Remote procedure calling using an existing descriptor mechanism

Abstract

Doors are implemented in an existing operating system by using a novel adaptation of existing data structures and procedures which represent and control data files of the operating system. A door is represented by a file descriptor and is managed by existing mechanisms of an operating system, such as the Unix operating system, which are also used to manage files. A door is represented by a door node, which is a novel extension of the conventional vnode structure which in turn is used in conventional operating systems to represent the state of a computer resource, e.g., a data file. A door node is adapted such that most conventional file access and control procedures, e.g., procedures open( ) and close( ), can be used to access and control door with minimal adaptation. A door node is formed by appending fields which are specific to a door node's representation of the state of a door to fields of the door node which are analogous to the fields of a vnode, which represents the state of a resource and which has a conventional structure. Thus, the fields of a door node which precede the fields specific to the representation of the state of a door are of the size, location, and format of analogous fields in a conventional vnode. A client process obtains a file descriptor which identifies a door by supplying the name of the door to the operating system.