GatewayResponse Interface

/**
     * Abstract function to build gateway response for a Transaction
     * The input is the response from gateway
     * It creates and returns GatewayResponse from the HttpResponse
     */
    public abstract commercepayments.GatewayResponse buildResponse(HttpResponse response);

    /**
     * Function to process transaction requests
     * Steps involved are:
     * 1. Build HttpRequest with the input Request from gateway context
     * 2. Send request and get the response from gateway
     * 3. Parse the response from gateway and return GatewayResponse
     */
    public commercepayments.GatewayResponse execute(){
                HttpRequest req;
        try{
            //Building a new request
            req = buildRequest();
        } catch(PayeezeValidationException e) {
            return getValidationExceptionError(e);
        }
        commercepayments.PaymentsHttp http = new commercepayments.PaymentsHttp();
        HttpResponse res = null;
        try{
            //Sending the request
            res = http.send(req);
        } catch(CalloutException ce) {
            return getCalloutExceptionError(ce);
        }
        try{
            //Parsing the response from gateway
            return buildResponse(res);
        } catch(Exception e) {
            return getParseExceptionError(e);
        }
    }