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A Gridbased ECommerce Architecture and Formal Specification

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Title: A Gridbased ECommerce Architecture and Formal Specification


1
A Grid-based E-Commerce Architecture and Formal
Specification
  • Yu-Yue DU 1,2,3 , Chang-Jun JIANG 1,3
  • 1 Tongji University, Department of Computer
    Science Engineering, China
  • 2 Liaocheng University, Department of
    Computer Science, China
  • 3 Laboratory of Computer Science, Institute of
     Software, 
  • Chinese Academy of Sciences, China

2
Main Contributions
  • Present a new E-commerce architecture based on
    the Grid Computing environment.
  • It can implement various electronic bargains on
    Grid resources between geographically dispersed
    users.
  • Apply Petri nets to formal modeling and analysis
    of the architecture.
  • Some main properties are represented and verified
    formally using Petri net language.

3
1 Introduction (1)
  • Grid computing can offer seamless access to rare
    and limited resources as the high-performance
    cooperation of geographically distributed
    computer systems.
  • We wish to have an environment where cooperative
    jobs between participants can be executed either
    on local or remote computer systems
    electronically and quickly, and in most cases
    automatically.

4
1 Introduction (2)
  • We will present and analyze an E-commerce
    environment on the basis of the Grid Computing,
    notation G-E-commerce architecture, for a model
    of future E-commerce platforms.
  • The G-E-commerce is offered collectively by
    multiple distributed modules or geographically
    dispersed business models, possibly provided and
    owned by different organizations.

5
1 Introduction (4)
  • G-E-commerce can assist users with the
    negotiation and maximize well-balanced profits
    between players, and improve the trade response
    time.

6
1 Introduction (5)
  • It is very important that a software system is
    analyzed and verified formally before the
    implementation.
  • We use Petri nets and workflow technologies to
    model and analyze the G-E-commerce.

7
2 A Grid Computing Setting (1)
  • In the Grid Computing setting, source provider
    must posse ultimate control over their resources.
  • It is not feasible for the Grid Computing system
    to insist that the resources are restricted on a
    centralized scheduling authority that is
    responsible for allocating resources to
    consumers.

8
2 A Grid Computing Setting (2)
  • Suppose that the Grid Computing architecture
    cannot force resource providers to remove or
    replace elements of their existing software base.
  • The architecture must accessible as a set of
    services layered on top of installed, extant
    software rather than as a replacement.

9
2 A Grid Computing Setting (3)
  • We adopt the decentralized approaches with
    several centralized resource brokers, when
    designing a Grid resource allocation scheme.
  • A centralized resource broker is responsible for
    fielding the resource requests of the users
    registering in it and making resource assignments.

10
2 A Grid Computing Setting (4)
  • Each broker may combine with the other to
    implement a cooperative task crossing broker
    boundaries.

11
3 An E-Commerce Grid Architecture (1)
  • We present an E-commerce architecture within a
    global grid environment.
  • It couples a wide variety of geographically
    distributed trade resources such as goods and
    special instruments, and represents them as a
    unified integrated resource.

12
3 An E-Commerce Grid Architecture (2)
  • If all trade resources from various entities are
    managed by G-E-commerce architecture, this will
    result in a performance bottleneck to locate the
    resources satisfying the needs of a user.
  • In fact, there are frequently trade relations
    between some affined business organizations but
    rarely between the other ones.

13
3 An E-Commerce Grid Architecture (3)
  • G-E-commerce architecture consists of Grid Trade
    Brokers (GTB) and User Grid Agents (UGA).
  • Each GTB is responsible for the negotiation and
    exchange of the resources from the affinitive
    organizations, while each UGA submits user
    requests to the GTB and accepts the trading
    results from the GTB.

14
3 An E-Commerce Grid Architecture (4)
  • When the UGAs of coordinative users are managed
    by the same GTB, it can implement autonomously
    the business negotiation and execute this
    bargaining.
  • if the UGAs of the users participating in a
    bargaining are not in the same GTB, this means
    that there exist the negotiation and exchange
    crossing GTB boundaries (see Fig.1).

15
Fig.1 G-E-commerce scenario composed of two GTBs
and five UGAs

16
3 An E-Commerce Grid Architecture (5)
  • Each user essentially interacts with its
    corresponding UGA, whereas each UGA interacts
    directly with a GTB.
  • A GTB acts on the other GTBs when there is a
    bargaining crossing GTB boundaries.

17
3 An E-Commerce Grid Architecture (6)
  • UGAs have stronger ability for expressing user
    requirements.
  • Communication between UGAs and a GTB is performed
    based on the Agent Communication Language (ACL),
    which is independent of user software systems.

18
3 An E-Commerce Grid Architecture (7)
  • A user may want randomly to add to or to remove
    from the architecture, but she must first put in
    for registering or withdrawing.
  • The UGA services are implemented by the User
    Agent Daemon, which runs on grid machines, and
    the User Agent Server, which runs on the machines
    in a GTB.

19
3 An E-Commerce Grid Architecture (8)
  • UGAs provide also security-sensitive services
    such as remote execution, the Daemon and the
    Server rely on public-key cryptography to
    authenticate each other.
  • The requirements of each user are described in
    terms of the code form provided by the specified
    UGA when it registers.

20
3 An E-Commerce Grid Architecture (9)
  • The describing elements provided contain
    generally
  • service types
  • user identity
  • range of trade price
  • size of resources such as the number of sale
    products
  • trade deadline.

21
3 An E-Commerce Grid Architecture (10)
  • The GTB services are implemented by the User
    Agent Server, the Task Manager and the Trade
    Information Server, which run all on grid
    machines.
  • The User Agent Server is used to receive user
    service requests from UGAs and to forward trading
    results to UGAs.

22
3 An E-Commerce Grid Architecture (11)
  • Trade Information Server provides the exhibition
    of bulletin information and market directory for
    registered grid users, and can rearrange trade
    information in the order required.
  • Users may competitively set the resource price
    and advertise their services and requirements in
    the market directory.

23
3 An E-Commerce Grid Architecture (12)
  • Task Manager consists of a set of the tasks sent
    by UGAs, which can be executed independently.
  • Task Manager is responsible for choosing resource
    providers for consumers vice versa, through
    price-benefit analysis providing the
    well-balanced the profits.

24
3 An E-Commerce Grid Architecture (13)
  • Task Manager also provides control commands for
    each bargaining to pause, kill, and monitor the
    execution of applications and tasks.
  • When some players are matched optimally for the
    same kind of goods, GTBs inform instantaneously
    the involved users via their UGAs and initiate
    this bargaining.

25
3 An E-Commerce Grid Architecture (14)
  • During the bargaining execution, resource
    providers and consumers may further negotiate for
    resource trade price, time and performance to
    maximize their objectives.
  • Each bargaining in the Task Manager is composed
    of two executables or scripts the home task and
    the grid task. The home task runs on the user
    machine.

26
3 An E-Commerce Grid Architecture (15)
  • Task Manager invokes the home task when the
    requirements of the corresponding user are
    satisfied optimally by the services of the other
    users.
  • The grid task runs on a grid machine and performs
    this bargaining.
  • Once finishing this bargaining, the grid task
    will send in time the trading results to the
    corresponding providers and consumers.

27
3 An E-Commerce Grid Architecture (16)
  • Fig.2 shows a sequence of the actions that place
    in executing a bargaining under the G-E-commerce
    architecture composed of two user grid agents
    belonging to the same GTB.
  • Step (3) is used to add user requirements to and
    to delete user requirements implemented or
    withdrawn from the Trade Information Server.

28

29
3 An E-Commerce Grid Architecture (17)
  • Step (4) is used to transfer the matched user
    requests from the User Agent Server to the Task
    Manager, and to transmit in turn the message
    describing the end of a bargaining.
  • The negotiation between the providers and
    consumers can be implemented automatically inside
    GTBs, if they want to do so. In this case, steps
    7, (8a), (8b), (9a) and (9b) can be omitted

30
4 Petri Net Model of G-E-Commerce (1)
  • we focus on the modeling of a Grid Trade Broker
    using Petri nets (see Fig.3).
  • Two types of places control places and data
    places, and two types of tokens control tokens
    and data tokens.
  • Control places are used to deposit control
    tokens, data places to deposit data tokens.

31
4 Petri Net Model of G-E-Commerce (2)
  • By means of workflow technologies, each component
    has only one control token at any moment, and is
    a cyclic workflow process.
  • Each transition represents an action, and its
    firing means that the action is executed.

32
4 Petri Net Model of G-E-Commerce (3)
  • Fig. 3 shows the Petri net model of a Grid Trade
    Broker only including a pair of collaborative
    User Grid Agents (a provider and a consumer).
  • The passing value dependencies between the three
    components are represented by data places.

33
4 Petri Net Model of G-E-Commerce (4)
  • Each component has a cyclic workflow and has
    placed one control token in its initial marking.
  • The three workflows may run in parallel on
    different grid machines while implementing their
    cooperative work within the Grid Trade broker.

34

35
4 Petri Net Model of G-E-Commerce (5)
  • Notice that there is only one trade process in
    the Trade Manager of this example.
  • In practice, we may deploy in parallel several
    same trade processes running on different grid
    machines, to enhance the performance of Trade
    Manager and to avoid the overload of the matched
    user requests.

36
5 Analysis of G-E-Commerce (1)
  • By Fig.3, we can obtain the following properties
    of G-E-commerce and their formal representations.
  • Property 1 (All firing sequences of the actions
    in each component is monitored strictly by the
    specified workflow process.)
  • For any reachable marking M in the Petri net
    model, i?1,2,3, there exists a unique
    j?1,2,?,8 such that M(Cij)1.

37
5 Analysis of G-E-Commerce (2)
  • Property 2 (Each user request from a registered
    User Grid Agent can be processed by the User
    Agent Server.)
  • If M is a marking in the Petri net model of the
    User Agent Server, M(C21)1, and
    M(UGA-1)?1?M(UGA-2)?1, then there is a marking M?
    reachable from M such that M?(C28)1.

38
5 Analysis of G-E-Commerce (3)
  • Property 3 (The User Agent Server does not
    discriminate any UGA, while the Trade Manager
    does not discriminate any pair of matched users.)
  • Let M be a marking in the Petri net model, for
    any i?1,2, if accept-i is firable at M, then it
    can fire eventually at a marking reachable from
    M. And each token in matched-user will be removed
    eventually by firing start-trade.

39
5 Analysis of G-E-Commerce (4)
  • Property 4 (The bargaining of each pair of
    matched users is finished eventually in the Trade
    Manager.)
  • If there exists a marking M reachable from the
    initial marking M0 such that M(C31)1 and
    M(matched-user) ?1, then ?M??R(M) and M?(C37)1.

40
6 Conclusion and Future Work (1)
  • G-E-commerce can be employed as the next
    generation E-commerce platform, once the
    corresponding software system is developed.
  • It makes sufficiently use of the Grid sources to
    implement quickly various electronic transactions
    between the remote users.

41
6 Conclusion and Future Work (2)
  • The usage of the Grid Trade Broker can avoid
    leading to a performance bottleneck.
  • Further work will be to apply high-level Petri
    nets and branching-time temporal logic to
    modeling and verification of the G-E-commerce
    architecture.
  • we will also develop a model-checking tool of
    G-E-commerce.

42
  • Thank You
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