Web services is a large subject. This comprises its architecture, as well as components such as SOAP, WSDL, RESTful web services, and Web services security.
This article covers all of the key Web services topics that you must be familiar with in order to answer any level questions. It is important that you must be well versed with the basic concepts before interview.
You’ll also find the most frequently asked web services interview questions and answers. This way you can skip on to a certain segment if necessary.
The comprehensive list of web services interview questions will surely help you to crack any interview.
Basic Web Services Interview Questions and Answer
What is a Web Service?
A web service is a type of software that may be used over the Internet. It employs the XML messaging system and provides end users with a user-friendly interface.
Give me a real-world example of a web service.
IBM Web Services Browser is an example of a web service. It’s available on the IBM Alphaworks website. This browser displays a number of web service demos. SOAP, WSDL, and UDDI are the most common ways to use web services. All of these provide a plug-and-play interface for accessing web services such as stock quotes, traffic reports, and weather forecasts, among others.
What are the elements that make up a web service?
The following are the many components of web services:
- SOAP- Simple Object Access Protocol
- UDDI- Universal Description, Discovery, and Integration
- WSDL- Web Service Description Language
- RDF- Resource Description Framework
- XML- Extensible Markup Language
What is your definition of a web service protocol stack?
It’s essentially a collection of protocols for exploring and executing web services. Service Transport, XML Messaging, Service Description, and Service Discovery are the four layers that make up the overall stack.
Can you describe each of these protocol stack layers?
HTTP, SMTP, FTP, and Blocks Extensible Exchange Protocol all use the Service Transport layer to convey messages between different applications (BEEP). Messages are encoded in XML format by the XML Messaging layer so that they may be understood at both ends, such as XML-RPC and SOAP. The Service Description layer, often known as WSDL, describes the user interface for a web service. The Service Discovery layer organizes services into a common registry and provides simple publishing capabilities, such as UDDI.
What exactly do you mean by XML-RPC?
RPC stands for Distant Process Call, and it is a technique of calling a procedure or function that is available on any remote computer.
Extensible Markup Language (XML) is an acronym for “Extensible Markup Language.” As a result, XML-RPC is a simple protocol for performing RPCs utilizing XML communications. This has long been regarded as a useful tool for linking various surroundings as well as establishing connections amongst a wide range of systems.
What is a web service and how does it work?
A web service uses open standards like HTML, XML, WSDL, and SOAP to interact across different applications. On Solaris, you can create a Java-based web service that can be accessed from your Windows Visual Basic programmed. You may also use C# to create new web services that are invoked from your Java Server Pages (JSP)-based web application that runs on Linux.
Define SOAP
Simple Object Access Protocol (SOAP) is an acronym for Simple Object Access Protocol. It’s a web service access protocol based on XML. It works on any platform and in any language. You can interface with other programming language applications by utilizing SOAP.
What is the meaning of Entrust Identification Service?
The Entrust Security Transaction Platform provides the Entrust Identification Service. This platform enables businesses to manage the identities that are trusted to carry out Web services transactions.
What exactly is UDDI?
Universal Description, Discovery, and Integration (UDDI) is an acronym for Universal Description, Discovery, and Integration. It is a framework for describing, identifying, and integrating web services that is based on XML. It includes a list of web services that are available. WSDL is a component of UDDI.
Moderate Web Services Interview Questions and Answer
What is the architecture of a web service?
The architecture of a web service framework is divided into three tiers. The following are the duties of these layers:
Service Provider: As the name implies, the duty of the service provider is to construct the web service and make it available to client applications for use over the internet.
Service Requestor: A service requestor is essentially any web service consumer, such as a client application. Applications for clients can be written in any language. They send XML queries through the available network connection to access web services for any form of functionality.
The Service Registry is a centralized directory that aids in the discovery of web services for client applications. Existing web services can be found here, and developers can also create new ones.
To make existing web services available to client applications, the Service Provider uses the Service Registry’s ‘Publish‘ interface. The Service Requestor can bind or invoke services using all of the information provided by the Service Registry.
What are the benefits of XML-RPC?
The following are the main features of XML-RPC:
- RPCs are carried out with the help of a basic XML language.
- HTTP POST is used to send XML encoded requests.
- The XML response is incorporated into the HTTP response.
- It is considered platform agnostic.
- It allows several applications to communicate with one another.
- The HTTP protocol is used to transfer data between client and server computers.
- It provides a limited XML vocabulary for specifying the nature of requests and responses.
What are some of the advantages of using web services?
We’ve already talked about web services, their architecture, and their components. Let’s have a look at some of its benefits:
- Every program is now available on the internet, and it is the web service that gives the client apps with the capabilities they want.
- Web services allow current functionalities to be exposed over the network, allowing other applications to utilize them in their own programs .
- It offers elements such as ‘Interoperability,’ which governs communication between different applications, data sharing, and service sharing.
- For communication, web services employ the standardized web service protocol stack, which is made up of four layers: Service Transport, XML messaging, Service description, and Service discovery.
- Because it uses SOAP (Simple Object Access Protocol) instead of the HTTP protocol, it has a low communication cost.
- It’s simple to set up, integrate, and reuse.
- As part of the loose coupling feature, it allows for straightforward integration between distinct features.
What exactly is BEEP?
Blocks Extensible Exchange Protocol (BEEP) is an acronym for Blocks Extensible Exchange Protocol. BEEP is tasked with developing new protocols for a wide range of applications, including instant messaging, network administration, and file sharing. It’s known as the new Internet Engineering Task Force (IETF), and it’s built directly on top of TCP. It contains a number of built-in features, including:
- Authentication
- Security
- Handshake Protocol
How well do you understand RESTful Web Services?
Representational State Transfer (REST) is an acronym for Representational State Transfer. The stateless client-server architectural paradigm for designing web-based applications is known as REST.
RESTful Web services are defined as web services that employ HTTP methods to implement the REST architecture idea. Data and functionality are offered as resources in this architectural paradigm, and they are accessed via URIs (Uniform Resource Identifiers).
RESTful web services improve the performance of web services by inducing qualities such as:
- Performance
- Scalability
- Modifiability
What is the best way to document a web service?
Web services are considered self-documenting since they offer complete information on the accessible methods and parameters for WSDL, an XML-based standard. WebService and WebMethod properties can also be used to offer additional information to explain web services.
What are the scenarios in which ASP.NET web services are required?
When a web service requires a three-tier architecture, ASP.NET web services are used. It provides convenient ways to employ intermediate tier components over the internet. The key benefit of.NET Web services is that they can communicate across firewalls since they employ the SOAP transport protocol.
What do you mean when you say “distributed technologies”?
The demand for distributed technologies has increased as the proportion of distributed applications has increased. It allows application units to be segmented and transferred to various computers on separate networks.
Can you tell the difference between web services, CORBA, and DCOM?
Web services use the HTTP protocol to send and receive messages to and from applications. Data is encoded using XML.
CORBA and DCOM use non-standard protocols like IIOP and RPC to send and receive messages to and from applications.
What is the most significant challenge that SOAP users face?
The ‘Firewall security mechanism’ is one of the biggest stumbling blocks encountered by SOAP users. In this situation, all HTTP ports are blocked, with the exception of those that bypass the firewall. A technical issue of mixing message transport specification with message structure has been identified in some circumstances.
Advance Web Services Interview Questions and Answer
What exactly are JAVA web services? What are the many ways to develop web services?
Java webservices is a set of tools for creating and deploying simple web services on the Java platform.
There are two ways that are used to establish web services.
- Approach from the top down
- a top-down strategy
What is JAXP and how does it work?
JAXP is a JAVA API for XML processing that lets you write, read, manipulate, and convert XML data. Other Java APIs, such as JAX-RPC, JAXM, JAXR, JAXB, and others, can be used to execute various functions.
Do you want to bring up the JAXB binding framework?
There are three Java Packages that make up the JAXB binding framework.
xml.bind: This package defines abstract classes and interfaces for usage with content classes directly.
xml.bind.util: This package offers utility classes for managing marshalling, unmarshalling, and validation events in XML documents.
xml.bind.helper: This utility package implements parts of the javax.xml.bind interfaces in part. These APIs should not be used directly by applications that use the JAXB architecture.
Give a basic example of how an XML document in the JAVA framework can be Marshal and Unmarshal?
Marshalling is the process of transforming an XML document into a Java-readable format, whereas UnMarshalling is the opposite procedure. Let’s look at how Java marshals and unmarshals an XML document.
What components make up a SOAP message?
The elements of a SOAP document are the same as those of any other XML document:
Envelope: This is the root element that must be included. It determines the start and end of the SOAP message by converting the XML document.
Header: This element holds the message’s optional header attributes, which provide application-specific information. This element can appear numerous times and is used to introduce new features and functions.
Body: This is a required element that contains the call and response messages. It’s also known as the envelope’s child element, which contains all of the application-derived XML data sent as part of the SOAP message.
Fault element: The fault element is in charge of handling errors that arise during message processing. This element appears as a child element of the body if the mistake is present. There can only be one defective block, though.
Enumerate a few syntax rules that apply to SOAP messages?
The following are some essential syntactic rules that apply to SOAP messages:
SOAP (Simple Object Access Protocol) message-
- XML must be used to encode the data.
- The SOAP envelope namespace must be used.
- The SOAP encoding namespace must be used.
- The DTD reference must not be included.
- XML processing instructions are not allowed.
What are the main web service security concerns?
Web services demand a very high level of security to enable trustworthy transactions and secure confidential information, which can only be achieved with the Entrust Secure Transaction Platform. Web service security issues are classified into three categories, as detailed below:
Confidentiality: A single web service can have several applications, and each node in the service path could be a weak link. Whenever the client sends messages or XML requests to the server using the service path, they must be encrypted. As a result, protecting communication secrecy is essential.
Authentication: Authentication is used to verify the identity of users and to ensure that the person who is accessing the online service has the right to use it. The user’s activity is also tracked through authentication. For this aim, there are a number of choices to consider:
- Authentication at the application level
- HTTP basic authentication and HTTP digest
- Client certificates
Network security is a critical problem that necessitates the use of techniques to filter web service traffic.
When is it necessary to change the default binding?
In some circumstances, you’ll need to change the default binding, such as:
- Creating API documentation for the JAXB packages, classes, methods, and constants created from the schema
- For circumstances where the normal XML name-to-Java identifier mapping cannot automatically support semantically relevant customised names,
- Overriding the default binding, such as associating a model group with a class rather than a list.
What is the difference between Push and Pull parsing?
Pull Parsing: Streaming pull parsing is a programming approach in which a client application calls methods on an XML parsing library when it needs to interface with an XML infoset, implying that the client will only receive XML data when it is requested.
Push Parsing: In Push Parsing, the parser sends the application parsing events or XML data. The parser takes control of the parsing process in the push paradigm, and the parser invokes the implemented handler functions.
What exactly are JAXM messaging models?
For JAXM, there are two communications models: synchronous and asynchronous.
Synchronous messaging model: In this model, the client connects directly with the source. In this case, the client sends the request and waits for it to be processed.
Asynchronous messaging model: In this approach, the client sends the message to the messaging provider, who then sends it back to the client. The message is subsequently routed to the end source by the messaging provider.
 Conclusion
Though the web services topic is very vast but we have tried to compile the important Web Services Interview Questions. The questions are categorized into basic, moderate and intermediate levels. This will help you to prepare for the interview in a systematic manner.
