POST Web Service

//POST: Create new data or resources in Salesforce.    
    @future(callout=true)
    public static void postContact() {
        // Define the endpoint URL using a named credential
        // SourceOrgNamedCredential is your SourceORG Named Credential
        HttpRequest req = new HttpRequest();
        req.setEndpoint('callout:SourceOrgNamedCredential/services/apexrest/Contact/');
        req.setMethod('POST');
        
        // Set request headers
        req.setHeader('Content-Type', 'application/json');
        req.setHeader('Accept', 'application/json');
        
        // Create the request body
        Map<String, Object> requestBody = new Map<String, Object> {
            'contactFirstName' => 'Shubham',
            'contactLastName' => 'Vaishnav'
        };
        req.setBody(JSON.serialize(requestBody));
        
       try {
        // Send the request
        Http http = new Http();
        HttpResponse response = http.send(req);
        
        // Check if the response is successful (status code 200)
        if (response.getStatusCode() == 200) {
            // Handle the response
            system.debug('Contacts successfully created.');
            system.debug('response body: ' + response.getBody()); 
        } else {
            // Handle other response
            System.debug('response received: ' + response.getStatusCode() + ' - ' + response.getStatus());
        }
    } catch (Exception e) {
        // Handle exception during HTTP callout
        System.debug('Error sending contact to target org: ' + e.getMessage());
    }
        
    }