An alias in API Gateway holds stage-specific property values that can be shared by multiple policy configurations. Aliases referenced by policy configurations are substituted during runtime. Changing an alias value affects all referencing policies. Aliases are referenced through a name therefore alias names have to be unique within an API Gateway. The corresponding alias value is substituted in place of an alias name during run-time. Thus the same alias can be referred to in multiple policies and the change in a particular alias would affect all the policy properties. Aliases have optional stage information, in addition to a name and value, which allows to define stage-specific aliases in a multi-stage environment. For details about stage-specific aliases, see webMethods API Gateway Staging and Promotion Asset Promotion. An alias definition without stage information applies to the API Gateway instance where the alias is defined.

Not all policies support the full set of aliases that are available in API Gateway. Some aliases are applicable only with certain policies and for certain policy parameters. For details, see Supported Alias and Policy Combinations.

You can create six types of alias: