Webservice Interview Questions

The followings are some commonly asked interview questions related to Web Services. These questions are alphabetically sorted. For other interview questions on other technical topics, go to my page here.

  1. Define SOAP?
  2. Explain the web service architecture?
  3. How do you generate web service client from WSDL files?
  4. How do you test a web service?
  5. Name few standards used in web services.
  6. What are some WSDL operations?
  7. What are the common components of web service?
  8. What is a bottom up approach?
  9. What is a provider and a consumer?
  10. What is a response caching?
  11. What is a top down approach?
  12. What is a web service protocol stack?
  13. What is a web service?
  14. What is an end point?
  15. What is REST protocol?
  16. What is SOAP-UI?
  17. What is UDDI?
  18. What is WSDL?
  19. What is XML RPC?
  20. What kinds of tools can you use for creating RESTful Web Services?
  21. Why would you choose REST instead of SOAP?

Twenty Differences Between SOAP and REST Webservices

Even though comparing SOAP and REST Webservices will be like comparing apples and oranges because one is a protocol the other is an Architecture, I have made an attempt to expose twenty differences aimed at helping people make a decision on using one vs another. Also if you are new to SOAP Webservices, read my article here on using SOAP UI tool to demonstrate the use of SOAP Request Response.

Acronym Simple Object Access Protocol Representational State Transfer
Efficiency SOAP Uses XML which is not very efficient and may not be a good fit for some languages. SOAP can be slow and is definitely a heavyweight choice. REST is a lightweight protocol and is fast.
Format SOAP has one common and expressive format REST response can be of multiple types.
Security Security can be implemented using WS-Security, WS-Trust and WS-SecureConversation Security is implemented in terms of HTTP andSSL
Protocols SOAP can be used over other protocols not just HTTP such as HTTPS, SMTP, TCP, UDP, JMS. SOAP itself is a protocol. REST is completely based on HTTP and URI’s. REST is not a protocol in itself
Reliability End to end communication is reliable via WS-ReliableMessaging which does retries. The client does not need to retry. REST expects the client implementation to handle communication failures by retrying
Simplicity More complex due to client creation requirements. SOAP also has several parts to it such as envelope, Header, Body, Attachments and Fault. Raw HTTP calls via GET, POST, PUT, DELETE and is simpler invoke
Data The request and response are in XML format. The response object can be on several formats such as XML, JSON, RDF etc.
Capabilities Exposes  Operation and types of data. Exposes Resources
Describing interface WSDL No particular standard
Transactions Support ACID transactions via WS-AtomicTransaction No particular standard
Caching SOAP Reads cannot be cached REST reads can be cached.
Dependency SOAP cannot use REST RESTful architecture may use HTTP or SOAP as the underlying communication protocol.
Scalability Less scalable than REST More Scalable than SOAP
Network Works pretty well in distributed enterprise environments REST assumes direct point to point communication
Extensibility SOAP is extensible in the forms of WS* standards. There are no particular standards in extending REST.
Learning Curve SOAP has a steep learning curve REST has a smaller learning curve.
Interface SOAP  interfaces are not uniform REST provides a uniform interface.
Formal Contract SOAP provides a format contract between the provider and consumer There is no formal contract between the provider and consumer in a RESTful webservice.
State SOAP provides mechanism for stateful communication REST is a totally stateless operation.

Complete Tutorial On Using SOAP-UI to Mock Web Service Request / Response

I found SOAP-UI tool while I was looking for ways to mock the web services temporarily while I and my team were waiting on the real web-service to be ready for doing integration test with our front end application. SoapUI is an open source web service testing application for service-oriented architectures (SOA). Its functionality covers web service inspection, invoking, development, simulation and mocking, functional testing, load and compliance testing.

This tutorial covers some basic stuffs of using this tool to create Mock request/response from sample WSDL (Web Service Description Language). Although the tool offers advanced options and features, this scope of this article would be enable the readers to download, install and run a mock service using a simple WSDL file.

Here is the WSDL file that I will be using in this tutorial.

<definitions name="SampleService" targetNamespace="http://www.sanjaal.com/wsdl/SampleService.wsdl" 

	<message name="SampleRequest">
		<part name="firstName" type="xsd:string"/>
	<message name="SampleResponse">
		<part name="greeting" type="xsd:string"/>
	<portType name="Sample_PortType">
		<operation name="sampleOperation">
			<input message="tns:SampleRequest"/>
			<output message="tns:SampleResponse"/>
	<binding name="SampleBinding" type="tns:Sample_PortType">
		<soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>
		<operation name="sampleOperation">
			<soap:operation soapAction="sampleOperation"/>
				<soap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" 
					namespace="urn:sanjaal:sample-service" use="encoded"/>
				<soap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" 
					namespace="urn:sanjaal:sample-service" use="encoded"/>
	<service name="Sample_Service">
		<documentation>WSDL File for SampleService</documentation>
		<port binding="tns:Sample_Binding" name="Sample_Port">
			<soap:address location="http://www.sanjaal.com/sample-service"/>

Download SOAP-UI:

SOAP UI tool is free and open source tool and can be downloaded from the website www.soapui.org. I prefer to download in the zip format, which you can just unzip to any location of your choice and are ready to start to work with. But they have other binary distributions with installers. No matter which option you use, there will be folder where SOAP UI is installed or unzipped.

As you can see in the screenshot below, I had unzipped the SOAP-UI tool to C:soapui-4.5.1 folder.

To start the tool, navigate to the bin folder and double click on soapui.bat file. You can also run this bat file from command prompt.

SOAP-UI Webservice Mock Tutorial

Once the bat file runs, you will see a blank Soap-UI tool running.
SOAP-UI Webservice Mock Tutorial

To start a new project, click on File > New soapUI Project or just hit Ctrl + N
SOAP-UI Webservice Mock Tutorial

You will be prompted with a New soapUI Project dialog box where you can provide a name for your project. You will also see that you can browse your WSDL file using this dialog.
SOAP-UI Webservice Mock Tutorial

Go ahead and browse your WSDL file. If you don’t have a WSDL file, you can copy the content of the sample WSDL we have provided at the beginning of this tutorial and save it to a file as .wsdl extension – such as sample.wsdl
SOAP-UI Webservice Mock Tutorial

Once the WSDL file is loaded, you will see something similar to the following. The view depends on how many operations you have defined in the WSDL file, what names you have chosen etc. For each operation, you will see the Requests created by default.
SOAP-UI Webservice Mock Tutorial

To mock a service for this request, right click on the Binding (again depends on what names you choose for your binding), and click on Generate Mock Service
SOAP-UI Webservice Mock Tutorial

You will be prompted with a Generate MockService dialog where you can choose operations, path (which will be a part of your endpoint definition) and you can even tell the tool what port to use for this service. Make sure to choose the port that has already not been taken.
SOAP-UI Webservice Mock Tutorial

Once you hit OK on the above dialog,  it will ask for what you want to name this WebService Mock. Give it a name – it can be anything.
SOAP-UI Webservice Mock Tutorial

You will then see that on the navigator, a MockService with the name that you provided on the prior screenshot is created. When you double clock on the operation name of your choice, it will open a window on the right hand side where you have option to run the Mock Service (The small green icon). Click on that icon to start the MockService
SOAP-UI Webservice Mock Tutorial

The following window shows that the MockService is running (red button stops the service), it also displays what port it is running on.
SOAP-UI Webservice Mock Tutorial

Double click on the request from the left hand navigation. If you want to change the end point, you can edit the URL on this screen. Once you have selected the right end point, click on the small green icon on the request window.
SOAP-UI Webservice Mock Tutorial

If the mock service is running correctly, you will see the response on the right window.
SOAP-UI Webservice Mock Tutorial
Once the service is running, you can also connect to it from your browser. My endpoint is defined at: http://localhost:8088/sampleService which is my webservice URL.

Just type in the url without the service name (in my case I typed just http://localhost:8088). You will see a page seeing what all services are running.
SOAP-UI Webservice Mock Tutorial

If you click on the service of your choice, you will be shown with the WSDL.
SOAP-UI Webservice Mock Tutorial

You have successfully completed learning how to mock a webservice using SOAP-UI.