A/WWW Enterprises 28 Sept 1995 AstroBrowse: Survey of Current Technology A. Warnock A/WWW Enterprises

A/WWW Enterprises 28 Sept 1995 Why Open Protocols? n Anyone can write servers n Anyone can write clients n Leverage off of existing development n Formalized standards

A/WWW Enterprises 28 Sept 1995 What’s Available Now? n ftp n telnet n gopher (really telnet) n WAIS (Z ) n Z39.50 v2, v3 n http + CGI

A/WWW Enterprises 28 Sept 1995 http & CGI Scripts n http does only a few things get files (w/ MIME type) put parameters (from forms) execute scripts (CGI) n CGI runs scripts on server accepts parameters from client parameter input via command line or stdin pipes output to stdout

A/WWW Enterprises 28 Sept 1995 Z39.50 Capabilities - Search n Arbitrary queries - text, numeric, words, phrases, fields n Stateful n Multiple search engine APIs n Query for capabilities (EXPLAIN) n Record & Database-level security n Authentication

A/WWW Enterprises 28 Sept 1995 Z39.50 Capabilities - Retrieval n Multiple formats (unstructured text, HTML, US MARC,...) n Element sets (brief records, full records, other combinations of fields/attributes) n Permanent result sets n Automated data conversion

A/WWW Enterprises 28 Sept 1995 Harvest n Client/server system to build searchable collection from remote sites n Search engines: agrep freeWAIS glimpse n Document oriented

A/WWW Enterprises 28 Sept 1995 Advanced Developments n URIs: URN, URC n Java and CCI n PDF/http integration n Dynamic document & data generation n SQL interfaces n Spatial searching n Distributed collections

A/WWW Enterprises 28 Sept 1995 Example: DODS n Distributed Oceanographic Data System P. Cornillon, URI/GRO G. Flierl, MIT Programmers at URI/GRO Next phase: T. Habermann, NGDC

A/WWW Enterprises 28 Sept 1995 DODS Basic Architecture n Network-based data retrieval Use existing applications Enhanced API libraries supporting http interface (accept file names or URLs) Data-aware http servers supporting API library functions

A/WWW Enterprises 28 Sept 1995 DODS Intermediate Architecture n Data format mapping standardized operations on different formats - e.g., extract a variable from an HDF file and pass it to a FITS reader n NASA/GCMD as Data Locator Service query for URLs

A/WWW Enterprises 28 Sept 1995 DODS Advanced Architecture n NGDC Metadata description language Freeform & GeoVu n Network encoding n Special Purpose http servers precession, dataset overlap, subsetting n Dynamic updating of locator descriptions

A/WWW Enterprises 28 Sept 1995 Relevant URLs n Harvest n DODS n Z n Glimpse

A/WWW Enterprises 28 Sept 1995 Relevant URLs n URI documents n Freeform & GeoVu n Isite n Global Change Master Directory