1. Compare and contrast web applications with web services, indicating the need for web services

Web Service

W3C (World Wide Web Consortium) describes web service as a system of software allowing different machines to interact with each other through network. Web services achieve this task with the help of XML, SOAP, WSDL and UDDI open standards.

XML: The full form of XML is ‘Extensible Markup Language’ which is used to share data on the web and in universal format.

SOAP: Standing for ‘Simple Object Access Protocol’ which is an application communication protocol that sends and receives messages through XML format. It is one of the best ways to communicate between applications over HTTP which is supported by all browsers and servers.

WSDL: Written in XML, WSDL stands for Web Services Description Language and is used to describe web service. WSDL comprises three parts such as Definitions (usually expressed in XML including both data type definitions), Operations and Service bindings. Operations denote actions for the messages supported by a Web service.

There are three types of operations:

1. One way

2. Request response

3. Notification

Service bindings: Service bindings is a connecting to the port.

UDDI: Universal Description, Discovery, and Integration (UDDI) provides the description of a set of services supporting the depiction and discovery of businesses, organizations, and other Web Services providers. It is based on common set of industry standards, including HTTP, XML, XML Schema, and SOAP.

Web Application

An application that the users access over the internet is called a web application. Generally, any software that is accessed through a client web browser could be called a web application.

What is client?

So what is a client? A ‘client’ can be referred to the program that the person use to run the application in the client-server environment. The client-server environment refers to multiple computers sharing information such as entering info into a database. Here the “client” is the application that is used to enter the info, while the “server” is the application that is used to store the information.

Web Services vs Web Applications

Web Services can be used to transfer data between Web Applications.
Web Services can be accessed from any languages or platform.
A Web Application is meant for humans to read, while a Web Service is meant for computers to read.
Web Application is a complete Application with a Graphical User Interface (GUI), however, web services do not necessarily have a user interface since it is used as a component in an application.
Web Application can be access through browsers.

2. Discuss what WSDL is and the use of it in the context of web services

Web Services Description Language (WSDL) is a format for describing a Web Services interface. It is a way to describe services and how they should be bound to specific network addresses. WSDL has three parts:

Definitions
Operations
Service bindings

Definitions are generally expressed in XML and include both data type definitions and message definitions that use the data type definitions. These definitions are usually based upon some agreed upon XML vocabulary. This agreement could be within an organization or between organizations. Vocabularies within an organization could be designed specifically for that organization. They may or may not be based on some industry-wide vocabulary. If data type and message definitions need to be used between organizations, then most likely an industry-wide vocabulary will be used. For more on XML vocabularies,

XML, however, is not necessary required for definitions. The OMG Interface Definition Language (IDL), for example, could be used instead of XML. If a different definitional format were used, senders and receivers would need to agree on the format as well as the vocabulary. Nevertheless, over time, XML-based vocabularies and messages are likely to dominate. XML Namespaces are used to ensure uniqueness of the XML element names in the definitions, operations, and service bindings.

Operations describe actions for the messages supported by a Web service. There are four types of operations:

One-way: Messages sent without a reply required
Request/response: The sender sends a message and the received sends a reply.
Solicit response: A request for a response. (The specific definition for this action is pending.)
Notification: Messages sent to multiple receivers. (The specific definition for this action is pending.)

Operations are grouped into port types. Port types define a set of operations supported by the Web service.

Service bindings connect port types to a port. A port is defined by associating a network address with a port type. A collection of ports defines a service. This binding is commonly created using SOAP, but other forms may be used. These other forms could include CORBA Internet Inter-ORB Protocol (IIOP), DCOM, .NET, Java Message Service (JMS), or WebSphere MQ to name a few.

3. Explain the fundamental properties of a WSDL document and the use of WSDL document in web services and client development

WSDL is an XML-based file which basically tells the client application what the web service does. It is known as the Web Services Description Language(WSDL).

In this tutorial, we are going to focus on the last point which is the most important part of web services, and that is the WSDL or the Web services description language.

The WSDL file is used to describe in a nutshell what the web service does and gives the client all the information required to connect to the web service and use all the functionality provided by the web service.

In this tutorial, you will learn-

Structure of a WSDL Document

A WSDL document is used to describe a web service. This description is required, so that client applications are able to understand what the web service actually does.

The WSDL file contains the location of the web service and
The methods which are exposed by the web service.

The WSDL file itself can look very complex to any user, but it contains all the necessary information that any client application would require to use the relevant web service.

Below is the general structure of a WSDL file

Definition
TargetNamespace
DataTypes
Messages
Porttype
Bindings
service

One key thing to note here is that definition of messages, which is what is passed by the SOAP protocol is actually defined in the WSDL document.

The WSDL document actually tells a client application what are the types of SOAP messages which are sent and accepted by the Web service.

In other words, the WSDL is just like a postcard which has the address of a particular location. The address provides the details of the person who delivered the postcard. Hence, in the same way, the WSDL file is the postcard, which has the address of the web service which can deliver all the functionality that the client wants.

WSDL Elements

The WSDL file contains the following main parts

1. The <types> tag is used to define all the complex datatypes, which will be used in the message exchanged between the client application and the web service. This is an important aspect of the client application, because if the web service works with a complex data type, then the client application should know how to process the complex data type. Data types such as float, numbers, and strings are all simple data types, but there could be structured data types which may be provided by the web service.

For example, there could be a data type called EmployeeDataType which could have 2 elements called "EmployeeName" of type string and "EmployeeID" of type number or integer. Together they form a data structure which then becomes a complex data type.

2. The <messages> tag is used to define the message which is exchanged between the client application and the web server. These messages will explain the input and output operations which can be performed by the web service. An example of a message can be a message which accepts the EmployeeID of an employee, and the output message can be the name of the employee based on the EmpoyeeID provided.

3. The <portType> tag is used to encapsulate every input and output message into one logical operation. So there could be an operation called "GetEmployee" which combines the input message of accepting the EmployeeID from a client application and then sending the EmployeeName as the output message.

4. The <binding> tag is used to bind the operation to the particular port type. This is so that when the client application calls the relevant port type, it will then be able to access the operations which are bound to this port type. Port types are just like interfaces. So if a client application needs to use a web service they need to use the binding information to ensure that they can connect to the interface provided by that web service.

5. The <service> tag is a name given to the web service itself. Initially, when a client application makes a call to the web service, it will do by calling the name of the web service. For example, a web service can be located at an address such as http://localhost/Guru99/Tutorial.asmx . The service tag will actually have the URL defined as http://localhost/Guru99/Tutorial.asmx, which will actually tell the client application that there is a web service available at this location.

Why WSDL

A web service is an important component in building modern day web applications. Their main purpose is to allow multiple applications built on various programming languages to talk to each other. For instance, we can have a .Net web application talks to a Java application via a Web service.

A web service has the following key features

It is built using the XML programming language. Almost all modern day technologies such as .Net and Java have corresponding commands that have the ability to work with XML. Hence, XML was taken as the most appropriate language for building web services.
Web services communicate over HTTP. HTTP is a protocol used by all web-based applications. Hence, it just made sense to ensure that Web services also had the ability to work over the HTTP protocol.
Web services conform to a particular language specification. This specification is set by the W3C, which is the governing body for all web standards.
Web services have a description language known as WSDL, which is used to describe the web service.

The WSDL file is written in plain old XML. The reason that it is in XML is so that the file can be read by any programming language.

So if the client application was written in .Net, it would understand the XML file. Similarly, if the client application was written in the Java programming language then also it would be able to interpret the WSDL file.

The WSDL file is what binds everything together. From the above diagram, you can see that you can create a web service in the .Net language.

So this is where the service gets implemented. If you did not have the WSDL file and wanted a Java class to consume the web service, you would need a lot of coding effort to achieve this.

But now with the WSDL file which is in XML, which can be understood by any programming language, you can now easily have a Java class consume the .Net web service. Hence, the amount of coding effort is greatly reduced.

4. Discuss the structure of the WSDL document, explaining the elements in WSDL

A WSDL document has a definitions element that contains the other five elements, types, message, portType, binding and service. The following sections describe the features of the generated client code.

WSDL supports the XML Schemas specification (XSD) as its type system.

definitions

Contains the definition of one or more services. JDeveloper generates the following attribute declarations for this section:

· name is optional.

· targetNamespace is the logical namespace for information about this service. WSDL documents can import other WSDL documents, and setting targetNamespace to a unique value ensures that the namespaces do not clash.

· xmlns is the default namespace of the WSDL document, and it is set to http://schemas.xmlsoap.org/wsdl/.

· All the WSDL elements, such as <definitions>, <types> and <message> reside in this namespace.

· xmlns:xsd and xmlns:soap are standard namespace definitions that are used for specifying SOAP-specific information as well as data types.

· xmlns:tns stands for this namespace.

· xmlns:ns1 is set to the value of the schema targetNamespace, in the <types> section.

types

Provides information about any complex data types used in the WSDL document. When simple types are used the document does not need to have a types section.

message

An abstract definition of the data being communicated. In the example, the message contains just one part, response, which is of type string, where string is defined by the XML Schema.

operation

An abstract description of the action supported by the service.

portType

An abstract set of operations supported by one or more endpoints.

binding

Describes how the operation is invoked by specifying concrete protocol and data format specifications for the operations and messages.

port

Specifies a single endpoint as an address for the binding, thus defining a single communication endpoint.

service

Specifies the port address(es) of the binding. The service is a collection of network endpoints or ports.

5. Compare the PortType and operation elements in WSDL with the java equivalences

portType (Analogs to Java interface)

PortType is an abstraction part of WSDL.
An abstract set of operations supported by one or more endpoints.

A single Web service can support a number of different protocols. The structure of the data depends on the protocol that you use to invoke the Web service. Because of this, you need a way to map from the operations to the endpoints from which they can be accessed. The portType element takes care of this mapping.

6. Compare and contrast the binding and service elements in WSDL

binding

Binding is an concrete part of WSDL.
Describes how the operation is invoked by specifying concrete protocol and data format specifications for the operations and messages.
bindings are three types

1. SOAP Binding:
SOAP binding allows either document or rpc style with either encoding or literal. Encoding indicates how a data value should be encoded in an XML format (These rules specify how "something" is encoded/serialized to XML and then later decoded/de-serialized from XML back to "something"). Literal means that the data is serialized according to a schema (this is just plain XML data). With transportation type http, jms, smtp...

2. HTTP GET & POST binding:
WSDL includes a binding for HTTP 1.1's GET and POST verbs in order to describe the interaction between a Web Browser and a web site.

3. MIME binding: WSDL includes a way to bind abstract types to concrete messages in some MIME format.

7. Explain how SOAP is used with HTTP

SOAP ( Simple Object Access Protocol) is a message protocol that allows distributed elements of an application to communicate. SOAP can be carried over a variety of lower-level protocols, including the web-related Hypertext Transfer Protocol (HTTP). SOAP defines a header structure that identifies the actions that various SOAP nodes are expected to take on the message, in addition to a payload structure for carrying information. The concept of routing a message through a string of nodes that perform different functions is how SOAP supports things like addressing, security and format-independence. Essentially, the headers identify roles, which in turn provide the SOA features which SOAP then routes to. Stringing messages through a sequence of steps is uncommon in today’s microservice-centric development environments.

8. Discuss how SOAP can be used for functional oriented communication?

SOAP Communication Model.

All communication by SOAP is done via the HTTP protocol. Prior to SOAP, a lot of web services used the standard RPC (Remote Procedure Call) style for communication. This was the simplest type of communication, but it had a lot of limitations.

Let's consider the below diagram to see how this communication works. In this example, let's assume the server hosts a web service which provided 2 methods as

GetEmployee - This would get all Employee details
SetEmployee – This would set the value of the details like employees dept, salary, etc. accordingly.

In the normal RPC style communication, the client would just call the methods in its request and send the required parameters to the server, and the server would then send the desired response.

The above communication model has the below serious limitations

1. Not Language Independent – The server hosting the methods would be in a particular programming language and normally the calls to the server would be in that programming language only.

2. Not the standard protocol – When a call is made to the remote procedure, the call is not carried out via the standard protocol. This was an issue since mostly all communication over the web had to be done via the HTTP protocol.

3. Firewalls – Since RPC calls do not go via the normal protocol, separate ports need to be open on the server to allow the client to communicate with the server. Normally all firewalls would block this sort of traffic, and a lot of configuration was generally required to ensure that this sort of communication between the client and the server would work.

To overcome all of the limitations cited above, SOAP would then use the below communication model

1. The client would format the information regarding the procedure call and any arguments into a SOAP message and sends it to the server as part of an HTTP request. This process of encapsulating the data into a SOAP message was known as Marshalling.

2. The server would then unwrap the message sent by the client, see what the client requested for and then send the appropriate response back to the client as a SOAP message. The practice of unwrapping a request sent by the client is known as Demarshalling.

9. Explain the structure of SOAP message in message oriented communication, indicating the elements used

SOAP messaging
A SOAP message may need to be transmitted together with attachments of various sorts, ranging from facsimile images of legal documents to engineering drawings. Such data are often in some binary format. For example, most images on the Internet are transmitted using either GIF or JPEG data formats.

A SOAP message is an ordinary XML document containing the following elements:

A required Envelope element that identifies the XML document as a SOAP message
An optional Header element that contains header information
A required Body element that contains call and response information
An optional Fault element that provides information about errors that occurred while processing the message

A SOAP message package contains a primary SOAP message. It may also contain additional entities that are not lexically within the SOAP message but are related in some manner. These entities may contain data in formats other than XML. The primary SOAP message in a message package may reference the additional entities. Such additional entities are often informally referred to as 'attachments.'"

10. Discuss the importance of the SOAP attachments, explaining the MIME header

What is MIME?

The MIME stands for Multi-Purpose Internet Mail Extensions. As the name indicates, it is an extension to the Internet email protocol that allows it’s users to exchange different kinds of data files over the Internet such as images, audio, and video. The MIME is required if text in character sets other than ASCII. Virtually all human-written Internet email and a fairly large proportion of automated email is transmitted via SMTP in MIME format. Actually, MIME was designed mainly for SMTP, but the content types defined by MIME standards are important also in communication protocols outside of email, such as HTTP. In 1991, Nathan Borenstein of Bellcore proposed to the IETF that SMTP be extended so that Internet (but mainly Web) clients and servers could recognize and handle other kinds of data than ASCII text. As a result, new file types were added to “mail” as a supported Internet Protocol file type.

MIME headers

Now, let’s see the MIME headers. There are many sub parts come under MIME headers. Let’s see each in detail.

1) MIME-Version

2) Content-Type

3) Content-Disposition

4) Content-Transfer-Encoding

Securing SOAP With Attachments

Attachments may be associated with SOAP messages, as outlined in SOAP Messages with Attachments [SwA]. This profile defines how such attachments may be secured for integrity and confidentiality using the OASIS Web Services Security: SOAP Message Security standard. This does not preclude using other techniques. The requirements in this profile only apply when securing SwA attachments explicitly according to this profile.

This profile considers all attachments as opaque whether they are XML or some other content type. It is the sole responsibility of the application to perform further interpretation of attachments, including the ability to sign or encrypt portions of those attachments.

11. Identify different set of frameworks/libraries for SOAP web service development, in different environments (Java, .Net, PHP, etc...)

Name	Platform	Messaging Model(Destination)	Specifications	Protocols
Apache Axis	Java/C++	Client/Server	WS-ReliableMessaging, WS-Coordination, WS-Security, WS-AtomicTransaction, WS-Addressing	SOAP, WSDL
Apache Axis2	Java	Client/Server/ Asyn Support	WS-ReliableMessaging, WS-Security, WS-AtomicTransaction, WS-Addressing, MTOM, WS-Policy, WS-MetadataExchange	SOAP1.1, SOAP1.2, MTOM, WSDL 2.0, WSDL, REST
Apache CXF	Java	Client/Server/ Asyn Support	WS-ReliableMessaging, WS-Security, WS-Addressing, MTOM, WS-Policy, WS-SecureConversation, WS-SecurityPolicy, WS-Trust	SOAP1.1, SOAP1.2, MTOM, WSDL 2.0, WSDL, REST
CodeIgniter	PHP	Client/Server	An open source MVC web application framework	XML-RPC
gSOAP	C and C++	Client/Server Duplex/Async	WS-Addressing, WS-Discovery, WS-Policy, WS-ReliableMessaging, WS-Security, WS-SecurityPolicy	SOAP1.1, SOAP1.2, MTOM, WSDL 1.1, WSDL 2.0, REST, XML-RPC, JSON, JSON-RPC, XML
Java Web Services Development Pack / GlassFish	Java	Client/Server	WS-Addressing, WS-Security, ???	SOAP, WSDL, ???
Jello Framework	GAE/Java	Client/Server/Asyn Support	End-to-End Java framework for Google App Engine including comprehensive Data Authorization model, a powerful RESTful engine, and out-of-the-box UI views.	REST, OData, JSON
Jersey	Java	Client/Server	Project Jersey is the production-ready reference implementation for the JAX-RS specification by Oracle (Originally Sun)	REST
.NET Framework	C#, VB.NET	Client/Server	WS-Addressing, WS-MetadataExchange, WS-Security, WS-Policy, WS-SecurityPolicy, WS-Trust, WS-SecureConversation, WS-ReliableMessaging, WS-Coordination, WS-AtomicTransaction	SOAP, WSDL, MTOM
Web Services Interoperability Technology	Java	Client/Server	WS-Addressing, WS-ReliableMessaging, WS-Coordination, WS-AtomicTransaction, WS-Security, WS-Security Policy, WS-Trust, WS-SecureConversation, WS-Policy, WS-MetadataExchange	SOAP, WSDL, MTOM, JSON, XML
Web Services Invocation Framework	Java	Client	???	SOAP, WSDL
Windows Communication Foundation	.NET	Client/Server/Asyn support	WS-Addressing, WS-MetadataExchange, WS-Security, WS-Policy, WS-SecurityPolicy, WS-Trust, WS-SecureConversation, WS-ReliableMessaging, WS-Coordination, WS-AtomicTransaction,WS-Discovery	SOAP1.1, SOAP1.2, WSDL, XML, JSON, REST, MTOM, MSMQ, IPC, P2P, TCP, UDP, WebSocket
WSO2 WSF/PHP	PHP	Client/Server	SOAP MTOM, WS-Addressing, WS-Security, WS-SecurityPolicy, WS-Secure Conversation, WS-ReliableMessaging	SOAP, WSDL
XFire became Apache CXF	Java	Client/Server	WS-Addressing, WS-Security	SOAP, WSDL
XML Interface for Network Services	Java	Server ?	??	SOAP, XML-RPC, WSDL, JSON-RPC, JSON
Dframe Framework	PHP	Client/Server	Web application Components helping build MVC project.	JSON, REST
Yii	PHP	Client/Server	Open source, object-oriented, component-based MVC	REST
Smart.Framework	PHP	Client/Server	a free, BSD licensed, open-source web framework	JSON, REST, SOAP
Symfony2	PHP	Client/Server	PHP web application framework	JSON, REST, SOAP
Zend Framework	PHP	Client/Server	Web application framework implemented in PHP	SOAP, JSON, JSON-RPC, REST, XML-RPC

Copyright From Wikipedia, the free encyclopedia.

12. Explain the annotations in JAX-WS, providing examples of their use

JAX-WS annotations

1.1 @WebService

This JAX-WS annotation can be used in 2 ways. If we are annotating this over a class, it means that we are trying to mark the class as the implementing the Web Service, in other words Service Implementation Bean (SIB). Or we are marking this over an interface, it means that we are defining a Web Service Interface (SEI), in other words Service Endpoint Interface.
Now lets see the java program demonstrating both of the mentioned ways:
WSAnnotationWebServiceI.java

package com.javacodegeeks.examples.jaxWsAnnotations.webservice;

import javax.jws.WebMethod;

import javax.jws.WebService;

import javax.jws.soap.SOAPBinding;

import javax.jws.soap.SOAPBinding.Style;

@WebService

@SOAPBinding(style=Style.RPC)

public interface WSAnnotationWebServiceI {

@WebMethod

float celsiusToFarhenheit(float celsius);

}

In the above program we can see that we haven’t provided any optional element along with the @WebService annotation. And here it is used to define SEI. Regarding the other annotations used in the above program, we shall see their description a little ahead.
WsAnnotationsWebServiceImpl.java

package com.javacodegeeks.examples.jaxWsAnnotations.webservice;

import javax.jws.WebService;

@WebService(endpointInterface="com.javacodegeeks.examples.jaxWsAnnotations.webservice.WSAnnotationWebServiceI")

public class WsAnnotationsWebServiceImpl implements WSAnnotationWebServiceI {

@Override

public float celsiusToFarhenheit(float celsius) {

return ((celsius - 32)*5)/9;

}

In the above program we can see that we have provided an optional element endpointInterface along with the @WebService annotation. And here it is used to define SIB. endpointInterface optional element describes the SEI that the said SIB is implementing.
While implementing a web service as in above example, it is not mandatory for WsAnnotationsWebServiceImpl to implement WSAnnotationWebServiceI, this just serves as a check. Also, it is not mandatory to use an SEI, however, as a basic design principle “We should program to interface”, hence we have adapted this methodology in above program.
Other optional elements to @WebService can be like wsdlLocation that defines location of pre-defined wsdl defining the web service, name that defines name of the web service etc.

1.2 @SOAPBinding

Demonstration of @SOAPBinding JAX-WS annotation has already been shown in first program in 1.1. This annotation is used to specify the SOAP messaging style which can either be RPC or DOCUMENT. This style represents the encoding style of message sent to and fro while using the web service.
With RPC style a web service is capable of only using simple data types like integer or string. However, DOCUMENT style is capable of richer data types for a class let’s say Person, which can have attributes like

String
name

, Address address etc.
Document style indicates that in the underlying web service, underlying message shall contain full XML documents, whereas in the RPC style, the underlying message contains parameters and return values in request and response message respectively. By default the style is Document.
The other important optional attribute is use. It represents the formatting style of the web service message. Its value can either be literal or encoded.

1.3 @WebMethod

@WebMethod JAX-WS annotation can be applied over a method only. This specified that the method represents a web service operation. For its demonstration, please refer to first program in 1.1.

1.4 @WebResult

To understand this JAX-WS annotation, let’s write SEI & SIB again:

package com.javacodegeeks.examples.jaxWsAnnotations.webresult;

import javax.jws.WebMethod;

import javax.jws.WebResult;

import javax.jws.WebService;

import javax.jws.soap.SOAPBinding;

import javax.jws.soap.SOAPBinding.Style;

@WebService

@SOAPBinding(style
  = Style.RPC)

public interface WSAnnotationsWebResultI {

@WebMethod

@WebResult(partName="farhenheitResponse")

float celsiusToFarhenheit(float celsius);

}

WSAnnotationsWebResultImpl.java

package com.javacodegeeks.examples.jaxWsAnnotations.webresult;

import javax.jws.WebService;

@WebService(endpointInterface="com.javacodegeeks.examples.jaxWsAnnotations.webresult.WSAnnotationsWebResultI")

public class WSAnnotationsWebResultImpl implements WSAnnotationsWebResultI {

@Override

public float celsiusToFarhenheit(float celsius) {

return ((celsius - 32)*5)/9;

}

Now let’s publish this endpoint:
WSPublisher.java

package com.javacodegeeks.examples.jaxWsAnnotations.webresult;

import javax.xml.ws.Endpoint;

public class WSPublisher {

public static void main(String[] args) {

Endpoint.publish("http://127.0.0.1:9999/ctf", new WSAnnotationsWebResultImpl());

}

On publishing the generated WSDL (at URL: http://127.0.0.1:9999/ctf?wsdl) would be like:
Refer to the highlighted line in above wsdl, the part name has been changed to “farhenheitResponse” as was defined using @WebResult. What interest here is that @WebResult can be used to determine what the generated WSDL shall look like.

<definitions

xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"

xmlns:wsp="http://www.w3.org/ns/ws-policy" xmlns:wsp1_2="http://schemas.xmlsoap.org/ws/2004/09/policy"

xmlns:wsam="http://www.w3.org/2007/05/addressing/metadata" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"

xmlns:tns="http://webresult.jaxWsAnnotations.examples.javacodegeeks.com/"

xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://schemas.xmlsoap.org/wsdl/"

targetNamespace="http://webresult.jaxWsAnnotations.examples.javacodegeeks.com/"

name="WSAnnotationsWebResultImplService">

<types />

<message name="celsiusToFarhenheit">

<part name="arg0" type="xsd:float" />

</message>

<message name="celsiusToFarhenheitResponse">

<part name="return" type="xsd:float" />

</message>

<portType name="WSAnnotationsWebResultI">

<operation name="celsiusToFarhenheit">

<input

wsam:Action="http://webresult.jaxWsAnnotations.examples.javacodegeeks.com/WSAnnotationsWebResultI/celsiusToFarhenheitRequest"

message="tns:celsiusToFarhenheit" />

<output

wsam:Action="http://webresult.jaxWsAnnotations.examples.javacodegeeks.com/WSAnnotationsWebResultI/celsiusToFarhenheitResponse"

message="tns:celsiusToFarhenheitResponse" />

</operation>

</portType>

<binding name="WSAnnotationsWebResultImplPortBinding" type="tns:WSAnnotationsWebResultI">

<soap:binding transport="http://schemas.xmlsoap.org/soap/http"

style="rpc" />

<operation name="celsiusToFarhenheit">

<soap:operation soapAction="" />

<input>

<soap:body use="literal"

namespace="http://webresult.jaxWsAnnotations.examples.javacodegeeks.com/" />

</input>

<output>

<soap:body use="literal"

namespace="http://webresult.jaxWsAnnotations.examples.javacodegeeks.com/" />

</output>

</operation>

</binding>

<service name="WSAnnotationsWebResultImplService">

<port name="WSAnnotationsWebResultImplPort" binding="tns:WSAnnotationsWebResultImplPortBinding">

<soap:address location="http://127.0.0.1:9999/ctf" />

</port>

</service>

</definitions>

In the above program,

part
name

has value return.
Other elements to @WebResult are WebParam.Mode that defines the direction in which parameter is flowing, targetNamespace to define XML namespace for the parameter.

1.5 @WebServiceClient

To understand @WebServiceClient JAX-WS annotation, let us first publish the endpoint written in 1.1 using below program:
WSPublisher.java

package com.javacodegeeks.examples.jaxWsAnnotations.webservice;

import javax.xml.ws.Endpoint;

public class

WSPublisher
  {

public static void

main(String[]
  args) {

Endpoint.publish("http://127.0.0.1:9999/ctf

",
  new

WsAnnotationsWebServiceImpl());

}

Before moving further we should understand wsimport utility provided by Java that eases the task of writing client for a SOAP based web service. We won’t go into much detail here about wsimport, instead let’s first save the wsdl file with name ‘ctf.wsdl’ and then write following command on the command prompt:
wsimport -keep -p client ctf.wsdl

1.6 @RequestWrapper

@RequestWrapper JAX-WS annotation is used to annotate methods in the Service Endpoint Interface with the request wrapper bean to be used at runtime. It has 4 optional elements; className that represents the request wrapper bean name, localName that represents element’s local name, partName that represent the part name of the wrapper part in the generated WSDL file, and targetNamespace that represents the element’s namespace.

1.7 @ResponseWrapper

@ResponseWrapper JAX-WS annotation is used to annotate methods in the Service Endpoint Interface with the response wrapper bean to be used at runtime. It has 4 optional elements; className that represents the response wrapper bean name, localName that represents element’s local name, partName that represent the part name of the wrapper part in the generated WSDL file, and targetNamespace that represents the element’s namespace.

1.8 @Oneway

@Oneway JAX-WS annotation is applied to WebMethod which means that method will have only input and no output. When a @Oneway method is called, control is returned to calling method even before the actual operation is performed. It means that nothing will escape method neither response neither exception.

1.9 @HandlerChain

Web Services and their clients may need to access the SOAP message for additional processing of the message request or response. A SOAP message handler provides a mechanism for intercepting the SOAP message during request and response.
A handler at server side can be a validator. Let’s say we want to validate the temperature before the actual service method is called. To do this our validator class shall implement interface SOAPHandler
Next we shall implement SOAP handler xml file that may also contain sequence of handlers.
After this we shall configure @HandlerChain JAX-WS annotation in SEI:

13. Discuss how a web service can be tested using different approaches (using a dummy client or a dedicated tool, etc...)

What is Web Service Testing?

Web Services Testing is testing of Web services and its Protocols like SOAP & REST. To test a Webservice you can

1. Test Manually

2. Create your own Automation Code

3. Use an off-the shelf automation tool like SoapUI.

WebService Testing involves following steps -

1. Understand the WSDL file

2. Determine the operations that particular web service provides

3. Determine the XML request format which we need to send

4. Determine the response XML format

5. Using a tool or writing code to send request and validate the response

Suppose we want to test a WebService which provides Currency Conversion Facility. It will the current conversion rates between the different countries currency. This service we can use in our applications to convert the values from one currency to the other currency.

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12. Explain the annotations in JAX-WS, providing examples of their use

JAX-WS annotations

1.1 @WebService

1.2 @SOAPBinding

1.3 @WebMethod

1.4 @WebResult

1.5 @WebServiceClient

1.6 @RequestWrapper

1.7 @ResponseWrapper

1.8 @Oneway

1.9 @HandlerChain

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