外文翻譯--socket網(wǎng)絡(luò)編程的設(shè)計與實現(xiàn)（英文）

1、A Design and Implementation of Active Network Socket Programming K.L. Eddie Law, Roy Leung The Edward S. Rogers Sr. Department of Electrical and Computer Engineering University of Toronto Toronto, Canada eddie@comm.to

2、ronto.edu, roy.leung@utoronto.ca Abstract—The concept of programmable nodes and active networks introduces programmability into communication networks. Code and data can be sent and modified on their ways to destinat

3、ions. Recently, various research groups have designed and implemented their own design platforms. Each design has its own benefits and drawbacks. Moreover, there exists an interoperability problem among platforms.

4、 As a result, we introduce a concept that is similar to the network socket programming. We intentionally establish a set of simple interfaces for programming active applications. This set of interfaces, known as Ac

5、tive Network Socket Programming (ANSP), will be working on top of all other execution environments in future. Therefore, the ANSP offers a concept that is similar to “write once, run everywhere.” It is an open prog

6、ramming model that active applications can work on all execution environments. It solves the heterogeneity within active networks. This is especially useful when active applications need to access all regions within

7、 a heterogeneous network to deploy special service at critical points or to monitor the performance of the entire networks. Instead of introducing a new platform, our approach provides a thin, transparent layer on to

8、p of existing environments that can be easily installed for all active applications. Keywords-active networks; application programming interface; active network socket programming; I. INTRODUCTION In 1990, Clark and

9、Tennenhouse [1] proposed a design framework for introducing new network protocols for the Internet. Since the publication of that position paper, active network design framework [2, 3, 10] has slowly taken shape in

10、the late 1990s. The active network paradigm allows program code and data to be delivered simultaneously on the Internet. Moreover, they may get executed and modified on their ways to their destinations. At the mome

11、nt, there is a global active network backbone, the ABone, for experiments on active networks. Apart from the immaturity of the executing platform, the primary hindrance on the deployment of active networks on the In

12、ternet is more on the commercially related issues. For example, a vendor may hesitate to allow network routers to run some unknown programs that may affect their expected routing performance. As a result, alternativ

13、es were proposed to allow active network concept to operate on the Internet, such as the application layer active networking (ALAN) project [4] from the European research community. In the ALAN project, there are act

14、ive server systems located at different places in the networks and active applications are allowed to run in these servers at the application layer. Another potential approach from the network service provider is to

15、 offer active network service as the premium service class in the networks. This service class should provide the best Quality of Service (QoS), and allow the access of computing facility in routers. With this appro

16、ach, the network service providers can create a new source of income. The research in active networks has been progressing steadily. Since active networks introduce programmability on the Internet, appropriate execut

17、ing platforms for the active applications to execute should be established. These operating platforms are known as execution environments (EEs) and a few of them have been created, e.g., the Active Signaling Protoco

18、l (ASP) [12] and the Active Network Transport System (ANTS) [11]. Hence, different active applications can be implemented to test the active networking concept. With these EEs, some experiments have been carried out t

19、o examine the active network concept, for example, the mobile networks [5], web proxies [6], and multicast routers [7]. Active networks introduce a lot of program flexibility and extensibility in networks. Several

20、research groups have proposed various designs of execution environments to offer network computation within routers. Their performance and potential benefits to existing infrastructure are being evaluated [8, 9]. U

21、nfortunately, they seldom concern the interoperability problems when the active networks consist of multiple execution environments. For example, there are three EEs in ABone. Active applications written for one par

22、ticular EE cannot be operated on other platforms. This introduces another problem of resources partitioning for different EEs to operate. Moreover, there are always some critical network applications that need to r

23、un under all network routers, such as collecting information and deploying service at critical points to monitor the networks. In this paper, a framework known as Active Network Socket Programming (ANSP) model is prop

24、osed to work with all EEs. It offers the following primary objectives. ? One single programming interface is introduced for writing active applications. ? Since ANSP offers the programming interface, the design of

25、EE can be made independent of the ANSP. 0-7803-7533-X/02/$17.00 (C) IEEE 76 74 78others’ information. There are various ways to enforce the access control. One simple way is to have one virtual machine for one insta

26、nce of active applications. This relies on the security design in the virtual machines to isolate services. ANTS is one example that is using this method. Nevertheless, the use of multiple virtual machines requires

27、 relatively large amount of resources and may be inefficient in some cases. Therefore, certain environments, such as ASP, allow network services to run within a virtual machine but restrict the use of their service

28、s to a limited set of libraries in their packages. For instance, ASP provides its thread library to enforce access control. Because of the differences in these types of thread mechanism, ANSP devises a new thread li

29、brary to allow uniform accesses to different thread mechanisms. C. Soft-Store Soft-store allows capsule to insert and retrieve information at a router, thus allowing more than one capsules to exchange information with

30、in a network. However, problem arises when a network service can execute under different environments within a router. The problem occurs especially when a network service inserts its soft-store information in one e

31、nvironment and retrieves its data at a later time in another environment at the same router. Due to the fact that execution environments are not allowed to exchange information, the network service cannot retrieve i

32、ts previous data. Therefore, our ANSP framework needs to take into account of this problem and provides soft-store mechanism that allows universal access of its data at each router. D. Global View of a Unified Networ

33、k When an active application is written with ANSP, it can execute on different environment seamlessly. The previously smaller and partitioned networks based on different EEs can now be merging into one large active n

34、etwork. It is then necessary to advise the network topology across the networks. However, different execution environments have different addressing schemes and proprietary routing protocols. In order to merge the

35、se partitions together, ANSP must provide a new unified addressing scheme. This new scheme should be interpretable by any environments through appropriate translations with the ANSP. Upon defining the new addressing

36、 scheme, a new routing protocol should be designed to operate among environments to exchange topology information. This allows each environment in a network to have a complete view of its network topology. E. Langua

37、ge-Independent Model Execution environment can be programmed in any programming language. One of the most commonly used languages is Java [13] due to its dynamic code loading capability. In fact, both ANTS and ASP a

38、re developed in Java. Nevertheless, the active network architecture shown in Figure 2 does not restrict the use of additional environments that are developed in other languages. For instance, the active network dae

39、mon, anted, in Abone provides a workspace to execute multiple execution environments within a router. PLAN, for example, is implemented in Ocaml that will be deployable on ABone in future. Although the current activ

40、e network is designed to deploy multiple environments that can be in any programming languages, there lacks the tool to allow active applications to run seamlessly upon these environments. Hence, one of the issues th

41、at ANSP needs to address is to design a programming model that can work with different programming languages. Although our current prototype only considers ANTS and ASP in its design, PLAN will be the next target to

42、 address the programming language issue and to improve the design of ANSP. Figure 2. ANSP Framework Model. F. Heterogeneity of Capsule Header Structure The structures of the capsule headers are different in different

43、EEs. They carries capsule-related information, for example, the capsule types, sources and destinations. This information is important when certain decision needs to be made within its target environment. A unified

44、model should allow its program code to be executed on different environments. However, the capsule header prevents different environments to interpret its information successfully. Therefore, ANSP should carry out

45、appropriate translation to the header information before the target environment receives this capsule. III. ANSP PROGRAMMING MODEL We have outlined the design issues encountered with the ANSP. In the following, the

46、design of the programming model in ANSP will be discussed. This proposed framework provides a set of unified programming interfaces that allows active applications to work on all execution environments. The framewo

47、rk is shown in Figure 2. It is composed of two layers integrated within the active network architecture. These two layers can operate independently without the other layer. The upper layer provides a unified program

48、ming model to active applications. The lower layer provides appropriate translation procedure to the ANSP applications when it is processed by different environments. This service is necessary because each environm

49、ent has its own header definition. The ANSP framework provides a set of programming calls which are abstractions of ANSP services and resources. A capsule-based model is used for ANSP, and it is currently extended to