Over the past several years, a number of information discovery and access tools have been introduced in the Internet, including Archie, Gopher, Netfind, and WAIS. These tools have become quite popular, and are helping to redefine how people think about wide-area network applications. Yet, they are not well suited to supporting the future information infrastructure, which will be characterized by enormous data volume, rapid growth in the user base, and burgeoning data diversity. In this paper we indicate trends in these three dimensions and survey problems these trends will create for current approaches. We then suggest several promising directions of future resource discovery research, along with some initial results from projects carried out by members of the Internet Research Task Force Research Group on Resource Discovery and Directory Service.

Naming is critical in distributed systems. Names identify files, services, processors, and users. A name service translates the names of objects to the information needed to access those objects. The growth of distributed systems brings with it an increase in the number of objects to be named. Existing naming techniques are derived from techniques used on centralized systems and are not sufficient for organizing the large number of objects that are becoming available. This dissertation presents the Virtual System Model, a new model for naming that helps users organize the information available in large systems. The Virtual System Model has four principal features: support for customizable name spaces, tools to help users construct name spaces, support for synonyms, and a m...

This paper introduces the Jade File System, which provides a uniform way to name and access files in an internet environment. Jade is a logical system that integrates a heterogeneous collection of existing file systems, where by heterogeneous we mean that the underlying file systems support different file access protocols. Because of autonomy, Jade is designed under the restriction that the underlying file systems may not be modified. In order to avoid the complexity of maintaining an internet-wide, global name space, Jade permits each user to define a private name space. Jade's name space supports two novel features: It allows multiple file systems to be mounted under one directory, and it permits one logical name space to mount other logical name spaces. A prototype of Jade has been implemented to examine and validate its design. The prototype consists of interfaces to the Unix File System, the Sun Network File System, and the File Transfer Protocol. This paper gives an overview of J...

Nebula is a file system that explicitly supports information management. It differs from traditional systems in three important ways. First, Nebula implements files as sets of attributes. Each attribute describes some property of the file such as owner, protection, functions defined, sections specified, project, or file type. The content of the file is represented by a special text attribute. Second, Nebula supports associative access of files within a scoped index. A scoped index restricts associative access to a subset of the files in one or more file systems. Finally, Nebula replaces traditional directories with database views. A directory implements a naming closure; i.e. the name of a file is assigned by the directories in which it resides. A view is a query that selects file objects from a scoped index. Thus, the name of a file is a property of the file, not the view. Like directories, views can be named and included in other views. When a file (or view) is created, it is placed ...

This thesis addresses the challenge of locating people, resources, and other objects in the global Internet. As the Internet grows beyond a million hosts in tens of thousands of organizations, it is increasingly difficult to locate any particular object. Hierarchical name services are frustrating, because users must guess the unique names for objects or navigate the name space to find information. Descriptive (i.e. relational) name services offer the promise of simple resource location through a non-procedural query language. Users locate resources by describing resource attributes. This thesis makes the promise of descriptive name services real by providing fast query processing in large internets. The key to speed in descriptive query processing is constraining the search space using two new techniques, called an active catalog and meta-data caching. The active catalog constrains the search space for a query by returning a list of data repositories where the answer to the query is li...

As the size of a distributed system grows it becomes increasingly difficult for users to find their way around. One solution for this problem is user centered naming. A problem with user centered naming is that it has the potential to cause confusion and to make sharing difficult. This problem can be avoided if the system supports closure. Although the same name may refer to different objects at different times, the context in which the name is to be evaluated is always known.

Over the past several years, a number of information discovery and access tools have been introduced in the Internet, including Archie, Gopher, Netfind, and WAIS. These tools have become quite popular, and are helping to redefine how people think about wide area network applications. Yet, they are not well suited to supporting the future information infrastructure, which will be characterized by enormous data volume, rapid growth in the user base, and burgeoning data diversity. In this paper we indicate trends in these three dimensions, and survey problems these trends will create for current approaches. We then suggest several promising directions of future resource discovery research, along with some initial results from projects carried out by members of the Internet Research Task Force Research Group on Resource Discovery and Directory Service.

The Spring name service does not prescribe particular naming polices; instead it serves as a foundation for building various policies. Our default policy is an environment containing name spaces for naming systemsupplied objects, for a user's objects, for objects shared across applications, and for objects private to a process. Some name spaces are private, while others are shared. Any name space can be configured by attaching arbitrary name spaces from different parts of the distributed environment. We also use ordered merge constructions for further flexibility in tailoring name spaces. Each executing process is given a private name space to which other name spaces, such as the user's name space, system-supplied name spaces, and other shared name spaces are attached. Our scheme gives great flexibility in sharing objects and name spaces in a distributed computing environment. Name spaces can be configured dynamically to take advantage of local resources during distributed execution. ...

In this paper we present a number of techniques for supporting distributed applications that span many nodes across administrative boundaries in wide area internetworks. The techniques derive from experiences with research prototypes we have built in a variety of application areas. Several of the prototypes have achieved exceptionally far reaching distribution, operating in conjunction with machines in thousands of sites around the world. The techniques are applicable to a broad range of distributed applications. They concern problems with fault tolerance, administrative decentralization, scalability of operational semantics, organizing decentralized information, controlling the spread of distributed operations, and user interfaces.

The role of workstations in future systems has been a hotly debated topic. Some believe the workstation is useful primarily as a terminal and that the computing of the future will be done on large multiprocessor systems. Others believe that workstations will be the processors of those multiprocessor systems. Still others believe that the role of the workstation will be between the two extremes, providing simple processing capabilities such as editing for the local user.