IT-SC book: Advanced CORBA Programming with C++ in Software

Generator Code-39 in Software IT-SC book: Advanced CORBA Programming with C++
IT-SC book: Advanced CORBA Programming with C++
Creating Code 39 In C#.NET
Using Barcode maker for .NET framework Control to generate, create USS Code 39 image in .NET applications.
25 Request Invocation
Encode Code-39 In .NET
Using Barcode drawer for ASP.NET Control to generate, create Code 39 Extended image in ASP.NET applications.
Clients manipulate objects by sending messages The ORB sends a message to an object whenever a client invokes an operation To send a message to an object, a client must hold an object reference for the object The object reference acts as a handle that uniquely identifies the target object and encapsulates all the information required by the ORB to send the message to the correct destination When a client invokes an operation via an object reference, the ORB does the following: Locates the target object Activates the server application if the server is not already running Transmits any arguments for the call to the object Activates a servant for the object if necessary Waits for the request to complete Returns any out and inout parameters and the return value to the client when the call completes successfully Returns an exception (including any data contained in the exception) to the client when the call fails The entire request invocation mechanism is completely transparent to the client, to whom a request to a remote object looks like an ordinary method invocation on a local C++ object In particular, request invocation has the following characteristics Location transparency The client does not know or care whether the target object is local to its own address space, is implemented in a different process on the same machine, or is implemented in a process on a different machine Server processes are not obliged to remain on the same machine forever; they can be moved around from machine to machine without clients becoming aware of it (with some constraints, which we discuss in 14) Server transparency The client does not need to know which server implements which objects Language independence The client does not care what language is used by the server For example, a C++ client can call a Java implementation without being aware of it The implementation language for objects can be changed for existing objects without affecting clients Implementation independence The client does not know how the implementation works For example, the server may implement its objects as proper C++ servants, or the server may actually implement its objects using non-OO techniques (such as implementing objects as lumps of data) The client sees the same consistent objectoriented semantics regardless of how objects are implemented in the server
Generating Code 3 Of 9 In VS .NET
Using Barcode encoder for .NET framework Control to generate, create Code 39 Full ASCII image in .NET framework applications.
IT-SC book: Advanced CORBA Programming with C++
Code 39 Creation In VB.NET
Using Barcode drawer for VS .NET Control to generate, create Code 3 of 9 image in .NET framework applications.
Architecture independence The client is unaware of the CPU architecture that is used by the server and is shielded from such details as byte ordering and structure padding Operating system independence The client does not care what operating system is used by the server The server may even be implemented without the support of an operating system for example, as a real-mode embedded program Protocol independence The client does not know what communication protocol is used to send messages If several protocols are available to communicate with the server, the ORB transparently selects a protocol at run time Transport independence The client is ignorant of the transport and data link layer used to transmit messages ORBs can transparently use various networking technologies such as Ethernet, ATM, token ring, or serial lines 251 Object Reference Semantics Object references are analogous to C++ class instance pointers but can denote objects implemented in different processes (possibly on other machines) as well as objects implemented in the client's own address space Except for this distributed addressing capability, object references have semantics much like ordinary C++ class instance pointers have Every object reference identifies exactly one object instance Several different references can denote the same object References can be nil (point nowhere) References can dangle (like C++ pointers that point at deleted instances) References are opaque (the client is not allowed to look at their contents) References are strongly typed References support late binding References can be persistent References can be interoperable These points deserve further explanation because they are central to the CORBA object model Each reference identifies exactly one object Just as a C++ class instance pointer identifies exactly one object instance, an object reference denotes exactly one CORBA object (which may be implemented in a remote address space) A client holding an object reference is entitled to expect that the reference will always denote the same object while the object continues to exist An object reference is allowed to stop working only when its target object is permanently destroyed After an object is destroyed, its references become permanently non-functional This means that a reference to a destroyed object cannot accidentally denote some other object later
Reading Data Matrix 2d Barcode In .NET
Using Barcode scanner for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications.
Data Matrix ECC200 Creator In .NET
Using Barcode maker for Visual Studio .NET Control to generate, create ECC200 image in Visual Studio .NET applications.
Barcode Creation In Java
Using Barcode encoder for Java Control to generate, create barcode image in Java applications.
Printing Barcode In Java
Using Barcode generator for Java Control to generate, create barcode image in Java applications.
Code 39 Generator In VS .NET
Using Barcode drawer for ASP.NET Control to generate, create Code-39 image in ASP.NET applications.
Barcode Generator In VB.NET
Using Barcode creator for .NET Control to generate, create barcode image in VS .NET applications.
Bar Code Creation In C#.NET
Using Barcode encoder for .NET framework Control to generate, create bar code image in Visual Studio .NET applications.
Bar Code Reader In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
Print UPC-A Supplement 2 In VS .NET
Using Barcode drawer for ASP.NET Control to generate, create Universal Product Code version A image in ASP.NET applications.