Applied XML Programming for Microsoft .NET.pdf - Csbdu.in

When to Marshal by ValueSo how do you know when MBV is a good option? Let's say that MBV is a compellingoption when the following conditions are true:• The object is not particularly large and complex.• You're going to make intensive use of the object.• You have no special security concerns.• The object has no dependencies on remote resources such as files,databases, devices, or system resources.Some rather illustrious .NET Framework classes that support remoting through theMBV technique are the DataSet and DataTable classes.MBV ObjectsThe .NET Remoting system serializes all the internal data of MBV objects and passesthe stream to the calling AppDomain, as illustrated in Figure 12-2.Figure 12-2: How .NET Remoting marshals objects by value.After the data is in the client AppDomain, a new local object is instantiated andinitialized and starts handling calls. To write remotable objects that are exchanged byvalue, you need to make them serializable, either by declaring the SerializableAttributeattribute or by implementing ISerializable. Aside from this, nothing else is required forinstances of the class to be passed by value across AppDomains.Marshaling Objects by ReferenceWhen an object is marshaled by reference, the client process receives a reference tothe server-side object, rather than a copy. This means that any call directed to theobject is always resolved on the server within the native context of the object. Theremoting infrastructure governs the call, collecting all information about the call andsending it to the server process. On the server, the correct object is located and askedto execute the call using the client's arguments. When the call is finished, the resultsare packaged and sent back to the client. Unlike MBV, MBR uses the network only fortransmitting arguments and return values. Figure 12-3 shows the architecture of MBRremoting.429