/sys$common/syshlp/helplib.hlb System Services, $DNS (VAX Only)  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    On VAX systems, the DIGITAL Distributed Name Service (DECdns)
    clerk allows client applications to store resource names and
    addresses.

    The $DNS system service completes asynchronously; that is, it
    returns to the client immediately after making a name service
    call. The status returned to the client call indicates whether a
    request was successfully queued to the name service.

    The DIGITAL Distributed Name Service Clerk Wait ($DNSW) system
    service is the synchronous equivalent of $DNS. $DNSW is identical
    to $DNS in every way except that $DNSW returns to the caller
    after the operation completes.

    Format

      SYS$DNS  [efn] ,func ,itmlst ,[dnsb] ,[astadr] ,[astprm]

    Arguments

 efn

    OpenVMS usage:ef_number
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Number of the event flag to be set when $DNS completes. The efn
    argument is a longword containing this number. The efn argument
    is optional; if not specified, event flag 0 is set.

    When $DNS begins execution, it clears the event flag. Even if the
    service encounters an error and completes without queuing a name
    service request, the specified event flag is set.

 func

    OpenVMS usage:function_code
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Function code specifying the action that $DNS is to perform. The
    func argument is a longword containing this function code.

    A single call to $DNS can specify one function code. Most
    function codes require or allow for additional information to
    be passed in the call with the itmlst argument.

 itmlst

    OpenVMS usage:item_list_3
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    Item list supplying information to be used in performing the
    function specified by the func argument. The itmlst argument is
    the address of the item list. The item list consists of one or
    more item descriptors, each of which is three longwords.

    The descriptors can be in any order in the item list. Each item
    descriptor specifies an item code. Item codes are specified
    as either input or output parameters. Input parameters modify
    functions, set context, or describe the information to be
    returned. Output parameters return the requested information.
    The item list is terminated by a longword of 0.

    Refer to the OpenVMS System Services Reference Manual to view the
    item code diagram and descriptor fields table.

 dnsb

    OpenVMS usage:dns_status_block
    type:         quadword (unsigned)
    access:       write only
    mechanism:    by reference
    Status block to receive the final completion status of the $DNS
    operation. The dnsb argument is the address of the quadword $DNS
    status block.

    Refer to the OpenVMS System Services Reference Manual to view
    the $DNS status block structure diagram and status block fields
    table.

 astadr

    OpenVMS usage:ast_procedure
    type:         procedure value
    access:       call without stack unwinding
    mechanism:    by reference
    Asynchronous system trap (AST) routine to be executed when I/O
    completes. The astadr argument is the address of the AST routine.

    The AST routine executes in the access mode of the caller of
    $DNS.

 astprm

    OpenVMS usage:user_arg
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Asynchronous system trap parameter passed to the AST service
    routine. The astprm argument is a longword value containing the
    AST parameter.