DCOM over the internet

[Tim Archer]

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.

[Bill Slater]

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.

[Darin Darin]

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.
>
>
>
>
>