Web Services (Guide to Become Full Stack Developer)

In the continuation of the last blog, Back-End Stack (Guide to Become Full Stack Developer), this blog is dedicated to Web services.

So, first of all, let’s discuss, what are web services.

Web services describe the open standard (XML, SOAP, HTTP, etc.) based web applications that interact with other web applications to exchange data. Web services can convert your existing applications into web applications. Or, a web service is a standardized medium to propagate communication between the client and server applications on the World Wide Web.

Web services provide a common platform that allows multiple applications built on various programming languages to have the ability to communicate with each other.

Some web services are


WSDL stands for Web Services Description Language. It is the standard format for describing a web service that was developed jointly by Microsoft and IBM.

WSDL has three parts:

Definitions: 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.

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

1. One-way: Messages sent without a reply required

2. Request/response: The sender sends a message and the receiver sends a reply.

3. Solicit-response: A request for a response. (The specific definition for this action is pending.)

4. 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: 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 like CORBA Internet Inter-ORB Protocol (IIOP), DCOM, .NET, Java Message Service (JMS), or WebSphere MQ can also be used.


SOAP is an XML-based protocol for accessing web services over HTTP. It has some specifications that could be used across all applications. SOAP is known as the Simple Object Access Protocol, but in later times was just shortened to SOAP v1.2. SOAP is a W3C recommendation for communication between two applications.

SOAP has its own advantages it defines its own security known as WS Security and is language and platform-independent, which allows SOAP web services to be written in any programming language and executed in any platform.

SOAP also has its own disadvantages like it is slow, as it uses XML format that must be parsed to be read. It defines many standards that must be followed while developing SOAP applications. So it is slow and consumes more bandwidth and resources. SOAP uses WSDL and doesn’t have any other mechanism to discover the service.


UDDI is an XML-based standard for describing, publishing, and finding web services, whereas UDDI stands for Universal Description, Discovery, and Integration.

Universal Description, Discovery, and Integration (UDDI) provides the definition of a set of services supporting the description and discovery of

1. businesses, organizations, and other Web Services providers,

2. the Web Services they make available, and

3. the technical interfaces which may be used to access those services.

The idea is to “discover” organizations and the services that organizations offer, much like using a phone book or dialing information.

UDDI is based on a common set of industry standards, including HTTP, XML, XML Schema, and SOAP. It provides an infrastructure for a Web Services-based software environment for both publicly available services and services only exposed internally within an organization. The UDDI Business Registry system consists of three directories:

UDDI white pages: basic information such as a company name, address, and phone numbers, as well as other standard business identifiers like Dun & Bradstreet and tax numbers.

UDDI yellow pages: detailed business data, organized by relevant business classifications. The UDDI version of the yellow pages classifies businesses according to the newer NAICS (North American Industry Classification System) codes, as opposed to the SIC (Standard Industrial Classification) codes.

UDDI green pages: information about a company’s key business processes, such as operating platform, supported programs, purchasing methods, shipping and billing requirements, and other higher-level business protocols.


Representational State Transfer (REST) is a software architectural style that defines a set of constraints to be used for creating web services. Web services that conform to the REST architectural style, or RESTful web services, provide interoperability between computer systems on the Internet. RESTful web services allow the requesting systems to access and manipulate textual representations of web resources by using a uniform and predefined set of stateless operations. RESTful web services are lightweight, highly scalable, and maintainable and are very commonly used to create APIs for web-based applications. REST is an architectural style, not a protocol.

The advantages of RESTful Web Services are that they are fast as there is no strict specification like SOAP. It consumes less bandwidth and resources. RESTful web services can use SOAP web services as the implementation. RESTful web service permits different data formats such as Plain Text, HTML, XML, and JSON. Also, these web services can be written in any programming language and executed on any platform.

So, now that we have gained knowledge of different web services the question is, how to develop these APIs and what are the points we should keep in mind while developing these web services?

  1. For that, first, we need to understand what kind of application we are working with and what are its requirements. This will help us in following or creating API much faster with less alteration.
  2. We should follow API standard docs like those provided by JSONAPI.ORG or we should create our own API stand docs, this will help us in creating symmetrical API and also increases the understanding of the developer who will be using these APIs in the future.
  3. Security is one of the major concerns we should keep in mind while developing web services, as many of the Third-Party applications will be using our APIs. So, all the APIs must be protected by some authorization header or authorization token system.
  4. Proper error handling should be there with a proper response code. Most of the developers skip this part which creates a problem for the other developer to debug their applications. As it’s hard to catch whether the error is coming through API or from their own application.
  5. And in the last one should practice creating API, as it helps in creating more clean optimized APIs in their future development process.


Nowadays most of the framework and web service developers are more on RESTful API than SOAP API, as the former is faster and their development is much easier than that of the latter. There are many frameworks, like Laravel, Django, express, etc., are available for creating web services but we should check first that what kind of application we are dealing with and what challenges we can face in the future scope.