in SOA?

Ans:

Following are the main characteristics of services in SOA:

A) SOA components are loosely coupled. When we say loosely coupled that means every service is self contained and exists alone logically. For instance we take the ‘payment gateway’ service and attach it to a different system.

B) SOA services are black boxes. In SOA, services hide there inner complexities. They only interact using messages and send services depending on those messages. By visualizing services as black boxes, services become more loosely coupled.

C) SOA service should be self defined: SOA services should be able to define themselves.

D) SOA services are maintained in a listing: SOA services are maintained in a central repository. Applications can search the services in the central repository and use them accordingly.

E) SOA services can be orchestrated and linked to achieve a particular functionality: SOA services can be used/orchestrated in a plug and play manner. For instance, the figure ‘Orchestration’ shows two services ‘Security service’ and ‘Order processing service’. You can achieve two types of orchestrations from it: one you can check the user first and then process the order, or vice-versa. Yes, you guessed right, using SOA we can manage a workflow between services in a loosely coupled fashion.

 3. Can You Describe The Complete Architecture Of Soa?

Ans:

  • Please note this architecture diagram is not tied up with implementations of Microsoft, IBM etc. It’s a general architecture. Any vendor who implements SOA needs to fulfill the below SOA components. How they do it is completely their own technological implementation.
  • The main goal of SOA is to connect disparate systems. In order that these disparate systems work they should message each other. ESB (Enterprise Service Bus) acts like a reliable post office which guarantees the delivery of messages between systems in a loosely coupled manner. ESB is a special layer which delivers messages between applications. In the figure we have shown a huge plump pipe. It’s not hardware or some wire etc. It’s a group of components/software which helps you send and receive messages between the disparate applications. Do not try to code your own ESB, you can think of buying one from Microsoft, IBM, Oracle, Progress, etc.

4. What is SOA?

Ans:

SOA stands for Service Oriented Architecture. SOA is an architecture for building business applications using loosely coupled services which act like black boxes and can be orchestrated to achieve a specific functionality by linking together.

5. Are web-services SOA?

Ans:

  • SOA is a thinking, it’s an architectural concept, and web service is one of the technical approaches to complete it. Web services are the preferred standards to achieve SOA.
  • In SOA we need services to be loosely coupled. A web service communicates using the SOAP protocol which is XML based, which is very loosely coupled. It answers the what part of the service.
  • SOA services should be able to describe themselves. WSDL describes how we can access the service.
  • SOA services are located in a directory. UDDI describes where we can get the web service. This is nothing but the implementation of the SOA registry.

6. What are the main benefits of SOA?

Ans:

  • SOA helps create greater alignment between IT and line of business while generating more flexibility – IT flexibility to support greater business flexibility. Your business processes are changing faster and faster and global competition requires the flexibility that SOA can provide.
  • SOA can help you get better reuse out of your existing IT investments as well as the new services you’re developing today. SOA makes integration of your IT investments easier by making use of well-defined interfaces between services. SOA also provides an architectural model for integrating business partners’, customers’ and suppliers’ services into an enterprise’s business processes. This reduces cost and improves customer satisfaction

7. Talking about Service identification, which approach between top-down and bottom-up methodologies encourages re-use and maintenance?

Ans:

Since the top-down approach is business-driven it can be practical to separate the different concerns of business and IT on different plans, providing a common ground in between. So in most situations it the most appropriate if you want to improve reuse and ROI in the medium/long term. 

8. What Are The Different Design Patterns In Soa?

Ans:

  • Synchronous 
  • Asynchronous Fire and Forget 
  • Asynchronous Delayed Response.

9. Do you recall any pattern which could be used to leverage loose coupling?

Ans:

  • The Mediation pattern, using an enterprise service bus (ESB), will help in achieving this.
  • Mediation will take loose coupling to the highest level. It will establish independence between consumers and providers on all levels, including message formats, message types (including SOAP, REST, XML, binary) and transport protocols (including HTTP, HTTPS, JMS).
  • Architecturally speaking this means the separation of concerns between consumers and providers on the transport, message type, and message format levels.

10. The Service of a SOA should be engineered as stateless or stateful?

Ans:

Service should be stateless. It may have a context within its stateless execution, but it will not have an intermediary state waiting for an event or a call-back. The retention of state-related data must not extend beyond a request/response on a service. This is because state management consumes a lot of resources, and this can affect the scalability and availability that are required for a reusable service.

11. What Are The Components Comprise An Oracle Soa Suite Installation?

Ans:

The following components comprise an Oracle SOA Suite installation:

  • Service Infrastructure
  • Oracle Mediator
  • Oracle Adapters
  • Business Events and Events Delivery Network
  • Oracle Metadata Repository
  • Oracle Business Rules
  • Oracle WSM Policy Manager
  • Oracle BPEL Process Manager (Business Process Execution Language)
  • Human Workflow
  • Oracle Business Activity Monitoring
  • Oracle User Messaging Service
  • Oracle B2B
  • Oracle JDeveloper
  • Oracle Enterprise Manager

The following components are included with Oracle SOA Suite, but available as a separate download:

  • Oracle Service Bus (provides service virtualization and protocol transformations for oracle SOA appl)
  • Oracle Complex Event Processing

12. What is composition of a Service?

Ans:

 Composition is the process by which services are combined to produce composite applications or composite services. A composite application consists of the aggregation of services to produce an enterprise portal or enterprise process. A composite service consists of an aggregation of services that produces another reusable service. It’s just like combining electronic components to create a computer motherboard, and then using that motherboard in a computer. Think of the motherboard as a reusable composite service that is a component of the computer, and of the computer as the composite application.

13. How do I integrate my Legacy applications with SOA?

Ans:

 Legacy applications are frequently at the core of your IT environment. With the right skills and tools, you need to identify discrete elements within your legacy applications and “wrap” them in standards-based interfaces and use them as services within your SOA.

14. How does the ESB fits in this picture?

Ans:

The Enterprise Service Bus is a core element of any SOA. ESBs provide the “any to any” connectivity between services within your own company, and beyond your business to connect to your trading partners. But SOA does not stop at just implementing an ESB. Depending on what your goals are, you may want to use an ESB to connect other services within your SOA such as information services, interaction services and business process management services. Additionally, you will need to consider development services and IT service management services. The SOA reference architecture can help you lay out an SOA environment that meets your needs and priorities. The ESB is part of this reference architecture and provides the backbone of an SOA but it should not be considered an SOA by itself.

15. In SOA do we need to build systems from scratch?

Ans:

No. If you need to integrate or make an existing system as a business service, you just need to create loosely coupled wrappers which will wrap your custom systems and expose the systems functionality in a generic fashion to the external world.

16. What’s the difference between services and components?

Ans:

 Services are logical grouping of components to achieve business functionality. Components are implementation approaches to make a service. The components can be in JAVA, C#, C++ but the services will be exposed in a general format like Web Services.

17. The concept of SOA is nothing new, however why has everyone started to talk about SOA only in recent years?

Ans:

Yes, I agree the basic concepts of SOA aren’t new, however some technology changes in the last 10 years made service-oriented architecture more practical and applicable to more organizations than it was previously. Among this:

  • Universally-accepted industry standards such as XML, its many variants, and Web-services standards have contributed to the renewed interest in SOA.
  • Data governance frameworks, which are important to a successful SOA implementation, have been well tested and refined over the years.
  • A variety of enabling technologies and tools (e.g., modeling, development, infrastructure/middleware, management, and testing) have matured.
  • Understanding of business and business strategies has grown, shifting attention from technology to the people, cultural changes, and processes that are key business success factors.

18. What is the most important skill you need to adopt SOA? Technical or Cultural?

Ans:

 Surely cultural. SOA does require people to think of business and technology differently. Instead of thinking of technology first (e.g., If we implement this system, what kinds of things can we do with it?), practitioners must first think in terms of business functions, or services (e.g., My company does these business functions, so how can I set up my IT system to do those things for me most efficiently?).It is expected that adoption of SOA will change business IT departments, creating service-oriented (instead of technology-oriented) IT organizations.

19. What are the main obstacles in the way of SOA?

Ans:

1. Shortage of skills. 

2. Justifying the ROI of SOA projects. 

20. Can I buy an SOA or must I build one?

Ans:

 To move your organization toward greater service orientation, you need to take a balanced approach to building versus buying. To create the infrastructure for an SOA, you’ll need the right commercial off-the-shelf software that complements (rather than replaces) your existing IT infrastructure. This is a “buy” statement. On the “build” side, you may also choose to access know-how and hands-on involvement to use these software products effectively and get the most out of them. This infrastructure and the associated tools can help you create the business services that run on your SOA. Again, there is some “building” associated with this. So the real answer is that you need a certain measure of both building and buying.

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    21. Do I need SOA Governance to get started?

    Ans:

    A key aspect of successful SOA implementations is having business involved in the effort from the beginning. One of the values from SOA you can gain is improved Business/IT Alignment. SOA Governance supplies the decision rights, processes, and policies for business and IT to work together. After a service is deployed, there must be management aspects in place to control and monitor the service. You do not need a lot of SOA Governance to get started, but enough to work with the level of Smart SOA you are implementing.

    22.What are SOA Entry Points?

    Ans:

    To get started quickly with SOA, you need to select an initial project that focuses on a particular business opportunity that can be completed in a reasonably short time frame. The SOA Entry points are project areas that have been shown to provide business value in a timely manner. Each Entry Point provides a key SOA related solution:

    • People – collaboration improving productivity by giving employees and partners the ability to create a personalized, consolidated way to interact with others.
    • Process – optimize and deploy processes on the fly and monitor the effectiveness of the altered processes.
    • Information – improve business insight and reduce risk by using trusted information services delivered in line and in context.
    • Reuse – newly created and reusable services are the building blocks of SOA. Reuse gives users flexibility through reduced cycle time and elimination of duplicate processes.
    • Connectivity – although, in the past, connectivity has been a requirement, SOA brings new levels of flexibility to these linkages. The connectivity provided by SOA has distinct value on its own and as a building block for additional SOA initiatives.

    23. What are the common pitfalls of SOA?

    Ans:

    One of the most common pitfalls is to view SOA as an end, rather than a means to an end. Developers who focus on building an SOA solution rather than solving a specific business problem are more likely to create complex, unmanageable, and unnecessary interconnections between IT resources.

    Another common pitfall is to try to solve multiple problems at once, rather than solving small pieces of the problem. Taking a top-down approach—starting with major organization-wide infrastructure investments—often fails either to show results in a relevant time-frame or to offer a compelling return on investment.

    24. Is SOA really needed on your opinion?

    Ans:

    SOA is not for everyone. While SOA delivers significant benefits and cost savings, SOA does require disciplined enforcement of centralized governance principals to be successful. For some organizations, the cost of developing and enforcing these principals may be higher than the benefits realized, and therefore not a sound initiative.

    25. What are the ends, contract, address, and bindings?

    Ans:

    The service can be made available to clients from different ends. All these services must be exposed through one of these ends.

    The end will consist of the following:

    • Contract: It is an agreement which is agreed upon between two parties. It defines how clients are expected to communicate. It specifies the different parameters and returns values that are to be used.
    • Address: This specifies where a user can find a service. There is an address URL which points to the location of services.
    • Binding: This determines how to access the end. It specifies the process for communication and how it is to be done.


    26. What Is The Most Important Skill Needed To Adopt Soa ?Technical Or Cultural?

    Ans:

     Surely cultural. SOA does require people to think of business and technology differently. Instead of thinking of technology first (e.g., If we implement this system, what kinds of things can we do with it?), practitioners must first think in terms of business functions, or services (e.g., My company does these business functions, so how can I set up my IT system to do those things for me most efficiently?).
    It is expected that adoption of SOA will change business IT departments, creating service-oriented (instead of technology-oriented) IT organizations.

    27. How can you achieve loose coupling in SOA?

    Ans:

    To achieve loose coupling you can use a service interface like WSDL for a SOAP web service. To limit the dependency, you can hide the service implementation from the consumer. Loose coupling can be handled by encapsulating different functionalities in a way in which it will limit the impact of changes to the implementation of different service interfaces. Also, sometime you may have to change the interface and manage versioning without impacting the customers. Also one can manage multiple security constraints, multiple transports, and other specifications.

     28. Is Oracle Soa Same As Oracle Fusion Middleware?

    Ans:

    No because SOA is one of the parts in Fusion middleware and SOA behaves like a user interface whereas Fusion is a big platform.


    29. What Is Sca?

    Ans:

    Service Component Architecture (SCA) provides a programming model for building applications and systems based on a Service Oriented Architecture. SCA is a model that aims to encompass a wide range of technologies for service components and for the access methods which are used to connect them.

    30. Are web services and SOA the same?

    Ans:

    SOA is an architectural concept while web services are used to complete them. Web services are the preferred standards that are satisfied to achieve the architectural specifications of SOA. When one uses SOA all services need to be loosely coupled. Also, SOA services should be able to describe themselves and WSDL services will be describing how we can access the services. Also, these services can be accessed through WSDL. SOA services are located in a directory and here UDDI describes where these web services can be found.

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    31. What is a reusable service?

    Ans:

    Reusable service is a stateless functionality that has the required granularity. It can be a part of a composite application or composite server. A reusable service should be identified with any activity prescribed by business and which has its specifications. A service constraint may be security, QoS, SLA or any usage policies. It may be defined by different runtime contracts, multiple interfaces, and different implementations. A reusable service is looked over by enterprise-level throughout its lifecycle, starting from design time through its runtime. Its reuse should also be promoted through a pre-defined process and its reuse can be measured.

    32. Explain Business Layers and Plumbing Layers in SOA.

    Ans:

    SOA architecture can be divided into two layers. The first layer shows direct relevance to any business and it carries out different business connections. The second layer is a technical layer that tells about how to manage the different computer resources that we have like a database, web server, etc. This segregation is done in order to identify any particular service. Consider any simple system like an order management system. It will have many components which interact with each other to complete the system. The two layers of this system will be where the plumbing layer will contain data access layer, AJAX and many other functionalities.

    33. What are the disadvantages of SOA?

    Ans:

     The main disadvantage of SOA is to see SOA as an end. Due to this developers tend to create complex unmanageable and unnecessary interconnections between resources. Instead, the developer can focus on the business problem that is existing. Another disadvantage can be that rather than solving small pieces of problem you can take the top-down approach where major companies invest and very often fail to show desired results where there is the relevant timeframe.

    34. Explain what is a composition of service.

    Ans:

     By using composition services are combined to produce composite applications. This application consists of an aggregation of services where an enterprise portal or process is created. A composite service consists of an aggregation of different services which will provide reusable services. It acts like combining electronics components and create reusable composite services.

    35. What is ESB and where does it fit in?

    Ans:

    ESB stands for Enterprise Service Bus. Unlike other relationships, it provided any to any connectivity between different companies. Also, you may need to consider deployment services, IT services, etc. The SOA architecture enables SOA to meet all life’s priorities. The ESB is part of this reference architecture and provides the backbone of an SOA but it should not be considered an SOA by itself.

    36. In SOA do we need to build a system from scratch?

    Ans:

    No, if we need to integrate any existing system you just can loosely couple wrappers which help in wrapping all customer services and expose all functionalities in a generic manner.

    37. What is the difference between Monolithic, SOA and Micro services Architecture?

    Ans:

    Monolithic Architecture is similar to a big container wherein all the software components of an application are assembled together and tightly packaged.

    A Service-Oriented Architecture is a collection of services which communicate with each other. The communication can involve either simple data passing or it could involve two or more services coordinating some activity.

    Microservice Architecture is an architectural style that structures an application as a collection of small autonomous services, modeled around a business domain.

    38. What is SOA [Service-Oriented Architecture]?

    Ans:

     SOA is an IT architecture strategy for business solution (and infrastructure solution) delivery based on the concept of service-orientation. It is a set of components which can be invoked, and whose interface descriptions can be published and discovered. It aims at building systems that are extensible, flexible and fit with legacy systems. It promotes the re-use of basic components called services.

    39. What Are The Main Features Of Soa?

    Ans:

    • SOA separates business functions into services (endpoints), which are made accessible over a network in order to allow users to combine and reuse them in their applications.
    • The SOA services can be developed in different languages and OS’es as long as they follow the SOA principles.
    • Services are unassociated and loosely coupled units that do not directly rely on each other for their full functioning. Rather than services embedding calls to each other in their source code, they use defined protocols that describe how services pass and parse messages using description metadata.
    •  Orchestration is a process where business functionality from various services are combined in a system fully aware of all available services and the associated metadata that defines these services and their characteristics.

    40. Mention The Soa Principles?

    Ans:

    •  SOA principles were first defined by Thomas Erl. These 8 principles are underlying to any good architecture that utilizes SOA design to build their products and services:
    • Standardized service contract: Services adhere to a communications agreement, as defined collectively by one or more service-description documents.
    • Service loose coupling: Services maintain a relationship that minimizes dependencies and only requires that they maintain an awareness of each other.
    • Service abstraction: Beyond descriptions in the service contract, services hide logic from the outside world.

    Service reusability: Logic is divided into services with the intention of promoting reuse.

    • Service autonomy: Services have control over the logic they encapsulate.
    • Service statelessness: Services minimize resource consumption by deferring the management of state information when necessary
    • Service discoverability: Services are supplemented with communicative meta data by which they can be effectively discovered and interpreted.
    • Service composability: Services are effective composition participants, regardless of the size and complexity of the composition.

    41. How Do You Transform An Enterprise Business In A Soa?

    Ans:

    •  Transforming an enterprise business to Service Oriented Architecture includes obtaining standardized service contracts, service reusability, service abstraction, service loose coupling, service composability and so on.
    • Of course SOA is an architectural model agnostic to technology platforms and every enterprise can pursue the strategic goals associated with service-oriented computing using different technologies. However in the current marketplace, Web Services are probably the technology platform that better suits SOA principles and are most used to get to this architecture.

    42. Why do we need SOA? 

    Ans:

     Service is the important concept. Services can be published, discovered and used in a technology neutral, standard form by the set of protocols of the web services. Other than being just architecture, SOA is the policies, practices, and frameworks by which it ensures the right services are provided and consumed. It becomes critical to implement processes that ensure that there are at least two different and separate processes— one for providers and the other for consumers, using SOA. The Business Service Bus is a starting point for developers that guide them to a coherent set that has been assembled for their domain. This is better than leaving developers to discover individual services and put them into context

    43.What are the Business Benefits of Service Oriented Architecture?

    Ans:

    SOA can help businesses respond more quickly and economically to changing market conditions. SOA can be considered an architectural evolution. It captures many of the best practices of previous software architectures. The goal of separating users from the service implementations is promoted by SOA. The goals like increased interoperability, increased federation and increased business & technology domain alignment can be achieved by SOA due to its architectural and design discipline. SOA is an architectural approach for constructing complex software-intensive systems from services. SOA realizes its business and IT benefits through utilizing an analysis and design methodology when creating services.

    44.What are the IT Benefits of Service-Oriented Architecture?

    Ans:

    IT benefits of SOA are:

    • The ability to build composite applications is provided.
    • Business services are offered across thvided
    • Provides truly real-time decision-making applications.
    • Reliability is enhanced
    • It is not necessary that Services be at a particular system or network
    • The approach is completely loosely coupled
    • Hardware acquisition costs are reduced
    • At every level there’s Authentication and authorization support
    • Existing development skills are leveraged
    • Provides a data bridge between incompatible technologies
    • The search and connectivity to other services is dynamic

    45. What is the SOA Suite 11g Components?

    Ans:

    • Oracle Adapters
    • Oracle Mediator
    • Business Events and Events Delivery Network
    • Oracle Business Rules
    • Human Workflow
    • Oracle Business Activity Monitoring
    • Oracle Enterprise Manager

    46. What is choreography? How does it differ from orchestration? 

    Ans:

    In choreography there is no business process to control the integration between the systems; each system will directly integrate with one another in sequence where as in Orchestration there is a business process which controls all the services (Source/Target) which is part of the integration. 

    47. What Are Dspmaxthread And Recieverthread Properties? Why Are They Important?

    Ans:

    Receiver Threads property specifies the maximum number of MDBs that process Async across all domains. Whereas the dspMaxThread are the maximum number of MDBs that process Async and threads that operate across a domain. So, we need to ensure that the dspMaxThread value is not greater than Receiver Threads.

    48. What is Tweening?

    Ans:

     Also Known as in-betweening, it is the process of creating intermediary frames among two images to provide the appearance that the first image develops efficiently into the second image. It is a key process which is used in all types of animations. Refined animation software permits you to find particular objects in an image and describe how they will be able to move and change throughout the tweening process.

    49. What Is The Purpose Of Oracle Service Bus?

    Ans:

    •  Oracle Service Bus provides standalone service bus capabilities, enabling separation between application developers and target systems or services. Oracle Service Bus 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.
    • Service response messages follow the inverse path. Oracle Service Bus handles the deployment, management, mediation, messaging, security and governance of implementing SOA to enterprise applications.

    50. What Is The Purpose Of Business Events?

    Ans:

     Business events are messages sent as the result of an occurrence or situation, such as a new order or completion of an order. In Oracle SOA Suite, the mediator service component subscribes or publishes events. When an event is published, other applications can subscribe to it.

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    51. In how many ways can a process be deployed? 

    Ans:

    • Using Jdeveloper
    • Through Enterprise Manger Console
    • Through Weblogic Scripts.

    52. What are dspMaxThread and receiver Thread properties? Why are they important? 

    Ans:

    Receiver Threads property specifies the maximum number of MDBs that process Async across all domains. Whereas the dspMaxThread are the maximum number of MDBs that process Async and threads that operate across a domain. So, we need to ensure that the dspMaxThread value is not greater than Receiver Threads. 

    53. How does a Async request run in the backend? 

    Ans:

     The sequences of events involved in the delivery of invoke messages is as follows: 

    • The client posts the message to the delivery service. 
    • The delivery service saves the invocation message to the dlv_message table. The initial state of the message is 0 (undelivered). 
    • The delivery service schedules a dispatcher message to process the invocation message asynchronously. 
    • The dispatcher message is delivered to the dispatcher through the afterCompletion() call. Therefore, the message is not delivered if the JTA transaction fails. 
    • The dispatcher sends the JMS message to the queue. Places a very short JMS message in the in-memory queue (jms/collaxa/BPELWorkerQueue) in OC4J JMS. The small JMS message triggers the Worker Bean in the downstream step. 
    • This message is then picked up by a Worker Bean MDB, which requests the dispatcher for work to execute. If the number of Worker Bean MDBs currently processing activities for the domain is sufficient, the dispatcher module may decide not to request another MDB. 
    • MDB fetches the invocation message from the dispatcher. 
    • MDB passes the invocation message to Oracle BPEL Server, which updates the invocation message state to 1 (delivered), creates the instance, and executes the activities in the flow until a breakpoint activity is reached. 

    54. How to increase the transaction timeouts in SOA? 

    Ans:

     For the transaction timeout needs to be increased, all the below settings timeout value needs to be changed to the expected Timeout value. 

    • JTA
    • Engine Bean
    • Delivery Bean

    55. Is it possible to use MS SQL Server as a dehydration store with SOA Suite ?if yes how? 

    Ans:

    Yes it is possible. 

    To automatically maintain long-running asynchronous processes and their current state information in a database while they wait for asynchronous callbacks, you use a database as a dehydration store. Storing the process in a database preserves the process and prevents any loss of state or reliability if a system shuts down or a network problem occurs. This feature increases both BPEL process reliability and scalability. You can also use it to support clustering and failover. 

    56. What is SOA governance? What are its functions? 

    Ans:

    • Service-Oriented Architecture (SOA) governance is a concept used for activities related to exercising control over services in an SOA Some key activities that are often mentioned as being part of SOA governance are: 
    • Managing the portfolio of services: This includes planning development of new services and updating current services. 
    • Managing the service lifecycle: This is meant to ensure that updates of services do not disturb current services to the consumers. Using policies to restrict behavior: Consistency of services can be ensured by having the rules applied to all the created services. Monitoring performance of services: The consequences of service downtime or underperformance can be severe because of service composition. Therefore action can be taken instantly when a problem occurs by monitoring service performance and availability. 

    57. What is endpoint virtualization? 

    Ans:

    •  Generally a service bus is used for endpoint virtualization and in 11g stack; Oracle Service Bus (OSB) is the primary service bus. In exposed proxy’s message flow, it can route the request to any of your environment’s actual (physical) service on the basis of whatever logic.
    • Mediator can also be used to expose the service and in mediator routing rule, it can be routed to actual service. 

    58. What are DVM’s and how are they helpful in SOA? 

    Ans:

     DVM-Domain Value Map is static mappings between a source and target system which can be used in transformations. The value can be changed via SOA composer. 

    59. What is the difference between XREF and DVM? 

    Ans:

    • XREF- It is dynamic since the values to the XREF can be populated dynamically and it is stored in the XREF_DATA table in the SOA Dehydration store. 
    • DVM- Domain Value Map is static mappings between a source and target system which can be used in transformations. 

    60. What is Dehydration store? 

    Ans:

     Dehydration store is the database where the instances get stored when it gets dehydrated by the process on the occurrence of non-idempotent activities and also stores the information on the long running processes. 

    61. What is Decision service? 

    Ans:

     Oracle SOA Suite provides support for Decision components that support Oracle Business Rules. A Decision component is a mechanism for publishing rules and rule sets as a reusable service that can be invoked from multiple business processes. These rules can be changed without redeploying the code. 

    62. Why do we use BPEL and OSB? 

    Ans:

     OSB is the light-weight service bus wherever there is not much business logic involved and there is a need to just get the message routed between the systems OSB is used whereas when there is more business logic involved in the process, then BPEL will be used. 

    63. What is MDS? 

    Ans:

    • MDS –Metadata Store 

    Wsdl and Schemas to be used in the process can be published to the MDS and get it used in the code by referring the artifacts from the MDS 

    Advantages: 

    • JAR (Deployment unit) size will be reduced.
    • Duplication of the artifacts can be avoided between the services.

    64. What is a XA data source? How it differs from a non-XA data source? 

    Ans:

     An XA transaction involves a coordinating transaction manager, with one or more databases (or other resources, like JMS) all involved in a single global transaction. Non-XA transactions have no transaction coordinator, and a single resource is doing all its transaction work itself (this is sometimes called local transactions). 

    65. How can we secure our web services using Oracle SOA Suite? 

    Ans:

     When accessing the services should be restricted to the group,then service should be secured via WSM (Web service Manager). 

    66. How to deploy an XSL file without deployment of BPEL Process? 

    Ans:

     We will directly deploy the XSLT, options: – 

    • Using ANT script by file replacement in TMP folder. 
    • By creating a folder in BPEL PM Installation folder and specifying its location in our BPEL code with http call and replacing our xslt to that location. 

    67. What is HA File and FTP Adapters? 

    Ans:

     In the clustered environment, File and FTP adapters should be used as HA

    (High-Availability) 

    • Inbound: It is controlled by Control Files and avoids the race between the manages servers in reading the files where the reference of the files read by the managed servers will be maintained in the control directory. 
    • Outbound: It is controlled by DB Mutex table exist in the SOA dehydration store and this avoids duplicated been written to the same file when all the managed servers in the clusters process the same messages. 

    68. What is singleton Property in SOA? 

    Ans:

    In the clustered environment when the processing of the message should happen via only one SOA managed server, then the property singleton needs to be defined at the adapter level. 

    69. What is a pick activity? Can I have a pick activity with no onMessage branch? 

    Ans:

     Pick activity picks the messages from service (Source) which has multiple operations or the BPEL process needs to receive the messages from multiple source systems. Pick activity should have at least one Message branch. 

    70. What is a flow activity? What is a flowN activity and how does it leverage the flow activity? 

    Ans:

    Flow activity is used, when parallel execution of the flow is needed and to use this property “non blocking invoke should be set as true “at the partner link level and no. of execution of parallel flow is defined and static. Where as in Flown the no. of execution of parallel flow is not static and it is determined during run time. 

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    71. What do you mean by non-idempotent activity? Which all activities are non-idempotent by default? 

    Ans:

     Activities like Pick, Wait, receive, reply and checkpoint() are called non-Idempotent activity and during the execution of the process whenever these activities are encountered then it gets dehydrated to the dehydration store. 

    72. How can we embed or use Java code in BPEL? 

    Ans:

    Using JAVA embedding activity in BPEL, Java code can be embedded in BPEL and can be used. 

    73. How does pick activity differ from a receive activity? 

    Ans:

     Pick activity can act as a multiple receive activity in some business scenarios. If we have two inbound operations and both can trigger the bpel process then we will go with pick activity as we can’t have two receive activity with create Instance box checked. 

    74. How can we make a partner link dynamic? 

    Ans:

     If we have to send the request to a different service which has the same wsdl then dynamic partner link will be used and using addressing schema we can set the endpoint dynamic to send the request to the desired service. 

    75. What is a nonBlockingAll property? 

    Ans:

     Non- blocking invoke is used when Parallel flow needs to be executed where new thread will be created for each invoke activity and which will execute simultaneously. 

    76. What is getPreference property? How do we set it and what advantage it provides? 

    Ans:

     Hard coding is not a good practice, so to avoid hard coding preference variables can be used and the value of the preference variable is accessed using getPreference().The preference variable value can be changed without re-deploying the code via em console MBean property. 

    77. How can we improve the performance of an XSL file? 

    Ans:

     By avoiding use of various if statements and using choose and by using for-each group in place of for-each. 

    78. How do we handle transactions in BPEL? 

    Ans:

    •  Property needs to be defined to start the new transaction or to continue with the same transactions 
    • Property Name: Transaction and if this has value as required then the BPEL process will be continued in the same transaction where as if the value is defined as requiresnew then it will start the new transaction. 

    79. What are transient and durable BPEL processes? 

    Ans:

    • Durable:-It is long running process and initiated through a one-way invocation and do incur one or more dehydration points in the database during execution Ex: Asynchronous 
    • Transient:-It is a short-lived process, request-response style processes and do not incur dehydration during their process execution Ex: Synchronous.

    80. When will you go for the Sync process? 

    Ans:

    Whenever the service returns the response in a few seconds, it is recommended to go for synchronous BPEL process if not the BPEL process should be Asynchronous the reason is calling application can’t proceed further in case of synchronous process. 

    81. What is a syncFileRead operation? Is it an inbound or an outbound operation? Can my process begin with syncFileRead operation? 

    Ans:

     When a file has to be read in the middle of the BPEL process, then we will use syncFileRead Operation, means some process should initiate the file read process and it is an outbound operation and process can’t begin with Sync File read. 

    82. Can we use a File Adapter to get a file without reading its content? 

    Ans:

     Yes, by selecting the Do not read file content check box in the Jdeveloper wizard while configuring the “Read operation.” 

    83. How to increase performance increase in bpel (Db Adapter/file adapter)? 

    Ans:

    We can increase the performance by writing indexes and sequences. 

    (Or) Go to application server —-> Configurations —–> Change Xml file 

    84. Explain error handling in BPEL and what is an error handling framework? How is an error handling framework better than simple error handling in BPEL? 

    Ans:

    EHF –Whenever any error thrown by the BPEL process/Mediator then EHF will check whether exist in Fault-Bindings.xml files and if so then the action in the Fault-Policy.xml file will be taken and if the action is not found then the fault will the thrown and it will be handled in the catch block. 

    85. How do we resubmit a faulted process? 

    Ans:

    • Scenario A: The BPEL code uses a fault-policy and a fault is handled using the “ora-human-intervention” activity, then the fault is marked as Recoverable and the instance state is set to “Running”. 
    • Scenario B: The BPEL code uses a fault-policy and a fault is caught and re-thrown using the “ora-rethrow-fault” action, then the fault is marked as Recoverable and the instance state is set to “Faulted”; provided the fault is a recoverable one (like URL was not available). 

    86. What are Predefined errors in BPEL? 

    Ans:

    • Custom errors
    • Timed out errors
    • BPM errors
    • Validation Errors

    87. What is a throw activity? What is it? 

    Ans:

    Throw activity will explicitly throw the fault and this fault will get caught by the catch block and the corresponding actions will get executed. 

    88. Explain About Web service?

    Ans:

    Web service is a type of software system which is used for exchanging the data and using information from one machine to another machine through a network. Generally Web services based on the standards such as TCP/IP, HTTP, Java, HTML and XML. Web services are pure xml based which is used for exchange information through the Internet to direct application to application interaction. These systems include programs, objects, messages or documents. Many software applications written in various programming languages and running on various platforms can use web services to exchange data over computer networks. You can develop Java-based web services on Solaris and that is accessible from your V.B Program that runs on windows. 

    89. What is the Difference between URI and URL? 

    Ans:

     A URI is an identifier for some resource, but a URL gives you specific information as to obtain that resource. A URI is a URL and as one commenter pointed out, it is now considered incorrect to use URL when describing applications. Generally, if the URL describes both the location and name of a resource, the term to use is URI. Since this is generally the case most of us encounter every day, URI is the correct term. 

    90. What is a Mediator? 

    Ans:

    •  The Mediator is in charge of interconnecting, within an SOA composite application, components that expose different interfaces. In addition, the Mediator can perform duties such as filtering and making routing decisions. 
    • The composite editor in Jdeveloper gives you the flexibility to define the interface now, to choose an existing interface, or to define the interface later as you wire components to the Mediator. Transforming data from one representation to another is, along with routing, one of the key functions of the Mediator. 

    91. What is the Difference between ESB and Mediator? 

    Ans:

    In 10g for routing, separate routers need to be kept along with ESB for routing and filter expressions.Whereas an 11g mediator contains routing rules and filter expressions itself. 

    92. What is the difference between concrete and abstract wsdl? 

    Ans:

    •  Concrete: Besides the information about how to communicate to the web service, it is the information on where the service exists. It has Bindings (Protocol the message should be sent) and Services(has endpoints for each bindings) . 
    • Abstract: It has information about how to communicate to the web service like types (Schema), Message (input and output messages service accepts) ,Operations (operation that can be performed on this service) and port Type.

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