What is a webservice?

You might be asking yourself “What is a webservice?” or “What is an AS400 webservice?” or maybe "What is the difference between an IBM i webservice and those on other systems?"

JARGON CLARIFICATION: Remember, there is no such thing as an IBM AS400 webservice, there never was, the trusty old 400 machine existed long before the internet rose to business capability. Nor is there any IBM iSeries webservices anymore, the IBM iSeries had internet capability but the last iSeries was sold over twenty years ago. You are using an IBM i Power System so from this point on I will use the correct terminology and refer to your IBM i webservice

Now that my jargon rant is over let get back to the discussion 🙂

Anyway, lets look at what a webservice is and perhaps do a quick, high level overview to explain the basics.

webservice talks to computers over the internet

Webservices are programs focussed on sharing information

Broadly speaking “Web Services” are programs that let one computer system talk to another computer system over the internet. For example, you might want to enter customer details into a office computer system and have those customer details be checked on an online ‘address checking’ website or something similar.

Today, Web Services are self-contained, self-described, component applications that can be published, located, and invoked across the Web.

Web Services provide a standard means of interoperating between different software applications running on a variety of platforms.

eXtensible Markup Language (XML) and Java Script Object Notation (JSON) provide the extensibility and language neutrality that is the key for standards-based interoperability of Web Services.

Web services communicate over a network through HTTP between the two systems. Many web services are identical to SOA (Services Oriented Architecture) and mainly rely on standards such as XML-RPC and SOAP (Simple Object Access Protocol)

Web Services have rapidly became state-of-art architectural approaches to allow the access of multiplatform and multilanguage systems..

Many companies have legacy applications which represent a high investment and Web Services promise to allow their access from the web without extensive modifications.

sharing data with web services

Webservices are programs that reply to a request for information

Web services consist of a group of standards intended to make it possible for diverse systems to communicate, without requiring a particular type of middleware, programming language or even operating system. They can be based on SOAP, REST or XML-RPC,.

SOAP is an open source message standard, based on an XML dictionary, that uses standard transport protocols widely used over the Internet such as HTML or SMTP. It represents a paradigm shift in the way applications communicate with each other, because it does not require any special middleware to allow diverse applications to communicate. The messages are text based and accessible by any application over the network. They are described by using a special XML based language called WSDL.

REST is a simpler type of Web Service where the user simply accesses a URL to obtain back an XML document without any standard specification.

XML-RPC is a way to send commands to another system by using and XML document.

ibm i web design

Web service allow to develop loosely coupled applications, by allowing systems based on different technologies and languages to communicate by using open standard largely based on XML.

Web service allow to develop loosely coupled applications, by allowing systems based on different technologies and languages to communicate by using open standard largely based on XML.

In Summary

  • Webservices allow the communication via internet standards XML and HTTP.
  • Webservices perform functions that can include anything from simple query responses to complex business processes.
  • Once a Web Service is deployed, other applications can discover and invoke it.
  • A web service has list of methods and procedures that can be used by any of the applications irrespective of the Programming Languages, Server OS, Hardware used to develop them.
  • Any type of applications can access the functionality provided by the web service and such functionality is called web methods or web APIs.
  • Any computer that has an access to the internet can have access to any public web service.
  • Once the web service is deployed on the Internet it can be used by any of the clients using HTTP and XML.

In short: A Webservice is a program that talks to *something* on the WEB.

Using Internet jargon "consuming a webservice" is the description for using a webservice to get information from a web server somewhere in the cloud.

If you are unfamiliar with web technology this can sound like technobabble!

So, let's go through all the aspects of webservice terminology and try to get them firmly planted in your mind:

What does CONSUME a WEBSERVICE mean?

In the RPG world you would CALL a program.

In the webservice world you CONSUME a webservice. This means connecting to a webservice and receiving it's reply and doing something with it.

{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}
Pen
>