visual basic barcode generator Network in Java

Creator PDF417 in Java Network

Network
Scanning PDF 417 In Java
Using Barcode Control SDK for Java Control to generate, create, read, scan barcode image in Java applications.
PDF417 Generator In Java
Using Barcode printer for Java Control to generate, create PDF-417 2d barcode image in Java applications.
Figure 5.5 Client and server roles in CORBA
PDF-417 2d Barcode Decoder In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
Bar Code Generation In Java
Using Barcode maker for Java Control to generate, create barcode image in Java applications.
Network
Bar Code Recognizer In Java
Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications.
Encoding PDF 417 In Visual C#.NET
Using Barcode printer for .NET framework Control to generate, create PDF-417 2d barcode image in Visual Studio .NET applications.
Distributed Objects and Application Servers
Draw PDF 417 In .NET Framework
Using Barcode creation for ASP.NET Control to generate, create PDF 417 image in ASP.NET applications.
PDF 417 Printer In .NET
Using Barcode maker for VS .NET Control to generate, create PDF417 image in .NET applications.
the server when it makes a remote procedure call and then the server, in turn, calls a method on the object owned by the client. This is called the client callback method and is illustrated in Figure 5.6. In this example, Application A (acting as a client of Application B) first obtains a reference to an object (Object 1) located on the server in Application B. However, when the client uses the object reference to call a remote method, it also passes a reference to an object (Object 2) it owns to Application B on the server. In the process of executing the method, Application B calls a method on the client object (Object 2) using the object references it received from Application A, as shown in Step 3 in Figure 5.6. Again, this calling of the method on the client object is known as the client callback method.
Drawing PDF-417 2d Barcode In Visual Basic .NET
Using Barcode generation for .NET Control to generate, create PDF417 image in Visual Studio .NET applications.
EAN128 Generation In Java
Using Barcode drawer for Java Control to generate, create GS1 128 image in Java applications.
Step 1
EAN / UCC - 13 Creation In Java
Using Barcode generation for Java Control to generate, create EAN13 image in Java applications.
GS1 DataBar Truncated Creator In Java
Using Barcode encoder for Java Control to generate, create DataBar image in Java applications.
Application A Object 2 Object 1 ref.
2 Of 5 Industrial Creator In Java
Using Barcode creator for Java Control to generate, create Standard 2 of 5 image in Java applications.
EAN-13 Supplement 5 Generator In None
Using Barcode drawer for Font Control to generate, create GS1 - 13 image in Font applications.
Method Invocation Obtaining Reference
GS1 DataBar Expanded Creation In .NET Framework
Using Barcode encoder for .NET Control to generate, create GS1 DataBar Truncated image in .NET framework applications.
Creating Code 3/9 In None
Using Barcode generator for Microsoft Word Control to generate, create Code 3 of 9 image in Word applications.
Application B
Code128 Generation In None
Using Barcode drawer for Software Control to generate, create Code 128C image in Software applications.
Barcode Scanner In Java
Using Barcode Control SDK for Eclipse BIRT Control to generate, create, read, scan barcode image in BIRT reports applications.
Object 1
GTIN - 12 Drawer In Java
Using Barcode printer for Eclipse BIRT Control to generate, create UPC Symbol image in Eclipse BIRT applications.
Reading EAN-13 Supplement 5 In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
Network Step 2
Application A Object 2
Object 2 ref.
Object 2 ref. Method Invocation
Application B
Object 2 ref.
Object 1
Network Step 3
Application A Object 2
Object 1 ref.
Callback
Application B
Object 2 ref.
Object 1 Network
Figure 5.6 Client call method: the server calling a client method
Five
Roles of Client Stubs and Server Skeletons
An IDL file is used with an IDL compiler by developers to generate what are called client stubs and server skeletons. The IDL compiler is language specific, and the client stubs and server skeleton it creates serve as the glue that connects the language independent IDL interface definition to the language-specific implementation code. Note that, in principle, the server skeleton and client stubs can be generated in two different programming languages by using two different IDL compilers. Client stubs for each interface are used in the client code, and client stubs for a particular interface provide a dummy implementation for each method in that interface. Client stubs do not execute the server functionality but rather communicate with the ORB to marshal and unmarshal parameters. On the server side, the sever skeleton provides a framework on which the server implementation is built. For each method of the interface, the IDL compiler generates an empty method in the server skeleton, which the developer then uses to provide an implementation. The roles of the client stub and server skeleton are illustrated in Figure 5.7. The roles of each will become clearer in the next section, where we develop a sample CORBA server and a sample CORBA client.
CORBA Communication Model
In a distributed environment, the application will have to communicate over a network. A network consists of a physical layer at the bottom. In turn, this physical layer may consist of a wired network, such as a telephone line, a fiber-optic cable, a wireless link, or a combination of these
Client Application
Client Stub
Client Stub
Server Skeleton Server Implementation
Server Skeleton Server Implementation
Figure 5.7 The roles of the client stub and server skeleton
Distributed Objects and Application Servers
networking technologies. Above this physical layer is a transport layer, which is responsible for moving packets of data from one point to another. The most common transport protocol in use is TCP/IP. Another transport protocol is DCE (the Open Software Foundation s Distributed Computing Environment protocol). CORBA defines a high-level, generalized protocol called the General Inter-ORB Protocol (GIOP). This protocol is not used directly but instead is specialized by a particular protocol that would be used directly. The Internet Inter-ORB Protocol (IIOP) is such a specialized protocol. IIOP is the specialized form of GIOP and is used with TCP/IP transport protocol. An ORB must support IIOP in order for it to be considered CORBA compliant. CORBA applications are built on top of specialized protocols such as IIOP. Although IIOP is the most common protocol used by CORBA applications, CORBA applications are not limited to using only one of these specialized protocols. An application s architecture can be designed to use a bridge that would interconnect, for example, DCE-based application components with IIOP-based application components. This type of architecture is shown in Figure 5.8.
Component
Component
ORB IIOP TCP/IP Network
IIOP IIOP
Bridge DCE-GIOP DCE Network ORB
DCE-GIOP Component DCE-GIOP ORB
Component
networks
Use of a bridge to interconnect applications running on different types of
Five
CORBA Services
The Object Management Architecture (OMA), of which CORBA is a part, defines a number of services that are useful for applications being integrated. These services include a naming service, security service, concurrency control service, transaction service, and life cycle service. We briefly discuss some of these services in this section, starting with the naming service, because this service is almost indispensable.
Naming Service The naming service allows CORBA objects to register and get located by name. It uses the notion of a naming context, which consists of a set of unique names. This service also supports a federated architecture in which the named servers can be distributed across the network and work in cooperation with each other. As previously mentioned, this naming service could be considered as containing the seeds of the future development of the SOA registry. It should be noted that as part of the standard binding mechanism, CORBA objects are given names by which other objects can look them up, as you will see later in the sample code. This feature can be thought of as a rudimentary naming service. However, the actual naming service is much more scalable. Security Service Security in an integrated environment takes on an added importance because an application, in principle, can be accessed from any other application in the enterprise. The security service provides interfaces for the following security features:
Authentication Used to verify that the user is who they claim to be Authorization Controls the access to various services or objects Keeps a record of all the user actions Security auditing
Nonrepudiation Provides capabilities similar to digital signatures, which means the origin of the data and/or the receipt of the data can be proven irrefutably
Concurrency Control Service The concurrency control service provides an interface for managing concurrency in shared CORBA objects. The management is done through support for several types of locks. The common types of locks supported are readers-writers locks and intention locks. Transaction Service
Transaction services are an integral part of any nontrivial application. A transaction requires a set of tasks to be atomic. For example, in the case of a bank application, to coordinate the transfer between two accounts, a transaction should be initiated
Copyright © OnBarcode.com . All rights reserved.