The Web materials and resources of Chapter 3 - Section 2 are listed here.

Chapter 3, Web Services-Core functionality and standards

Section 2, Implementing Web services

Section synopsis

In this section, we will explore Web services implementation approaches and various available APIs. By the end of this section, students will come to know about service implementation,testing, publication and invocation platforms.

Before lecture

📚 ToRead

Objective : Implementing Web service - Learning WSDL standard.

  1. From Web Service Implementation and Composition Techniques 1st ed. 2017 Edition, springer
    • Chap 2. Web Services – SOAP and WSDL
  2. From Web services : principles and technology
    • Chap 5. Describing Web services
  3. From PhP web services, second edition, 2016
    • Chap 7. RPC and SOAP Services
  4. From Master Php 7, 2017
    • Chap 11. Building Services
  5. From Building Web Services with Java: Making Sense of XML, SOAP, WSDL, and UDDI 2nd Edition
    • Chap 4. Describing Web Services
    • Chap 5. Implementing Web Services with Apache Axis

📝 ToDo

The objective of this section, is to get familiarized with several Web service implementation platforms in various programming languages.

Running lecture demos:

In order to implement Web services either in Bottom-Up or Top-Down Web services, you will need, a service container and a SOAP engine. Web services examples of this course are deployed in Apache, and are written in Php.

To run demo Web services provided with this lecture, you need first to clone the following repository on your machine: https://github.com/neilabenlakhal/webservices2.git.

Then, you need the following tools installed :

  • AMPPS,MAMP, WAMP, LAMP, or XAMPP software stack enabling Apache, Mysql and PHP. This includes everything you need for implementing Web services.

  • NUSOAP and SOAP.dll: PhP comes with a Top-Down enabling Web services implementation API (Soap.dll). But for implementing Web services along the Bottom-Up approach, we will be using NUSOAP, a rewrite of SOAPx4, provided by NuSphere and Dietrich Ayala. It is a set of PHP classes - no PHP extensions required - that allow developers to create and consume Web services based on SOAP 1.1, WSDL 1.1 and HTTP 1.0/1.1. Please download NUSOAP, unzip it and add it to your www folder in your installed AMPPS platform.

Testing others Web services implementation platforms :

Every programming language has one or several APIs to implement Web services that support SOAP based communication. for this ToDo3_2 section, you are highly advised to do the following Lab exercises, to get familiarized with implementing Web services in Java and .NET.

  • Implementing web services in JAVA: Java API for XML Web Services (JAX-WS) is a technology for building web services and clients that communicate using XML. There are currently many platforms that implement it, Apache CXF and Apache Axis 2 are two implementations of JAX-WS.

    -Apache Axis2 project: is a Java-based implementation of both the client and server sides of the Web services equation. Apache Axis2 provides a complete object model and a modular architecture that makes it easy to add functionality and support for new Web services-related specifications and recommendations. Axis2 enables you to easily perform the following tasks:

    • Send SOAP messages.
    • Receive and process SOAP messages.
    • Create a Web service out of a plain Java class.
    • Create implementation classes for both the server and client using WSDL.
    • Easily retrieve the WSDL for a service.

    -Apache CXF: is an open source services framework. CXF helps you build and develop services using frontend programming APIs, like JAX-WS (SOAP) and JAX-RS (REST). These services can speak a variety of protocols such as SOAP, XML/HTTP, RESTful HTTP, or CORBA and work over a variety of transports such as HTTP, JMS or JBI.

  • Implementing web services with Windows Communication Foundation (WCF): WCF is a framework for building service-oriented (SOAP/REST) applications. Using WCF, you can send data as asynchronous messages from one service endpoint to another. A service endpoint can be part of a continuously available service hosted by IIS, or it can be a service hosted in an application. An endpoint can be a client of a service that requests data from a service endpoint. The messages can be as simple as a single character or word sent as XML, or as complex as a stream of binary data.

  • Practical Exercises :

  • Web service testing :

In order to test web services we will be using :

SOAPUI the open source version, an API (SOAP/REST) testing tool.

After lecture :

💻 ToCode

The objective of this ToCode3_2 section is to create a Web services composition (WSC) composed of two(2) Web services : WS1 and WS2.

  • WS1: is a Web service you have to implement yourself.
  • WS2: is a Web service you have to choose from internet, then, write a client against WS2.
  • WS1 and WS2 are to be invoked sequentially by a Web interface transparently.

Sample scenarios you can consider :

  • WS1 makes a fictive travel reservation for a customer. The total amount will be returned in TND. WS2 will provide a reservation confirmation with the total amount in another currency, for instance USD.

  • WS1 lets a user choose a preferred vacation destination, and WS2, will provide the user with the weather forecast, for the designated destination and date.

Step 1

Implement a SOAP web service (bottom-up approach)– we will call it WS1.

  • Write a PHP web service using NUSOAP library. Your web service should have at least (2)two methods. one of them having a table as input/output. Your generated WSDL file should define at least one complex data type.
  • Write a client in PHP to your Web service (one of the (2)two methods).

Implement a SOAP web service (Top-down approach) – we will call it WS-TD. - Write another PhP web services. Your web service should have one method.
- Write a client in PHP to your Web service.
- Generate your Web service contract using php2WSDL.
- Create another client for your web service in another programming language of your choice.

Step 2

Search for your WS2 : it should supports SOAP-based invocation. Test the web service and write a client.

Step 3

Write a client for WS1 and WS2. Hint: The output of WS1 must be an input to WS2.

Step 4

Call WS1 and WS2 composition using a Web interface.

What to submit ?

-Create a folder and name it ToCode3_2. Create four(4) subfolders named : WS1, WS2, WS-TD, and WSC.

  • Store the source code, of the WS and the client of each WS. Add SOAPUI tests of you WS1, WS2, and WS-TD (print screens).

  • Store the source code of the composition in WSC with print screen of its execution interface with results. You may add an explanatory description of your composition with each web service methods, input and output parameters.

  • Push your ToCode3_2 to your GIT repository.
  • Send the following on Microsoft Teams : Link of your git repository.
  • Make sure that your git repositories are private and only open to collaborators you have already added.

Additional resources:

Several web services WSDL files :

Several Web services web sites :