RESTFul Web Service Interview Questions
1. What is differences between RESTful web services and SOAP web services ?
Ans:Though both RESTful web series and SOAP web service can operate cross platform they are architecturally different to each other, here is some of differences between REST and SOAP:
1) REST is more simple and easy to use than SOAP. REST language is based on use of nouns and verbs (better readability)
2) REST uses HTTP protocol for producing or consuming web services while SOAP uses XML.
Ans:Though both RESTful web series and SOAP web service can operate cross platform they are architecturally different to each other, here is some of differences between REST and SOAP:
1) REST is more simple and easy to use than SOAP. REST language is based on use of nouns and verbs (better readability)
2) REST uses HTTP protocol for producing or consuming web services while SOAP uses XML.
- The SOAP WS is transport protocol neutral. Supports multiple protocols like HTTP(S), Messaging, TCP, UDP SMTP, etc.
- The REST is transport protocol specific. Supports only HTTP or HTTPS protocols.
3) REST is lightweight as compared to SOAP and preferred choice in mobile devices and PDA’s. REST does not need XML parsing, no message header (to and from), hence less bandwidth
4) REST supports different format like text, JSON and XML while SOAP only support XML.
4) REST supports different format like text, JSON and XML while SOAP only support XML.
- The SOAP WS permits only XML data format.You define operations, which tunnels through the POST. The focus is on accessing the named operations and exposing the application logic as a service.
- The REST permits multiple data formats like XML, JSON data, text, HTML, etc. Any browser can be used because the REST approach uses the standard GET, PUT, POST, and DELETE Web operations. The focus is on accessing the named resources and exposing the data as a service. REST has AJAX support. It can use the XMLHttpRequest object. Good for stateless CRUD (Create, Read, Update, and Delete) operations.
GET – represent()
POST – acceptRepresention()
PUT – storeRepresention()
DELETE – removeRepresention()
5) SOAP based reads cannot be cached. REST based reads can be cached. Performs and scales better.
6) Different error handling:
REST: requires HTTP error handling
SOAP: can have user defined error
7) REST only supports synchronous message because of its reliance of HTTP and HTTPS
8) SOAP WS supports both SSL security and WS-security, which adds some enterprise security features like maintaining security right up to the point where it is needed, maintaining identities through intermediaries and not just point to point SSL only, securing different parts of the message with different security algorithms, etc.
The REST supports only point-to-point SSL security. The SSL encrypts the whole message, whether all of it is sensitive or not.
9) The SOAP has comprehensive support for both ACID based transaction management for short-lived transactions and compensation based transaction management for long-running transactions. It also supports two-phase commit across distributed resources.
The REST supports transactions, but it is neither ACID compliant nor can provide two phase commit across distributed transactional resources as it is limited by its HTTP protocol.
10) The SOAP has success or retry logic built in and provides end-to-end reliability even through SOAP intermediaries. REST does not have a standard messaging system, and expects clients invoking the service to deal with communication failures by retrying.
POST – acceptRepresention()
PUT – storeRepresention()
DELETE – removeRepresention()
5) SOAP based reads cannot be cached. REST based reads can be cached. Performs and scales better.
6) Different error handling:
REST: requires HTTP error handling
SOAP: can have user defined error
7) REST only supports synchronous message because of its reliance of HTTP and HTTPS
8) SOAP WS supports both SSL security and WS-security, which adds some enterprise security features like maintaining security right up to the point where it is needed, maintaining identities through intermediaries and not just point to point SSL only, securing different parts of the message with different security algorithms, etc.
The REST supports only point-to-point SSL security. The SSL encrypts the whole message, whether all of it is sensitive or not.
9) The SOAP has comprehensive support for both ACID based transaction management for short-lived transactions and compensation based transaction management for long-running transactions. It also supports two-phase commit across distributed resources.
The REST supports transactions, but it is neither ACID compliant nor can provide two phase commit across distributed transactional resources as it is limited by its HTTP protocol.
10) The SOAP has success or retry logic built in and provides end-to-end reliability even through SOAP intermediaries. REST does not have a standard messaging system, and expects clients invoking the service to deal with communication failures by retrying.
2. What is REST and RESTful web services?
Ans:This is the first REST interview question on most of interviews as not everybody familiar with REST and also start discussion based on candidates response. Anyway REST stands for REpresentational State Transfer (REST) its a relatively new concept of writing web services which enforces a stateless client server design where web services are treated as resource and can be accessed and identified by there URL unlike SOAP web services which were defined by WSDL.
Web services written by apply REST Architectural concept are called RESTful web services which focus on System resources and how state of Resource should be transferred over http protocol to a different clients written in different languages. In RESTful web services http methods like GET, PUT, POST and DELETE can can be used to perform CRUD operations.
Ans:This is the first REST interview question on most of interviews as not everybody familiar with REST and also start discussion based on candidates response. Anyway REST stands for REpresentational State Transfer (REST) its a relatively new concept of writing web services which enforces a stateless client server design where web services are treated as resource and can be accessed and identified by there URL unlike SOAP web services which were defined by WSDL.
Web services written by apply REST Architectural concept are called RESTful web services which focus on System resources and how state of Resource should be transferred over http protocol to a different clients written in different languages. In RESTful web services http methods like GET, PUT, POST and DELETE can can be used to perform CRUD operations.
3.What is difference between top-down and bottom-up approach of developing web services ?
Ans:In top-down approach first WSDL document is created and than Java classes are developed based on WSDL contract, so if WSDL contract changes you got to change your Java classes while in case of bottom up approach of web service development you first create Java code and then use annotations like @WebService to specify contract or interface and WSDL field will be automatically generated from your build.
Ans:In top-down approach first WSDL document is created and than Java classes are developed based on WSDL contract, so if WSDL contract changes you got to change your Java classes while in case of bottom up approach of web service development you first create Java code and then use annotations like @WebService to specify contract or interface and WSDL field will be automatically generated from your build.
4.What happens if RestFull resources are accessed by multiple clients ? do you need to make it thread-safe?
Ans:Since a new Resource instance is created for every incoming Request there is no need to make it thread-safe or add synchronization. Multiple clients can safely access RestFull resources concurrently.
Ans:Since a new Resource instance is created for every incoming Request there is no need to make it thread-safe or add synchronization. Multiple clients can safely access RestFull resources concurrently.
5.What will you do when an error code has to be returned to the client
OR
How will you handle application error scenarios in RESTful web service?
OR
How will you handle application error scenarios in RESTful web service?
6.What is a web service?
Ans:A Web service is a method of communication between two electronic devices over the Web (Internet). The W3C defines a “Web service” as “a software system designed to support interoperable machine-to-machine interaction over a network”. It has an interface described in a machine-processable format (specifically Web Services Description Language, known by the acronym WSDL). Other systems interact with the Web service in a manner prescribed by its description using SOAP messages, typically conveyed using HTTP with an XMLserialization in conjunction with other Web-related standards.”
Ans:A Web service is a method of communication between two electronic devices over the Web (Internet). The W3C defines a “Web service” as “a software system designed to support interoperable machine-to-machine interaction over a network”. It has an interface described in a machine-processable format (specifically Web Services Description Language, known by the acronym WSDL). Other systems interact with the Web service in a manner prescribed by its description using SOAP messages, typically conveyed using HTTP with an XMLserialization in conjunction with other Web-related standards.”
7.Can I use GET request instead of PUT to create resources?
Ans:No, you are supposed to use PUT or POST. GET operations should only have view rights.
Ans:No, you are supposed to use PUT or POST. GET operations should only have view rights.
8.What all kind of output formats can one generate using RESTful web service?
9.What all tools have you used to write RESTful web service?
10.What is meant by JAX-WS and JAX-RS?
Ans:Java API for XML Web Services(JAX-WS)
Java API for RESTful Web Services (JAX-RS)
Ans:Java API for XML Web Services(JAX-WS)
Java API for RESTful Web Services (JAX-RS)
11.What are the different application integration styles?
Ans. There are a number of different integration styles like
1. Shared database
2. batch file transfer
3. Invoking remote procedures (RPC)
4. Exchanging asynchronous messages over a message oriented middle-ware (MOM).
Ans. There are a number of different integration styles like
1. Shared database
2. batch file transfer
3. Invoking remote procedures (RPC)
4. Exchanging asynchronous messages over a message oriented middle-ware (MOM).
12.What are the different styles of Web Services used for application integration?
Ans. SOAP WS and RESTful Web Service
Ans. SOAP WS and RESTful Web Service
13.How would you decide what style of Web Service to use? SOAP WS or REST?
Ans. In general, a REST based Web service is preferred due to its simplicity, performance, scalability, and support for multiple data formats. SOAP is favored where service requires comprehensive support for security and transactional reliability.
The answer really depends on the functional and non-functional requirements. Asking the questions listed below will help you choose.
Ans. In general, a REST based Web service is preferred due to its simplicity, performance, scalability, and support for multiple data formats. SOAP is favored where service requires comprehensive support for security and transactional reliability.
The answer really depends on the functional and non-functional requirements. Asking the questions listed below will help you choose.
- Does the service expose data or business logic? (REST is a better choice for exposing data, SOAP WS might be a better choice for logic).Do the consumers and the service providers require a formal contract? (SOAP has a formal contract via WSDL)
- Do we need to support multiple data formats?
- Do we need to make AJAX calls? (REST can use the XMLHttpRequest)
- Is the call synchronous or asynchronous?
- Is the call stateful or stateless? (REST is suited for stateless CRUD operations)
- What level of security is required? (SOAP WS has better support for security)
- What level of transaction support is required? (SOAP WS has better support for transaction management)
- Do we have limited band width? (SOAP is more verbose)
- What’s best for the developers who will build clients for the service? (REST is easier to implement, test, and maintain)
14. What tools do you use to test your Web Services?
Ans:SoapUI tool for SOAP WS and the Firefox “poster” plugin for RESTFul services.
Ans:SoapUI tool for SOAP WS and the Firefox “poster” plugin for RESTFul services.
15.What is the difference between SOA and a Web service?
Ans:SOA is a software design principle and an architectural pattern for implementing loosely coupled, reusable and coarse grained services. You can implement SOA using any protocols such as HTTP, HTTPS, JMS, SMTP, RMI, IIOP (i.e. EJB uses IIOP), RPC etc. Messages can be in XML or Data Transfer Objects (DTOs).
Web service is an implementation technology and one of the ways to implement SOA. You can build SOA based applications without using Web services – for example by using other traditional technologies like Java RMI, EJB, JMS based messaging, etc. But what Web services offer is the standards based and platform-independent service via HTTP, XML, SOAP, WSDL and UDDI, thus allowing interoperability between heterogeneous technologies such as J2EE and .NET.
Ans:SOA is a software design principle and an architectural pattern for implementing loosely coupled, reusable and coarse grained services. You can implement SOA using any protocols such as HTTP, HTTPS, JMS, SMTP, RMI, IIOP (i.e. EJB uses IIOP), RPC etc. Messages can be in XML or Data Transfer Objects (DTOs).
Web service is an implementation technology and one of the ways to implement SOA. You can build SOA based applications without using Web services – for example by using other traditional technologies like Java RMI, EJB, JMS based messaging, etc. But what Web services offer is the standards based and platform-independent service via HTTP, XML, SOAP, WSDL and UDDI, thus allowing interoperability between heterogeneous technologies such as J2EE and .NET.
16.Web services when you can use traditional style middle-ware such as RPC, CORBA, RMI and DCOM?
Ans:The traditional middle-wares tightly couple connections to the applications and it can break if you make any modification to your application. Tightly coupled applications are hard to maintain and less reusable. Generally do not support heterogeneity. Do not work across Internet. Can be more expensive and hard to use.
Web Services support loosely coupled connections. The interface of the Web service provides a layer of abstraction between the client and the server. The loosely coupled applications reduce the cost of maintenance and increases re-usability. Web Services present a new form of middle-ware based on XML and Web. Web services are language and platform independent. You can develop a Web service using any language and deploy it on to any platform, from small device to the largest supercomputer. Web service uses language neutral protocols such as HTTP and communicates between disparate applications by passing XML messages to each other via a Web API. Do work across internet, less expensive and easier to use.
Ans:The traditional middle-wares tightly couple connections to the applications and it can break if you make any modification to your application. Tightly coupled applications are hard to maintain and less reusable. Generally do not support heterogeneity. Do not work across Internet. Can be more expensive and hard to use.
Web Services support loosely coupled connections. The interface of the Web service provides a layer of abstraction between the client and the server. The loosely coupled applications reduce the cost of maintenance and increases re-usability. Web Services present a new form of middle-ware based on XML and Web. Web services are language and platform independent. You can develop a Web service using any language and deploy it on to any platform, from small device to the largest supercomputer. Web service uses language neutral protocols such as HTTP and communicates between disparate applications by passing XML messages to each other via a Web API. Do work across internet, less expensive and easier to use.
17.What are the different approaches to developing a SOAP based Web service?
Ans. Following are the two approaches.
Ans. Following are the two approaches.
- The contract-first approach, where you define the contract first with XSD and WSDL and the generate the Java classes from the contract.
- The contract-last approach where you define the Java classes first and then generate the contract, which is the WSDL file from the Java classes.
Note: The WSDL describes all operations that the service provides, locations of the endpoints (i.e. where the services can be invoked), and simple and complex elements that can be passed in requests and responses.
18.What are the pros and cons of each approach, and which approach would you prefer?
Ans:
Contract-first Web service
PROS:
Ans:
Contract-first Web service
PROS:
- Clients are decoupled from the server, hence the implementation logic can be revised on the server without affecting the clients.
- Developers can work simultaneously on client and server side based on the contract both agreed on.
- You have full control over how the request and response messages are constructed — for example, should “status” go as an element or as an attribute? The contract clearly defines it. You can change OXM (i.e. Object to XML Mapping) libraries without having to worry if the “status” would be generated as “attribute” instead of an element. Potentially, even Web service frameworks and tool kits can be changed as well from say Apache Axis to Apache CXF, etc
CONS:
- More upfront work is involved in setting up the XSDs and WSDLs. There are tools like XML Spy, Oxygen XML, etc to make things easier. The object models need to be written as well.
- Developers need to learn XSDs and WSDLs in addition to just knowing Java.
Contract-last Web service
PROS:
PROS:
- Developers don’t have to learn anything related to XSDs, WSDLs, and SOAP. The services are created quickly by exposing the existing service logic with frameworks/tool sets. For example, via IDE based wizards, etc.
- The learning curve and development time can be smaller compared to the Contract-first Web service.
CONS:
- The development time can be shorter to initially develop it, but what about the on going maintenance and extension time if the contract changes or new elements need to be added? In this approach, since the clients and servers are more tightly coupled, the future changes may break the client contract and affect all clients or require the services to be properly versioned and managed.
- In this approach, The XML payloads cannot be controlled. This means changing your OXM libraries could cause something that used to be an element to become an attribute with the change of the OXM.
19.So, which approach will you choose?
Ans:The best practice is to use “contract-first“, and here is the link that explains this much better with examples –> contract-first versus contract-last web services In a nutshell, the contract-last is more fragile than the “contract-first”. You will have to decide what is most appropriate based on your requirements, tool sets you use, etc.
- See more at: http://www.javaface.com/19-restful-web-service-interview-questions/#sthash.igREgt5t.dpufAns:The best practice is to use “contract-first“, and here is the link that explains this much better with examples –> contract-first versus contract-last web services In a nutshell, the contract-last is more fragile than the “contract-first”. You will have to decide what is most appropriate based on your requirements, tool sets you use, etc.
1) Define Web Service?
A web service is a kind of software that is accessible on the Internet. It makes use of the XML messaging system and offers an easy to understand, interface for the end users.
2) What is new in this field for past few years?
The initiation of XML in this field is the advancement that provides web service a single language to communicate in between the RPCs, web services and their directories.
3) Give me an example of real web service?
One example of web services is IBM Web Services browser. You can get it from IBM Alphaworks site. This browser shows various demos related to web services. Basically web services can be used with the help of SOAP, WSDL, and UDDI . All these, provide a plug-and-play interface for using web services such as stock-quote service, a traffic-report service, weather service etc.
4) How you define web service protocol stack?
It is basically set of various protocols that can be used to explore and execute web services. The entire stack has four layers i.e. Service Transport, XML Messaging, Service Description and Service Discovery.
5) Can you define each of these layers of protocol stack?
The Service Transport layer transfer messages between different applications, such as HTTP, SMTP, FTP, and Blocks Extensible Exchange Protocol (BEEP). The XML Messaging layer encodes messages in XML format so that messages can be understood at each end, such as XML-RPC and SOAP. The Service Description layer describes the user interface to a web service, such as WSDL. The Service Discovery layer centralizes services to a common registry and offer simple publish functionality, such as UDDI.
6) Define XML – RPC?
It is a protocol that makes use of XML messages to do Remote Procedure Calls.
7) Define SOAP?
SOAP is an XML based protocol to transfer between computers.
8) Define WSDL?
It means Web Services Description Language. It is basically the service description layer in the web service protocol stock. The Service Description layer describes the user interface to a web service.
9) What kind of security is needed for web services?
The security level for web services should be more than that of what we say Secure Socket Layer (SSL). This level of security can be only achieved from Entrust Secure Transaction Platform. Web services need this level of security to ensure reliable transactions and secure confidential information .
10) Do you have any idea about foundation security services?
As implies from its name, these services are the foundation or basics of integration, authentication, authorization, digital signatures and encryption processes.
11) Define Entrust Identification Service?
Entrust Identification Service comes from the Entrust Security Transaction Platform. This platform allows companies to control the identities that are trusted to perform transactions for Web services transactions.
12) What UDDI means?
UDDI stands for Universal, Description, Discovery, and Integration. It is the discovery layer in the web services protocol stack.
13) Define Entrust Entitlements Service?
This service verifies entities that attempt to access a web service. For Example, the authentication service, the Entitlements Service ensures security in business operations.
14) Define Entrust Privacy Service?
As its name implies, it deals with security and confidentiality. This service encrypts data to ensure that only concerned parties can access the data.
15) What do you mean by PKI?
It means Public-Key Infrastructure.
16) What tools are used to test a web service?
I have used SoapUI for SOAP WS and Firefox poster plugin for RESTFul Services.
17) Differentiate between a SOA and a Web service?
SOA is a design and architecture to implement other services. SOA can be easily implemented using various protocols such as HTTP, HTTPS, JMS, SMTP, RMI, IIOP, RPC etc. While Web service, itself is an implemented technology. In fact one can implement SOA using the web service.
18) Discuss various approaches to develop SOAP based web service?
We can develop SOAP based web service with two different types of approaches such as contract-first and contract-last. In the first approach, the contract is defined first and then the classes are derived from the contract while in the later one, the classes are defined first and then the contract is derived from these classes.
19) If you have to choose one approach, then what will be your choice?
In my point of view, the first approach that is the contract-first approach is more feasible as compared to the second one but still it depends on other factors too.
20) Is there any special application required to access web service?
No, you don’t need to install any special application to access web service. You can access web service from any application that supports XML based object request and response.
21) Can you name few free and commercial implementations for web services?
The implementations I know are Apache SOAP, JAX-WS Reference Implementation, JAX-RS Reference Implementation, Metro, Apache CXF, MS.NET and Java 6.
22) Name browser that allows access to web service?
JavaScript XmlHttpRequest object is required to access web service via browsers. The browsers that support this object are Internet Explorer, Safari and Mozilla-based browsers like FireFox.
23) What is REST?
REST stands for Representational State Transfer. REST itself is not a standard, while it uses various standards such as HTTP, URL, XML/HTML/GIF/JPEG (Resource Representations) and text/xml, text/html, image/gif, image/jpeg, etc (MIME Types).
24) How one can provide API to users?
To provide an API to the users, one can easily do this with an “open table”. All you need to do is to write open table which is basically an XML schema that point to a web service.
25) Name the various communication channels in web service?
Web service is integrated with three protocols such as HTTP/POST, HTTP/GET, and SOAP. It provides three different communication channels to clients. Client can choose any communication method as per requirements.
26) How can you document web service?
Web services are contemplated as self-documenting because they provide entire information regarding the available methods and parameters used for XML based standard, known as WSDL. One can also provide more information to explain web services via their own WebService and WebMethod attributes.
27) What are the situations, when we need ASP.NET web services?
ASP.NET web services are used when one need to implement three tier architecture in a web service. It allows handy ways to use middle tier components through internet. The main advantage of .NET Web services is that they are capable enough to communicate across firewalls because they use SOAP as transport protocol.
28) What are distributed technologies?
The increasing ratio of distributed applications has raised demand for distributed technologies. It allows segmenting of application units and transferring them to different computers on different networks.
29) Differentiate between web services, CORBA and DCOM?
Web services transfer/receive messages to/from application respectively, via HTTP protocol. It uses XML to encode data.
CORBA and DCOM transfer/receive messages to/from application respectively, via non-standard protocols such as IIOP and RPC.
30) Can you tell few benefits of web services?
The biggest advantage of web service is that is supported by wide variety of platforms. Moreover, in near future, web services may spread its boundary and enhance new methods that will provide ease to clients. The enhancement will not affect the clients, even if they offer old methods and parameters.
31) Can you name some standards used in web services?
The standards used in web services are WSDL (used to create interface definition), SOAP (used to structure data), HTTP (communication channels), DISCO (used to create discovery documents) and UDDI (used to create business registries).
32) Explain in brief, what DISCO is?
DISCO means discovery. It groups the list of interrelated web services. The organization that provides web services, issues a DISCO file on its server and that file contains the links of all the provided web services. This standard is good when client knows the company already. Also it can be used within a local network as well.
33) Explain in brief, what UDDI is?
UDDI (Universal Description, Discovery, and Integration) provides consolidated directory for web services on the internet. Clients use UDDI to find web services as per their business needs. It basically hosts the web services from various companies. In order to share web services, you need to publish it in UDDI.
34) Explain the .NET web services supported data types?
.Net web services uses XML-based standards to transfer/receive information. Thus, .NET web services can only works with data types known by XML schema standard. Like FileSteam, Eventlog etc. are not recognized by the XML schema standards and hence, not supported in web services.
35) How a .NET web service is tested?
ASP.NET uses a test page routinely, when one calls for the URL of .asmx file in any browser. This page shows complete information regarding web services.
36) How a .NET web service is consumed?
Since we know that web services are constructed on XML standards. Therefore, clients need to have complete understanding of XML-based messages to interchange messages. Clients can communicate with web services through .NET framework that offers proxy mechanisms. These proxy mechanisms have detailed information regarding data sharing within web services that can be easily used by the clients.
37) Can you name the two Microsoft solutions for distributed applications?
The two Microsoft solutions for distributed applications are .NET Web Services and .NET Remoting.
38) Differentiate between .NET Web Services and .NET Remoting?
As far as protocol is concerned, .NET Web Service uses HTTP, while, .NET Remoting uses any protocol i.e. TCP/HTTP/SMTP. When it comes to performance, .NET Remoting is comparatively, faster than.NET Web Service. Also, as .NET Web Services are hosted via IIS, therefore, it is far more reliable than the .NET Remoting.
39) Name the components to be published while deploying a Web Service?
The components that need to be published during a web service deployment are Web Application Directory, Webservice.asmx File, Webservice.Disco File, Web.Config File and Bin Directory.
40) What are the steps performed by the client to access a web service?
First of all a web reference to the web service is created by the client in his application. Then a proxy class is generated. After that an object of the proxy class is created and at last, the web service is accessed via that proxy object.
41) How web services are implemented in .NET?
To implement web services in .NET, HTTP handlers are used that interrupt requests to .asmx files.
42) Explain few disadvantages of Response Caching?
Response Caching is useless or incompetent when method accepts extensive amount of values because caching means to store lot of information. Also, if the method depends on external source of information, and that are not provided within the parameters then such methods are bypassed.
43) What is the alternate solution to Response Caching?
One can use Data Caching (System.Web.Caching.Cach) instead of Response Caching.
44) Brief few drawbacks of using GET and POST methods to communicate with the web service?
These methods are less secure and inhibit users to pass structures and objects as arguments. Also, it doesn’t allow users to pass ByRef arguments.
45) How can one access a class as a web service?
To access a class as a web service, one should inherit the class from the System.Web.Services.WebService class and qualify the class with the WebService attribute.
46) How can one access the web service class method via internet?
To access web service class method via internet, one should qualify a method with the WebMethod attribute.
47) How a SOAP message is structured?
A SOAP message is consists of SOAP Envelope, SOAP Headers, and SOAP Body.
48) Can you name different kinds of web services?
There are two types of web services in total i.e. SOAP based web service and RESTful web service.
This question is already mentioned earlier.
49) What’s different in RESTful web services?
The RESTful web services contains no contract or WSDL file.
50) Give me few reasons to use RESTful web service?
The RESTFul web services are simple to implement and test. It supports various data formats such as XML, JSON etc.
1) What is REST and RESTful web services ?
this is the first REST interview question on most of interviews as not everybody familiar with REST and also
start discussion based on candidates response. Anyway REST stands for REpresentational State Transfer (REST) its a relatively new concept of writing web services which enforces a stateless client server design where web services are treated as resource and can be accessed and identified by there URL unlike SOAP web services which were defined by WSDL.
Web services written by apply REST Architectural concept are called RESTful web services which focus on System resources and how state of Resource should be transferred over http protocol to a different clients written in different languages. In RESTful web services http methods like GET, PUT, POST and DELETE can can be used to perform CRUD operations.
2) What is differences between RESTful web services and SOAP web services ?
Though both RESTful web series and SOAP web service can operate cross platform they are architecturally different to each other, here is some of differences between REST and SOAP:
1) REST is more simple and easy to use than SOAP
2) REST uses HTTP protocol for producing or consuming web services while SOAP uses XML.
3) REST is lightweight as compared to SOAP and preferred choice in mobile devices and PDA's.
4) REST supports different format like text, JSON and XML while SOAP only support XML.
5) REST web services call can be cached to improve performance.
3) What is Restlet framework ?
Restlet is leading RESTful web framework for Java applications is used to build RESTFul web services it has two part Restlet API and a Restlet implementation much like Servlet specification. There are many implementation of Restlet framework available you just need to add there jar in your classpath to use them. By using Restlet web framework you can write client and server.
4) What is Resource in REST framework ?
it represent a "resource" in REST architecture. on RESTLET API it has life cycle methods like init(), handle() and release() and contains a Context, Request and Response corresponding to specific target resource. This is now deprecated over ServerResource class and you should use that. see Restlet documentation for more details.
5) Can you use Restlet without any web-container ?
Yes, Restlet framework provide default server which can be used to handle service request in web container is not available.
6) What is difference between Restlets and Jersey ?
This REST web service interview questions is open for you all, post you answer in comment section.
7) What is RESTEasy ?
RESTEasy is another REST framework introduced in JBoss Application Server. This was rather easy REST interview questions. you can answer in detail only if you have used this or working in JBoss.
8) What are the tools used for creating RESTFull web services ?
You can use AJAX(Asynchronous JavaScript with XAML) and Direct Web Removing to consume web serives in web application. Both Eclipse and NetBeans also supported development of RESTFul services.
9) How to display custom error pages using RestFull web services ?
In order to customize error you need to extend StatusService and implement getRepresentation(Status, Request, Response) method with your custom code now assign instance of your CustomStatusService to appropriate "statusService property".
10) Which HTTP methods are supported by RestFull web services ?
Another common REST interview questioning RESTFul web service each Resource supports GET, POST, PUT and DELETE http methods.GET is mapped to represent(), POST - acceptRepresentation(), PUT- storeRepresentation and DELET for rmeoveRepresentation.
11) What is difference between top-down and bottom-up approach of developing web services ?
In top-down approach first WSDL document is created and than Java classes are developed based on WSDL contract, so if WSDL contract changes you got to change your Java classes while in case of bottom up approach of web service development you first create Java code and then use annotations like @WebService to specify contract or interface and WSDL field will be automatically generated from your build.
12) What happens if RestFull resources are accessed by multiple clients ? do you need to make it thread-safe?
Since a new Resource instance is created for every incoming Request there is no need to make it thread-safe or add synchronization. multiple client can safely access RestFull resources concurrently.
That’s all on REST interview questions , I will add couple of more REST Interview questions whenever I got them from my friend circle.
Read more: http://javarevisited.blogspot.com/2012/01/rest-web-services-framework-interview.html#ixzz3TFPVQD7t
Q1. What are the different styles of Web Services used for application integration? and What are the differences between both SOAP WS and RESTful WS?
A1. SOAP WS and RESTful Web Service. Web services are very popular and widely used to integrate similar (i.e. Java applications) and disparate systems (i.e. legacy applications and applications written in .Net etc) as they are language neutral.
A1. SOAP WS and RESTful Web Service. Web services are very popular and widely used to integrate similar (i.e. Java applications) and disparate systems (i.e. legacy applications and applications written in .Net etc) as they are language neutral.
| SOAP Web service | RESTful Web service |
| Transport is platform & protocol neutral. Supports multiple protocols like HTTP(S), Messaging, TCP, UDP, SMTP, etc. | Transport is protocol specific. Supports only HTTP or HTTPS protocols. |
| SOAP uses its own protocol and focuses on exposing pieces of application logic (not data) as services. SOAP exposes operations. SOAP is focused on accessing named operations, which implement some business logic through different interfaces. | REST is about exposing a public API over the internet to handle CRUD (Create, Read, Update, and Delete) operations on data. REST is focused on accessing named resources through a single consistent interface. |
| SOAP only permits XML data formats. | REST permits many different data formats like XML, JSON data, text, HTML, atom, RSS, etc. JSON is less verbose than XML and is a better fit for data and parses much faster. |
| SOAP based reads cannot be cached. The application that uses SOAP needs to provide cacheing. | REST based reads can be cached. Performs and scales better. |
Supports both SSL security and WS-security, which adds some enterprise security features. Supports identity through intermediaries, not just point to point SSL.
WS-Security maintains its encryption right up to the point where the request is being processed.
WS-Security allows you to secure parts (e.g. only credit card details) of the message that needs to be secured. Given that encryption/decryption is not a cheap operation, this can be a performance boost for larger messages.
It is also possible with WS-Security to secure different parts of the message using different keys or encryption algorithms. This allows separate parts of the message to be read by different people without exposing other, unneeded information.
SSL security can only be used with HTTP. WS-Security can be used with other protocols like UDP, SMTP, etc.
|
Supports only point-to-point SSL security.
The basic mechanism behind SSL is that the client encrypts all of the requests based on a key retrieved from a third party. When the request is received at the destination, it is decrypted and presented to the service. This means the request is only encrypted while it is traveling between the client and the server. Once it hits the server (or a proxy which has a valid certificate), it is decrypted from that moment on.
The SSL encrypts the whole message, whether all of it is sensitive or not.
|
| Has comprehensive support for both ACIDbased transaction management for short-lived transactions and compensation based transaction management for long-running transactions. It also supports two-phase commit across distributed resources. | REST supports transactions, but it is neither ACID compliant nor can provide two phase commit across distributed transactional resources as it is limited by its HTTP protocol. |
| SOAP has success or retry logic built in and provides end-to-end reliability even through SOAP intermediaries. | REST does not have a standard messaging system, and expects clients invoking the service to deal with communication failures by retrying. |
Which one to favor? In general, a REST based web service is preferred due to its simplicity, performance, scalability, and support for multiple data formats. SOAP is favored where service requires comprehensive support for security and transactional reliability.
Q2. Differentiate between SOA (Service Oriented Architecture) versus WOA (Web Oriented Architecture)?
A2. WOA extends SOA to be a light-weight architecture using technologies such as REST and POX (Plain Old XML). POX compliments REST. JSON is a variant for data returned by REST Web Services. It consumes less bandwidth and is easily handled by web developers mastering the Javascript language
A2. WOA extends SOA to be a light-weight architecture using technologies such as REST and POX (Plain Old XML). POX compliments REST. JSON is a variant for data returned by REST Web Services. It consumes less bandwidth and is easily handled by web developers mastering the Javascript language
SOA and WOA differ in terms of the layers of abstraction. SOA is a system-level architectural style that tries to expose business capabilities so that they can be consumed by many applications. WOA is an interface-level architectural style that focuses on the means by which these service capabilities are exposed to consumers. You can start out with a WOA and then grow into SOA.
Q3. How would you decide what style of Web Service to use? SOAP WS or REST?
A3. In general, a REST based Web service is preferred due to its simplicity, performance, scalability, and support for multiple data formats. SOAP is favored where service requires comprehensive support for security and transactional reliability.
A3. In general, a REST based Web service is preferred due to its simplicity, performance, scalability, and support for multiple data formats. SOAP is favored where service requires comprehensive support for security and transactional reliability.
The answer really depends on the functional and non-functional requirements. Asking the questions listed below will help you choose.
1) Does the service expose data or business logic? (REST is a better choice for exposing data, SOAP WS might be a better choice for logic).
2) Do consumers and the service providers require a formal contract? (SOAP has a formal contract via WSDL)
3) Do we need to support multiple data formats?
4) Do we need to make AJAX calls? (REST can use the XMLHttpRequest)
5) Is the call synchronous or asynchronous?
6) Is the call stateful or stateless? (REST is suited for statless CRUD operations)
7) What level of security is required? (SOAP WS has better support for security)
8) What level of transaction support is required? (SOAP WS has better support for transaction management)
9) Do we have limited band width? (SOAP is more verbose)
10) What’s best for the developers who will build clients for the service? (REST is easier to implement, test, and maintain)
2) Do consumers and the service providers require a formal contract? (SOAP has a formal contract via WSDL)
3) Do we need to support multiple data formats?
4) Do we need to make AJAX calls? (REST can use the XMLHttpRequest)
5) Is the call synchronous or asynchronous?
6) Is the call stateful or stateless? (REST is suited for statless CRUD operations)
7) What level of security is required? (SOAP WS has better support for security)
8) What level of transaction support is required? (SOAP WS has better support for transaction management)
9) Do we have limited band width? (SOAP is more verbose)
10) What’s best for the developers who will build clients for the service? (REST is easier to implement, test, and maintain)
Q4. What tools do you use to test your Web Services?
A4. SoapUI tool for SOAP WS and the Firefox “poster” plugin for RESTFul services.
A4. SoapUI tool for SOAP WS and the Firefox “poster” plugin for RESTFul services.
Q5. What is the difference between SOA and a Web service?
A5. SOA is a software design principle and an architectural pattern for implementing loosely coupled, reusable and coarse grained services. You can implement SOA using any protocols such as HTTP, HTTPS, JMS, SMTP, RMI, IIOP (i.e. EJB uses IIOP), RPC etc. Messages can be in XML or Data Transfer Objects (DTOs).
A5. SOA is a software design principle and an architectural pattern for implementing loosely coupled, reusable and coarse grained services. You can implement SOA using any protocols such as HTTP, HTTPS, JMS, SMTP, RMI, IIOP (i.e. EJB uses IIOP), RPC etc. Messages can be in XML or Data Transfer Objects (DTOs).
Web service is an implementation technology and one of the ways to implement SOA. You can build SOA based applications without using Web services – for example by using other traditional technologies like Java RMI, EJB, JMS based messaging, etc. But what Web services offer is the standards based and platform-independent service via HTTP, XML, SOAP, WSDL and UDDI, thus allowing interoperability between heterogeneous technologies such as J2EE and .NET.
Q6. Why not favor traditional style middle-ware such as RPC, CORBA, RMI and DCOM as opposed to Web services?
A6. The traditional middle-wares tightly couple connections to the applications. Tightly coupled applications are hard to maintain and less reusable. Generally do not support heterogeneity. Do not work across Internet and can be more expensive and hard to use.
A6. The traditional middle-wares tightly couple connections to the applications. Tightly coupled applications are hard to maintain and less reusable. Generally do not support heterogeneity. Do not work across Internet and can be more expensive and hard to use.
Web Services support loosely coupled connections. The interface of the Web service provides a layer of abstraction between the client and the server. The loosely coupled applications reduce the cost of maintenance and increases re-usability. Web Services present a new form of middle-ware based on XML and Web. Web services are language and platform independent. You can develop a Web service using any language and deploy it on to any platform, from small device to the largest supercomputer. Web service uses language neutral protocols such as HTTP and communicates between disparate applications by passing XML or JSON messages to each other via a Web API. Do work across internet, less expensive and easier to use.
Why to create Web Service / Whats the benefit of Web Service ?
Web Services are easier to communicate between applications running on different platform and build on different language. It allows easy integration with other applications.
What are the different standards protocols for WebService ?
XML-RPC is a remote procedure call (RPC) protocol which uses XML to encode its calls and HTTP as a transport mechanism. In XML-RPC objects or structures are exchanged between 2 applications.
JAX-RPC : Java API for XML-based RPC, JAX-RPC refers to Java API for XML-based RPC. It specify java technology for for web-based services and clients using RPC or remote procedure calls which are based on XML based protocol like SOAP.
JAX-WS : Java API for XML Web Services, which is part of Java EE Platform & Glassfish Project.It also provides annotation based Web Service.
JAX-RPC Vs JAX-WS: JAX-WS replaced the JAX-RPC API in Java Platform, Enterprise Edition 5.It provides enhancement over JAX-RPC.
What is REST ?
REST is architectural style for building web service using HTTP protocol, where webservices are treated as resources and some basic HTTP methods like GET, POST, DELETE are used
to identify standard action on resources.RESTful web API (also called a RESTful web service) is a web API implemented using HTTP and the REST principles.
What is SOAP ?
SOAP, originally defined as Simple Object Access Protocol, is a protocol specification for exchanging structured information in XML form.
What are the underlying protocol over which you can send SOAP request ?
You can send SOAP message via Hypertext Transfer Protocol (HTTP), Simple Mail Transfer Protocol (SMTP), HTTPS(Secured HTTP).
What is WSDL ? What does WSDL Contains ?
WSDL(Web Services Description Language) is an XML grammar for specifying a public interface for a Web service.
WSDL contains following key information :
Information on all publicly available functions, set of operations(through Tag in WSDL).
Information about messages exchanges using &
Binding information which provides information about how those messages can be exchanged, more specifically in that you need to specify transport protocol(HTTP/SMTP) and binding style(RPC or Document).
Address information for locating the specified service etc.
What is UDDI ?
UDDI is used for publishing and finding businesses and Web services.
What are Tools/API are there for developing/testing web service?
Testing Tools for Web Service : SoapUI for SOAP Web Service, Firefox plugin for testing RESTFul Services.
REST APIs : Spring REST Web Service using MVC, Jersey API, CFX, Axis, Restlet etc.
SOAP APIs : Axis, Spring Web Service etc
Discuss various approaches to develop SOAP based web service ?
There are 2 approaches : Contract-first & Contract-last.
Contract-first starts with defining first XML schema / WSDL and then creating the Java classes based on them. In Contract-last approach Java classes are defined first than WSDL is generated from that.
What is differences between RESTful web servicesand SOAP web services ?
Check this post REST Vs SOAP, When To Use What ?
What is the difference between HTTP POST and PUT requests in REST ?
POST is used to create where as PUT is used to (update , if does not exist create it)/ Replace.
What are the different formats supported by REST API?
As it runs on HTTP , it will support formats supported by HTTP like HTML, JSON, AMF, IMAGE etc.
What is difference between RPC or Document Style Web Service ? How you decide to which one to choose ?
In Document Style Web service we can send the XML message as part of SOAP request which is not possible in RPC Style Web Service. Document Style WebService is most suitable in some application where XML message is treated as document and content of that document can change and intention of web servicedoes not depend on content of XML message.
For example in most of financial application Trade is represented as XML document for which document style is most preferred.
Would you use JSON or XML as content type in REST web Service ?
Check this post JSON Vs XML
what are the real world examples of REST Web Service ?
Check here Examples of REST API
Web Services are easier to communicate between applications running on different platform and build on different language. It allows easy integration with other applications.
What are the different standards protocols for WebService ?
XML-RPC is a remote procedure call (RPC) protocol which uses XML to encode its calls and HTTP as a transport mechanism. In XML-RPC objects or structures are exchanged between 2 applications.
JAX-RPC : Java API for XML-based RPC, JAX-RPC refers to Java API for XML-based RPC. It specify java technology for for web-based services and clients using RPC or remote procedure calls which are based on XML based protocol like SOAP.
JAX-WS : Java API for XML Web Services, which is part of Java EE Platform & Glassfish Project.It also provides annotation based Web Service.
JAX-RPC Vs JAX-WS: JAX-WS replaced the JAX-RPC API in Java Platform, Enterprise Edition 5.It provides enhancement over JAX-RPC.
What is REST ?
REST is architectural style for building web service using HTTP protocol, where webservices are treated as resources and some basic HTTP methods like GET, POST, DELETE are used
to identify standard action on resources.RESTful web API (also called a RESTful web service) is a web API implemented using HTTP and the REST principles.
What is SOAP ?
SOAP, originally defined as Simple Object Access Protocol, is a protocol specification for exchanging structured information in XML form.
What are the underlying protocol over which you can send SOAP request ?
You can send SOAP message via Hypertext Transfer Protocol (HTTP), Simple Mail Transfer Protocol (SMTP), HTTPS(Secured HTTP).
What is WSDL ? What does WSDL Contains ?
WSDL(Web Services Description Language) is an XML grammar for specifying a public interface for a Web service.
WSDL contains following key information :
Information on all publicly available functions, set of operations(through
Information about messages exchanges using &
Binding information which provides information about how those messages can be exchanged, more specifically in that you need to specify transport protocol(HTTP/SMTP) and binding style(RPC or Document).
Address information for locating the specified service etc.
What is UDDI ?
UDDI is used for publishing and finding businesses and Web services.
What are Tools/API are there for developing/testing web service?
Testing Tools for Web Service : SoapUI for SOAP Web Service, Firefox plugin for testing RESTFul Services.
REST APIs : Spring REST Web Service using MVC, Jersey API, CFX, Axis, Restlet etc.
SOAP APIs : Axis, Spring Web Service etc
Discuss various approaches to develop SOAP based web service ?
There are 2 approaches : Contract-first & Contract-last.
Contract-first starts with defining first XML schema / WSDL and then creating the Java classes based on them. In Contract-last approach Java classes are defined first than WSDL is generated from that.
What is differences between RESTful web servicesand SOAP web services ?
Check this post REST Vs SOAP, When To Use What ?
What is the difference between HTTP POST and PUT requests in REST ?
POST is used to create where as PUT is used to (update , if does not exist create it)/ Replace.
What are the different formats supported by REST API?
As it runs on HTTP , it will support formats supported by HTTP like HTML, JSON, AMF, IMAGE etc.
What is difference between RPC or Document Style Web Service ? How you decide to which one to choose ?
In Document Style Web service we can send the XML message as part of SOAP request which is not possible in RPC Style Web Service. Document Style WebService is most suitable in some application where XML message is treated as document and content of that document can change and intention of web servicedoes not depend on content of XML message.
For example in most of financial application Trade is represented as XML document for which document style is most preferred.
Would you use JSON or XML as content type in REST web Service ?
Check this post JSON Vs XML
what are the real world examples of REST Web Service ?
Check here Examples of REST API
Define Web Service?
A web service is a kind of software that is accessible on the Internet. It makes use of the XML messaging system and offers an easy to understand, interface for the end users.
What is REST and RESTful web services ?
REST stands for REpresentational State Transfer (REST) its a relatively new concept of writing web services which enforces a stateless client server design where web services are treated as resource and can be accessed and identified by there URL unlike SOAP web services which were defined by WSDL.
Web services written by apply REST Architectural concept are called RESTful web services which focus on System resources and how state of Resource should be transferred over http protocol to a different clients written in different languages. In RESTful web services http methods like GET, PUT, POST and DELETE can can be used to perform CRUD operations.
What is differences between RESTful web services and SOAP web services ?
Though both RESTful web series and SOAP web service can operate cross platform they are architecturally different to each other, here is some of differences between REST and SOAP:
1) REST is more simple and easy to use than SOAP
2) REST uses HTTP protocol for producing or consuming web services while SOAP uses XML.
3) REST is lightweight as compared to SOAP and preferred choice in mobile devices and PDA's.
4) REST supports different format like text, JSON and XML while SOAP only support XML.
5) REST web services call can be cached to improve performance.
What is Restlet framework ?
Restlet is leading RESTful web framework for Java applications is used to build RESTFul web services it has two part Restlet API and a Restlet implementation much like Servlet specification. There are many implementation of Restlet framework available you just need to add there jar in your classpath to use them. By using Restlet web framework you can write client and server.
What is Resource in REST framework ?
it represent a "resource" in REST architecture. on RESTLET API it has life cycle methods like init(), handle() and release() and contains a Context, Request and Response corresponding to specific target resource. This is now deprecated over ServerResource class and you should use that. see Restlet documentation for more details.
Can you use Restlet without any web-container ?
Yes, Restlet framework provide default server which can be used to handle service request in web container is not available.
What are the tools used for creating RESTFull web services ?
You can use AJAX(Asynchronous JavaScript with XAML) and Direct Web Removing to consume web serives in web application. Both Eclipse and NetBeans also supported development of RESTFul services.
How to display custom error pages using RestFull web services ?
In order to customize error you need to extend StatusService and implement getRepresentation(Status, Request, Response) method with your custom code now assign instance of your CustomStatusService to appropriate "statusService property".
Which HTTP methods are supported by RestFull web services ?
Another common REST interview questioning RESTFul web service each Resource supports GET, POST, PUT and DELETE http methods.GET is mapped to represent(), POST - acceptRepresentation(), PUT- storeRepresentation and DELET for rmeoveRepresentation.
What is difference between top-down and bottom-up approach of developing web services ?
In top-down approach first WSDL document is created and than Java classes are developed based on WSDL contract, so if WSDL contract changes you got to change your Java classes while in case of bottom up approach of web service development you first create Java code and then use annotations like @WebService to specify contract or interface and WSDL field will be automatically generated from your build.
Define SOAP?
SOAP is an XML based protocol to transfer between computers.
Define WSDL?
It means Web Services Description Language. It is basically the service description layer in the web service protocol stock. The Service Description layer describes the user interface to a web service.
Differentiate between a SOA and a Web service?
SOA is a design and architecture to implement other services. SOA can be easily implemented using various protocols such as HTTP, HTTPS, JMS, SMTP, RMI, IIOP, RPC etc. While Web service, itself is an implemented technology. In fact one can implement SOA using the web service.
Discuss various approaches to develop SOAP based web service?
We can develop SOAP based web service with two different types of approaches such as contract-first and contract-last. In the first approach, the contract is defined first and then the classes are derived from the contract while in the later one, the classes are defined first and then the contract is derived from these classes.
If you have to choose one approach, then what will be your choice?
In my point of view, the first approach that is the contract-first approach is more feasible as compared to the second one but still it depends on other factors too.
What are the types of information included in SOAP header?
Header of SOAP contains information like that,
1. In SOAP header client should handle authentication and transaction.
2. The SOAP message should process by client.
3. EncodingStyle is also has in header.
What are the disadvantages of SOAP?
Some disadvantages .
1. It is much slower than middleware technologies.
2. Because we used HTTP for transporting messages and not use to defined ESB or WS-Addressing interaction of parties over a message is fixed.
3. Application protocol level is problematic because usability of HTTP for different purposes is not present.
A web service is a kind of software that is accessible on the Internet. It makes use of the XML messaging system and offers an easy to understand, interface for the end users.
What is REST and RESTful web services ?
REST stands for REpresentational State Transfer (REST) its a relatively new concept of writing web services which enforces a stateless client server design where web services are treated as resource and can be accessed and identified by there URL unlike SOAP web services which were defined by WSDL.
Web services written by apply REST Architectural concept are called RESTful web services which focus on System resources and how state of Resource should be transferred over http protocol to a different clients written in different languages. In RESTful web services http methods like GET, PUT, POST and DELETE can can be used to perform CRUD operations.
What is differences between RESTful web services and SOAP web services ?
Though both RESTful web series and SOAP web service can operate cross platform they are architecturally different to each other, here is some of differences between REST and SOAP:
1) REST is more simple and easy to use than SOAP
2) REST uses HTTP protocol for producing or consuming web services while SOAP uses XML.
3) REST is lightweight as compared to SOAP and preferred choice in mobile devices and PDA's.
4) REST supports different format like text, JSON and XML while SOAP only support XML.
5) REST web services call can be cached to improve performance.
What is Restlet framework ?
Restlet is leading RESTful web framework for Java applications is used to build RESTFul web services it has two part Restlet API and a Restlet implementation much like Servlet specification. There are many implementation of Restlet framework available you just need to add there jar in your classpath to use them. By using Restlet web framework you can write client and server.
What is Resource in REST framework ?
it represent a "resource" in REST architecture. on RESTLET API it has life cycle methods like init(), handle() and release() and contains a Context, Request and Response corresponding to specific target resource. This is now deprecated over ServerResource class and you should use that. see Restlet documentation for more details.
Can you use Restlet without any web-container ?
Yes, Restlet framework provide default server which can be used to handle service request in web container is not available.
What are the tools used for creating RESTFull web services ?
You can use AJAX(Asynchronous JavaScript with XAML) and Direct Web Removing to consume web serives in web application. Both Eclipse and NetBeans also supported development of RESTFul services.
How to display custom error pages using RestFull web services ?
In order to customize error you need to extend StatusService and implement getRepresentation(Status, Request, Response) method with your custom code now assign instance of your CustomStatusService to appropriate "statusService property".
Which HTTP methods are supported by RestFull web services ?
Another common REST interview questioning RESTFul web service each Resource supports GET, POST, PUT and DELETE http methods.GET is mapped to represent(), POST - acceptRepresentation(), PUT- storeRepresentation and DELET for rmeoveRepresentation.
What is difference between top-down and bottom-up approach of developing web services ?
In top-down approach first WSDL document is created and than Java classes are developed based on WSDL contract, so if WSDL contract changes you got to change your Java classes while in case of bottom up approach of web service development you first create Java code and then use annotations like @WebService to specify contract or interface and WSDL field will be automatically generated from your build.
Define SOAP?
SOAP is an XML based protocol to transfer between computers.
Define WSDL?
It means Web Services Description Language. It is basically the service description layer in the web service protocol stock. The Service Description layer describes the user interface to a web service.
Differentiate between a SOA and a Web service?
SOA is a design and architecture to implement other services. SOA can be easily implemented using various protocols such as HTTP, HTTPS, JMS, SMTP, RMI, IIOP, RPC etc. While Web service, itself is an implemented technology. In fact one can implement SOA using the web service.
Discuss various approaches to develop SOAP based web service?
We can develop SOAP based web service with two different types of approaches such as contract-first and contract-last. In the first approach, the contract is defined first and then the classes are derived from the contract while in the later one, the classes are defined first and then the contract is derived from these classes.
If you have to choose one approach, then what will be your choice?
In my point of view, the first approach that is the contract-first approach is more feasible as compared to the second one but still it depends on other factors too.
What are the types of information included in SOAP header?
Header of SOAP contains information like that,
1. In SOAP header client should handle authentication and transaction.
2. The SOAP message should process by client.
3. EncodingStyle is also has in header.
What are the disadvantages of SOAP?
Some disadvantages .
1. It is much slower than middleware technologies.
2. Because we used HTTP for transporting messages and not use to defined ESB or WS-Addressing interaction of parties over a message is fixed.
3. Application protocol level is problematic because usability of HTTP for different purposes is not present.
