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Introduction
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============
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Metacat is a repository for data and metadata (descriptions of data) that helps
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scientists find, understand and effectively use the data sets they manage or
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that have been created by others. Thousands of data sets are currently
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documented in a standardized way and stored in Metacat systems, providing the
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scientific community with a broad range of science data that--because the
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data are well and consistently described--can be easily searched, compared,
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merged, or used in other ways.
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Not only is the Metacat repository a reliable place to store metadata and data
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(the database is replicated over a secure connection so that every record is
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stored on multiple machines and no data is ever lost to technical failures), it
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provides a user-friendly interface for information entry and retrieval.
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Scientists can search the repository via the Web using a customizable search
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form. Searches return results based on user-specified criteria, such as desired
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geographic coverage, taxonomic coverage, and/or keywords that appear in places
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such as the data set's title or owner's name. Users need only click a linked
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search result to open the corresponding data-set documentation in a browser
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window and discover whom to contact to obtain the data themselves (or how to
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immediately download the data via the Web).
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Metacat's user-friendly Registry application allows data providers to enter
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data set documentation into Metacat using a Web form. When the form is
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submitted, Metacat compiles the provided documentation into the required format
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and saves it. Information providers need never work directly with the XML_
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format in which the metadata are stored or with the database records themselves. In
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addition, the Metacat application can easily be extended to provide a
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customized data-entry interface that suits the particular requirements of each
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project. Metacat users can also choose to enter metadata using the Morpho
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application, which provides data entry wizards that guide information providers
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through the process of documenting each data set.
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The metadata stored in Metacat includes all of the information needed
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to understand what the described data are and how to use them: a
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descriptive data set title; an abstract; the temporal, spatial, and taxonomic
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coverage of the data; the data collection methods; distribution information;
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and contact information. Each information provider decides who has access to
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this information (the public, or just specified users), and whether or not to
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upload the data set itself with the data documentation. Information providers
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can also edit the metadata or delete it from the repository, again using
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Metacat's straightforward Web interface.
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Metacat is a `Java servlet`_ application that runs on Linux, Mac OS, and
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Windows platforms in conjunction with a database, such as 
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PostgreSQL_ (or Oracle_), and a Web
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server. The Metacat application stores data in an XML_ format using `Ecological
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Metadata Language`_ (EML) or other metadata standards such as `ISO 19139`_ or the
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`FGDC Biological Data Profile`_. For more
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information about Metacat or for examples of projects currently using Metacat,
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please see http://knb.ecoinformatics.org.
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.. _XML: http://en.wikipedia.org/wiki/XML
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.. _Java servlet: http://en.wikipedia.org/wiki/Java_Servlet
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.. _PostgreSQL: http://www.postgresql.org/
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.. _Oracle: http://www.oracle.com/
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.. _Ecological Metadata Language: http://knb.ecoinformatics.org/software/eml
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.. _ISO 19139: http://marinemetadata.org/references/iso19139 
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.. _FGDC Biological Data Profile: http://www.fgdc.gov/standards/projects/FGDC-standards-projects/metadata/biometadata 
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What's in this Guide
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--------------------
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This Administrator's guide includes information for installing, configuring,
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managing and extending Metacat for both Linux, Mac OS, and Windows systems. 
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Chapter Four contains instructions for downloading and installing Metacat and the
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applications required to run the software on Linux and Microsoft platforms.
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Chapter Five covers how to configure Metacat, both for new and upgraded
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installations. Chapter Seven details the ways in which you can customize the
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Metacat interface so users can access and submit information easily: using
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Metacat's generic web-interface (the Registry), creating your own HTML forms,
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and creating your own desktop client (like Morpho). Chapter Eight discusses how
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to work with Metacat's embedded Geoserver. Chapter Nine describes how to set up the
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Metacat's replication service, which permits Metacat servers to share data with
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each other, effectively backing up metadata and data files. Chapter Ten looks
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at the Metacat Harvester, a program that automates the retrieval of EML
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documents from one or more sites and their subsequent upload (insert or update)
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to Metacat. Chapter Eight discusses logging, Chapter Twelve contains instructions
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for creating a site map, which makes individual metadata entries available via
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Web searches. Metacat's `Java API`_ is available for developers.
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.. _Java API: ./api/index.html
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Metacat Features
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Metacat is a repository for data and metadata (documentation about data), that 
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helps scientists find, understand and effectively use the data sets they manage or 
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that have been created by others. Specifically,
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* Metacat is an open source web application, which can run on Linux, MacOS, and Windows operating systems and is written in Java
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* Metacat's Web interface facilitates the input and retrieval of data 
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* Metacat's optional mapping functionality enables you to query and visualize the geographic coverage of stored data sets
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* Metacat's replication feature ensures that all Metacat data and metadata is stored safely on multiple Metacat servers
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* The Metacat interface can be easily extended and customized via Web forms, skins, and/or user-developed client tools in Java and other languages
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* The Metacat harvester automates the process of retrieving and storing EML documents from one or more sites
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* Metacat can be customized to use Life Sciences Identifiers (LSIDs), uniquely identifying every data record
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* Metacat has a built-in logging system for tracking events such as document insertions, updates, deletes, and reads
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* The appearance of Metacat's Web interface can be customized via skins. 
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* Metacat fully supports the DataONE Member Node interface, allowing Metacat deployments to easily participate in the DataONE federation
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.. figure:: images/screenshots/image007.png
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   :align: center
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   Metacat's default home page. Users can customize the appearance using skins.
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