in
In the previous section, we introduced the main commercial technology for software system structure: patent software and open system software. I will introduce you to customer / server technology to you this section.
Client-server technology is the result of supporting software technology evolution of application systems. In particular, the evolution of client-server technology has become an important factor in information technology extension, which is accompanied by the growing growth of application business processes. The initial technology focuses on file sharing. File Sharing is still a paradigm in the Internet that accounts for dominance, which uses HTTP and other protocols to support access to available global file systems. The file server technology evolves into database server technology, forming the ability of the second generation to account for the status. We must focus on that file server technology is closely related to the evolution of distributed computing technologies.
Recent client-server technology is gradually being replaced by the N level. Based on the Java application server, the N-layer solution includes support for thin client user interface while enhancing scalability and reliability.
One of the most successful network technologies comes from the solar microsystem company, called a network file server. The solar microsystems successfully became actual standards by providing free reference technologies for the realization source code on any platform. Network file server technology is based on open network computing, another technology of the solar microsystem company, is one of the first generation successful distributed computer technology. The network file server is based on the process-oriented technology, which is bound by the C programming language, just like other important remote procedure call technology (distributed computing environment). Both techniques have led to a widely realized file sharing. Database Server Technologies utilize these sub-layered distributed computing power to provide different client platforms to remote access to the database system.
Another important technique in the process of generating the database era is a transactional monitor. Transaction Monitor allows us to maintain consistent and reliable data integrity maintenance through distributed systems. Transaction monitoring technology has become an important additional capability of distributed technology to ensure performance and integrity of the execution.
Groupware technology also appeared in the late 1980s, it started from email, evolved into higher forms of interaction, some of which can also see on the Internet (such as chat room and video) meeting). Recently, object-oriented, distributed computing, and Internet technologies have been combined to support adaptive computing environments, which can be extended to all computers. This generation technology is mainly supported by the application server of Java and Microsoft based on the solar microsystems.
The client-server technology was originally evolved from the host based technology. The host-based technology is the natural and desirable product of a single processor system, which can be traced back to the origin of the calculation. In hosting technology, the processing and management of data in the system is completed. The host is surrounded by many peripheral clients, and these terminals simply support the performance of information. In the client-server technology era, client computers have become important processing resources. The processing speed of the client system in the personal computer revolution continues to rise, and now its processing speed can compete with the previous small machine and mainframe, and even beyond them. Initially, the client-server technology supports the client-server technology to connect to the backend mainframe, miniature machine and workstation server system through the LAN. The technology that supports this communication in the software layer is called a midware.
"Talent may express deep things in a simple way." - Charles Bukowski
history
Initially, middleware is a conventional capabilities that support client-server network communication between PC and server platforms. With the development of technology, the middleware is gradually embedded in the operating system so that it has become a common ability to client platforms and server platforms. Client systems with middleware now support services for applications that are running locally and through the network. Client-server technology has added a small amount of challenge to the performance of embedded capabilities. In fact, there are many different situations, including the recovery of large machine platforms (important business "called network computers, and the ability of network computers to start similar to the multi-machine era. (Figure 5). Figure 5. Origin of client server technology
Object technology is organized around the client-server capabilities. Object technology is divided into two main types. Some of them are organized for process services for software development. Examples of this technique include object-oriented analysis and object-oriented design. Object-oriented analysis is composed of definitions of information technology capabilities of the current and future business processes. Object-oriented modeling provides a wealth of performance for business entities and business processes. This is different from the process and relational database technology, which requires application designers to compromise the performance of the business environment in accordance with the technical constraints of the control flow and data. Due to the simple and natural communication of status information in the process, object-oriented analysis provides mechanisms for simulating reality, and it is relatively easy to communicate with end users. Since the communication with the end user is easier, the design and confirmation of the object-oriented system is easier to implement.
Object-oriented design is another main software phase, which has been successfully commercialized by the software program market. Object-oriented design consists of software structural planning and capabilities that support software defects and fast prototypes of software capabilities.
Other main types of object technology are concentrated. In its center, it is object-oriented middleware technology. Object-oriented middleware supports distributed computing and multiple different software technology (including operating systems, programming languages, and database). Object-oriented programming languages are direct expression of object paradigm. Object-oriented programming language supports data and process packages, using the form of abstract data types in the component object. There are now many object-oriented programming languages, just like there are many process-oriented programming languages. Object-oriented programming languages with dominating status include C , Java language and C #, but there are a large number of groups support Eiffel and other languages. Object-oriented middleware allows these language interactions to constitute applications. Object-oriented programming languages are a possible choice for implementing application software. We may also use object-oriented analysis and design to support programming for process language. This situation often occurs, as many groups of development environments use the process-oriented language (such as C programming language and COBOL) as their own mainstream language.
One of the most important features of object-oriented is that developers don't need to be careful. If the implementation of the next layer is a process or object-oriented, there is no problem as long as the application is properly encapsulated. The distributed object middleware supports opaque package properties that make this operation possible. Integration of business software and traditional and object-oriented applications is also activated by the results of these package properties (Figure 6).
Figure 6. Role of middleware
Object-oriented middleware technology can be seen as a by-product-oriented by-product. Starting from the operating system, the process of supporting the process-oriented communication process has been added to activate the evolution of file sharing and client-server capabilities (Figure 7). These technologies include remote procedure call (RPC) technologies (such as open network computing, ONC) and distributed computing environments (DCE). RPC technology leads the technique of the interposition character, and the technology is a simpler way to deliver messages. Currently, all of these technologies are still active on the application system and on the Internet. Object-oriented middleware technology provides the ability to next generation, which packs more application functions into the lower construction.
Figure 7. Middleware reference model
Distributed Components We noticed some interesting things: the previous generation of process communication technology is committed to all applications' interoperability. The technique of currently facing the components also uses the same way. The distributed object-oriented middleware has the advantages of overcoming the defects of the previous generation technology. We have found that even if the remote process call technology activates the integration of distributed software, in order to understand the system, the original level of these technologies is still requiring a firm application design. Otherwise, once these systems are implemented, they tend to be quite fragile and difficult to maintain. In 1996, Microsoft released DCOM and used it as a multimedia middleware technology used on the Internet. DCOM still exposes a lot of lower-level original details, which means the decline of the remote process call. DCOM adds some object-oriented ability and supporting C programming ordinary integration. Simply adding the ability to support C does not necessarily overcome the process-oriented procedures for DCOM's predecessor (called distributed computing environment) to expose excessive complexity to distributed system developers. However, with the current version of the product - after Microsoft .NET, Microsoft established a business development environment, which can compete smoothly with the more mature J2EE application server. General Object Request Broker Architecture is the first technique for supporting distributed object-oriented computing from the downward. Figure 8 shows that Microsoft's technical foundation is actually isolated from information technology of all other vendors in the technical market. Other vendors support multiple open system technology, which is the result of the standard steps that you agree. Corba is widely accepted, it is the standard of distributed objects that are not subject to the manufacturer. Corba simplifies distributed calculations in many ways. The most important progress is that CORBA provides language-independent, allowing multiple programming languages in different environments to use object messaging interactions. Figure 8. Distributed technology
There are still other technologies above the middleware, which supports further integration of the application function. In Microsoft Technology, these technologies are grouped into a brand name - .NET. .NET technology includes a thorough transformation of middleware capabilities, which deletes interface definition languages. At present, CORBA capabilities have been widely used, and it supports integration of multiple programming languages from multiple vendor platforms. CORBA technology is a product of an open system alliance (called object management working group, OMG). OMG has approximately 700 member organizations that include all major information technology manufacturers, such as the solar microsystems, HP, IBM, Netscape and Microsoft. OMG solves the interoperability of application software by gathering the focus to standardize the programming interface. With the previous generation of remote call technology, the only standard interface that is widely used is a network file server, which is the most original software interoperability above mobile media exchange. End users provide their own needs and interact with open system programs, as they determine the form of technologies that will be used by the development of end user systems. In particular, experienced technical users can encourage open system associations and software vendors to provide more complete capabilities to develop complex systems. This will reduce technology risks and create more methods for application developers. CORBA technology invokes around component standardized objects (Figure 9). There are several types of objects in the object management architecture (which is the OMG paradigm). Object Request Agents is important because all other types of objects are communicating through it. The object management architecture is a conceptual hierarchical architecture that is constantly growing in the characteristics of domain applications (Domain Application). Most of the general capacity contained in object technology is standardized by object requesting agents. The next level of ability is called CORBA service, which provides enabled for system implementation. The functionality of the CORBA service is better than the current operating system, and the service of the operating system is typically bundled on the platform. The CORBA service takes a distributed operational capacity (it supports application software and business software cross-platform, inter-environmental integration) forward. Figure 9. Object management architecture
CORBA technology is currently useful, and in fact it is mainstream technology that can be used on each operating system platform. Some more innovative platforms include Netscape Communicator (objectively, it can be seen as an operating system platform), which is integrated with CORBA and all deliverables. Microsoft also supports the CORBA technology market by issuing specifications (so that it can interact with Microsoft's lower constructors). OMG has developed interaction specifications for COM and COM Microsoft technology. These standards can be used in the products currently in the main CORBA execution system. In addition, third-party manufacturers also provide direct support for CORBA. These manufacturers include Black and White Software (which provides graphical user interface toolkit), database vendors, system management vendors, and professional market vendors (such as real-time and computer auxiliary software engineering tools). CORBA provides Interface Definition Language (IDL), which is an object-oriented key basic capability. The interface definition language is the symbol defining the software boundary. IDL is a normative language that allows us to describe the computer software architecture of the application system and include international standards for intertility. The CORBA interface definition language has been adopted by the international standardization organization and is a formal standard copy of the telecommunications system. IDL is an international standard DIS14750. Similarly, IDL is a universal symbol defining an application programming interface in a software architecture. Because IDL is independent of programming languages, a single specification is sufficient to define software interfaces in any language or platform environment. The IDL interface supports integration of object-oriented design and traditional software. Since the Object Management Working Group is the only authoritative community for the development of the object-oriented standard specification of the software interface, IDL is synonymous with the object technology open system. IDL supports integration that supports multiple programming languages and computing platforms (Figure 10). With IDL, anyone can specify the software interface, it is easy to compile and integrate into available programming languages. These capabilities are also available in business, and generally support distributed communications. Figure 10. Technical independence of interface definition language
This section discusses how mainstream technology evolves into client-server technology, and how middleware provides distributed computing software capabilities. Since the client-server technology is combined with object technology, it is now possible to provide object-oriented ability, which allows traditional systems across all programming environments. In addition, the interoperability between CORBA and Microsoft COM covers a popular desktop platform of many organizations. Vendors that support open systems also support CORBA. Internet vendors that dominate the dominant are delivered to CORBA and associate the protocol stack with many licensed people. CORBA is a standard for object-oriented middleware. Its products can now be used, which acts as a Horizontal service specification that allows applications. OMG is developing vertical norms that will provide direct support for application-level interoperability. ISO has made the CORBA IDL name as a standard defined by software interfaces across multiple platforms. Object-oriented is a common paradigm of real-world information and business process modeling. Object Technologies support integration of different types of information technology (including traditional systems) (Figure 11). Binding to object-oriented and component techniques can be created in large system concepts, and it is becoming the competitive advantage of application companies and end users.
Figure 11. Interoperability panorama of object technology
