Hello,


Code:

global class CurrencyExchangeRateScheduler implements Schedulable
{
    public String sessionId;
  
    public CurrencyExchangeRateScheduler()
    {
        String username = 'username';
        String password = 'password+security_token';
      
        partnerSoapSforceCom.Soap sp = new partnerSoapSforceCom.Soap();
      
        partnerSoapSforceCom.LoginResult loginResult = sp.login(username, password);
          
        sessionId = loginResult.sessionId;
       
    }
  
    global void execute(SchedulableContext ctx)
    {
        UpdateDailyCurrencyExchangeRate(sessionId);
    }
  
    @Future(callout=true)
    public static void UpdateDailyCurrencyExchangeRate(string sessionId)
    {
        system.debug('sessionId: '+sessionId);
      
        ...
        ...
        ...
        ...
 
 
        Http h = new Http();
        HttpRequest req = new HttpRequest();
        req.setHeader('Authorization', 'OAuth ' + sessionId);
        req.setHeader('Content-Type', 'application/json');
        req.setMethod('POST');
      
        for(CurrencyType currType : currencies)
        {
            if(!currType.IsCorporate)
            {
                req.setEndpoint(URL.getSalesforceBaseUrl().toExternalForm() + '/services/data/v28.0/sobjects/CurrencyType/'+currType.id+'?_HttpMethod=PATCH');

                req.setBody('{ "ConversionRate" : 2.5 }');

                HttpResponse response = h.send(req);    
   
                system.debug('response: '+response);
             }
        }
    }
}

Debug: response: System.HttpResponse[Status=Unauthorized, StatusCode=401]

The code works perfectly fine when I am loggedin to the org. But when the class is scheduled and I am not loggedin, the response status is 'Unauthorized' and the currency table is not updated.

How can I get the session Id when User is not loggedin?