11. A non-transitory computer-readable medium for building an integrated system using a formal language, the non-transitory computer-readable medium having computer instructions stored thereon that are executable by a processing device to perform or control performance of steps comprising: designing one or more models for one or more software components to be included in the integrated system, wherein the one or more models describe one or more requirements for the one or more software components; assigning one or more contracts to the one or more models, wherein the one or more contracts are written in the formal language and the one or more contracts include one or more low-level contracts and one or more high-level contracts; integrating the one or more models based on the composition of the one or more contracts to form an integrated model, wherein the integrated model includes each requirement for the one or more software components which is described by the one or more models which form the integrated model; and analyzing the one or more contracts and the integrated model to determine whether the one or more contracts include each requirement described by the integrated model, wherein the one or more low-level contracts are designed relative to the one or more high-level contracts so that analysis of the one or more low-level contracts alone indicates whether an error will be present in the one or more high-level contracts.
11. A non-transitory computer-readable medium for building an integrated system using a formal language, the non-transitory computer-readable medium having computer instructions stored thereon that are executable by a processing device to perform or control performance of steps comprising: designing one or more models for one or more software components to be included in the integrated system, wherein the one or more models describe one or more requirements for the one or more software components; assigning one or more contracts to the one or more models, wherein the one or more contracts are written in the formal language and the one or more contracts include one or more low-level contracts and one or more high-level contracts; integrating the one or more models based on the composition of the one or more contracts to form an integrated model, wherein the integrated model includes each requirement for the one or more software components which is described by the one or more models which form the integrated model; and analyzing the one or more contracts and the integrated model to determine whether the one or more contracts include each requirement described by the integrated model, wherein the one or more low-level contracts are designed relative to the one or more high-level contracts so that analysis of the one or more low-level contracts alone indicates whether an error will be present in the one or more high-level contracts. 18. The non-transitory computer-readable medium of claim 11 , wherein the steps further comprise determining that the one or more contracts do not include at least one requirement described by the integrated model.