Top 80 Web Services Interview Questions

Web services interview questions based this tutorial covers some important questions and answers to be asked in technical interview.

Web Service is an important topic to be ask in technical interview for the post of software developer and web developer.

Web services interview questions are generally asked in every technical interview conducted by various software and web development company.

Many fresher software developers don’t qualify for this post due to many reasons.

One of the basic reasons for the disqualification is, they cannot satisfy the interviewer by their answers.

I saw this problem So; I have decided to create a dedicated tutorial on web services interview questions and answers that asked in the web service interview.

To give you the exact data and interview question, I have contacted some of the software developers and take down their questions that they have answered in their interview. Student should also read this software engineering tutorial for software engineering concepts.

This web services interview questions based tutorial contains the some important web services interview questions related to various web services concepts. This tutorial will consist web services interview questions for experienced and testers.

So, have a look at the below questions.

Basic Web Services Interview Questions

Some basic web services interview questions and answers are discussed below.

Q1. What do you mean by web services?

Answer: Web service  can be think as a component that provides communication or information exchange between two application over a network. Web services are accessed by client application over the network. This model is very similar as client server model. Web services generally uses three things

• XML messaging system specially for data tagging
• SOAP for message transfer.
• WSDL to denote the service availability.

Q2. What are the components of web service?

Answer: There are various  components of web services architecture. Some main components of web services architecture are described below.

• UDDI – Universal description, discovery and integration.
• SOAP-  Simple object access protocol.
• WSDL – Web service description language.
• RDF- Resource description framework
• XML – Extensible markup Language.

Q3. Write examples of real web services.

Answer:  Some examples of web services is  IBM web service browser. This browser basically represents the several demos associated with web services. UDDI, SOAP and WSDL supports  in providing the web services.

These provides plug in and play interface for using the web services. Some of the services are provided by them are a traffic report service, weather service and stock quote service.

Q4. Explain  interoperability with respect to web services?

Answer:  In general the term interoperability is the ability of different products or systems or system components to work together without any special effort.

With respect to web services interoperability can be defined as the communication among the different applications and sharing of data. There should be no restriction on the application to be in communication.

Q5.What are new features in web services?

Answer: The initiation of XML is the advancement in the field of web services. XML helps web services to communicate between remote procedure calls, web services and their directories.

Q6.What is web service protocol stack?

Answer:  Web service protocol stack is the set of protocols that can be used to explore and execute the web services.

Q7.What are different layers of web services protocol stack?

Answer: Web services protocol stack has four layers. These layers are as follow

• Service transport.
• XML messaging.
• Service Description.
• Service discovery.

Q8.Explain web services architecture.

Answer:  Web service architecture consist of  several components. Each component has a  specific objective. Web service architecture and it’s characteristics are as follow

Service Provider – Service provider is responsible for creating a web services and make it accessible to the client application over the internet for their usage.

Service requestor – Service requestor is the consumer of the web service. In client server model a client application works as service requestor. They send XML request to access the web service over the available network connection.

Service Registry : This  is a centralized directory that supports in locating  the web services for  a client application.

Q9. What is XML RPC in context to web services?

Answer: RPC is the remote procedural call. RPC is a mechanism for invoking or calling the method or services which is available on remote computer. XML is just an extensible markup language.

XML RPC is protocol that use XML messaging for remote procedure call. This is a method for connecting different types of environments and establishes connection between varieties of computers.

Q10. What do you understand by UDDI.

Answer:  UDDI stand for universal, description, discovery and integration. UDDI is a discovery layer in web service protocol.

Q11. What are various features of UDDI?

Answer:  various features of UDDI are explained here

• It is an open framework and is platform independent.
• SOAP, CORBA and JAVA RMI are used for communication.
• It acts as a database which contains all WSDL files.
• It helps business to discovers and enable interaction between them over the internet.

Q12. Tell the name of languages used by UDDI.

Answer:   Language used by UDDI is known as WSDL web service description Language.

Q13. What is BEEP with reference to web Services?

Answer: Full form of BEEP is Block Extensible Exchange Protocol. This is a set of building of new protocols for variety of application such as instant messaging , network management and file transfer. BEEP provides various features such as authentication, security, error handling and handshake protocol.

Q14. Give the name of some tools used for testing of web service.

Answer:  Tools used for testing the web services are as follow

• SoapUI
• REST Client

Q15. Give the name of some special applications used for accessing the web services?

Answer:  The main requirement for accessing the web services is that it must support XML based request response.

Q16. Define SOAP.

Answer:  Simple object access protocol is XML to transfer information between computers.

Q17. What is WSDL?

Answer: WSDL stands for Web Service Description Language.  This is the service description layer in web service protocol.

Q18. What type of security is needed by web service?

Answer: Security level of web services should be higher than the security of Secure Socket Layer.  This level of security can be achieved through Secure Transaction Platform. Web service need this level of security to ensure the reliable transaction and secure confidential information.

Q19.What is entrust Identification service?

Answer:  Entrust identification service comes from the entrust security transaction platform.This transaction platform allows many companies to control the identities so that they can be trusted to do transactions associated with web services transactions.

Q20. What  do you understand by the term PKI?

Answer:  PKI is associated with security. PKI means Public key Infrastructure. Public key is used to encrypt the message. Example of Public key infrastructure is RSA public key algorithm.

Q21. Write the difference between SOA and Web Services.

Answer:  SOA is a design and architecture to implement other service. SOA can be implemented using various protocols such as HTTP, HTTPS,JMS, RMI,RPC etc. Soa can be clearly understood by soa architecture diagram and service oriented architecture for dummies

Q22.Give the name of some approaches used  to develop the SOAP based web service.

Answer:  SOAP based web service can be developed by using two approaches such as contract-first and contract-last. In contract-first approach contract is defined first and then class is derived from the contract where as in second approach first the classes are defined and after that contract is derived from these classes.

RESTFul Web Services Interview Questions

Some restful Web services interview questions and answers are discussed below

Q23.What is restful web services?

Answer:  The term REST stands for representational state transfer. REST is the stateless client server architectural style for developing the application to be access over the web. When HTTP also uses the concept of REST then this is known as RESTful.

RESTful web service enables the web service to work best with by including properties like

• Performance
• Scalability
• Modifiability

Q24. What is difference between SOAP and REST.

Answer:  Difference between SOAP and REST is explained here in this table

SOAP	REST
This is a standard protocol for web service creation	Architectural style for web service creation
Web service and client are tightly coupled and defined some standard to be strictly followed.	It does not follow too many standard. Loosely coupled.
Usually Less preferred and permit XML format only	More preferred and permit data format like text, html and json.
JAVA API  for SOAP web service is JAX-WX	Java API for REST web service is JAX-RS

Advanced Web Services Interview Questions

Some important advanced level web services interview questions and answers are given below.

Q25. What are the different elements of WSDL documents?

Answer:  The different elements of the WSDL document along with a brief description is enlisted below:

Types: This defines the message data types, which are in the form of XML schema, used by the web services.

Message: This defines the data elements for each operation where messages could be the entire document or an argument that is to be mapped.

Port Type: There are multiple services present in WSDL. Port type defines the collection of operations that can be performed for binding.

Binding: It determines and defines the protocol and data format for each port type.

Operations: This defines the operations performed for a message to process the message.

 Q26. Explain the way to provide the API to user.

Answer:  To provide API to the users one can easily do this with open table. We need to write open table which is basically an XML Schema that point to a web service.

Q27.What are various communication channels in web services?

Answer:  Web Services use three different communication channels with the help of three protocols HTTP/POST, HTTP/GET and SOAP. Client can use any communication methods as per his need.

Q28.What is distributed technologies?

Answer:  Distributed technologies allow the execution of program on different computers or server located at different location. It simply allows the segmenting of application units and transferring them on different computer over the network. Student can read this distributed computing  tutorial to know more about distributed technologies.

Q29. Write the difference among the web services, CORBA and DCOM.

Answer: Web Service transfer message to/from application through HTTP protocol and it use XML to encode the data.

CORBA and DCOM transfer message to/from application through non standard protocols like IIOP and RPC.

Q30. What are various advantages of using web services?

Answer:  Now a day web services are supported by variety of platform. Web Service may spread its boundary and enhance new methods that will provide ease to client.

Q31.Explain some standards used in web services?

Answer: Some standard used in web services are WSDL (used to create interface definition), SOAP (to structured the data) HTTP Communication Channel. DISCO used to create discovery document and UDDI ( used to create business registers)

Q32.How a .net web service tested?

Answer: ASP.NET use test page after regular interval of time. When one calls the url of .asmx file in any browser. This page shows complete information regarding the web services. 

Q33.Write the name of two Microsoft solutions for distributed application.

Answer:  .NET Web Service and .NET  remoting.

Q34. What is difference between . NET web service and .NET remoting?

Answer: As far as protocol is concerned . NET web service use HTTP and .NET remoting can use any protocol like TCP/HTTP/SMTP. Other difference is that .NET remoting is faster than .NET web Service. Another difference is that .NET web Service is hosted via IIS and it makes .Net Web service more reliable as compare to .net remoting.

Q35.How web services are implemented in .NET?

Answer: To implement web services in .net we use HTTP Handler that interrupt requests to .asmx file.

Q36.What are various steps performed by Client to access the web services?

Answer:  Following steps are performed by the client to access the web service

• At first a web reference to web service is created by the client in his application.
• A proxy class is generated.
• An object of the proxy class is created
• Web service is access by the proxy object.

Q37. What is the disadvantage of Response Caching.

Answer: Caching mean storing information. In remote caching information is stored from external spruces.

Q38. How to overcome problem of Response Caching?

Answer: To overcome response caching problem use Data Caching (System.Web.Caching.Cache) instead of Response Caching.

Q39. How a class can be access as web services?

Answer: In order to access a class as web service we have to inherit the class from System.Web.Services. WebServices class and qualify the class with web service attribute.

Q40. Give the name of two types of web services.

Answer:  Two types of web services are SOAP based web services and Restful web service.

Q41. What is Entrust Identi_cation Service?

Answer: Entrust Identification Service is categorized under Entrust Secure Transaction Platform that provides essential security capabilities to ensure secure transactions. This usually allows companies to fully control the identities that are trusted to perform web service transactions.

Q 42. What is Entrust Entitlements Service?

Answer: Entrust Entitlement service is those whose task is to verify the services that are attempting to access the web services. It basically ensures security in business operations as well as some authentication services.

Q43.What is advantage of using RESTFUL Services.

Answer:  Advantages of RESTFUL Services is that , restful services are easy to implement and test. It support various data formats and as XML and JSON.

Q44.What is JAVA Web Service?

Answer:  Java web service is used to build and deploy basic web service on JAVA Platform.

Q45. What are methods to create web service?

Answer:  There are two methods to create web services are TOP Down Approach and TOP Up Approach.

Q46.What is JAXP?

Answer: JAXP is a JAVA  API for XML processing that enable an application to write, read, manipulate and transform XML data. Similarly to perform various other functions there are other JAVA API’s as well like JAX RPC, JAXM,JAXR, JAXB.

Q47. What do you understand by JAXB binding Framework?

Answer:   JAXB binding framework is available in three Java Packages.

• bind: This packages defines abstract classes and interfaces that are used directly with content class.
• bind.util: This packages contains utility classes that may availed by client application to manage marshalling, unmarshalling and validation events.
• binder.helper: This helper packages gives partial implementation for some of the javax.xml.bind.interface. These APIs are not directly used by applications using JAXB architecture.

Q48. How a XML document can be Marshal in JAVA?

Answer:  Marshalling is a process of converting the XML document in JAVA readable form while unmarshalling is the reverse process. The process of unmarshalling is as follow

JAXBContext  jc = JAXBContext.newInstance(“com.acme.foo”);

//unmaeshal from foo.xml

Unmarshaller u = jc.createUnmarshaller () ;

FooObject fooObj= (FooObject)u.unmarshal (new File (“foo.xml”) );

// marshal to sytem.out

Marshaller m = jc.createMarshaller ();

m.marshal (fooObj, System.out);

Q49.  What type of Validation a JAXB client can perform?

Answer:  There are two types of validation perform by JAXB Platform.

• Unmarshal Time Validation
• On-Demand Validation.

Q50.What are the various ways of event handling during marshal and unmarshal operation?

Answer:  There are three ways of doing this task

• Using the default Event Handler
• Register and implement a custom event handler
• Use the validation Event Collector  Utility

Q51.Where does a JAXB compiler is located?

Answer: JAXB schema binding compiler is placed in

<JWSDP_Home>/jaxb/bin directory. This directory has two scripts, xjc.sh (Solaris/Linux) and xjc.bat (Windows).

Q52. What do you mean by XML signature?

Answer: XML is also used to digitally sign any arbitrary data. This data may be either in binary or XML form.  This data can be recognized using URIs in one or more elements that acts as reference. XML signature can be described in one or more forms these forms are detached, enveloping  and enveloped.

Q53.What is STAX?

Answer: STAX stands for streaming for xml. It is an API to read and write XML document and it is originating from java programming.

Q54.What is inline customization with reference to JAXB?

Answer: Customization to JAXB bindings made by means of inline binding declarations in an XML schema file that take the form of <xsd:appinfo> elements embedded in schema <xsd:annotation>elements.

Q55. What are some usual XML APIs.?

Answer: The usual XML APIs have two types of API first is DOM based AOI and second is Tree based APIs. The complete document is rendered into memory as a tree structure for random availability and this is achieved through calling application Event based APIs: The application need registers to get events as entities which are encountered in a document which is known as source document.

Q56.What is  PUSH parsing?

Answer: Push Parsing is the parsing technique in which parser pushes the parsing events or XML data for an application. In push parsing model the parser got the hold over the parsing process and the parser calls the implemented handler methods.

Q57. What is PULL parsing?

Answer:  Streaming pull parsing is referred to a programming model in which a client application calls methods on an XML parsing library, when it needed to communicate with an XML info set it means the client will get only XML data if it is asked for.

Q58.What are various packages available in XML digital signature APIs?

Answer:  Generally Six packages are available in XML digital signature API. These are as follow

• crypto
• crypto.dsig
• crypto.dsig.keyinfo
• crypto.dsig.spec
• crypto.dom
• crypto.dsig.dom

Q59. What is JAXR?

Answer: JAXR is the JAVA programming APIs for Java platform application to access and

Programmatically interact with various kinds of meta-data registries.

Q60. Explain the JAXR architecture.

Answer: JAXR is the JAVA programming APIs for Java platform application to access and

Programmatically interact with various kinds of meta-data registries.

Q61. Explain JAXM messaging MODEL.

Answer: Messaging models for JAXM are of two types synchronous and asynchronous model.

• Synchronous messaging model: In this type of model, client directly communicates with the source. In this, the client will send the request and waits.
• Asynchronous messaging model: In this model, client directs the message to the messaging provider and returns back.

Q62. Explain web service architecture.

Answer: Web service architecture consist three main roles. As per web service architecture and it’s characteristics these role are as follow

• Provider: provider creates the web services and make it available to client application.
• Requestor: A requestor is nothing but a client application that need to connect a web services. The client application can be .net or java or nay other language based application.
• Broker: Broker is the application that provides access to UDDI.

Q63.Explain different  core components of HTTP request and HTTP response?

Answer:  Core components of HTTP request are as follow

HTTP Request Components	Meaning
Verb	Indicate HTTP methods like GET, PUT, POST, etc
URI	Identi_es the resource on server
HTTP VERSION	Indicates version
Request Header	Contains metadata like client type, cache settings, message body format, etc
Header Body	Represent content of the message

Core components of HTTP Response are as follow

HTTP Response	Meaning
HTTP VERSION	Represent version
Response Header	Consists of metadata like content length, content type, server length, etc for HTTP response message.
Response Body	Represent response message content

Q64.What is the format of URI in REST architecture?

Answer:  The format of URI is as follow

<protocol>://<service-name>/<ResourceType>/<ResourceID>

Q65. What do you understand by term stateless  with respect to web services?

Answer: In REST architecture have some restriction such as REST web service is not allowed to keep a client state on the server. This condition is known as ‘Statelessness’. In such a condition, the client passes its context to the server and in turn, the server stores the context in order to process the client’s further requests.

Q66. What are advantages and disadvantages of statelessness?

Answer: The advantages of statelessness include

• Each and every method requests are treated independently.
• Application design is simplified as it does not maintain the client’s previous interaction.
• Works with HTTP protocol as it shares the feature of being statelessness.

The disadvantage of statelessness includes

• Every time client interaction takes place, web services are to be provided with extra information about each request so that they can interpret the client’s state.

Q67.What are the elements of a SOAP message?

Answer: A SOAP message has following four elements

• First element is Envelope element that identifies the XML document as a SOAP message.
• Second element is Header element that contains header information.
• Third element is Body element that contains call and response information.
• Fourth element is a Fault element containing errors and status information.

Q68. What are syntax rules applicable on a SOAP message?

Answer: Must use the SOAP encoding namespace.

• Must not contain the DTD reference.
• Must not contain XML processing instructions.

Q69. What is SOA?

Answer:  SOA is known as service oriented architecture and it defines an architecture pattern consisting of services. Here application components provides services to other components using communication protocols over the network. This communication involve data exchanging or some coordination activity  between services and soa vs microservices.

Some of the key principles on which SOA is based are as follow. These principles are based on soa architecture diagram and service oriented architecture for dummies.

• The service contract should be standardized containing all the descriptions of the services.

• There is loose coupling determining the less dependency between the web services and the client.
• It should follow Service Abstraction rule, which says the service should not expose the Manner in which functionality is executed for client application.
• Services should be reusable in order to work with various application types.
• Services should be stateless having the feature of discoverability.
• Services break big problems into little problems and allow diverse subscribers to use the services

Q70.What is SOAPUI?

Answer:  SOAPUI is an open-source, free and cross-platform functional testing solution. Mentioned below are some actions performed by SOAPUI:

• It can help create functional, security and load testing test suites.
• Data-driven testing and scenario-based testing is also performed.
• It has the ability to impersonate web services as well as has got built-in reporting abilities.

Note : Students can access this SOAPUI Information Page  to know more about this testing tool.

Q71.Explain some securities issues related to web services?

Answer: Various security issues related to web services are as follow

Authentication: Authentication is a technical mechanism used to verify the identity of the users and authentication also ensures that the user using the web service has the right for using this or not ?

Authentication also helps in tracking the user’s activity. There are several options that can be considered for this purpose

• Application-level authentication
• HTTP digest and HTTP basic authentication
• Client certificates

Network Security: This is another serious issue that requires tools to alter web services.

Q72. What are the foundation of security services?

Answer:  Foundation security services consist of following concepts.

• Integration
• Authentication
• Authorization
• Digital Signatures
• Encryption processes.

Q73.What is Entrust privacy service?

Answer: As the name suggests, Entrust Privacy Service is a mechanism that perform encryption of the data so that only concerned parties are able to access the data. Main objective of Entrust privacy service is to maintain the confidentiality and security features of information security.

This also one of the important web services interview questions.

 Q74.What are different elements of WSDL document?

Answer:  The different parts of  the WSDL document and their description are given below.

Types: This part of WSDL document defines the data types of the message and generally this s is available in the form of XML schema as used by the web services.

Message: This par of the WSDL document defines the data elements for each operation. In this part messages could be the either the entire document or it may be an argument that is to be mapped.

Port Type: There are multiple services present in WSDL. Port type is the part of WSDL document that defines the collection of operations that can be performed for binding.

Binding: Binding part of the WSDL document basically determines and defines the protocol and data format for each port type.

Operations: This defines the operations performed for a message to process the message.

Q75.What are message elements in WSDL?

Answer: The message element in  WSDL describes the data that has been exchanged between the consumer and the web service providers.

Every web service consists of two messages and each message has zero or more <part> parameters.

These two messages discussed in this web services interview questions are as follow –

Input: Describes the parameter for the web service.

Output: Describes the return data from the web service

Q76.Enlist the operation type response used in WSDL.

Answer:  Operation type responses in WSDL are of four types and these are as follow-

Solicit-Response: This is basically used to sends a request and then waits for a response. 

Notification:  Notification element of WSDL document sends a message but does not wait for a response.

Among these operation Request-Response is the widely used common operation type also explained in this web services interview questions.

Q77. Is binding between SOAP and WSDL possible?

Answer: Yes we can bind WSDL to SOAP. The binding is possible through two Attributes.

Name: Defines the name of the binding.

Type: Defines the port for the binding.

For SOAP binding we declared two attributes.

Transport: This attribute defines the SOAP protocol to be used i.e. HTTP.

Style: This attribute may be either ‘rpc’ or ‘document’.

Q78. Explain <definition> element.

Answer: Definition element is the root of WSDL document  and it defines the

name of the web service as well as act as a container for all the other elements.

Q79.Explain attributes of <Port> element in WSDL.

Answer: A <port> element in WSDL basically defines an individual endpoint by specifying a single address for a binding. The binding attribute refers to the binding using the linking rules defined by WSDL.

Q80. What are various points that should be considered by port while Binding.

Answer: WSDL supports the  extensibility elements that are used to specify binding information.  Some  important points that should be kept into consideration while binding are as follow.

A port must not

• Specify more than one address.
• Specify any binding information other than address information

Conclusion and Summary

In this tutorial we have discussed the web services interview questions and answers related to following important concepts.

• Interview Questions and Answers related to basics concepts of web services such as web service architecture, features of web services, examples and different roles in web service.
• Web services interview questions and related to SOAP, WSDL and UDDI.
• Interview questions and answers related to RESTFul web service and .Net web service.
• Web services interview questions and answers related to JAXP, JAXB, JAXR, XML Signature and STAX.
• Interview Questions and answers Related to XML Document and Parsing.
• Web services interview questions and answers related to security services and HTTP request and HTTP Response.

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