How to make Http callouts in batch class

global class BatchSync implements Database.Batchable<sObject>,   Database.AllowsCallouts {
 public String query = 'Select ID, Name from Account';
 global Database.QueryLocator start(Database.BatchableContext BC) {
    return Database.getQueryLocator(query);
 }
     global void execute(Database.BatchableContext BC, List<Account> records) {         
        String endpoint;        
        for ( integer i = 0; i< records.size(); i++ ){
         try {                  
          HttpRequest req = new HttpRequest();
          HttpResponse res = new HttpResponse();
          Http http = new Http();
          // Set values to Params
          endpoint = 'Your endpoint';
          req.setHeader('Authorization', header);
          req.setHeader('Content-Type', 'application/json');
          req.setEndpoint(endpoint);
          req.setMethod('POST');
          req.setBody('Information you wanna send');
          req.setCompressed(true); // This is imp according to SF, but please check if
                                 // the webservice accepts the info. Mine did not :P
                                 // Had to set it to false
          if (!Test.isRunningTest()) {      
            res = http.send(req);
            String sJson = res.getBody();
            System.debug('Str:' + res.getBody());
          }             
          // now do what u want to with response.               
          }
          catch (Exception e) {         
            System.debug('Error:' + e.getMessage() + 'LN:' + e.getLineNumber() );           
          }
       }
    }   
    global void finish(Database.BatchableContext BC){    
    }
}