Standard Gateway
A gateway is a piece of software that causes one DBMS to look like another. That is, the gateway accepts the programming interface, SQL grammar, and data stream protocol of a single DBMS and translates it to the programming interface, SQL grammar, and data stream protocol of the hidden DBMS. For example, applications written to use SQL Server can also access DB2 data through the Micro Decisionware DB2 Gateway; this product causes DB2 to look like SQL Server. When gateways are used, a different gateway must be written for each target database.
Although gateways are limited by architectural differences among DBMSs, they are a good candidate for standardization. However, if all DBMSs are to standardize on the programming interface, SQL grammar, and data stream protocol of a single DBMS, whose DBMS is to be chosen as the standard? Certainly no commercial DBMS vendor is likely to agree to standardize on a competitor's product. And if a standard programming interface, SQL grammar, and data stream protocol are developed, no gateway is needed.