Two or more WebLogic domains can be configured so that they trust each other. When you've set up trust between two different WebLogic domains, you enable authenticated WebLogic users in one domain to access protected resources in another domain. For instance, an authenticated user in one domain may invoke a protected web service or an EJB in another domain without requiring any additional authentication. Let's say that we have two WebLogic domains, A and B. Trust between the domains means that the subject's principals in one domain say, A are accepted by the other domain, B (and vice versa) and are treated as if they were local principals of domain B. The Authorization Providers within domain B remain unaware of the fact that the subject's principals belong to domain A.
Two WebLogic domains will trust each other only if they both have the same Credential attribute. The Credential attribute represents a string value that is assigned to a domain and then is used to sign principals that belong to subjects created in that domain. Ordinarily, if you haven't explicitly set the domain credential, it is assigned a random value when the Administration Server is first booted. All Managed Servers in the domain subsequently import this credential when they are booted as well. In order to set the Credential attribute for a WebLogic domain, select your domain from the left pane of the Administration Console, choose the View Domain-Wide Security Settings option, and select the Configuration/Advanced tab. If two domains share the same Credential attribute value, the signatures of the principals will match and be recognized by both domains. Thus, in order to establish trust between several domains, you need to simply ensure they are assigned the same value for the Credential attribute.
 WebLogic 7.0 users should simply select the Security/Advanced tab after selecting the domain node.
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