Hardware System Integration of E-commerce

10.2 Hardware System Integration of E-commerce

10.2.1 Integration of Server

1. Method of server integration

(1) Architecture As for architecture of server, three tiers architecture of application server is

advised to use in server integration. Application server uses individual process to handle business and transaction management, and transfers all data operation to the third tier, which is database server of data process tier. In certain instance, it could also be transferred to other systems. The core of application server architecture is between Web server and database server, and uses special application server to complete business process, instead of using customary method, which is directly to access database server from Web server.

(2) Load balance All the application server systems have load balance capability, namely

distributing requests from users appropriately to each application server to make them burden system load respectively. Through load balance, users could add some new servers, and install corresponding software and configure them when expanding system, instead of changing any application, to meet requirements for scalable performance.

There are many ways to implement load balance for server, but each has its advantages and disadvantages. First of all, it depends on load balance algorithm. There are two main load balance algorithms currently. One is accurate load distribution, namely there is a distributor in the system, which distributes system requests to appropriate application sever to handle. The other load distribution is based on statistics, namely received requests are directly distributed to each back application server according to probability based on predefined weights. There are two ways in implementing application server, one is based on process, and the other is based on thread. The way based on process is to pre-generate all processes of application server, and a certain process of application server handles all things when receiving a request. The way based on thread is to create few application server processes in each computer, and a temporarily created thread handles received request. The way based on process is faster because it does not need to create any thread. But a process engrosses more resources than a thread, a computer could run fewer processes at the same time than threads, therefore its parallel handling capability is weaker than the way based on thread.

(3) High reliability Generally speaking, reliability is referred to fault tolerance and fault recovery.

Fault tolerance means system could still operate normally when certain faults occur, including hardware fault, software error and network fault. There are two

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grades in fault tolerance. In the primary grade, the processing request cannot be handled when fault occurs. The more consummate grade means these requests are transferred to other servers to continue to be handled without user’s awareness. Of course, this grade provides better service, but it generally pays for performance and complexity. Each application chooses some fault tolerance grade according to its characteristics. In the premise of discovering fault and tolerance error, more consummate application server should carry out fault recovery. After the fault occurred, if the fault has been removed automatically or manually, then these application servers should recover to work and continuously serve users. The technology is related to technology that provides high usability.

(4) Connection limitation of database To solve this problem, database connection pool is generally used in server

integration, namely database connections are completed at initial stage or first use, and are not released later. The created connections are repeatedly used when handling the following requests. This method could greatly reduce process time of database, in favor of increasing the whole system performance, and at the same time could make the use of restricted database connections improve efficiently. Therefore, database connection pool technology is widely used in various application server products.

(5) Distributing session management There are two methods to solve this problem: one is to store its own session

information in each server. Thus it needs to be based on session rather than request when distributing load, otherwise it will cause inconsistence of session information. The other one is to specially create a session server to store session information. It is convenient for load distribution algorithm and fault tolerance. But its disadvantage is adding one network communication time and slowing handling speed.

(6) Embedded object To increase openness of server, embedded objects integrated in servers can be

generally placed in application servers or back-end of application server. Embedded objects which are placed in application server could turn object access into local access, without any network communication, so it has better performance. But these objects could exist in application server at the same time, so it could not implement long-term internal state of objects. There are two kinds of implementations when embedded objects are placed in application server. One is symmetrical, namely each application server installs all objects; the other is asymmetrical, namely, cooperating with load distribution program, some objects are only installed in certain servers. If embedded objects are placed in back-end of application server, one level is actually added, namely embedded object level, to make the whole system become four levels. It would increase network communication and reduce performance, however, design of objects is more flexible, and various existing object connection interface can be used. Currently, standard object access interfaces are mainly CORBA and DCOM. CORBA is

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standard interface defined by OMG (Object Management Group), which is widely applied abroad including EJB. DCOM is the standard defined by Microsoft, which could directly connect to ActiveX. Currently there are some application servers having their own object access interfaces.

(7) High-speed cache mechanism To realize optimal performance, many servers use high-speed caching mechanism

when integrated. There are two places using cache in application, namely page cache and database cache. Page cache is to record pages corresponding to particular URLs in cache, in order to directly use them when the same URL is accessed in future. Database cache is to record access results of database, thus it only needs to access the cache when the same SQL accesses database again, instead of operating the database. The premise of getting well effect of this kind of cache is that the main cost of system is database access. Because system needs to carry out work of creating page, the effect of cache is not as good as that of page cache, but it is more applicable.

Several technology issues mentioned above need to be resolved in server integration currently. There are many other problems; such as how to implement cross platform even mixed platform and how to implement management of application. The above solutions cannot be judged simply, rather applicable to different types of system. For example, common commercial systems oriented to the public need high performance. If it is referred to e-bank system, the requirement of security would exceed requirement of high performance, which needs more consummate security policy. Therefore, users first need to fully understand their requirements when integrating application server, then determine every main technical problem, choosing appropriate solution, and find products which use these solutions to complete their systems at last.

2. Integration of server

(1) Development phase of application server In the first phase, server expanding interfaces provided by Web server are used,

and they are developed with C or Perl, such as CGI and API. The manner could make developer freely handle various Web requests, dynamically generate response page, and implement various complicated Web system requirement. The main problem of the development manner is the need of high skilled developer, who needs to understand low level of programming method and HTTP. In addition, debugging for the system is rather difficult.

In the second phase, some scripts mainly including ASP, PHP and Livewire in server end are used in the development. The chief advantage of the method is that it can simplify development process. The main problem of this method is bad expansibility of the system. When system is busy, there is no efficient method to expand. Moreover, from the perspective of a nit-picker, the method goes against the implementation of various high-performance algorithms, and could not provide high usability, and has bad integration effect.

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In the third phase, a new Web application development method comes out, namely application server method. The core structure and the main problems to

be resolved are similar, and the difference is just the different algorithms of various solutions. (2) Problems of server integration ķ Architecture: The chief characteristic of server is server end architecture

which owns at least three layers. If application requests are all transferred to application server in application process layer through request receiving layer (generally Web server), application logic, business logic and data logic would be mixed up and interface, application and data would not be distinguished.

ĸ Load balance: When users build their initial systems, they could not accurately forecast the future system scale. If the scale of system is designed to

be small, it would not accommodate large scale development in future. If the scale of system is designed to be large, it might cause waste of investment. Application server architecture could be used to add a layer, which makes system more complicated, but will bring many advantages. The basic advantage is to bring system scalable performance.

Ĺ High reliability: The architecture of application server is a special form of distributed system, and one most important characteristic of distributed system is to build high reliable system. Therefore, one solution to increase reliability is to use application server architecture.

ĺ Connection restriction of database: As well known, database process is the most time-consuming step in the whole business process. Connection and release of database is particularly time-consuming. So database connection is needed to

be restricted. Ļ Distributing session management: Because standard HTTP request is one connection of each request, technologies such as Cookie and IP address identification are generally used in system integration to implement session management in order to make it easy to use application. In single server, session management is relatively easy to implement, but storage place of session information is a problem in multi-servers.

ļ Embedded object: Embedded objects are provided in server integration to complete various low layer functions, and implement connection with other systems. But differences which mainly represent in the positions of objects and object interfaces in embedded objects among various application servers are quite large. It causes problems when different servers are connected. It needs to design position and interface of object according to different system requirements.

Ľ High-speed cache mechanism: The efficiency of server not only depends on the response to requests of server, but also response amount at unit time, which is called peak value. Cache issue is very important in this situation. High-speed cache mechanism is needed to be considered carefully in system integration.

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3. Integration of high performance server

(1) Consideration for purchasing server As the heart of network architecture and operation, server is very important,

and PC servers which have high performance and low price increasingly take up most quotient of server market. Owing to its business’s particularity, ISP/ICP not only gains unprecedented development chance from its increasingly networking requirements, and its business development also plays an important part in promoting information construct of the whole society; PC server as the source of power of network is key to ISP/ICP, and operation of ISP/ICP greatly depends on PC server. Therefore, how to choose the appropriate PC server is very important to ISP/ICP. We will introduce the general principle of purchasing PC server and particularity of purchasing of ISP/ICP industry.

After the level of PC server is determined, it needs indicators to measure its performance. There are usually six performance indicators, namely manageability, usability, expandability, security, high performance and modularization.

ķ Manageability is standard performance of PC server, and is also the important difference from Unix server, because it is better than that of Unix server. Windows NT is not only consistent with other operation systems in working interface, but also is compatible with all kinds of application software based on Windows system. These ease management of PC server. At the same time, PC server provides system with abundant management tool software and especially the installation software makes installing of the server or expending (adding hard disk, memory etc.) as easy as installing PC.

ĸ Usability is referred to normal use time percent of server during a period of time. There are two methods to improve usability of server: reducing average fault time of hardware and using special mechanism. The mechanism could automatically execute system or component switch to eliminate or reduce accidental power down when fault occurs. However, regardless using which method, system or component has to be redundant, and system cost is increased too.

Ĺ Security is the life of network, and security of PC server is just the security of network. To improve security of server, component redundancy of server is very important. Some servers realize complete device redundancy in power supply, network card, SCSI card, hard disk and PCI channel, and support PCI network card automatically switch, which greatly optimize security performance of server. Of course, redundancy of device component needs two sets of totally same components, which greatly increases system cost.

ĺ High performance is referred to high integrating performance of server, including running speed, disk space, fault tolerance, expandable capability, stability, durative, monitoring function and power supply. In addition, it is needed to note hot-plug performance of disk and power supply, adaptability of network card and redundancy design and correcting function of related components.

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Ļ Expandability is one of the important performances of PC server. Because the number of workstations or clients is randomly added, expandability performance of server is needed to be fully considered to keep server working stable and secure.

ļ Modularization design refers to components such as power supply, network card, SCSI card, hard disk and fan are modularized structure and have hot-plug function, and it would be online maintained to greatly reduce system halt. The particular one is distributed power supply technology, each important component has its own supply system, and one component whose power supply is damaged would not affect security and continual working of the whole system.

These six aspects are usually considered by all kinds of users when they are purchasing PC server. They affect each other and are still individual, and they have different important extent as to different applications and industries, thus users have to do tradeoff. Moreover, factors such as brand, price, service, strength of manufacturer also should be put into consideration.

(2) Particularity of application and purchase in ISP/ICP industry It is easy to figure out that ISP/ICP mainly belongs to department application

and a few enterprise applications according to the above division of application domain. One or more aspects emphasized are determined according to business characteristics of ISP/ICP in performance.

Business characteristics of ISP/ICP: many enterprises and individuals join Internet and build homepage to extend affection, which mainly brings new developing chance for ISP/ICP who provides Internet service. Particularly along with telecommunication infrastructures become more mature, bandwidth problem which harasses exploring speed is gradually resolved, and the main business pattern turns from foregone “virtual host” business to “hosting trusteeship” business gradually. Currently, ISP mainly engages in connecting service IAP.

According to forecast of experts and authority organizations, current ISP/ICP is developing in four directions: the first one is backbone network administration, which mainly engages in long loop access service and scalable management through seizing large number of customers; the second one is to provide increment business service, including dialing connection and cache to make customers quickly access, and to provide VPN business consultation and design; the third one is to provide Internet solution, namely to provide SAP and Oracle application solution and various special information consultation, in order to help customer implement e-commerce, and to provide B2B and B2C solution; the fourth one is data center, including hosting trusteeship, application hosting and enterprise e-commerce creation, management and maintenance.

Data center service business is the most necessary business of PC server among four directions, and is also the main motivation of each ISP/ICP massive purchase. The main customers of host trusteeship are ISP/ICP themselves, and the main customers of application trusteeship are websites of press media, and the main customers of creation, management and maintenance of enterprise e-commerce respectively are virtual host servers, system integrators and enterprises.

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Consideration when purchasing PC server: ķ Usability. It is very important to ISP/ICP. Otherwise, business will be

interrupted by neglect, causing large or destructive damage.

ĸ Space. Because host trusteeship has become one of main businesses of ISP/ICP, how to provide server devices as many as possible in limited space becomes the most important foundation of expanding business scale by ISP/ICP.

Ĺ Manageability. This is key performance which referred to maintenance of system, resource exploitation and user resource management and support. ĺ High performance. It directly affects execution in other aspects. These four aspects together determine whether PC server fully meets requirements

of key business and whether ISP/ICP standing in front edge of Internet could play key role, in order to instruct the whole world into “information expressway”.

10.2.2 Integration of Communication Network

1. Integration of LAN

Integration of LAN is to implement secure and fast access among computer networks through enterprise network construction to provide good hardware platform for enterprise implementation OA and application information management system running on computer network, thus achieving the goal of making full use of various computer information technology to make enterprise office work and management gradually realize networking, information and modernization.

(1) Principle of LAN integration LAN is the infrastructure of all information network applications, and whether

its design is reasonable is very important to application and development of network. The whole design of network not only needs to consider recent goal, but also needs to make space for expanding, so it needs unified plan and design. Constructing a modern network system, we should use advanced and mature technology and guarantee its advance in a relatively long time. The principles of LAN integration are as follows:

ķ Practicability principle: Network system should use mature and reliable technology and device to achieve practical, economic and efficient goal.

ĸ Openness principle: Network system should use open standard and technology. Ĺ Reliability principle: Network system should ensure high reliability and

high average of no fault time and low fault rate.

ĺ Security principle: Network system should have good security to ensure network system and data run safely.

Ļ Advance principle: Network system should use advanced technology and device to capture future development trend of network.

ļ High efficiency principle: Network system should have high use rate of resource.

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Ľ Expandability principle: Network system should have well expandability in scale and performance.

Network system should have high performance/low price, technology first, price second. (2) Three work modes of LAN integration Server-Based: also called “workstation/file server” structure, which is composed

of several workstations connected with one or more file servers by LOC. Workstations store server file, and share storage devices.

ķ Client/Server: one or more larger computers which are called servers share management and access of database, and other application process work is distributed to other computers in the network, which composes a distributed process system.

ĸ Peer-to-Peer: It is the same as server-based and C/S in topology. In peer-to-peer, there are no particular servers. Each workstation plays part as client

or server. (3) Network structure of LAN integration According to construct goal of network system and integrating with current

development state of network technology, LAN integration structure typically adopts star network structure with 100Mbps Fast Ethernet as backbone and 100Mbps switch to desktop.

Backbone connection takes on data switch of the whole computer network, so it must have good performance and high security and reliability. Backbone connection uses high performance backbone switch, which has 100M port and is used as fast connection with function servers and office buildings.

The second level of connection takes on data switch of each office building, each floor or office, and switches data through backbone switches and other second level switches. It uses 100M Ethernet switches with up band fiber and switches to desktop with 100M port by connecting backbone switches with fiber.

(4) Device choice of LAN integration Switch is an important LAN interconnection device, which works in the

second layer of ISO/OSI reference model, namely data link layer. The switch function of LAN switch and identification of MAC address tables are totally processed by their internal processor. There are currently two kinds of processors ASIC and RISC used in switch products of each network factory. The switch based on ASIC chip has less frames lost, shorter network delay, and is more stable than switch based on RISC chip.

There are basically two methods for switch to process the data package: cut-through and store-and-forward. The cut-through switch just reads destination address before data package is sent to network, thus making the shortest delay; the store-and-forward switch needs to verify input data package, which makes long delay but could remove error data package. Current first-class switch products could support both methods at the same time and automatically switch. If transmitted data packages have less errors, cut-through is used, otherwise

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store-and-forward is used; if network is busy, cut-through is used, otherwise store-and-forward being used.

(5) Selection of LAN switch should follow the following principles Supporting pure link switch and spanning tree algorithm, having fast backboard

switch bus, large throughput of data package and stable structure. Supporting many kinds of standard LAN protocols, standard network management and cut-through and store-and-forward data package processing methods.

Low drop rate of frame and small network delay. Maintaining large numbers of MAC addresses in the bridge table. Supporting virtual network, supporting module function, having enough Uplink

insertion slots, appropriate cache size and performance/price for each port. (6) Other devices and selection Information jack: super five-class double-hole information jack supports fast

transmission of voice and data, which is used for connection between device and horizontal subsystem.

Cable: upper five-class UTP is used in horizontal subsystem, which could support 622Mbps or even faster data transmission.

2. WAN integration

If prevalence of micro computers leads to the interaction among several computers and the LAN, prevalence of network leads to the development of WAN, realizing interaction communication and resource sharing in a wider range. The main difference between LAN and WAN is that the scale of WAN is lager, and the structure of WAN is more complicated, and WAN protocol is more diverse.

(1) Problems that WAN integration faces How to connect two heterogeneous networks physically? How to implement interaction and communication between two networks? How to get rid of the differences between them on protocols? How to handle the differences between speed and bandwidth? (2) Methods of WAN integration The main work is to solve the above problems in the process of WAN integration.

Common components to coordinate and transmit are repeaters, bridge, router, gateway, and so on.

Repeaters: Repeaters are used to extend the network’s distance when the transmission medium exceeds the net segment’s length. They work in the physical layer without providing isolation function of net segments.

Special repeaters: ķ Hub (multi-port repeaters): Hub is a device which accumulates communication

lines with the star topology, which works in the physical layer just like a bus, and is the most popular device in the network. It can be divided into independent hub, modular hub, iterative hub and intellectual hub in terms of configuration.

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Intellectual hub corrects the faults of general hub, adds the ability of bridge connection, gets rid of frames that do not belong to it, enlarges the frequency width of net segment, and has the abilities of network management and monitoring the speed of PC net card connected with port automatically.

ĸ Switch: The destination address of switch Ethernet data package sends the ether-package from the source port to the destination port, theses ether-packages

can be sent to different destination ports at the same time, to improve the actual throughput of network. Switch can create several transmission paths at the same time, so there will be obvious effect on the net segment connecting by many servers. It is mainly used to connect hub, server or distributed backbone network. It can be divided into straight switch and storage transportation in terms of technologies adopted.

Ĺ Bridge: Filtration and transportation, study function, connection with different transmission media, without the capacity of route selection.

ĺ Router: It is a device to implement network interaction among many LAN and mediums, and is more complicated than bridge. Its major functions are grouping

transportation, providing isolation, supporting spare network router and so on.

Ļ Gateway: Its major function is to change one protocol to another, or change one data format to another format, or change one speed to another speed, in order to match with each other and join two totally different networks. In Internet, gateway is a computer device which can decide whether to send out information user requested from the local network according to IP address of computer used by user, meanwhile, it can also receive information which outside sends to the local network computer.

The above devices should be used to solve the problem of integration flexibly when WAN is integrating. The appropriate WAN connection devices should be selected in terms of the current situation combining with different network structures, network devices, network protocols and network speeds in each LAN.

3. Integration of high speed network

Currently, the dominating backbone technology adopts KM Ethernet which provides ten times performance than the fast Ethernet, and is compatible with current 10/100 Ethernet standard. Meanwhile, the virtual network standard 802.1Q developed for 10/100/1000Mbps and priority standard 802.1p have been popularized, KM network has already been the major technology for the network backbone.

KM Ethernet will provide perfect transmission ways to properly protect investment on the network infrastructure.

Compared with previous solutions on the main network such as fast Ethernet, FDDI, ATM, KM Ethernet provides another reliable and economic method to improve the backbone connection between switches and connections between switch and server.

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(1) Notes of high-speed network integration High performance requirement of network system: Core switch satisfies the

requirement of great capacity data switch, connection center’s communication link bandwidth can satisfy performance requirement of network. Whether enterprise network, MAN or WAN, information applications are developing rapidly, new multimedia application and new data application raise higher requirements. According to the principles of designing enterprise LAN, first, it should be considered to satisfy the data switch capacity network scale demands of core devices and link bandwidth from edge device to the core.

High reliable and usable requirements of device in network need system integration. All the key components of core switch should implement redundant work and replace online, and the recovery time of fault can completes in second range interval. Multilevel fault tolerant design based on individual device reliability can improve usability of system further. When designing enterprise network, high-reliability and high-usability is vital, it is required not only because the components of device are redundant, but also because the links of network are redundant implementing with technologies in physical layer, link layer and the third layer, to guarantee network can provide information access service at any time and everywhere.

ķ Expansible requirement of network integration: It includes the expansible capacity of switch hardware and capacity of implementing new application.

ĸ Flexible expansion requirement of core switch: The core switch should have flexible port expansion capacity, module expansion capacity to satisfy the expansion of network scale; meanwhile it improves performance to satisfy the requirements of higher performance. Capacities of supporting new application, products have the technology devices supporting new application to implement new application conveniently and fast.

When high-speed network is being integrated, first of all, requirements of network users of current scale should be satisfied, and then network should have the flexible expansion capacity of user port considering the expansion of business development and scale in future. When designing large-scale garden area network, distributed switch should be adopted to implement flexible expansion capacity of module and port.

(2) Security requirements of network integration The security of network is vital to network design; reasonable network security

control can make information resource in application environment protected effectively. In enterprise network, only system administrator can operate and control the key servers and the core network devices. Application client end only has the right of accessing sharing resource; network should avoid any illegal applications. Package filtration function based on protocol, Mac address and IP address could be carried on garden area network devices. Dividing virtual subnet on design of large scale network, on one hand can separate from lots of broadcast in subnet effectively, on the other hand, can isolate communications among

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subnet to control access right of resource and improve security of network. Network security control capacity during designing garden area network must be emphasized to make network connected arbitrarily and control network access from the second or the third layer.

(3) Manageable requirement of network Any device in the network can be controlled through network management

platform; the device status of network and trouble warning can be controlled through network management platform, to simplify management work and improve efficiency of network management.

It is necessary to choose advanced network management software in network integration. The goal of network management is to implement zero-manage way and based on certain policies. The developing trend of network management software is network management interface, whose flexible operation methods simplify administrator’s work. On the selection of network devices, it is demanded that network devices support standard network management protocol SNMP and RMON/RMON11, the core device should support RAP protocol to implement network management function properly. Manageability of device should be required when designing garden area network, meanwhile, advanced network management software can support functions of network maintenance, monitoring and configuration.

(4) Network devices adopt open technology and support standard protocols Adopting standard protocols could protect user’s investment and improve the

interoperations of device. Devices used in network design should adopt standard protocols developed by dominating technologies, have good interoperation, support seamless connection and communication among different series of products in the same company or products in different companies. On the principles of designing campus network, special advanced technology in different companies should be exerted, meanwhile, it should emphasize the standard of technology and protocol, to decrease problems of devices interconnection and network maintenance, and effectively protect the user’s investment.

It should be considered that whether the selected devices can be upgraded. After new standard appeared, system should upgrade to the new standard. Therefore, the position of company in products and technologys area and its capacity of participating in making up standard should be noted. In the modern world, the technologies of communication and computer change every day. Network integration not only should adapt to the development trend of new technology ensuring the advancement of system, but also consider the maturity on technology decreasing the risk brought by immature elements because of the new technology and new products.

Kilomega Ethernet has the advantage of bandwidth over other technologies, and still has developing space, reference standard organization are setting down the technology criterion and standard of 10G Ethernet network. Meanwhile, priority control mechanism and protocol standard based on Ethernet frame layer

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and IP layer and various QoS supporting technology are coming to be mature gradually, providing basement for implementing applications requested better service quality. With the progress of optical fiber manufacture and transmission technology, transmission distance of kilomega Ethernet could reach hundreds of kilometers, making it a technology selection to construct MAN and WAN gradually.

New network technology and devices may provide better integration methods for high-speed network. We should master the principles of integration seizing new technologies and new specialties without routinism. We just remember points needed to be noted described above.