Shore - A High-Performance, Scalable, Persistent Object Repository

Document Contents: See Also:

Objective:

The objective of the Shore project is to design, implement, and evaluate a persistent object system that will serve the needs of a wide variety of target applications including hardware and software CAD systems, persistent programming languages, geographic information systems, satellite data repositories, and multi-media applications. Shore expands on the basic capabilities of the widely-used EXODUS Storage Manager (developed at Wisconsin, funded by ARPA ) in a number of ways including support for typed objects, multiple programming languages, a ``Unix-like'' hierarchical name space for named objects, and a Unix-compatible interface to objects with a ``text'' field. This interface is intended to ease the transition of applications from the Unix file system environment to Shore as existing Unix tools such as vi, emacs, or cc will be able to store their data in Shore objects without modification.

Overview:

Shore has a layered architecture that allows users to choose the level of support appropriate for a particular application. We briefly overview this architecture here. The paper Shoring Up Persistent Applications describes the design of Shore in much greater detail.

The Shore Storage Manager (SM) is a persistent object storage engine that supports creation of persistent files of records. Each record can be any size, with efficient storage of records from a few bytes to megabytes or larger. Records may be retrieved by object identifier or by scanning files. The SM provides full concurrency control and recovery (the so-called ACID properties) with two-phase locking and write-ahead logging. It also provides robust implementations of btrees and rtrees and record access through logical object identifiers. The SM is designed to be used as a library to create value-added servers tailored to specific applications.

The Shore Value-Added Server (SVAS) builds on the functionality of the SM to provide typed objects, a Unix-like directory namespace, access control, and a client-server architecture supporting object-level caching, transactional semantics, and security at the server boundary. The NFS value-added server fully implements the standard NFS (Network File Server) protocol, allowing legacy applications to access Shore objects as if they were Unix files.

The Shore Data Language (SDL), which is based on the Object Database Management Group (ODMG) ODL language, supports language-independent description of object-oriented data types. The SDL compiler compiles definitions into type objects stored in the database and C++ language stubs. The combination of the SDL compiler and an extensive run-time library allows programmers to write applications that manipulate objects through type-safe object references. The library takes care of fetching objects on demand to an LRU client-level object cache, flushing changes to the server on transaction commit, and swizzing and unswizzling references as necessary.

Shore serves as the basis of other database projects, including Paradise at the University of Wisconsin and PREDATOR at Cornell University.

Paradise is a scalable, parallel geographic information system (GIS) that is capable of storing and manipulating massive data sets. By applying object-oriented and parallel database technologies to the problem of storing and manipulating geographic information, the Paradise project hopes to significantly advance the size and complexity of GIS data sets that can be successfully stored, browsed, and queried.

The PREDATOR object-relational database system from Cornell University is freely available for research and education purposes. PREDATOR is a multi-threaded client-server system built on Shore. It supports standard relational query-processing with SQL queries, extensibility with enhanced complex data types with user-defined methods and aggregates, and WWW access through a Java applet client.

Release Information:

Beta Release (0.9)

On May 3, 1995 we had our first beta release.

Beta Release (0.9.3)

A second Beta-rlease of Shore (version 0.9.3) was released on September 18, 1995. It is now obsolete.

Version 1.0

On August 6, 1996 we released Shore, version 1.0. Gzip'd tar files of the source, documentation and a binary release (sparc and pentium solaris 2.5), can be found at <ftp://ftp.cs.wisc.edu/shore/1.0/> . This release will be removed after release 1.1 is found to be stable.

Version 1.1

A updated release, with numerous bug fixes and performance enhancements was announced August 9, 1997. Gzip'd tar files of the source, documentation and a binary release (sparc and pentium solaris 2.5), can be found at <ftp://ftp.cs.wisc.edu/shore/1.1/>. If you encounter any problems with it, please send mail to shore_support@cs.wisc.edu.

Version 1.1.1

A minor bug-fix release relative to 1.1. The most important change is that it has been patched to work under Linux.

Mailing Lists

There are two Shore-related mailing lists: shore_support@cs.wisc.edu and shore_all@cs.wisc.edu.

shore_support@cs.wisc.edu

This mailing list reaches the Shore development team. Use this address to submit questions, comments, and bug reports to us. You cannot subscribe to this mailing list. Note that the name is spelled with an underscore, not a hyphen.

shore_all@cs.wisc.edu

This is a mailing list for users of (and those interested in) Shore. This list is managed by Majordomo software at the UW--Madison CS department. It is currently unmoderated, but in the event it gets cluttered with junk mail we will moderate it.

Use this list to discuss Shore with other users, ask for advice, exchange tips, etc. The list is also used by the maintainers to to notify interested parties about new releases and other changes in the Shore ftp archive

By default, replies will be sent only to the sender, rather than being posted to the entire list. If you want the entire list to see your reply, just copy the reply to shore_all.

The shore_all list is a public mailing list, meaning that anyone may subscribe to it. Only subscribers may post to the list.

Subscribing to shore_all

To subscribe or to change your subscription, send a message to majordomo@cs.wisc.edu. The Subject line of the message is ignored. The body should contain one or more of the following commands.

help
asks Majordomo to send you a brief summary of available commands.
subscribe shore_all
asks that you be added to the mailing list. Note that the list name is spelled with an underscore, not a hyphen.
unsubscribe shore_all
asks that you be removed from the mailing list.

Archives

We keep an archive of past messages to the list. Send a message containing to majordomo@cs.wisc.edu to get a list of the archive files available. The time period covered by each file should be obvious from the file name. To have a copy of a particular archive file mailed to you, send a message containing to majordomo@cs.wisc.edu. For example, will get an archive of messages sent during April 1997.

Last Modified:

August 19, 1997

Marvin Solomon / solomon@cs.wisc.edu.