windows-xp/Source/XPSP1/NT/inetsrv/iis/iisrearc/ul/misc/uri-ipc.txt

Can we provide (in the NSP timeframe) a generic URI-based IPC mechanism for
NT5 (and, in future releases, NT4 & Win9x)? More importantly, can this
mechanism be leveraged by UL?

The goal here is to totally separate the "listening" and "dispatching"
functionality. We'll provide a general IPC mechanism that everyone can
use. It just so happens that three of the customers will be a) the listener,
b) the worker processes, and c) the WAS.

Consider a completely stateless IPC mechanism based on only three APIs:

    ULONG
    RegisterUri(
        OUT PHANDLE UriHandle,
        IN HANDLE ParentUri OPTIONAL,
        IN PWSTR pUri,
        IN ULONG Flags
        );

    ULONG
    SendMessage(
        IN HANDLE UriHandle,
        IN PWSTR pSourceSuffix OPTIONAL,
        IN PWSTR pTargetUri,
        IN PVOID pData,
        IN ULONG DataLength,
        OUT PULONG pBytesSent OPTIONAL,
        IN LPOVERLAPPED pOverlapped OPTIONAL
        );

    typedef struct _MESSAGE
    {
        ULONG SourceUriLength;
        ULONG TargetUriLength;
        ULONG DataLength;
        ULONG Reserved;

        // WCHAR SourceUri[SourceUriLength];
        // WCHAR TargetUri[TargetUriLength];
        // UCHAR Alignment[varies];
        // UCHAR Data[DataLength];

    } MESSAGE, *PMESSAGE;

    ULONG
    ReceiveMessage(
        IN HANDLE UriHandle,
        OUT PMESSAGE pMessageBuffer,
        IN ULONG MessageBufferLength,
        OUT PULONG pBytesReceived OPTIONAL,
        IN LPOVERLAPPED pOverlapped OPTIONAL
        );

A request/response API can be built on top of these three primitives:


    1.  Process 1: Creates new GUID -> GUID1

    2.  Process 1: Registers "ipc:/GUID1" -> REG1

                    3.  Process 2: Registers "http://foo" -> REG2

                    4.  Process 2: Posts ReceiveMessage( REG2 )

    5.  Process 1: Creates request ID (another GUID?) -> RID1

    6.  Process 1: SendMessage(
                        REG1,
                        "RID1",
                        "http://foo/bar/xyz.htm",
                        {request_blob}
                        );

    7.  Process 1: Posts ReceiveMessage( REG1 )

                    8.  Process 2: ReceiveMessage() completes with
                            SourceUri = "ipc:/GUID1/RID1"
                            TargetUri = "http://foo/bar/xyz.htm"
                            Data = {request_blob}

                    9.  Process 2: SendMessage(
                                        REG2,
                                        "bar/xyz.htm",      <- URI "stem"
                                        "ipc:/GUID1/RID1",  <- old source URI
                                        {response_blob}
                                        );

    10. Process 1: ReceiveMessage() completes with
            SourceUri = "http://foo/bar/xyz.htm"
            TargetUri = "ipc:/GUID1/RID1"
            Data = {response_blob}




08/23/1999  I don't think this totally stateless idea is going to work.
            Well, it *could* work, but it places way to much burden on the
            client & server writers to properly manage concepts like
            keep-alive and dead peer detection. I'm now thinking we should
            go to more of a handle-based mechanism with a sockets-like
            flavor.