Integration/webservice Concepts

I saw people in industry are really crazy to learn Integration .Real thing is that integration is not a rocket science kind of thing .
In my view a developer who is logically good he will definitely good in integration .

Lets discuss about integration/web service .

Web service basically are of  two  types :
1.SOAP(Simple Object Access Protocol)

2.REST (Representational State Transfer) 

I know every body have  at least  idea about above two types of we service.

Again in each we can have Inbound and Outbound web service .

Lets discuss what is inbound and outbound web service . 

When we are writing a service for other and for us it is Inbound and for Other it is outbound web service .

Same way when we are consuming other's service then for us it is outbound and for them it is inbound web service .

I think now we are clear, what is inbound and out bound web service .

Lets discus as a sales force developer  how we can write inbound web service  for others .

Inbound Web Service Using SOAP :

Here we will learn how to write a sample web service using SOAP and how we can test ,also how we can write test class for this .

To write a web service we need to write a apex class . 

• Class should be global access specified .
• Methods should be start with web service key word .
• Any method that uses the Web Service keyword should  static  .
• Return type should not Map,Set,Pattern Object, Matcher Object,Exception Object . 
•  We cannot deprecate webService methods or variables in managed package 

Example 1:

Assume that we have written a web service  to get account name based on one external Id .

So while calling this web service  client needs to pass theexternal Id and in response it will return the name ,we can return other things as per our requirement .

global class AccountService{
    webservice static String getAccountName(String extid){
       if(extid != null){
        String accName=[SELECT Id,Name FROM Account WHERE APINameExtid =: extid LIMIT 1].Name;
        return accName;
       }
       return null;
    }
}
Replace APINameExtid with your external id Api name of field  created in Account .

Example 2 :