Server-side Development I

Web application

A web application is a software application that runs on a remote server. In most cases, Web browsers are used to access Web applications, over a network, such as the Internet.
Some web applications are used in intranets, in companies and schools, for example.
Web applications are different from other applications because they do not need to be installed.

Web services

Web services are server-side application components, which provides a set of services.
Web services are self-contained, modular, distributed, dynamic applications that can be described, published, located, or invoked over the network to create products, processes, and supply chains. These applications can be local, distributed, or web-based. Web services are built on top of open standards such as TCP/IP, HTTP, Java, HTML, and XML.

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WEB SERVICE DESCRIPTION LANGUAGE

WSDL is an XML vocabulary for describing Web services allowing developers to describe Web
Services and their capabilities, in a standard manner.
WSDL is often used in combination with SOAP and XML Schema to provide web services over the Internet.
A client program connecting to a web service can read the WSDL to determine what functions are available on the server.
Any special datatypes used are embedded in the WSDL file in the form of XML Schema.
The client can then use SOAP to actually call one of the functions listed in the WSDL.

Specifies three fundamental properties:

•What a service does - operations (methods) provided
by the service.

• How a service is accessed - data format and protocol
details.

•Where a service is located - Address (URL) details.

Structure of  WSDL

Elements in WSDL

•Types  –  a container for data type definitions using some type system (such as XSD).

•Message  –  an abstract, typed definition of the data being communicated.

•Operation  –  an abstract description of an action supported by the service.

•Port Type  –  an abstract set of operations supported by one or more endpoints.

•Binding  –  a concrete protocol and data format specification for a particular port type.

•Port  –  a single endpoint defined as a combination of a binding and a network address.

•Service  –  a collection of related endpoints.

Binding & Service

The <binding> element provides specific details on how a portType operation will actually be transmitted over the wire.


•The bindings can be made available via multiple transports including HTTP GET, HTTP POST, or SOAP.


•The bindings provide concrete information on what protocol is being used to transfer portType operations.


•The bindings provide information where the service is located.


•For SOAP protocol, the binding is <soap:binding>, and the transport is SOAP messages on top of HTTP protocol.


•You can specify multiple bindings for a single portType.


The binding element has two attributes : name and type attribute.


The name attribute defines the name of the binding, and the type attribute points to the port for the binding







The <service> element defines the ports supported by the web service. For each of the supported protocols, there is one port element. The service element is a collection of ports.


Web service clients can learn the following from the service element − 

                   •where to access the service,
                   •through which port to access the web service, and
                   •how the communication messages are defined.


The service element includes a documentation element to provide human-readable documentation.


The binding attributes of port element associate the address of the service with a binding element defined in the web service.

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SIMPLE OBJECT ACCESS PROTOCOL

SOAP messages are carried as the payload of some other network protocol, for example via HTTP or SMTP (Simple Mail Transfer Protocol) or FTP (File Transfer Protocol) or TCP/IP(Transmission Control Protocol/Internet Protocol)

SOAP combines the data capabilities of XML with the transport capability of HTTP

SOAP Message

• Envelope

Wraps entire message and contains header and body.
Defines an overall framework for expressing what is in a message; whoshould deal with it, and whether it is optional or mandatory.


• Header

optional element with additional info such as security or routing



• Body

Application-specific message content being communicated as arbitrary XML payloads in the request and response messages.
Fault element provides information about errors that occurred while processing the message.

Structure of SOAP message is shown below.

MIME Header

When a SOAP message is wrapped for transmission in HTTP (or another protocol, such as SMTP), suitable MIME headers must be created. At minimum, the wrapper must include the Content-Type and Content-Lengthheaders along with the SOAPAction header. Similarly, when a message is received, any MIME headers that accompany it must be extracted from the protocol-specific wrapper and be made part of the created SOAPMessage. The MIME headers associated with a SOAPMessage are held in an object of typejavax.xml.soap.MimeHeaders .

In terms of the structure of an encapsulated SOAP message, the MIME headers logically appear outside the envelope, where they form the protocol-specific wrapper. In the case of a SOAP message with attachments, in addition to the headers in the outer wrapper, the SOAP message part and each of the attachment parts have their own collection of MIME headers that are distinct from those of the wrapper.

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Java API for XML Web Services

Annotations

•javax.xml.ws.Action

Whether to allow an explicit association of a WS-Addressing Action message addressing property with input, output, and fault messages of the mapped WSDL operation.

•javax.xml.ws.BindingType

The binding to use for a Web Service implementation class.


•javax.xml.ws.FaultAction

Whether to allow an explicit association of a WS-Addressing Action message addressing property with the fault messages of the WSDL operation mapped from the exception class. The @FaultAction annotation is used inside an @Action annotation.

•javax.xml.ws.RequestWrapper

The request wrapper bean to be used at runtime for the methods in the endpoint interface.

•javax.xml.ws.ResponseWrapper

The response wrapper bean to be used at runtime for the methods in the endpoint interface.

•javax.xml.ws.ServiceMode

Whether a provider implementation works with the entire protocol message or with the payload only.

•javax.xml.ws.WebEndpoint

The getPortName() methods of a generated service interface.


•javax.xml.ws.WebFault

Service-specific exception classes to customize to the local and namespace name of the fault element and the name of the fault bean.



•javax.xml.ws.WebServiceClient

A generated service interface.

•javax.xml.ws.WebServiceProvider

A provider implementation class.


•javax.xml.ws.WebServiceRef

A reference to a Web Service.

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Web Service Testing 

Testing of web services is one of the important type of software testing approach, which is mainly used to determine the expectations for reliability, functionality, performance, etc.


As these days Automated testing is considered as one of the most trending methodology in the field of software testing, hence testing web apps based on RESTful APIs through automation will provide effective test results. Some of the best & popular tools for web services testing are:

•SoapUI

 
•TestingWhiz

 
•SOATest

 
•TestMaker 

•Postman

Among above mentioned tools, Testingwhiz and SoapUI as the most user-friendly tools for API testing. Automating API testing, as a part of automated web services testing solution that helps you to test whether your application communicates and accesses functions correctly from the Web by effectively verifying the behavior of web services connected to them.

SoapUI Tool

A popular open source Web Services Testing tool in use since 2005. SoapUI is one of the initial testing tools for WS and has an active and vibrant community. This framework supports cross platform as it is written in Java. SoapUI is a simple and easy to use GUI based tool to develop test suites across the SOAP and RESTful Web Services. It also supports command line (CLI) to execute the tests. SoapUI does support other languages such as Groovy and Javascript.

• Provides printable, exportable, and HTML-based reports at Project, TestSuite, TestCase, or LoadTest level.
• Comes integrated with Hudson, Bamboo, Maven, ANT and JUnit.
• Allows developing own set of features as SoapUI Plugins.
• Records, monitors and displays all the data.
• Supports WS-Security and SSL decryption.

TestingWhiz

TestingWhiz is a codeless test automation tool which comes with API/web services testing capability. It lets you perform functional, compliance, load testing and mocking of REST and SOAP web services via WSDL interface over HTTP and FTP. It also lets perform service denial and penetration checks to ensure the overall health of the web services. Plus, it also lets you perform end-to-end testing right from Web UI, business logic, to database and ETL without coding needs.

• Supports String comparison to validate the API response.
• Helps log API defects through integrated bug tracking tools like JIRA, Mantis and Fogbugz.
• Generates visual logs and reports of test execution with emailing facility.
• Allows distributed and parallel execution across multiple machines and nodes.
• Provide Continuous Integration with Jenkins, Bamboo & Hudson.
• Supports data-driven and keyword-driven testing.

SOAtest

SOAtest is an enterprise-grade tool by Parasoft for testing and validating APIs and API-driven apps. It provides robust support for functional unit, integration, security, simulation, mocking, compliance and load testing of technologies like REST, JSON, MQ, JMS, TIBCO, HTTP and XML.

• Provides end-to-end testing capability.
• Supports 120+ protocols/message types.
• Comes with an easy-to-use interface.
• Helps create sophisticated, extensible and reusable tests without coding.
• Supports continuous integration testing.

TestMaker

TestMaker is an open source tool to test and monitor performance of web, web services and SOA application by PushtoTest. It runs on Jython (Python written in Java). TestMaker can repurpose Selenium tests, SoapUI tests, Sahi tests or any tests written in Groovy, Java, Python, PHP, Ruby and Perl into functional, load and performance tests.

• Uses command-line prompt for functional, load and performance testing.
• Features an intuitive look and feel with a standard multi-windowed IDE.
• Provides a monitoring dashboard to run tests and display live results.
• Allows accessing all Java libraries and classes due to Jython language.

Postman

Postman is yet another API/ web services testing tool which comes with powerful HTTP client support. It has an easy-to-use request builder that allows you to write test cases and manage response data and response time for efficient testing and management of API test cases.

• Allows collecting and organizing APIs in a feature called Postman Collections.
• Facilitates collaboration and sharing of API data and controls with team.
• Comes with pasting text feature for hassle-free test creation on command line window.
• Allows writing Boolean tests within Postman Interface.

Jersey

An open source implementation of JAX-RS (Java API for XML REST Services) that is used for developing RESTful Web Services. It is created by Oracle (earlier Sun Microsystems). This framework is not a test framework but instead a simple WS client Java APIs to consume in TestNG/JUnit frameworks while developing the tests. A wrapper test framework with common functionality can be created on top of Jersey.

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References

https://simple.wikipedia.org/wiki/Web_application

https://www.tutorialspoint.com/webservices/what_are_web_services.htm

https://www.oreilly.com/library/view/java-web-services/0596003994/ch03s05.html

https://docs.oracle.com/cd/E13222_01/wls/docs103/webserv_ref/annotations.html#wp1103652

https://www.quora.com/What-is-the-testing-approach-towards-web-services

https://www.techsling.com/2016/02/12-great-tools-web-services-testing/