Implementation of an on-line asset library was viewed as a crucial step in institutionalizing reuse within CAASD. The library mechanism had to be low cost, easy to set up and maintain, accessible from the wide variety of computer platforms used by CAASD staff, and it had to meet the requirements for an asset library mechanism. Specifically, the asset library had to allow for the automated search and retrieval of on-line information in the form of text documents, images, software, and pointers to sources of more information (meta-assets) with minimal barriers between CAASD staff and the desired information.
The CAASD Reuse Team informally reviewed a number of asset library mechanisms. None fit the set of candidate requirements. The search was expanded. The two main tools that were evaluated and eventually used to build the CAASD asset library were the Internet Gopher and Wide Area Information Servers (WAIS). Given the recent advances in network information discovery and retrieval technology, this class of tools seemed to lend themselves to the solution of the problem.
The Internet Gopher client/server provides a distributed information delivery system around which a campus-wide information system (CWIS) can be readily constructed. While providing a delivery vehicle for local information, Gopher also facilitates access to other Gopher and information servers throughout the world. [#!ugt93!#]
WAIS is a networked information retrieval system that uses TCP/IP to connect client applications to information servers. Client applications request documents using user-supplied keywords and are able to retrieve text or multimedia documents stored on the servers. Servers search the full text index for the documents and return a list of documents containing the keywords. The client may then request the server to send a copy of any of the documents found. [#!edguer92!#]
Gopher allows a user to browse for assets using a menu structure. If a user wants to access an item, Gopher will ``go fer'' it and, if possible, ``show'' it to the user. Different Gopher clients have varying levels of capability with respect to ``showing'' assets to the user. All clients can display ASCII text documents. Other document types which the Gopher protocol defines, and which may or may not be supported by the specific client software for a computer platform, are sounds, bit-mapped images, and multimedia documents. If desired, the user may save the document on the local disk drive, print the document on a local printer, or mail the document to an email address. Gopher can connect to other asset library systems via the Gopher protocol, TELNET protocol (VT100 or TN3270 emulation), or anonymous ftp. Gopher also has interfaces to several information servers, including Archie servers, CSO name servers (a class of electronic phone books), and WAIS servers. Archie is a system which allows searching indexes of files available on anonymous ftp servers on the Internet [#!krol92!#]. CSO name servers allow users to access certain electronic phone books. The Gopher-WAIS interface allows the user to specify keywords to be used for a WAIS search. The results of the WAIS search are presented to the Gopher user as a custom directory. Items in the directory are assets which match the search criteria. In addition, WAIS uses a complex scoring algorithm for the assets and presents the assets in sorted order, based upon the score of each asset. This feature saves the user effort by automating the process of determining which assets are most relevant, based on the user's search criteria.
The implementation of the CAASD Resource Discovery System consists of an Internet Gopher server and a WAIS server running on a UNIX workstation. Gopher client software is available for UNIX workstations (X Window and character based), Macintoshes, IBM PCs (DOS, Windows, and OS/2), and NeXT workstations. Dumb terminals (for example, VT220s) may access the system by logging into a special account and running a ``secure mode'', character-based Gopher client. The CAASD Resource Discovery System has links to other Internet Gopher servers maintained within MITRE, telnet links to the MITRE on-line library catalogs, and links to anonymous ftp sites within MITRE.
The CAASD Resource Discovery System acts as a library mechanism for many different types of assets available for reuse by CAASD staff. Asset types include technical reports, letters, memos, briefings, meeting minutes, numerous databases, and software. All of these asset types are searched, browsed, and retrieved using the common mechanisms provided by the CAASD Resource Discovery System.
A number of tasks have been accomplished to assist CAASD staff to utilize the CAASD Resource Discovery System for the purpose of software reuse. Software description templates have been designed and distributed to CAASD staff. These templates are used to capture information about software developed within MITRE as well as information about software that was developed externally from MITRE, but used within MITRE. When the templates are filled in, these software descriptions are collected, indexed, and made available through the CAASD Resource Discovery System. In addition, catalogs and information about external software repositories, such as ASSET, AdaNET, and the NETLIB server at research.att.com, have been reformatted, indexed, and made available through the CAASD Resource Discovery System. Both of these efforts provide a means for searching through collections of descriptions of software assets available for reuse to CAASD staff. The software descriptions also provide information on how to retrieve the software assets. Finally, using the anonymous ftp facility available within the CAASD Resource Discovery System, a large number of software assets have been made available for direct retrieval by CAASD staff.
The CAASD Reuse Team is currently evaluating the use of enhancements to both Gopher and WAIS as well as the use of World-Wide Web (WWW) technology. Gopher enhancements include serving documents in multiple types (for example, Microsoft Word, PostScript, and ASCII text). WAIS enhancements include the use of boolean operators, partial keywords, and literal phrases in WAIS index searches. WWW technology merges hypertext and network information discovery and retrieval technologies in a very powerful paradigm.
All of the technology and software used to build the CAASD Resource Discovery System is freely available from the Internet community. Many information resources related to these technologies are also available in the form of network news groups and mailing lists. For more information, please consult the following sources.
Network news is discussed in comp.infosystems.gopher.
Network news is discussed in comp.infosystems.wais.
Network news is discussed in comp.infosystems.www.