Re: Generic deserialization
From: Lee Gillie (ANTISPAMIFICATION_lee_at_odp.com)
Date: 06/30/04
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Date: Wed, 30 Jun 2004 08:31:52 -0700
VERY helpful Ken!!! I greatly appreciate your taking time to teach
this old dog some new tricks.
Best regards - Lee Gillie - Spokane, WA
"Ken Kolda" <ken.kolda@elliemae-nospamplease.com> wrote in message
news:uysBvpjXEHA.3044@TK2MSFTNGP09.phx.gbl...
> The error you're getting is, as you suspected, due to the fact that
your
> class derives from MarshalByRefObject. When the consumer gets the
reference
> to this object and attempts to invoke one of its methods, it must
open a
> remoting channel back to the source, since that's where the object
actually
> resides. In this way, your "source" application acts as both client
and
> server. That's not a problem, but it sounds like that's not the
model you're
> trying to create.
>
> The issue is that you indicated that you don't your message server
service
> to know about the client's classes. If you mark your classes as
Serializable
> but not MBR, then the server must generally have the implementation
> available for the class, since the clss will be deserialized on the
server.
> But, assuming your server service has no need to ever know what the
> underlying object is (i.e. it just passes it to a consumer which
DOES know
> what type of object this is), you could do something like this:
>
> Create two wrapper classes in a separate assembly than from your
remoted
> server service classes, call them SourceWrapper and ConsumerWrapper.
The
> SourceWrapper would look something like:
>
> class SourceWrapper
> {
> public SourceWrapper(string serverUri)
> { // Save off Uri to instance variable }
>
> public void Send(object o)
> {
> // Serialize object using BinaryFormatter to get byte array
> // Call Activator.GetObject() to get the remoted Source
object from
> server
> // Invoke Source object's Send(), passing the bytes.
> }
> }
>
> The ConsumerWrapper would, conversely look like:
>
> class ConsumerWrapper : MarshalByRefObject
> {
> public event MessageArrivedEventHandler MessageArrived;
>
> public ConsumerWrapper(string serverUri)
> {
> // Get the Consumer object from server and add an event
handler or
> callback for this instance
> }
>
> private onMessageArrived(byte[] data)
> {
> // Deserialize object using Binary formatter
> // Raise MessageArrived event for client to be notified
> }
> }
>
> In other words, the SourceWrapper handles the serialization and the
> ConsumerWrapper handles the deserialization so the client app
doesn't have
> to worry itself about how this works. The server service in between
knows
> nothing except how to pass byte arrays around, so it's completely
generic.
>
> Hope that helps -
> Ken
>
>
> "Lee Gillie" <ANTISPAMIFICATION_lee@odp.com> wrote in message
> news:esoOd3iXEHA.1356@TK2MSFTNGP09.phx.gbl...
> > Trying to create a "generic" notification facility. Basically I
have a
> > number of services which currently use NT MAILSLOTS to broadcast
their
> > in-progress status to desktops on the LAN. In the mailslot there
is
> > usually complex delimited data as a string.
> >
> > My .NET approach is to instead use a "message server service".
Also
> > attempting to provide a component that will make either SOURCE or
> > CONSUMER objects. The SOURCE object has one simple "Send" method,
and
> > accepts a parameter of type "Object". Am making a "Consumer"
object
> > which posts an event, and again, a single parameter of type
OBJECT. I
> > am attempting to hide all the infrastructure and remoting as much
as
> > possible, from the caller of the component. The component is also
> > exposing a COM interface. The component makes either a source or
> > consumer conversation with the service via one single remoted
> > component, which can "broadcast" events to clients. All of this
works
> > great when the notify parameter is a string. But falls flat when
> > trying to do this with an item of type OBJECT.
> >
> > Here is my extreme lack of knowledge about serialization...
> >
> > Via the remoting method, I was able to send from a SOURCE to the
> > server, and it makes it back to the CONSUMER in a separate
process.
> > But the consumer is having trouble looking at the "object". I get
> > this:
> >
> > Run-time exception thrown :
> > System.Runtime.Remoting.RemotingException - This remoting proxy
has no
> > channel sink which means either the server has no registered
server
> > channels that are listening, or this application has no suitable
> > client channel to talk to the server.
> >
> > The "object" being sent through this system is a "class" using
only
> > fundamental data types, such as string, integer, and so on. The
class
> > is marked serializable, and I found a need to inherit from
MarshaByRef
> > to get the send side to work.
> >
> > My thought is that once I get this class instance serialized, it
is
> > completely self contained. Yet the message seems to indciate the
> > CONSUMER is somehow trying to get back to some remoting host, or
such.
> > Probably due to the MBR.
> >
> > Any hints on preparing my generic "object" parameter to be fully
> > self-sufficient would be greatly appreciated. In my component I
don't
> > have knowledge of my caller's classes. If I can, I would like to
not
> > burden my caller to perform serialization and deserialization, if
> > possible.
> >
> >
> > Can what I am trying to do even be done?
> >
> >
> >
>
>
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