Basic characteristics of network computing
Wang Huimin (reprinted from the Computer World News) May 4, 2003
Internet-based network information systems are a growing "ecological" system, "growth" is the basic characteristics of network computing in the Internet environment. Therefore, how to build a growing network computing system in the case of unpredictable future is the challenge we face today. A "chimney" and "integrated" have a point of view that my country's network application is not long, the scale is not large, there is no "chimney" in developed countries, so it is easy to develop network computing systems under the guidance of integrated design, but actual situation it's not true. For example, developers of network information systems in telecommunications, postal, social security, etc. are difficult to do when they do "three mutual (ie interconnect, interoperability, interoperability)". Users can't make specific needs. This is also no wonder that because users have no experience in local applications, how to integrate integrated demand? In this case, the user is often developing the integration problem that can be clear at the time, and then considering the integration issues of each partial system. From this point of view, though we have so many "chimneys" in the network computing system, but also lacks in-depth demand and experience in integration construction. Does this mean that we must first build a "chimney" old road? Answer and solve these problems need to in-depth study of the characteristics of network computing in the Internet environment, comply with the general law of network computing system construction. The network computing system "Non-Wood-free Forest, Solitary Do Not Forest" is integrated with multiple local autonomous systems distributed through the network to achieve broad sharing of resources (including information, applications, and computing resources). The problem that the network computing system needs to be solved is how to combine all local autonomous application systems into large systems capable of playing comprehensive performance. Therefore, there is no local system that has multiple autonomous systems, and there is no need for a network computing system, or that people will not present the so-called extensive shared demand. But this does not mean that we must first build a "chimney" and then remove the old road of "chimney". Our point is "planting trees", "planting trees (development) Local system) ", let the network computing system" grow ". "Wood is born in the boiling, Lin in the ground" so how to make the "tree" that is planted today, it is not "solitary", which is from "cutting" disaster or from "transplant". A simple way is to plant all "trees" on the same land. For network computing systems, the first is to establish separate local systems on the public platform. Based on the understanding of the construction law of network computing system, we believe that the design of network computing systems should follow "grow" principles, that is, the so-called "how to plant trees, make it forest" design. The growing design principle The so-called one system is growing refers to the system has "metabolic" and "growth property" under certain conditions. The component of the system can be updated, and the system's ability to generate the system's composition ingredients can be increasing. The "certain conditions" here can be factors such as input / output, aging, technical or functionality. Review computer technology's development process, many vital computing systems have some growability, and key technologies have also become mainstream technology, and people are well known: ● Object-oriented application system-oriented application system Several interface clear objects, object packaging features make the organizational component of the application system easy to replace, upgrade, and reuse. The development of components / architectural technologies based on object technology makes the application system more flexible extension capabilities. Object-oriented analysis, design, and programming methods, tools become mainstream technology for developing growing network computing systems.
● The hierarchical model of the hierarchical network system network system requires the lower member to provide a standard service interface for the upper layer member, and the upper layer is requested by the standard interface of the lower member, so the interface of the respective layers is constant, the internal mechanism of the lower member is maintained. Changes (such as changes in protocol components) do not have a large impact on the upper member, which makes the network system have a lower metabolic cost and easy to apply growth. Such hierarchies have been adopted by many systems to improve the mainstream technology of system metabolic capacity and growth. ● Distributed Application System Customer / Server Model Based on Customer / Server Model Separates the data management logic of distributed application systems to the application and performance logic, the former deploys on the server, the latter deployed on the client. The client is shared by the standard interface. The model makes the number of customers fully extended, and the upgrade of the server and database management system does not affect the normal operation of the distributed customers. ● Internet Information System Based on WWW Technology HTML file format allows any HTML browser to explain the colorful HTML page, the standard HTTP protocol enables the browser to interact with any HTTP server, unified URL address format allows users to transparently access Any HTTP server management page on the network. WWW technology allows any HTTP server or HTML browser to join the system at any time. WWW technology makes the Internet grow rapidly into new media. Based on historical analysis, we can combing several principles that grow out of network computing systems: the inheritance principle a short system is not a growing system. This principle requires better compatibility and reusability between the composition ingredients of the network computing system. Alternative principles can be alternative to ensuring the basis of systemomabability. This principle requires a good component of the components of the network computing system, and the cost of upgrading or transplant is low, and the impact on other components of the system is small. Scalability Principles Scalability is the basis for ensuring the growth capacity of the system. This principle requires a good "three mutual" between the composition ingredients of the network computing system, especially the dynamic combination and configuration capabilities. According to the above principles, the growthable design of the network computing system should pay attention to the following technical paths: hierarchical system design requires partially unrelated part of the environment in different levels to make the system can easily adapt to changes in the environment. And reuse existing components as much as possible; additional needles need to be placed in different hierarchical components in order to share or reuse public services, or spread on the public platform. Each level of the component system should be composed of several reusable, easy to replace components. The level of the localized system should be clear, between the levels, the association between components completely passed the standard interface, and should not involve implementing detail and other environmental factors. Standardization standards, especially those with widely accepted industrial standards for the reusability, portability, and interoperability of system components. Case Analysis Here, we analyze a two-dimensional architecture that current mainstream support network computing systems, one-dimension is a hierarchical platform architecture, and the other is a three-layer application architecture (Figure 1). Combined with our practice, we believe that the three-layer architecture is an effective application architecture that supports the growth of network computing systems. Three levels refer to the application of the performance layer, the application logic layer and the resource management (Figure 1). Figure 2 recommends a three-layer architecture solution, where the application performance layer is the user interface of the user using the network computing system, using a standard web browser, embedding the IIOP protocol Java ORB and Java Applet interpreter, Users use the network computing system in a standard browser. The application logic layer includes HTTP Server and application servers. Running a variety of network computing systems on the application server, such as database access objects, data integrated objects, decision support objects, task planning objects, data exchange objects, process control objects, and more.
