DCOM over the internet


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  1. #1
    Tim Archer Guest

    DCOM over the internet

    Is there a generic DCOM solution for Windows 2000 that will allow me to
    connect from any two machines accross the internet from any type of service
    provider (dial-up, cable modem, and DSL)?

    I am trying to get a DCOM connection to work accross the internet. Is DCOM
    possible through all providers including dial-up? I can't even connect to
    my home machine (cable modem) from my work machine (T-1). I believe there
    are problems with firewalls. I have read the MS articles about using DCOM
    through firewalls. However, it talks about configuring your firewall to
    allow certain traffic through certain ports and then configuring DCOM to use
    those ports. What about when this isn't possible such as dial-up service
    providers?

    I have tried COM internet services (CIS). Does this require Windows 2000
    server or Windows NT server, or will it work with Windows 2000 and the
    Windows NT workstation option pack? I have the "Enable COM internet
    services" check box from dcomcnfg in workstation and 2000 professional as
    well as the tunnelling protocol option. I configured this, but I couldn't
    get a connection using it at all (when I removed all other protocols).

    I would appreciate any information about this subject.





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  2. #2
    Bill Slater Guest

    Re: DCOM over the internet

    DCOM over the internet is extremely problematic as you have discovered. Since
    you have read the MS paper you know the basics about DCOM and firewalls. I have
    been able to get CIS working but it is very difficult and it is still not
    guaranteed to work for some firewalls. I generally have lots of problems if the
    firewall performs network address translation and there are some smart firewalls
    where CIS won't work at all. The firewall MUST allow https traffic through
    (allow HTTP CONNECT command) to work. Some sites won't even allow that.

    Three alternate suggestions are RDS (Remote Data Services) and SOAP (Simple
    Object Access Protocol) and XML.

    SOAP is in early stages of development but there is a lot of "buzz" about it
    since it is kind of a transparent "XML" way to transport data. I have not run
    across anyone actually using it in an application yet but have seen several
    articles about it. Perhaps there is someone on this ng that is? AFAIK, there are
    not a lot of good development tools for implementing SOAP solutions yet. Thus
    you must write your own code to encapsulate and translate messages. But MS
    recently released an SDK so maybe that is old info.

    I have used RDS rather successfully to replace CIS in an application. RDS was
    developed by MS to transport disconnected ADO recordsets across the internet,
    but it supports transport of most any native datatype. So you can make calls to
    your objects exactly like you do using DCOM. You just have to instantiate an
    RDS.DataSpace object first and then create your own custom object from that
    source. The downsides are that objects are late bound, making coding a little
    more difficult. Also RDS cannot marshall complex datatypes (except for
    recordsets) like custom objects and there are some server-side security issues
    since you must allow IIS to instantiate the objects. In order to get RDS, you
    must install ADO on the client side as well.

    You could also implement an XML solution where you transmit method parameters
    and data in an XML stream to a web page. The page contains the code to
    instantiate the object, call the method with the data passed, and return the
    results in a new XML stream. Downside here is a lot of web pages (one per method
    per object) plus it is slow.

    HTH

    Tim Archer wrote:

    > Is there a generic DCOM solution for Windows 2000 that will allow me to
    > connect from any two machines accross the internet from any type of service
    > provider (dial-up, cable modem, and DSL)?
    >
    > I am trying to get a DCOM connection to work accross the internet. Is DCOM
    > possible through all providers including dial-up? I can't even connect to
    > my home machine (cable modem) from my work machine (T-1). I believe there
    > are problems with firewalls. I have read the MS articles about using DCOM
    > through firewalls. However, it talks about configuring your firewall to
    > allow certain traffic through certain ports and then configuring DCOM to use
    > those ports. What about when this isn't possible such as dial-up service
    > providers?
    >
    > I have tried COM internet services (CIS). Does this require Windows 2000
    > server or Windows NT server, or will it work with Windows 2000 and the
    > Windows NT workstation option pack? I have the "Enable COM internet
    > services" check box from dcomcnfg in workstation and 2000 professional as
    > well as the tunnelling protocol option. I configured this, but I couldn't
    > get a connection using it at all (when I removed all other protocols).
    >
    > I would appreciate any information about this subject.


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  3. #3
    Darin Darin Guest

    Re: DCOM over the internet


    There's an FAQ at MS that has this to say about DCOM and Firewalls. "If it
    hurts when you laugh, don't laugh". I kid you not.

    Don't do it. Don't try. Don't bother to read up on it. Take the time you
    would have spent on it and learn TCPIP sockets programming and go there instead.
    I wish I had 2 years ago instead of jacking with DCOM. It's not worth it.




    "Tim Archer" <timothyarcher@hotmail.com> wrote:
    >Is there a generic DCOM solution for Windows 2000 that will allow me to
    >connect from any two machines accross the internet from any type of service
    >provider (dial-up, cable modem, and DSL)?
    >
    >I am trying to get a DCOM connection to work accross the internet. Is DCOM
    >possible through all providers including dial-up? I can't even connect

    to
    >my home machine (cable modem) from my work machine (T-1). I believe there
    >are problems with firewalls. I have read the MS articles about using DCOM
    >through firewalls. However, it talks about configuring your firewall to
    >allow certain traffic through certain ports and then configuring DCOM to

    use
    >those ports. What about when this isn't possible such as dial-up service
    >providers?
    >
    >I have tried COM internet services (CIS). Does this require Windows 2000
    >server or Windows NT server, or will it work with Windows 2000 and the
    >Windows NT workstation option pack? I have the "Enable COM internet
    >services" check box from dcomcnfg in workstation and 2000 professional as
    >well as the tunnelling protocol option. I configured this, but I couldn't
    >get a connection using it at all (when I removed all other protocols).
    >
    >I would appreciate any information about this subject.
    >
    >
    >
    >
    >


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