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GENERAL: Middleware            Bob Aiken, John Strassner, Cisco Systems
INTERNET DRAFT                                     Brian Carpenter, IBM
28 May 1999                   Ian Foster, Argonne National Laboratory
                    Clifford Lynch, Coalition for Networked Information
                                                   Joe Mambretti, ICAIR
                                                     Reagan Moore, UCSD
                Benjamin Teitelbaum, Advanced Networks & Services, Inc.

Terminology for network policy and services: a report of a workshop on  middleware.

Status of Memo

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, and
its working groups.  Note that other groups may also distribute working
documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference material
or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at

The list of Internet-Draft Shadow Directories can be accessed at

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, 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.

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Table of Contents


1.0  Contextual Framework
2.0  What is Middleware?
3.0  Application Perspective
4.0  Exemplary Components
5.0  Application Programming Interfaces and Signaling
7.0  Policy
8.0  Directories
9.0  Resource Management
10.0  Networked Information Discovery and Retrieval Services
11.0  Network QOS
12.0  Authentication, authorization, and access management.
13.0  Network Management, Performance, and Operations
14.0  Middleware to support multicast applications
15.0 Java and Jini TM
16.0 Security Considerations
17.0  Summary
18.0  Participants
19.0  URLs
20.0  Authors


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 and CIM/DEN-LDAP mapping work, being done in the
DMTF. (The recently constituted Grid Forum is also pursuing relevant

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.
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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
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.

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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 Servive, 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 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.

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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 middlware 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 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 signifigance without the system of DNS servers, and
indeed the administrative infrastructure of name registry; NTP, in
order to be useful, requires the existance 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
useable services.

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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 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

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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
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.

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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

* 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.
* Process management interface, whether for composing data movement
with remote execution, or for linking together multiple processing


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.

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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.

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

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.

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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 a device. For
example, a policy may specify "if source IP address is,
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

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.

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.

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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 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.

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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
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

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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 includesecurity 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.

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 reqirements are constantly emerging.

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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 mangement, 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 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).

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(See also the NSF/ERCIM report on metadata research issues at

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 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.

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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

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

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 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.

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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.

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.

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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 autghentication, authorization, accounting, and auditing of
access to and services provided bynetwork 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, 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.

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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

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 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.

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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.

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.

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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 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.

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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
-  enhanced locators that can locate resources and resource managers
-  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

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.

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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

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.

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20.0 Authors' Address

Editor: Bob Aiken

 Bob Aiken
 Cisco Systems, Inc.
 6519 Debold Rd.
 Sabillasville, Md.  21780 USA
 1 301 271 2919

 John Strassner
 Cisco Systems, Inc.
 170 West Tasman Drive
 San Jose, CA  95134

 Brian E. Carpenter
 IBM United Kingdom Laboratories
 MP 185, Hursley Park
 Winchester, Hampshire SO21 2JN, UK

 Ian Foster
Argonne National Laboratory
The University of Chicago
Argonne, IL 60439  USA
1 630 252 4619

Clifford Lynch
Coalition for Networked Information
21 Dupont Circle
Washington, DC  20036
1 202 296 5098

Joe Mambretti
International Center for Advanced Internet Research
1890 Maple, Suite 150
Northwestern University, Evanston, Illinois 60201
1 847 467 3911

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Reagan Moore
University of California, San Diego
9500 Gilman Drive
La Jolla, CA 92093-0505   USA

Benjamin Teitelbaum
Advanced Networks & Services, Inc.

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13. Full Copyright Statement

   Copyright (C) The Internet Society (1999).  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

   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

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