VIRTUAL ACTIVE IP NODE FOR COLLABORATIVE
ENVIRONMENTS
Francisco Puentes, Víctor Carneiro
Information and Communication Technologies Departament University of A Coruña. Campus de Elviña S/N, 15071 - A
Coruña (Spain)
Keywords: Virtual active networks
Abstract: The present document describes the VAIN architecture (Virtu
al Active IP Node), which enables users to
deploy new network services based on virtual active networks, and how it solves the challenge of
segmenting the incoming traffic that crosses nodes towards the services, conserving the original objective of
independence of the protocol (Tennenhouse,1996). Our solution is based on using network expressions that
use all the semantic contained in each incoming packet, which does not need to know the inner structure of
the protocols. VAIN architecture has been development to response to challenges outlined by electronic
commerce, specifically those regarding to collaborative environments and marketplaces. To achieve this
objective we have considered the following goals: first, a three layer conceptualization; second, a
transparent implantation and its integration with existing infrastructures; and third, a strategy of network
traffic distribution based in all the information within the input packets, which is named “expressions based
distribution”.
1 INTRODUCTION
Since its proposal (Tennenhouse,1996), active
networks (networks formed by programmable
devices which are able to perform tasks on demand
over the traffic that crosses them) have turned into a
special research area with excellent works and
projects. Its success within the research community
is probably due to the fact that all involved
researchers understand this technology as a step
forward, opposite to traditional networks, since
nowadays active networks are able to perform
processes than traditional networks can not.
Traditional networks make a special emphasis in the
net
work structure and guarantee the information
delivery to the application which it serves in a
suitable time. Each intermediate device which
constitute these networks are specialized in
receiving packets of information, performing a
minimum set of tasks (typically over protocol
headers and therefore they are limited to the
structural aspects of communications ignoring its
meaning, that is, the packet content), computing next
hop or output’s interface and delivering packets
towards the wire. These networks are data
exchanged systems in which compute capacity relay
on the final elements of the network (client and
server on C/S architecture, for example).
Therefore, nowadays we say the sem
antics of the
communication is responsibility of the final
elements. Actually, communication does not add
meaning to the applications of which it is formed.
Active networks allow communications to be an
essen
tial part of the application’s total meaning,
being able to focus on the solution, that is, the
application, instead of on the transmission part of the
logic. The fact that between two distant points exist
one or more intermediate nodes with the capacity of
sharing logic have a direct consequence: The data
sender or receiver can share logic without need to
become a central server or a transmitter of the
information.
1.1 The needs of a virtual
architecture
Within active networks research virtual active
networks (VANs) are a special area (Gong Su,2001).
VANs are semantic networks which emphasize in
the abstraction of the communications, looking for
new architectures. These VANs have a clear
advantage over no-virtual active networks: they are
flexible and independent of the physical
infrastructure that supports them. However, any
change in the physical infrastructure, for example in
traditional networks, will remarkably affect its
49
Puentes F. and Carneiro V. (2004).
VIRTUAL ACTIVE IP NODE FOR COLLABORATIVE ENVIRONMENTS.
In Proceedings of the Sixth International Conference on Enterprise Information Systems, pages 49-54
DOI: 10.5220/0002602900490054
Copyright
c
SciTePress
design, due to the fact that the design will be highly
depending on addressing, naming and devices.
Hence, in this paper we will go a step forward,
asserting that the existence of a virtual layer, which
contents part of the meaning, not only make the
design more flexible regarding the changes on its
lower structure, but also it allows new ways to think
about communications.
1.2 Active networks and
collaborative commerce
From its beginning, electronic commerce has
evolved from the old EDI to the recent frameworks
like ebXML. The on-line collaboration has enriched
the old ideas giving rise to new concepts, like
collaborative commerce and distributed
marketplaces.
On the other hand, the technologies that give support
to these new forms of on-line work/commerce are
based in the well known concepts of the client/server
architecture through the interchange of messages. In
any case the present solutions only consider the
syntax of the communication, in which the final
nodes interpret the messages. That is, the semantic
of the communication – its meaning – is handled at
the final nodes of the communication, between the
different implied organizations.
We can define the collaborative commerce as the
commercial relations between organizations which
define common objectives and work in a
collaborative way, participating jointly in processes
of business previously decided (Puentes,2003).
Between the tasks to carry out in this context we can
mention the planning and estimations, the
management of the inventory, the management of
the supplying chain, the product design and
development, the manufacture, the logistics and
support to final clients.
We can divide these tasks in two categories: those
that compose the value chain (and therefore
susceptible to be managed by means of outsourcing -
justified via the theory of the integration cost) and
those that serve as support of the communication
with competitors, clients and suppliers (these two
last ones comprising of the supplying chain). The
solutions to automate the first of these categories are
the family of technologies associated with the
collaborative work, the second with e-marketplaces.
The collaboration in this last one is also susceptible
to be reached through technologies that are applied
to the first one (Tennenhouse,1996).
Current solutions to these needs are solved through
an external organization, the integration
intermediary, which manages, control and order the
interactions between its users. This highly
centralized approach is consequence of the
conceptualization of the solutions under a C/S
scheme. Active networks have the suitable features
to support new ways of on-line working and thus to
allow new forms of collaborative work. Virtual
active networks provide the necessary level of
abstraction to give an independent solution from the
lower platform and to allow the designer to focus
specifically in the business logic. We have
implanted VAIN (Virtual Active IP Network)
architecture, which proposes a virtual design
specially thought for the on-line collaboration with
the aim of implanting virtual collaboration processes
as marketplaces.
More specifically, active networks have a set of
features that make them appropriate to implant the
semantic of the business layer under a single
Virtual plane
Execution plane
Communication plane
Virtual active node
Active node
Network device
Emissar
y
Receptor
Final communication line
N:1 projection
(not easy)
0:1 projection
(
eas
y)
Figure 1: Relations between planes
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solution: The nodes of an active network have the
features of flexibility and abstraction regarding their
behavior as elements of a communication network.
This necessity from adaptability to its environment
turns active nodes in a highly programmable element
since its behavior is susceptible to be modified
voluntarily; and abstraction, since the processes or
services are not known a priori will render to the
network to which it belongs.
On the other hand the forms to conceive the business
planes are directly related to the semantics of the
application in particular, which makes difficult to
elaborate a common technology for all casuistry.
The adaptation of the solution to the particular
semantics in each case, although viable, is not
optimal. Thanks to it the active networks can support
the implantation of solutions that have into account
not only the syntax of the logic of businesses, but
also their semantics on the own network, providing
different strategies and new and powerful designs.
1.3 Routing in active nodes
Active nodes are network devices that are able to
process packets of data crossing them. This capacity
of processing is dynamic, in such a form that the
incoming traffic can contain the code that the node
has to execute for a certain subgroup of packets that
it handles.
A very important stage of the routing in the
traditional devices is the selection of the following
jump which is done taking into account the
characteristics of the packet and the state of the same
device, which usually changes little between packet
and packet. We will talk in this document about this
selection as the distribution of the incoming traffic
in information flows, formed by individual packets
that fulfil a same criterion.
Basically, the proposed solutions until now presents
the feature of distributing the guest code data by
means of its inclusion in the processed traffic
(capsules, active packets) or by means of a dynamic
programming of the node (programmable nodes).
The execution of guest code (the semantic) in
execution environments makes the services. The
design of the node allows selecting what packet
must go towards a specific service.
One of the initial objectives of the active networks
research group (Tennenhouse,1996) has been to
design networks with capacity of fine re-
programming so that they can allow new protocols
in a transparent way. Therefore, a good design of an
active node does not have to circumscribe to a
specific protocol. In fact, it will allow the node to
manage new protocols.
Until now the proposed solutions have a basic
problem: how to segment the incoming traffic and to
distribute it towards its active services. It is
necessary a criterion in each individual packet to
allow selecting a specific target execution
environment. A first approach to solve this question
could be to use the origin and target address as a
selection criteria, with the main disadvantage of not
allowing to distinct more than a flow for each pair
(sender, receptor). Other way to solve this question,
which is the most used solution, is to use the field
"port" of the transport protocols to distribute the
traffic, nevertheless these causes that this traffic has
necessary a TCP or UDP layer (in the case of IP
networks) and therefore it is committed to use these
protocols., besides loosing the necessary flexibility.
Our approach is oriented to guarantee flexibility,
creating a design of active nodes that does not fit its
traffic to a particular protocol and thus allowing
using anyone, even without knowing it a priori, but
preserving the capacity to segment the traffic in a
powerful and individual way.
VAIN architecture has been thought to be used over
IP protocol, nevertheless this is not a limitation,
since it is possible to extend its operation to other
existing protocols or designs. VAIN does not force
at any moment to use a specific network protocol,
although it recognizes the traditional ones by means
of his declaration in the "network scheme". This
scheme can be completed in-band or out-band with
new designs without the need of re-programming the
node entirely or affecting other flows of information.
The following sections will show the VAIN
architecture describing its fundamental components:
The description of the model as three layer
architecture, the internal architecture of the node, its
implantation and the deployment stages for using it.
2 VAIN - VIRTUAL ACTIVE IP
NODE
As we have already said, VAIN has been designed
for marketplaces and collaborative commerce. This
goal is reached through an abstraction layer that
enables complex designs that look for the
collaboration between final entities. These entities
only need to agree in the operations of their business
since the architecture hides the peculiarities of the
network. At the same time this abstraction allows
independence between the virtual design and the
infrastructures of the communication supplier.
VIRTUAL ACTIVE IP NODE FOR COLLABORATIVE ENVIRONMENTS
51
2.1 Three layers virtual active
networks
Our solution is addressed to support collaborative
commerce on Internet and is based on
conceptualizing the active nodes as devices of three
layers: (1) Communications layer: where the
communication between active nodes and other
devices assures the network connectivity. (2)
Execution layer: its goal is to control the execution
of the Execution Environments (EE) and to
guarantee the right security and concurrence rules.
(3) Virtual layer: This one is the result of the
semantic of the guest code (the result of its
execution in an active node).
The sum of the layers of each one of the network
elements in an active network makes planes [figure
1]: (1) The communication plane includes the
traditional network on which is based the
infrastructure of active network. It has an own
addressing. The responsibility of this structure falls
into the transmission of packets between units of
commutation throughout all the plane (or sub plane).
(2) The execution plane is where the active nodes
give the required functionalities to equip the network
with the programming features. (3) And the virtual
plane establishes the lines, hosts, nodes and other
entities of the communication. It is projected over
the lower plane so that a given design is independent
of the lower ones (communications and execution).
As its name indicates, its semantic will change
depending on the services that implant it. This plane
organizes the partial semantics of the solution, that
is, the partial interaction of its elements in a tree
way, having as root the host leader and as terminals
the virtual active nodes called "meeting points".
The virtual active nodes correspond with EE of
physical nodes so that, although the design implies
more of a virtual node, it is executed in the same
physical node if the circumstances and restrictions
allow it. The communication lines establish the
directions and the starting and final points of the
flows of data between hosts and virtual nodes. They
do not correspond, necessary, with traditional
communication lines between network devices,
since they can be communications into the node.
Hosts can be source or target of these
communication lines and can be specialized.
2.2 Notation of a virtual plane
The different elements from the virtual plane are
integrated in the following notation [figure 2]: the
entities can have associated labels of diverse nature,
final hosts can take their name and direction; the
active nodes virtual labels do mention not only to its
address, but also to the requirements that must fulfil
(owner, features, modules, etc); meeting points
Initial or final entit
y
of the communication (leader hosts).
Pure virtual active node (VAN): point of execution of
g
uest code.
Meetin
g
point (MP) executin
g
g
uest code.
Meetin
g
area (MA): administrative zone of meetin
g
.
Area name
Virtual line of communications between elements (no safe line)
Virtual line of communications between elements (safe line, IPSec)
Line of communications with more than an element as ori
g
in
Line of communications with external elements to the virtual plane
Figure 2: Elements of the virtual plane
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(MP), like nodes of special purpose, inherit labels of
the pure virtual active nodes (VAN); meeting areas
(MA) have their administrative address and/or its
name; finally, the lines of communications can be
labeled with the name of the protocol – or protocols
– that they will support, in addition to the
restrictions in the ends, relative to the number of
maximum connections allowed. The [figure 2]
details the graphical elements associated with the
conceptual elements.
Two last graph lock up the semantics related
respectively to communications between an
indeterminate number of entities and
communications with entities outside the virtual
plane. First one adds to the design the notation to
show than an indeterminate number of elements (the
black point) will communicate with the related
entity. This graph will have, at the end of the well-
known organization, a label that indicates the
maximum number of simultaneous connections, as
well as the used protocol. An end of this line will
connect with a node whereas the other with a server
or service. A typical graph will represent a VAN
requesting guest code or necessary data for its
execution to an external server. Both graphs can be
represented by double lines to indicate a safe
communication.
3 THE VIRTUAL ACTIVE IP
NODE (VAIN) ARCHITECTURE
The technology that we have developed for the
construction of VAIN architecture is based on a
distribution process sufficiently rich and complex to
allow segmenting the incoming traffic using any
criterion, but conserving the flexibility of not fitting
the solution to a protocol or set of certain protocols.
The exposition has been "to make the distribution of
the incoming traffic using an expression that uses all
the possible semantics at the moment in which a
packet enters into the node". Our solution has been
to have as the criterion of segmentation of traffic to
flow, not only a concrete field of the head of packet
with a known protocol, but also a complex
expression that relates any value of this packet
without needing to know anything about the used
protocol.
As objective, this expression must recognize the
ownership of a certain packet and deliver a concrete
data flow to its corresponding service.
3.1 Stages of the distribution
There are two stages in the distribution: The creation
of the packet dictionary and the selection of the
target service.
The creation of the packet map, which is the
application of a network scheme that allows
recognizing the atomic units of information that the
packet contains, is carried out when the packet
enters in the node. The packet dictionary is created
at the same time that the map is outlined and intends
to define a set of pairs (field, value) that agglutinates
all the semantics recognized by the scheme of
network for that specific packet.
Finally, the selection process uses the dictionary
generated in the previous stage to evaluate the
network expressions and therefore to discover the
target services of the packet.
I/O Modules have two goals (1) To isolate node
engine from the special features of the data capture
and of the injection on the wire; (2) To allow
isolating the different net address formats. Although
VAIN have been created to run over IP, it is so easy
extending it to IPX, ATM or any other format that
fulfil requirements of an OSI net layer (or even link
layer).
3.2 The network scheme
The network expressions combine operands and
operators (logical, arithmetic, relational and bit
level) forming a complex expression. The operators
can be constant or references, the latter are solved by
using the packet dictionary created in the first stage
of the distribution.
Basically the network scheme indicates all structural
possibilities of a packet. Its declaration is made in
the node dictionary (its repository of information) in
XML format, and in memory, like a directed graph
(and at the same time like a list doubly connected).
The scheme can be public (one per node) or private
(one or more per service). The services can
incorporate entries (in runtime and in XML format)
so that the process recognizes private network
schemes. The packet dictionary is the result of the
creation its map. It is used as repository of
information in the resolution of the network
expressions, where references to the fields are
solved as they are needed.
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4 IMPLANTATION AND
CURRENT STATE
In this document we have shown an architecture
which allows us to increase the semantic of a
communication, stating that logic can be shared
between participants without the need of a central
point that coordinates them. Mainly, VAIN allow
each participant to design their own virtual active
network and extend it along Internet allowing
“points of presence” (services) which interact with
others one from others users.
Expressions based delivery is a powerful and
flexible tool to deliver input traffic into services,
allowing these to be able to be used smartly,
adapting itself to any situation, present and future.
The advantage of this strategy with respect to others
is clear: the independence of the native code of the
node regarding the traffic that crosses it. In addition
it allows the implantation of a node without knowing
the protocols that will handle those of network level
and link beforehand.
However the proposed solution presents a clear
drawback: efficiency. Inside the implantation of the
node finding and measuring bottle necks are
fundamental. In our architecture we have basically
two: the distribution of packets and the processing of
these in the services.
The design of the virtual plane that we have
proposed tries to link under a single implantation the
solutions to the collaboration challenges and
marketplaces, reached under different technological
solutions until now. The virtual plane joins the
partial semantics of the solution; our challenge from
now on is to add its complete, enriching the notation
and implanting gateway services to other
technological solutions. In addition to this the
transparency of the implantation must be maintained
in order to avoid reaching a point of critical mass,
which will cause the architecture to be a
construction sufficiently ineffective so that it avoids
its growth.
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