7. A computer-implemented method for providing a mashup, comprising: providing, in a processor, a mashup that performs an action on a resource included in the mashup; identifying an attribute of a user running the mashup to perform the action on the resource; and providing an access control, the mashup being associated to a permission artifact, the permission artifact specifying a principal and whether one of to permit and to prohibit the principal to take the action on the resource, wherein the access control is triggered only when the mashup attempts to perform the action on the resource, the access control (i) checks whether the attribute of the user running the mashup to perform the action is predefined as belonging to the principal specified in the permission artifact associated to the mashup, and then (ii) performs the one of to permit and to prohibit the action on the resource only when the attribute belongs to the principal, plural users that have a same single attribute belong to the principal when the same single attribute is defined as belonging to the principal, and the permission artifact further specifies: (i) the resource used by the mashup, and (ii) the action on the resource for which permission is needed.
7. A computer-implemented method for providing a mashup, comprising: providing, in a processor, a mashup that performs an action on a resource included in the mashup; identifying an attribute of a user running the mashup to perform the action on the resource; and providing an access control, the mashup being associated to a permission artifact, the permission artifact specifying a principal and whether one of to permit and to prohibit the principal to take the action on the resource, wherein the access control is triggered only when the mashup attempts to perform the action on the resource, the access control (i) checks whether the attribute of the user running the mashup to perform the action is predefined as belonging to the principal specified in the permission artifact associated to the mashup, and then (ii) performs the one of to permit and to prohibit the action on the resource only when the attribute belongs to the principal, plural users that have a same single attribute belong to the principal when the same single attribute is defined as belonging to the principal, and the permission artifact further specifies: (i) the resource used by the mashup, and (ii) the action on the resource for which permission is needed. 8. The method of claim 7 , further comprising: changing whether the single attribute belongs to the principal, thereby changing whether one of to permit and to prohibit the action on the resource for all of the plural users that have the same single attribute.