Keywords: protocols, internet, applications
Network Working Group B. Aiken
Request for Comments: 2768 J. Strassner
Category: Informational Cisco Systems
B. Carpenter
IBM
I. Foster
Argonne National Laboratory
C. Lynch
Coalition for Networked Information
J. Mambretti
ICAIR
R. Moore
UCSD
B. Teitelbaum
Advanced Networks & Services, Inc.
February 2000
Network Policy and Services:
A Report of a Workshop on Middleware
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Abstract
An ad hoc middleware workshop was held at the International Center
for Advanced Internet Research in December 1998. The Workshop was
organized and sponsored by Cisco, Northwestern University's
International Center for Advanced Internet Research (iCAIR), IBM, and
the National Science Foundation (NSF). The goal of the workshop was
to identify existing middleware services that could be leveraged for
new capabilities as well as identifying additional middleware
services requiring research and development. The workshop
participants discussed the definition of middleware in general,
examined the applications perspective, detailed underlying network
transport capabilities relevant to middleware services, and then
covered various specific examples of middleware components. These
included APIs, authentication, authorization, and accounting (AAA)
issues, policy framework, directories, resource management, networked
information discovery and retrieval services, quality of service,
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security, and operational tools. The need for a more organized
framework for middleware R&D was recognized, and a list of specific
topics needing further work was identified.
Table of Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.0 Contextual Framework . . . . . . . . . . . . . . . . . . . . 3
2.0 What is Middleware? . . . . . . . . . . . . . . . . . . . . 4
3.0 Application Perspective . . . . . . . . . . . . . . . . . . 6
4.0 Exemplary Components . . . . . . . . . . . . . . . . . . . . 7
5.0 Application Programming Interfaces and Signaling . . . . . . 8
6.0 IETF AAA . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.0 Policy . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.0 Directories . . . . . . . . . . . . . . . . . . . . . . . . 12
9.0 Resource Management . . . . . . . . . . . . . . . . . . . . 15
10.0 Networked Information Discovery and Retrieval Services . . . 17
11.0 Network QOS . . . . . . . . . . . . . . . . . . . . . . . . 18
12.0 Authentication, authorization, and access management . . . . 21
13.0 Network Management, Performance, and Operations . . . . . . 22
14.0 Middleware to support multicast applications . . . . . . . . 23
15.0 Java and Jini TM . . . . . . . . . . . . . . . . . . . . . . 24
16.0 Security Considerations . . . . . . . . . . . . . . . . . . 24
17.0 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 24
18.0 Participants . . . . . . . . . . . . . . . . . . . . . . . . 26
19.0 URLs/references . . . . . . . . . . . . . . . . . . . . . . 27
20.0 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 27
21.0 Full Copyright Statement . . . . . . . . . . . . . . . . . . 29
Introduction
This document describes the term "middleware" as well as its
requirements and scope. Its purpose is to facilitate communication
between developers of both collaboration based and high-performance
distributed computing applications and developers of the network
infrastructure. Generally, in advanced networks, middleware consists
of services and other resources located between both the applications
and the underlying packet forwarding and routing infrastructure,
although no consensus currently exists on the precise lines of
demarcation that would define those domains. This document is being
developed within the context of existing standards efforts.
Consequently, this document defines middleware core components within
the framework of the current status of middleware-related standards
activities, especially within the IETF and the Desktop Management
Task Force (DMTF). The envisioned role of the IETF is to lead the
work in defining the underlying protocols that could be used to
support a middleware infrastructure. In this context, we will
leverage the information modeling work, as well as the advanced XML
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and CIM/DEN-LDAP mapping work, being done in the DMTF. (The recently
constituted Grid Forum is also pursuing relevant activities.)
This document also addresses the impact of middleware on Internet
protocol development. As part of its approach to describing
middleware, this document has initially focused on the intersections
among middleware components and application areas that already have
well defined activities underway.
This document is a product of an ad hoc Middleware Workshop held on
December 4-5 1998. The Workshop was organized and sponsored by Cisco,
Northwestern University's International Center for Advanced Internet
Research (iCAIR), IBM, and the National Science Foundation (NSF).
The goal of the workshop was to define the term middleware and its
requirements on advanced network infrastructures as well as on
distributed applications. These definitions will enable a set of core
middleware components to subsequently be specified, both for
supporting advanced application environments as well as for providing
a basis for other middleware services.
Although this document is focused on a greater set of issues than
just Internet protocols, the concepts and issues put forth here are
extremely relevant to the way networks and protocols need to evolve
as we move into the implementation stage of "the network is the
computer". Therefore, this document is offered to the IETF, DMTF,
Internet2, Next Generation Internet (NGI), NSF Partnerships for
Advanced Computational Infrastructure (PACI), the interagency
Information Technology for the 21st Century (IT2) program, the Grid
Forum, the Worldwide Web Consortium, and other communities for their
consideration.
This document is organized as follows: Section 1 provides a
contextual framework. Section 2 defines middleware. Section 3
discusses application requirements. Subsequent sections discuss
requirements and capabilities for middleware as defined by
applications and middleware practitioners. These sections will also
discuss the required underlying transport infrastructure,
administrative policy and management, exemplary core middleware
components, provisioning issues, network environment and
implementation issues, and research areas.
1.0 Contextual Framework
Middleware can be defined to encompass a large set of services. For
example, we chose to focus initially on the services needed to
support a common set of applications based on a distributed network
environment. A consensus of the Workshop was that there was really
no core set of middleware services in the sense that all applications
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required them. This consensus does not diminish the importance of
application domain-specific middleware, or the flexibility needed in
determining customized approaches. Many communities (e.g.,
Internet2, NGI, and other advanced Internet constituencies) may
decide on their own set of common middleware services and tools;
however, they should strive for interoperability whenever possible.
The topics in this workshop were chosen to encourage discussion about
the nature and scope of middleware per se as distinct from specific
types of applications; therefore, many relevant middleware topics
were not discussed.
Another consensus of the Workshop that helped provide focus was that,
although middleware could be conceptualized as hierarchical, or
layered, such an approach was not helpful, and indeed had been
problematic and unproductive in earlier efforts.
The better approach would be to consider middleware as an
unstructured, often orthogonal, collection of components (such as
resources and services) that could be utilized either individually or
in various subsets. This working assumption avoided extensive
theological modeling discussions, and enables work to proceed on
various middleware issues independently.
An important goal of the Workshop was to identify any middleware or
network-related research or development that would be required to
advance the state of the art to support advanced application
environments, such as those being developed and pursued by NGI and
Internet2. Consequently, discussion focused on those areas that had
the maximum opportunity for such advances.
2.0 What is Middleware?
The Workshop participants agreed on the existence of middleware, but
quickly made it clear that the definition of middleware was dependent
on the subjective perspective of those trying to define it. Perhaps
it was even dependent on when the question was asked, since the
middleware of yesterday (e.g., Domain Name Service, Public Key
Infrastructure, and Event Services) may become the fundamental
network infrastructure of tomorrow. Application environment users
and programmers see everything below the API as middleware.
Networking gurus see anything above IP as middleware. Those working
on applications, tools, and mechanisms between these two extremes see
it as somewhere between TCP and the API, with some even further
classifying middleware into application-specific upper middleware,
generic middle middleware, and resource-specific lower middleware.
The point was made repeatedly that middleware often extends beyond
the "network" into the compute, storage, and other resources that the
network connects. For example, a video serving application will want
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to access resource discovery and allocation services not just for
networks but also for the archives and computers required to serve
and process the video stream. Through the application of general set
theory and rough consensus, we roughly characterize middleware as
those services found above the transport (i.e., over TCP/IP) layer
set of services but below the application environment (i.e., below
application-level APIs).
Some of the earliest conceptualizations of middleware originated with
the distributed operating research of the late 1970s and early 1980s,
and was further advanced by the I-WAY project at SC'95. The I-WAY
linked high performance computers nation-wide over high performance
networks such that the resulting environment functioned as a single
high performance environment. As a consequence of that experiment,
the researchers involved re-emphasized the fact that effective high
performance distributed computing required distributed common
computing and networking resources, including libraries and utilities
for resource discovery, scheduling and monitoring, process creation,
communication and data transport.
Subsequent research and development through the Globus project of
such middleware resources demonstrated that their capabilities for
optimizing advanced application performance in distributed domains.
In May 1997, a Next Generation Internet (NGI) workshop on NGI
research areas resulted in a publication, "Research Challenges for
the Next Generation Internet", which yields the following description
of middleware. "Middleware can be viewed as a reusable, expandable
set of services and functions that are commonly needed by many
applications to function well in a networked environment". This
definition could further be refined to include persistent services,
such as those found within an operating system, distributed operating
environments (e.g., JAVA/JINI), the network infrastructure (e.g.,
DNS), and transient capabilities (e.g., run time support and
libraries) required to support client software on systems and hosts.
In summary, there are many views of what is middleware. The consensus
of many at the workshop was that given the dynamic morphing nature of
middleware, it was more important to identify some core middleware
services and start working on them than it was to come to a consensus
on a dictionary-like definition of the term.
Systems involving strong middleware components to support networked
information discovery have also been active research areas since at
least the late 1980s. For example, consider Archie or the Harvest
project, to cite two examples. One could easily argue that the site
logs used by Archie or the broker system and harvest agents were an
important middleware tool, and additional work in this area is
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urgently needed in order to improve the efficiency and scope of web-
based indexing services.
"As long ago" as 1994, the Internet Architecture Board held a
workshop on "Information Infrastructure for the Internet" reported in
RFC 1862, which in many ways covered similar issues. Although its
recommendations were summarized as follows:
- increased focus on a general caching and replication architecture
- a rapid deployment of name resolution services, and
- the articulation of a common security architecture for information
applications."
it is clear that this work is far from done.
Finally, this workshop noted that there is a close linkage between
middleware as a set of standards and protocols and the infrastructure
needed to make the middleware meaningful. For example, the DNS
protocol would be of limited significance without the system of DNS
servers, and indeed the administrative infrastructure of name
registry; NTP, in order to be useful, requires the existence of time
servers; newer middleware services such as naming, public key
registries and certificate authorities, will require even more
extensive server and administrative infrastructure in order to become
both useful and usable services.
3.0 Application Perspective
From an applications perspective, the network is just another type of
resource that it needs to use and manage. The set of middleware
services and requirements necessary to support advanced applications
are defined by a vision that includes and combines applications in
areas such as: distributed computing, distributed data bases,
advanced video services, teleimmersion (i.e., a capability for
providing a compelling real-life experience in a virtual environment
based for example on CAVE technologies), extensions with haptics,
electronic commerce, distance education, interactive collaborative
research, high-rate instrumentation (60 MByte/s and above sustained),
including use of online scientific facilities (e.g. microscopes,
telescopes, etc.), effectively managing large amounts of data,
computation and information Grids, adaptable and morphing network
infrastructure, proxies and agents, and electronic persistent
presence (EPP). Many of these applications are "bleeding edge" with
respect to currently deployed applications on the commodity Internet
and hence have unique requirements. Just as the Web was an advanced
application in the early 1990s, many of the application areas defined
above will not become commonplace in the immediate future. However,
they all possess the capability to change the way the network is used
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as well as our definition of infrastructure, much as the Web and
Mosaic changed it in the early 90s. A notable recent trend in
networks is the increasing amount of HTTP, voice, and video traffic,
and it was noted that voice and video particularly need some form of
QoS and associated middleware to manage it.
A quick review of the requirements for teleimmersion highlight the
requirement for multiple concurrent logical network channels, each
with its own latency, jitter, burst, and bandwidth QoS; yet all being
coordinated through a single middleware interface to the application.
For security and efficiency those using online instruments require
the ability to steer the devices and change parameters as a direct
result of real-time analysis performed on the data as it is received
from the instruments. Therefore, network requirements encompass high
bandwidth, low latency, and security, which must all be coordinated
through middleware. Large databases, archives, and digital libraries
are becoming a mainstay for researchers and industry. The
requirements they will place on the network and on middleware will be
extensive, including support of authentication, authorization, access
management, quality of service, networked information discovery and
retrieval tools, naming and service location, to name only a few.
They also require middleware to support collection building and
self-describing data. Distributed computing environments (e.g.,
Globus, Condor, Legion, etc.) are quickly evolving into the computing
and information Grids of the future. These Grids not only require
adaptive and manageable network services but also require a
sophisticated set of secure middleware capabilities to provide easy-
to-use APIs to the application.
Many application practitioners were adamant that they also required
the capability for "pass through" services. This refers to the
ability to bypass the middleware and directly access the underlying
infrastructure such as the operating system or network), even though
they were eager to make use of middleware services and see more of it
developed to support their own applications. In addition,
authentication and access control, as well as security, are required
for all of the applications mentioned above, albeit at different
levels.
4.0 Exemplary Components
In an attempt to describe middleware and discuss pertinent issues
relating to its development and deployment, an exemplary set of
services were selected for discussion. These services were chosen to
stimulate discussion and not as an attempt to define an exclusive set
of middleware services. Also, it is the intent of this effort not to
duplicate existing IETF efforts or those of other standards bodies
(e.g., the DMTF), but rather to leverage those efforts, and indeed to
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highlight areas where work was already advanced to a stage that might
be approaching deployment.
5.0 Application Programming Interfaces and Signaling
Applications require the ability to explicitly request resources
based on their immediate usage needs. These requests have associated
network management controls and network resource implications;
however, fulfillment of these requests may require multiple
intermediate steps. Given the preliminary state of middleware
definition, there currently is no common framework, much less a
method, for an application to signal its need for a set of desired
network services, including quality and priority of service as well
as attendant resource requirements. However, given the utility of
middleware, especially with regard to optimization for advanced
applications, preliminary models for both quality and priority of
service and resource management exist and continue to evolve.
however, without an agreed-to framework for standards in this area,
there is the risk of multiple competing standards that may further
delay the deployment of a middleware-rich infrastructure. This
framework should probably include signaling methods, access/admission
controls, and a series of defined services and resources. In
addition, it should include service levels, priority considerations,
scheduling, a Service-Level-Agreement (SLA) function, and a feedback
mechanism for notifying applications or systems when performance is
below the SLA specification or when an application violates the SLA.
Any such mechanism implies capabilities for: 1) an interaction with
some type of policy implementation and enforcement, 2) dynamic
assessment of available network resources, 3) policy monitoring, 4)
service guarantees, 5) conflict resolution, and 6) restitution for
lack of performance.
Application programmers are concerned with minimizing the interfaces
that they must learn to access middleware services. Thus the
unification of common services behind a single API is of great
interest to middleware users. Examples of common APIs that may be
achievable are:
* Environmental discovery interface, whether for discovering hardware
resources, network status and capabilities, data sets,
applications, remote services, or user information.
* Remote execution interface, whether for distributed metacomputing
applications, or for access to a digital library presentation
service, or a Java analysis service.
* Data management interface, whether for manipulating data within
distributed caches, or replication of data between file systems, or
archival storage of data.
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* Process management interface, whether for composing data movement
with remote execution, or for linking together multiple processing
steps.
6.0 IETF AAA
The IETF AAA (authentication, authorization, and accounting) effort
is but one of many IETF security initiatives. It depends heavily on a
Public key infrastructure, which is intended to provide a framework
which will support a range of trust/hierarchy environments and a
range of usage environments (RFC1422 is an example of one such
model).
The IETF AAA working group has recently been formed. IETF AAA working
group efforts are focused on many issues pertaining to middleware,
including defining processes for access/admission control and
identification (process for determining a unique entity),
authentication (process for validating that identity), authorization
(process for determining an eligibility for resource
requests/utilization) and accounting (at least to the degree that
resource utilization is recorded). To some degree, AAA provides for
addressing certain levels of security, but only at a preliminary
level. Currently, AAA protocols exist, although not as an integrated
model or standard. One consideration for AAA is to provide for
various levels of granularity. Even if we don't yet have an
integrated model, it is currently possible to provide for basic AAA
mechanisms that can be used as a basis to support SLAs. Any type of
AAA implementation requires a policy management framework, to which
it must be linked. Currently, a well-formulated linking mechanism has
not been defined.
Middleware AAA requirements are also driven by the distributed
interoperation that can occur between middleware services. The
distribution of application support across multiple autonomous
systems will require self-consistent third-party mechanisms for
authentication as well as data movement. Conceptually, an
application may need access to data that is under control of a remote
collection, to support the execution of a procedure at a third site.
The data flow needs to be directly from the collection to the
execution platform for efficiency. At the same time, the procedure
will need access permission to the data set while it is acting on
behalf of the requestor. How the authentication is done between the
remote procedure and the remote data collection entities raises
significant issues related to transitivity of trust, and will require
establishment of a trust policy for third-party mechanisms. This is
exacerbated when a collection of entities, such as is required for
visualization applications, is involved.
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7.0 Policy
The IETF Policy Framework working group is addressing a policy
framework definition language, a policy architecture model, policy
terminology and, specifically, a policy model that can be used for
signaled as well as provisioned QoS. The policy meta-model links
high-level business requirements, such as those that can be specified
in an SLA, to low-level device implementation mechanisms, ranging
from specific access control and management of services, objects and
other resources to configuration of mechanisms necessary to provide a
given service.
Polices are an integral component of all middleware services, and
will be found within most middleware services in one form or another.
Policies are often represented as an "if condition then action"
tuple. Policies can be both complex and numerous; therefore, policy
management services must be able to identify and resolve policy
conflicts. They also need to support both static (i.e. loaded at
boot time via a configuration file) and dynamic (i.e. the
configuration of a policy enforcing device may change based on an
event) modes.
A generalized policy management architecture (as suggested by the
IETF policy architecture draft) includes a policy management service,
a dedicated policy repository, at least one policy decision point
(PDP), and at least one policy enforcement point (PEP). The policy
management service supports the specification, editing, and
administration of policy, through a graphical user interface as well
as programmatically. The policy repository provides storage and
retrieval of policies as well as policy components. These policy
components contain definitional information, and may be used to build
more complex policies, or may be used as part of the policy decision
and/or enforcement process. The PDP (e.g. resource manager, such as a
bandwidth broker or an intra-domain policy server) is responsible for
handling events and making decisions based on those events (e.g., at
time x do y) and updating the PEP configuration appropriately. In
addition, it may be responsible for providing the initial
configuration of the PEP. The PEP (e.g., router, firewall or host)
enforces policy based on the "if condition then action" rule sets it
has received from the PDP.
Policy information may be communicated from the PDP to the PEP
through a variety of protocols, such as COPS or DIAMETER. A proxy may
be used to translate information contained in these protocols to
forms that devices can consume (e.g., command line interface commands
or SNMP sets). Additional information, contained in Policy
Information Bases (PIBs), may also be used to translate from an
intermediate specification to specific functions and capabilities of
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a device. For example, a policy may specify "if source IP address is
198.10.20.132, then remark traffic with a DSCP of 5". The PIB would
be used to translate the device-specific meaning of the conditioning
specified by the DiffServ code point of 5 (e.g., a specific set of
queue and threshold settings).
Policy requires AAA functions, not only for access control, but also
to establish the trust relationships that will enable distributed
policy interactions. PDPs may require the requesting end systems and
applications to be authenticated before the PDP will honor any
requests. The PDP and PEP must be authenticated to each other to
reduce the probability of spoofing. This will be true whichever
protocol is utilized for supporting communications between these
entities. Audit trails are essential for all of these transactions.
In addition, trust management policies will need to be developed as
well as the supporting middleware mechanisms to enable inter-domain
policy negotiation.
Ultimately, many policy processes link entities to resources, And
therefore require interactions with entity identification mechanisms,
resource identification mechanisms, and allocation mechanisms. The
distributed computing community has already started efforts
developing policy definition languages and systems. Globus uses its
Resource Services Language (RSL) to define the resources and policies
associated with them. Condor uses a matchmaking bidding technique to
match those providing and those acquiring services. Similarly, the
IETF has several policy definition languages in varying stages of
development, including RPSL, RPCL, SPSL, PFDL, PAX, and Keynote.
Ultimately, these efforts should be merged into a single
specification (or at least a smaller group of specifications) to
enable distributed computing applications to be able to effectively
communicate and utilize network resources and services.
Directories play a crucial role in policy systems. Directories are
ideally suited for storing and retrieving policy information, due to
their exceptionally high read rates, ability to intelligently
replicate all or part of their information, per-attribute access
control, and use of containment. To this end, the IETF Policy
Framework working group (in conjunction with the DMTF) is developing
a core information model and LDAP schema that can be used to
represent policy information that applications can use. This core
model is used to provide common representation and structure of
policy information. Applications can then subclass all or part of the
classes in this core schema to meet their own specific needs, while
retaining the ability to communicate and interoperate with each
other.
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8.0 Directories
Directories are critical resource components that provide support to
many other elements in the middleware environment, especially policy.
As network-based environment evolves, it will no longer be viable to
encode policy information directly into each individual application.
The prevailing model in use today is for each application to store
its view of a device's data (e.g., configuration) in its own private
data store.These data include relevant information concerning network
resources and services as well as clients wanting to use those
resources (e.g., people, processes, and applications). The same
resource (or aspects of that resource, such as its physical vs.
logical characteristics) may be represented in several data stores.
Even if the device is modeled the same way in each data store, each
application only has access to its own data. This leads to
duplication of data and data synchronization problems.
The promise of technologies like CIM and DEN is to enable each
application to store data describing the resources that they manage
in a single directory using a common format and access protocol. This
results in the data describing the resource being represented only
once. Defining a logically centralized common repository, where
resources and services are represented in a common way, enables
applications of different types to utilize and share information
about resources and services that they use.
Not only does this solve the data duplication and synchronization
problems, it also provides inherent extensibility in describing the
characteristics of an object - a single entity can be represented by
multiple directory objects, each representing a different aspect of
the entity. Different applications can be responsible for managing
the different objects that together make up a higher-level object,
even if the applications themselves can not communicate with each
other. This enables these applications to effectively share and reuse
data. This provides significant benefits for users and applications.
In the short term, users and applications will benefit from having
all of the data in one place. In the long term, users and
applications will be able to take advantage of data managed by other
applications.
Directories are key to supporting advanced network-based application
environments. Directory purists say that the directory is not
middleware; rather, it is a dumb storage device that is made into an
intelligent repository by encapsulating it within middleware.
Although a directory associates attributes with objects, what makes
it different from a database are four key things:
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- directory objects are essentially independent of each other,
whereas database objects are related to each other (sometimes in
very complex ways)
- directories organize their information using the notion of
containment, which is not naturally implemented in databases
- directory objects can have specific access controls assigned to an
object and even attributes of an object
- directories, unlike databases, are optimized to perform a high
number of reads vs. writes.
Directories use a common core schema, supporting a common set of
syntaxes and matching rules, that defines the characteristics of
their data. This enables a common access protocol to be used to store
and retrieve data.
Containment can be used for many purposes, including associating
roles with objects. This is critical in order to support a real world
environment, where people and elements may assume different roles
based on time or other context.Containment may also be used to
provide different naming scopes for a given set of data.
Directories use attribute inheritance - subclasses inherit the
attributes of their superclasses. This enables one to define
generalized access control at a container (e.g., a group) and then
refine the access control on an individual basis for objects that are
inside that container (e.g., different objects have different access
privileges).
Currently, directories are used mostly to represent people, servers,
printers, and other similar objects. CIM, DEN, and other similar
efforts have encouraged directories to be used to contain common
objects in a managed environment. For networked applications, this
enables clients of the network (e.g., users and applications) to be
bound to services available in the network in a transparent manner.
The "Grid" community is making extensive use of directory services
for this purpose, using them to maintain information about the
structure and state of not only networks but also computers, storage
systems, software, and people. The DMTF is using directories to
contain CIM and DEN information, which enables a common information
model to be applied to objects in a managed environment. The IETF is
using directories for many different purposes, not the least of which
is to contain common policy information for users and applications of
an environment, as well as services and configuration information of
network devices.
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CIM and DEN are conceptual information models for describing the
management of entities ranging from network elements to protocols to
hosts and services. CIM and DEN are platform- and technology-
independent. DEN is an extension of CIM that, among other things,
describes how to map CIM data into a form usable by LDAP.
The CIM Specification describes the meta schema, information model,
language, naming, and mapping techniques to other management models,
such as SNMP MIBs and DMTF MIFs. DEN provides a good start on a
model that addresses the management of the network and its elements;
DEN is an extension of CIM to include the management of networks as a
whole and not just the individual elements. DEN addresses the
requirements for abstracting a complex entity, such as a router, into
multiple components that can be used to manage individual aspects of
that complex entity. The DEN information model, like CIM,
incorporates both static and dynamic information. DEN provides a
mapping to directories for the storage and retrieval of data. DEN
will also rely heavily on the use of AAA services in order to
maintain the integrity of the directory and its policies as well as
to manage the distribution of policies among the policy repositories,
PDPs and PEPs. Resource managers and applications will also rely
heavily on directories for the storage of policy and security
information necessary for the management and allocation of resources.
Since much of the information associated with a person, agent or
element is stored in a directory, and access to that information will
be controlled with appropriate security mechanisms, many voiced the
need for a single user/process sign on.
Future advanced applications (e.g., NGI, Internet2, PACI, Grids) may
require a variety of PDPs to manage a variety of resource types
(i.e., QOS, security, etc.). In this case, a general model would
have to be developed that defines the protocols and mechanisms used
by cooperating resource managers (i.e., PDPs) of different domains
and different genres of resource (i.e., network, security, storage,
proxy agents, online facility, etc.). For policies to be implemented
in a coherent fashion, it is necessary to have a mechanism that
discovers and tracks resources and utilization.
There is an architectural issue of central importance, which has most
recently surfaced in the directory area. Many applications, and many
middleware components, need what is essentially a highly scalable,
distributed database service. In other words, people want to take the
best of what directories and databases have to offer. This would
result in a distributed, replicated database that can use containment
to effectively organize and scope its information. It would be able
to have exceptional read response time, and also offer transactional
and relational integrity. It would support simple and complex
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queries. Such a service has never been defined as a middleware
component; the complexities involved in specifying and implementing
such a service are certainly formidable. However, in the absence of
such a general service, many middleware components have attempted to
use the closest service available, which is deployed - historically
first using DNS, and more recently, directory services.
It will be important to clarify the limitations of the appropriate
use of directory services, and to consider whether a more general
data storage and retrieval service may be required, or whether
directory services can be seamlessly integrated (from the point-of-
view of the applications using them) with other forms of storage and
retrieval (such as relational databases) in order to provide an
integrated directory service with these capabilities.
9.0 Resource Management
Policy implementation processes need to be linked to Resource
Managers in a more sophisticated way than those that currently exist.
Such processes must be dynamic, and able to reflect changes in their
environment (e.g., adjust the quality of service provided to an
application based on environmental changes, such as congestion or new
users with higher priorities logging onto the system). We need to
determine how different types of resource managers learn about one
another and locate each other - as well as deal with associated
cross-domain security issues. Another aspect of this problem is
developing a resource definition language that can describe the
individual elements of the resource being utilized, whether that is a
network, processor, agent, memory or storage. This will require
developing an appropriate metadata representation and underlying meta
schema that can be applied to multiple resource types.
Some models of resource managers are currently being used to provide
for the management of distributed computing and Grid environments
(e.g., Condor, Globus, and Legion). These resource managers provide
languages, clients, and servers to support accessing various types of
distributed computing resources (e.g. processors, memory, storage and
network access). There is a broad interest in the distributed and
parallel computing communities in developing an automated access
control architecture, using policies, to support the evolving IETF
differentiated services architecture. However, this work has not yet
been incorporated into any IETF working group charter. The term
"bandwidth broker" has been used to refer to the agents that will
implement this functionality through network resource management,
policy control, and automated edge device configuration. The IETF
Policy Framework working group is currently working on a policy
architecture framework, information model, and policy definition
language that is targeted initially at policy management within a
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single domain. However, this work is fundamental in defining inter-
domain policy management issues, such as those that are required in
implementing a network resource manager / bandwidth broker. Many
resource managers being deployed today rely on directory services for
storing policy information as well as X.509 for certificate-based
authentication and authorization to these resources. Middleware will
be required to translate the needs of distributed and parallel
computing applications within and across different policy domains. It
is crucial that a standard means for representing and using resource
management be developed.
Advance reservation of resources, as well as dynamic requests for
resources, is a crucial aspect of any resource management system.
Advance reservations are more of a policy issue than a provisioning
issue; however, the mechanisms for exchanging and propagating such
requests between resource managers located within different
administrative domains is a currently unsolved problem that needs to
be addressed. In addition, it is important to address the issue of
possible deadlock and/or the inefficient use of resources (i.e., the
time period between a request, or set of requests, being initiated
and honored and resources being allocated). There is also a need for
rendezvous management in resource allocation services, where an
application must gather resource reservations involving multiple
sites and services.
A mesh of cooperating resource managers, which interact with each
other using standards based protocols (e.g. COPS), could be the model
for a resource management infrastructure. Each of these may manage
different sets of resources. For example, one may be a bandwidth
broker that only manages network bandwidth, while another may be a
general-purpose resource manager that manages security, IP address
allocation, storage, processors, agents, and other network resources.
There are already plans for middleware resource managers that not
only allocate the resources but also manage the composition of a
group of services that may include security services, billing
services, shaping of multimedia composite images, etc.). Another form
of resource manager may provide mapping between a set of related
services (i.e., mapping an IP based RSVP request to an ATM SVC, as
was demonstrated in a pilot project on the vBNS).
Resource managers depend on the use of locator services to find other
resource managers as well as to locate the AAA server(s) for the
requestor and the associated directories containing applicable policy
information. They may also need to query the network to determine if
a policy request for bandwidth can be satisfied. It is essential that
these (and other) different uses of resource management be integrated
to provide an end-to-end service for applications and users alike.
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10.0 Networked Information Discovery and Retrieval Services
There are a wide range of middleware services broadly related to the
discovery and retrieval of networked information. Because such a
broad range of applications (and not just high-performance,
distributed, or parallel applications) requires these services, this
area is under very active development and new requirements are
constantly emerging.
Perhaps the most basic service in this area is persistent naming and
location services (and infrastructure) that can resolve names to
locations (i.e., URLs). The IETF has done considerable work in
defining a syntax for Uniform Resource Identifiers (URIs), which are
intended to be persistent name spaces administered by a wide range of
agencies. URIs are resolved to URLs using resolver services; there
are a number of different proposals for such resolver services, and
some implementations exist such as the CNRI Handler Service. Many
organizations are beginning to establish and manage URI namespaces,
notably the publishing community with their Digital Object Identifier
(DOI). however, there are many unresolved questions, such as how to
most effectively deal with the situation where the resource named by
a URI exists in multiple places on the network (e.g., find the
"closest" mirror in terms of network connectivity and resource
availability). There is a need for an extensive set of infrastructure
around resolvers, including how resources are registered and
identifiers are assigned, the ongoing management of data about the
current location of resources that are identified by a specific URI,
and the operation of sets of resolvers for various name spaces.
Finally, given a URI, one needs to locate the resolver services that
are connected with that namespace; the IETF has done initial work on
resolution service location for URI namespaces.
URIs are intended to be processed primarily by machines; they are not
intended to necessarily be easy to remember, though they are intended
to be robust under transcription (not sensitive to whitespace, for
example). More recently, the IETF has begun work on defining
requirements for human friendly identifier systems that might be used
to register and resolve mnemonic names.
Another set of issues revolves around various types of metadata -
descriptive, ratings, provenance, rights management, and the like,
that may be associated with objects on the network. The Resource
Description Framework (RDF) from the Worldwide Web Consortium (W3C)
provides a syntax for attaching such descriptions to network objects
and for encoding the descriptions; additional middleware work is
needed to locate metadata associated with objects that may be stored
in repositories, and to retrieve such metadata. Validation of
metadata is a key issue, and both IETF and W3C are working on XML
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canonicalization algorithms that can be used in conjunction with
public key infrastructure to sign metadata assertions. However, such
an approach implies a complex set of trust relationships and
hierarchies that will need to be managed, and policies that will need
to be specified for the use of these trust relationships in
retrieval.
There is specific work going on in defining various types of metadata
for applications such as rights management; ultimately this will
imply the development of middleware services. It will also impact the
use of directory, database, and similar services in the storage,
access, and retrieval of this information. Similarly, there will be a
need for services to connect descriptive metadata and identifiers
(URNs).
(See also the NSF/ERCIM report on metadata research issues at
http://www.ercim.org/publication/ws-proceedings/EU-NSF/metadata.html
http://www.ercim.org/publication/ws-proceedings/EU-NSF/metadata.ps
http://www.ercim.org/publication/ws-proceedings/EU-NSF/metadata.pdf
Finally, there is a need for a set of middleware services which build
upon the research work already integrated into services such as
Archie and Harvest. These services permit the efficient extraction of
metadata about the contents of network information objects and
services without necessarily retrieving and inspecting those
services. This includes the ability to dispatch "indexing agents" or
"knowbots" that can run at a site to compute such indexing, under
appropriate security and authentication constraints. In addition, a
set of "push-based" broker services which aggregate, filter and
collect metadata from multiple sites and provide them to interested
applications are also required. Such services can provide a massive
performance, quality, comprehensiveness and timeliness improvement
for today's webcrawler-based indexing services.
11.0 Network QoS
As noted earlier, applications may need to explicitly request
resources available in the network to meet their requirements for
certain types of communication, or in order to provide service with
an appropriate guarantee of one or metrics, such as bandwidth,
jitter, latency, and loss. One type of request that has been the
focus of much effort recently is for services beyond best effort,
particularly with respect to services running over IP. This is
particularly important for the advanced applications noted previously
(e.g., visualization and teleimmersion) as well as the emerging
importance of voice and video, especially voice and video operating
with lower bandwidth or voice and video co-mingled with data. One
perspective on this issue is to consider the effect of multiple drops
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in a single RTT, which is catastrophic for TCP applications but may
be of no special significance for real-time traffic. Providing for
improved services can be accomplished through a variety of quality of
service (QoS) and class of service (CoS) mechanisms. The first IETF
model was the Integrated Services (IntServ) model, which used RSVP as
the signaling mechanism. Since this model requires state in every
router for every session and to manage the traffic flows, it is
generally recognized to have scaling limits. However, it is very
appropriate for certain situations.
Differentiated Services, or DiffServ, grew out of a reaction against
the perceived scalability problems with the IETF IntServ model.
DiffServ is an architecture for implementing scalable service
differentiation in the Internet. Scalability is achieved by
aggregating traffic through the use of IP-layer packet marking.
Packets are classified and marked to receive a particular per-hop
forwarding behavior on nodes along their path. Sophisticated
classification, marking, policing, and shaping operations need only
be implemented at network boundaries or hosts. Network resources are
allocated to traffic streams by service provisioning policies which
govern how traffic is marked and conditioned upon entry to a
differentiated services-capable network, and how that traffic is
forwarded within that network. These simple PHBs are combined with a
much larger number of policing policies enforced at the network edge
to provide a broad and flexible range of services, without requiring
state or complex forwarding decisions to be performed in the core and
distribution layers.
Recently, the idea of "tunneling" RSVP over a DiffServ-capable
network has generated significant interest. This attempts to combine
the best features of both IntServ and DiffServ while mitigating the
disadvantages of each. This in turn has led the IETF to study ways to
ensure that Differv and Inteserv can not only coexist, but are also
interoperable.
The practical realization of either or both architectures depends on
many middleware components, some of which are described in this
document. The workshop discussion mainly focused on DiffServ
mechanisms and on what effect such mechanisms would have on
middleware and its ability to monitor and manage the network
infrastructure for the benefit of the applications. Both IntServ and
DiffServ only fully make sense if linked to a policy mechanism. This
mechanism must be able to make policy decisions, detect and resolve
conflicts in policies, and enforce and monitor policies.
Workshop participants almost unanimously agreed that they also
required a scalable inter-domain resource manager (e.g., a bandwidth
broker). Currently, if an RSVP session is run, each router along a
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path becomes involved, with flow policing at each hop. Bandwidth
Broker models include the bandwidth broker, a policy decision point
(which makes admission control and policy decisions) and the policy
enforcement points (i.e., edge routers) which provide for policing at
the first hop and for remarking aggregate flows so that subsequent
routers need only deal with the aggregate flows.
IETF protocols that could be used to implement a Bandwidth Broker
model (e.g., COPS, Diameter, and others) were also discussed. The
Diameter protocol is interesting in this context, because it provides
set up mechanisms for basic network resource allocations and
reallocations, as well as optional allocations.- All of these can be
used for various types of bandwidth broker implementations, including
those directed at QoS, using RSVP type information. Diameter
currently does not provide path information, but instead relies on
network pathway information established at ingress and egress nodes.
However, the status of Diameter is still open in the IETF.
COPS was initially developed as a mechanism for establishing RSVP
policy within a domain and remains intra-domain centric. It is a
useful intra-domain mechanism for allocating bandwidth resources
within a policy context. Work is now being conducted to use COPS for
establishing policy associated with a DiffServ-capable network. COPS
is designed to facilitate communication between the PDP and the PEP,
carrying policy decisions and other information.
To implement any type of Bandwidth Broker model, it is necessary to
establish a mechanism for policy exchanges. The Internet2's Qbone
working group is currently working to define a prototype inter-domain
bandwidth broker signaling protocol. This work is being coordinated
with IETF efforts.
Another mechanism is required for traffic shaping and SLA policing
and enforcement. One mechanism is fair queuing in its various forms,
which has been described as TDM emulation without the time and space
components. Techniques have been used for several years for fair
queuing for low speed lines. For DS-3 with 40 byte packets and OC-3c
speeds with 200-byte packets, weighted fair queuing uses a deficit
round-robin algorithm that allows it to scale. It is capable of flow
discrimination based on stochastically hashing the flows. An
additional expansion of this technique is to preface this technique
with class indicators. Currently, classification techniques are based
on IP precedence. However, classification will soon be achieved in
many routers using Diffserv code points (DSCPs) to specify the type
of conditioning to be applied. The complete requirements of policing
for DiffServ implementations, e.g., via bandwidth brokers, have not
yet been fully explored or defined.
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Network monitoring capabilities (i.e., querying the network for state
information on a micro and macro level) that support middleware and
application services were identified as a core requirement. In fact,
a network instrumentation and measurement infrastructure, upon which
a set of intelligent network management middleware services can be
built, is absolutely critical.
Current mechanisms (e.g. ICMP, SNMP) were not deemed robust enough
for middleware and applications developers to determine the state of
the network, or to verify that they were receiving the specific type
of treatment they had requested. This was judged especially true of
a network providing QoS or CoS. Indeed, it is not at all clear that
SNMP, for example, is even the right architectural model for
middleware to use to enable applications to determine the state of
the network. Other capabilities, such as OcxMon, RTFM, new MIBs, and
active measurement techniques (e.g., IPPM one-way delay metrics) need
to be made available to middleware services and applications.
The provisioning of differentiated services takes the Internet one
step away from its "dumb" best effort status. As the complexity of
the network increases (e.g. VPNs, QoS, CoS, VoIP, etc.), more
attention must be paid to providing the end-user/customer or network
administrator with the tools they require to securely and dynamically
manage an adaptable network infrastructure. Differentiated services
means that theoretically some traffic gets better service than other
traffic; subsequently, one can expect to pay for better service,
which means that accounting and billing services will be one of the
important middleware core components that others will rely upon. The
model and protocols necessary to accomplish this are not developed
yet.
12.0 Authentication, Authorization, and Accounting
The IETF's AAA working group is focusing on the requirements for
supporting authentication, authorization, accounting, and auditing of
access to and services provided by network resource managers (e.g.,
bandwidth brokers). These processes constitute an important security
infrastructure that will be relied upon by middleware and
applications. However, these components are only basic security
components. A public key infrastructure (PKI) was identified as a
crucial security service infrastructure component. For example, the
PKI will be required to support the transitivity of authentication,
authorization, and access control and, where appropriate, accounting
and billing. It was noted that, except for issues dealing with group
security and possibly more efficient and simple management, there are
no real technical challenges preventing the wide scale deployment of
a PKI support structure at this time. Instead, the main obstacles to
overcome are mostly political and economic in nature. However,
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additional middleware may be required to better facilitate a PKI.
That being said, some people believe that we do have some large
technical security challenges, revocation lists and security with
respect to changing group memberships being two examples.
Middleware and security support is also required for newer
applications (e.g., proxy agents that would act on a process or
application's behalf and gather the necessary certificates for access
and using resources). A particularly difficult example is remote
collaboration. Accessing a particular resource may require a user
and/or application to gather certificates from more than one policy-
controlling agent. It is also true that an entity may have various
identities that are dependent on the task they are performing (usage
or role based) or the context of the application. In order for the
PKI to become truly functional on a ubiquitous level, there needs to
exist a set of independent signing authorities that can vouch for the
top-level certificate authorities.
There are also higher-level middleware services which will build on
public key infrastructure, notary services and provenance
verification. As we move from a relatively dumb network (e.g. best
effort IP) to an Internet with embedded intelligence (e.g., DiffServ,
IntServ, bandwidth brokers, directory-enabled networks, etc.), the
secure exchange of information will become even more important. In
addition, as we start to provide differentiated services, accounting
and statistics gathering will become much more important. We also
need to provide for the integrity and security of collecting,
analyzing, and transporting network management and monitoring
information. And the issues of data privacy and integrity, along
with addressing denial of service and non-repudiation, cannot be
ignored.
13.0 Network Management, Performance, and Operations
Network management capabilities were identified as being paramount to
the success of middleware deployment, and subsequently to the success
of the application. Many of the issues addressed here are not part of
standard NOC operations. In a more complex world of QoS, CoS, and
micro prioritization, reactions to network failures must be handled
differently than current procedures. Allocations are more dynamic,
especially additions, deletions, and changes with additional sets of
requirements, such as priorities and new types of inter-domain
interactions. These will inevitably increase the complexity of
network management.
There are many microscopic and macroscopic network management
projects focusing on making both active and passive network
statistics and information available to end-users. Current visual
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debugging and analysis capabilities (e.g., those developed by
NLANR/CAIDA) are crucial tools for network administrators and
designers for understanding their networks. In addition, current
network management techniques and mechanisms, which were designed for
network designers and managers, need to be adapted to provide a
dynamic and relevant set of information to the middleware or
application service software. This will allow the programs to
dynamically adapt to the changing state of the network infrastructure
while ensuring the integrity and security of the network and other
resources.
Another aspect of network management that has not received the
necessary attention, is the need for modeling and analysis tools for
network and middleware designers. CIM and DEN show great promise in
providing a common framework for modeling the management of network
elements and services as well as users, applications, and other
resources of the network. Undoubtedly, middleware designers will
place new requirements on CIM and DEN that will cause these
approaches to evolve.
14.0 Middleware to support multicast applications
IP multicast - that is, the routing and forwarding of mutlicast
packets in an IP-based network, is in the view of the workshop part
of the basic network infrastructure. The Internet Group Multicast
Protocol, which manages the joining and leaving of multicast groups,
could also be considered a basic network service. However, there is a
tremendous need for middleware services to make multicast useable for
various applications, much like TCP played a key role in making IP
applications useable. Specifically, one might reasonably want
middleware services to provide authenticated control of multicast
services. Examples of these services include the creation and joining
of multicast groups, multicast address management, multicast channel
directories (there has already been considerable work in this area),
various forms of reliable multicast services (this has been an IRTF
research area), and to secure multicast groups through various
cryptographic strategies. In addition, because of the large impact
that multicast can have on a network, multicast management middleware
services, particularly in conjunction with QoS, will be needed, as
will services to link together multicasting within various networks
that do not directly interchange multicast routing information. It
should be noted, however, that several security issues with
multicast, especially groups with dynamic membership policies, still
need to be resolved.
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15.0 Java and Jini
Java was chosen as an example of a heterogeneous runtime support
system for the sake of discussion as to whether it could be qualified
as a development language particularly suitable for the development
of middleware. The consensus was that the Java language and compilers
are important in the current distributed model of the Internet and
for the support of middleware (i.e., middleware written using Java).
Also, a virtual Java machine located on a system can be considered
middleware as much as any operating system or network operating
systems would be considered middleware. Jini middleware technology
not only defines a set of protocols for discovery, join, and lookup,
but also a leasing and transaction mechanism to provide resilience in
a dynamic networked environment. Java and Jini will be dependent on
a functioning PKI, especially for signed applets. That being said,
there are security concerns with both Java and Jini that need to be
addressed, such as allowing the downloading of applets and servlets.
16.0 Security Considerations
This document is a report of a workshop in which security was a
common theme, as can be seen by the references to security through
out the document; but the workshop did not reach any specific
recommendations for new security-related terminology.
17.0 Summary
Middleware may have components and services that only exist in the
persistent infrastructure, but it will also have components that
enable and support end-to-end (i.e. application to application or
host to host) interaction across multiple autonomous administrative
domains. A set of core persistent middleware services is required to
support the development of a richer set of middleware services which
can be aggregated or upon which applications will be based (e.g., an
onion or layered model). This set of core middleware services will
help applications leverage the services and capabilities of the
underlying network infrastructure, along with enabling applications
to adjust in changes to the network. The particular set of such
services utilized by an application or process will be a function of
the requirements of the application field or affinity group (e.g.,
network management or high energy physics applications) wishing to
utilize the network or distributed data/computation infrastructure.
This document discusses some of the basic and core middleware
services, which include, but are not limited to: directories,
name/address resolution services, security services (i.e.,
authentication, authorization, accounting, and access control),
network management, network monitoring, time servers, and accounting.
Network level capabilities, such as multicast and DiffServ, are not
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classified as middleware; rather, they are enabling infrastructure
services upon which middleware will be built or which middleware may
use and manage. A second level of important middleware services,
which builds upon these core set of services, may include
accounting/billing, resource managers, single sign-on services,
globally unique names, metadata servers, and locators.
A recognized goal is to provide a set of middleware services that
enable access to and management of the underlying network
infrastructure and support applications wishing to make use of that
network-based infrastructure. It appears necessary to agree to a
framework of services for the support, provisioning and operations,
and management of the network. Today, we have piecemeal activities
already being pursued in various standards organizations. These
include efforts in the IETF and DMTF (e.g., AAA, Policy Framework,
DiffServ, DEN, CIM, etc.), as well as in the advanced application
environments (e.g., Grid Forum, the PACIs, NGI, Internet2, etc.).
Both of these efforts require the integration and management of many
infrastructure components, not just networks; however, we have no
overall framework that pulls all of these together, or a mechanism to
coordinate all of these activities. We are just embarking on the
development of a rich plan of middleware services. Consequently, we
have a lot of work yet to be done. For instance, as we move into an
electronic persistent presence (EPP) environment where multiple
instances of an identity or person (or even their proxy agents) are
supported, we will require enhanced locator and brokering services.
The directory (e.g., DNS or X.500) and locator services of today may
not be appropriate for this task.
One goal of the workshop was to identify research and development
areas in middleware that federal agencies and industry may choose to
support. The workshop highlighted a few areas that may benefit from
additional R&D support. These areas include, but are not limited to:
- inter-domain resource management architecture and protocols (e.g.,
inter-domain bandwidth brokers)
- resource languages that describe and enable the management of a
wide variety of resources (e.g., networks, data bases, storage,
online facilities, etc.
- avoiding deadlock and ensuring efficiency with resource managers
- network management tools and APIs that provide macroscopic and
microscopic real-time infrastructure
- information to middleware services and applications (not just MIBs
and SNMP access)
- domain and inter-domain accounting and billing
- monitoring and verification services of contracted infrastructure
services
- enhanced locators that can locate resources and resource managers
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- cross administrative policy negotiation and authentication
- middleware bypass (i.e. access to raw system or network resources
metadata (i.e., data that is used to describe data found in
directories or exchanged between services such as resource
managers, PDPs, PEPs, directories, accounting and billing
services, etc.)
- middleware support for mobile or nomadic use
- support for availability of resources (i.e. replication and load
balancing
This workshop was just one small step in identifying relevant
middleware topics, technologies and players. Even though this
workshop did not arrive at a consensual definition of middleware, it
did identify the need for additional work. Specifically, further work
is needed to identify and qualify middleware services for specific
affinity groups (e.g. Internet2, Education, the PACIs, Grids, etc.)
as well as to define a macroscopic framework that incorporates the
middleware work of the IETF, DMTF and other relevant organizations
such as the Grid Forum.
18.0 Participants
Deb Agarwal <deba@george.lbl.gov>, Bob Aiken <raiken@cisco.com>, Guy
Almes <almes@internet2.edu>, Chase Bailey <chase@cisco.com>, Fred
Baker <fred@cisco.com>, Pete Beckman <beckman@lanl.gov>, Javad
Boroumand <jborouma@nsf.gov>, Scott Bradner <sob@harvard.edu>, George
Brett <ghbrett@mindspring.com>, Rich Carlson <racarlson@anl.gov>,
Brian Carpenter <bcarpent@uk.ibm.com>, Charlie Catlett
<catlett@ncsa.uiuc.edu>, Bill Cheng <wtcheng@us.ibm.com>, Kim Claffy
<kc@caida.org>, Bill Decker <Wdecker@nsf.gov>, Christine Falsetti
<cfalsetti@arc.nasa.gov>, Ian Foster <foster@mcs.anl.gov>, Andrew
Grimshaw <grimshaw@cs.virginia.edu>, Ed Grossman
<egrossma@ncsa.uiuc.edu>, Ted Hanss <ted@internet2.edu>, Ron Hutchins
<ron@oit.gatech.edu>, Larry Jackson <jackson@ncsa.uiuc.edu>, Bill
Johnston <Wejohnston@lbl.gov>, Juerg von Kaenel <jvk@us.ibm.com>,
Miron Livny <miron@cs.wisc.edu>, Cliff Lynch <cliff@cni.org>, Joel
Mambretti <j-mambretti@nwu.edu>, Reagan Moore <moore@sdsc.edu>, Klara
Nahstedt <klara@cs.uiuc.edu>, Mike Nelson <mrn@us.ibm.com>, Bill
Nitzberg <nitzberg@nas.nasa.gov>, Hilarie Orman <ho@darpa.mil>, John
Schnizlein <jschnizl@cisco.com>, Rick Stevens <stevens@mcs.anl.gov>,
John Strassner <johns@cisco.com>, Ben Teitelbaum <ben@advanced.org>,
George Vanecek <g.vanecek@att.com>, Ken Klingenstein
<Ken.Klingenstein@Colorado.EDU>, Arvind Krishna
<akrishna@us.ibm.com>, Dilip Kandlur <kandlur@us.ibm.com
Aiken, et al. Informational [Page 26]
RFC 2768 A Report of a Workshop on Middleware February 2000
19.0 URLs/references
Please see http://www.mcs.anl.gov/middleware98 for copies of the
slides presented at the workshop as well as a list of related URLs on
applications, middleware and network services.
20.0 Authors' Addresses
Editor: Bob Aiken
EMail: raiken@cisco.com
Authors:
Bob Aiken
Cisco Systems, Inc.
6519 Debold Rd.
Sabillasville, Md. 21780 USA
Phone: +1 301 271 2919
EMail: raiken@cisco.com
John Strassner
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134
Phone: +1 408 527 1069
EMail: johns@cisco.com
Brian E. Carpenter
IBM United Kingdom Laboratories
MP 185, Hursley Park
Winchester, Hampshire SO21 2JN, UK
EMail: brian@hursley.ibm.com
Ian Foster
Argonne National Laboratory
The University of Chicago
Argonne, IL 60439 USA
Phone: +1 630 252 4619
EMail: foster@mcs.anl.gov
Aiken, et al. Informational [Page 27]
RFC 2768 A Report of a Workshop on Middleware February 2000
Clifford Lynch
Coalition for Networked Information
21 Dupont Circle
Washington, DC 20036
Phone: +1 202 296 5098
EMail: cliff@cni.org
Joe Mambretti
International Center for Advanced Internet Research
1890 Maple, Suite 150
Northwestern University, Evanston, Illinois 60201
Phone: +1 847 467 3911
EMail: j-mambretti@nwu.edu
Reagan Moore
University of California, San Diego
NPACI/SDSC, MC 0505
9500 Gilman Drive
La Jolla, CA 92093-0505 USA
EMail: moore@sdsc.edu
Benjamin Teitelbaum
Advanced Networks & Services, Inc.
EMail: ben@internet2.edu
Aiken, et al. Informational [Page 28]
RFC 2768 A Report of a Workshop on Middleware February 2000
21.0 Full Copyright Statement
Copyright (C) The Internet Society (2000). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Aiken, et al. Informational [Page 29]