A computer-implemented method for replacing a live version of an application with a staged version of the application,, the method comprising: executing a current live version of the application; receiving a request to transition a current staged version to replace the current live version so that the current staged version becomes the live version; reconciling one or more parameters associated with the current staged version with one or more corresponding parameters associated with the current live version;deactivating the current live version; transitioning the current live version to be an archived version, a design version, the staged version or completely deleting the live version; and transitioning the staged version to the live version; characterized in that the current staged version is executed in standby mode concurrent with said executing of the current live version, wherein the staged version and the live version are two different configurations of the same application, and wherein executing of the current staged version does not affect operation of the current live version, whereby testing and observing the current staged version, and wherein a hot-swap is made whereby said transitioning the current live version and the staged version becoming the live versiononce a determination is made that the behavior of the current staged version is acceptable or meets a predetermined standard of quality, and further wherein the application comprises one or more model predictive estimators or model predictive controllers designed to estimate or control the values of one or more process variables of an actual process in a plant or similar system when no measurement is available, wherein a multivariable model is used for prediction in said model predictive estimator or model predictive controller employing a multivariable model-based predictive control application designed to preform advanced process control, and whereby said transitioning of the staged version to the live version provides a change of the model configuration of said model predictive estimator or model predictive controller, wherein executing the current staged version in standby mode comprises running the model predictive estimator or model predictive controller of the staged version in standby mode, in which values of any parameters or variables are simulated and calculations are executed without affecting the live version; and whereby during deactivating the current live version the one or more model predictive estimators or model predictive controllers of the current live version are set to an inactive mode. executing a current live version of the application; receiving a request to transition a current staged version to replace the current live version so that the current staged version becomes the live version; reconciling one or more parameters associated with the current staged version with one or more corresponding parameters associated with the current live version;deactivating the current live version; transitioning the current live version to be an archived version, a design version, the staged version or completely deleting the live version; and transitioning the staged version to the live version; characterized in that the current staged version is executed in standby mode concurrent with said executing of the current live version, wherein the staged version and the live version are two different configurations of the same application, and wherein executing of the current staged version does not affect operation of the current live version, whereby testing and observing the current staged version, and wherein a hot-swap is made whereby said transitioning the current live version and the staged version becoming the live versiononce a determination is made that the behavior of the current staged version is acceptable or meets a predetermined standard of quality, and further wherein the application comprises one or more model predictive estimators or model predictive controllers designed to estimate or control the values of one or more process variables of an actual process in a plant or similar system when no measurement is available, wherein a multivariable model is used for prediction in said model predictive estimator or model predictive controller employing a multivariable model-based predictive control application designed to preform advanced process control, and whereby said transitioning of the staged version to the live version provides a change of the model configuration of said model predictive estimator or model predictive controller, wherein executing the current staged version in standby mode comprises running the model predictive estimator or model predictive controller of the staged version in standby mode, in which values of any parameters or variables are simulated and calculations are executed without affecting the live version; and whereby during deactivating the current live version the one or more model predictive estimators or model predictive controllers of the current live version are set to an inactive mode.