Metacat

Introduction

============

Metacat is a repository for data and metadata (descriptions of data) that helps

scientists find, understand and effectively use the data sets they manage or

that have been created by others. Thousands of data sets are currently

documented in a standardized way and stored in Metacat systems, providing the

scientific community with a broad range of science data that--because the

data are well and consistently described--can be easily searched, compared,

merged, or used in other ways.

Not only is the Metacat repository a reliable place to store metadata and data

(the database is replicated over a secure connection so that every record is

stored on multiple machines and no data is ever lost to technical failures), it

provides a user-friendly interface for information entry and retrieval.

Scientists can search the repository via the Web using a customizable search

form. Searches return results based on user-specified criteria, such as desired

geographic coverage, taxonomic coverage, and/or keywords that appear in places

such as the data set's title or owner's name. Users need only click a linked

search result to open the corresponding data-set documentation in a browser

window and discover whom to contact to obtain the data themselves (or how to

immediately download the data via the Web).

Metacat's user-friendly Registry application allows data providers to enter

data set documentation into Metacat using a Web form. When the form is

submitted, Metacat compiles the provided documentation into the required format

and saves it. Information providers need never work directly with the XML_

format in which the metadata are stored or with the database records themselves. In

addition, the Metacat application can easily be extended to provide a

customized data-entry interface that suits the particular requirements of each

project. Metacat users can also choose to enter metadata using the Morpho

application, which provides data entry wizards that guide information providers

through the process of documenting each data set.

The metadata stored in Metacat includes all of the information needed

to understand what the described data are and how to use them: a

descriptive data set title; an abstract; the temporal, spatial, and taxonomic

coverage of the data; the data collection methods; distribution information;

and contact information. Each information provider decides who has access to

this information (the public, or just specified users), and whether or not to

upload the data set itself with the data documentation. Information providers

can also edit the metadata or delete it from the repository, again using

Metacat's straightforward Web interface.

Metacat is a `Java servlet`_ application that runs on Linux, Mac OS, and

Windows platforms in conjunction with a database, such as 

PostgreSQL_ (or Oracle_), and a Web

server. The Metacat application stores data in an XML_ format using `Ecological

Metadata Language`_ (EML) or other metadata standards such as `ISO 19139`_ or the

`FGDC Biological Data Profile`_. For more

information about Metacat or for examples of projects currently using Metacat,

please see http://knb.ecoinformatics.org.

.. _XML: http://en.wikipedia.org/wiki/XML

.. _Java servlet: http://en.wikipedia.org/wiki/Java_Servlet

.. _PostgreSQL: http://www.postgresql.org/

.. _Oracle: http://www.oracle.com/

.. _Ecological Metadata Language: http://knb.ecoinformatics.org/software/eml

.. _ISO 19139: http://marinemetadata.org/references/iso19139 

.. _FGDC Biological Data Profile: http://www.fgdc.gov/standards/projects/FGDC-standards-projects/metadata/biometadata 

What's in this Guide

--------------------

This Administrator's guide includes information for installing, configuring,

managing and extending Metacat for both Linux, Mac OS, and Windows systems. 

Chapter Four contains instructions for downloading and installing Metacat and the

applications required to run the software on Linux and Microsoft platforms.

Chapter Five covers how to configure Metacat, both for new and upgraded

installations. Chapter Seven details the ways in which you can customize the

Metacat interface so users can access and submit information easily: using

Metacat's generic web-interface (the Registry), creating your own HTML forms,

and creating your own desktop client (like Morpho). Chapter Eight discusses how

to work with Metacat's embedded Geoserver. Chapter Nine describes how to set up the

Metacat's replication service, which permits Metacat servers to share data with

each other, effectively backing up metadata and data files. Chapter Ten looks

at the Metacat Harvester, a program that automates the retrieval of EML

documents from one or more sites and their subsequent upload (insert or update)

to Metacat. Chapter Eight discusses logging, Chapter Twelve contains instructions

for creating a site map, which makes individual metadata entries available via

Web searches. Metacat's `Java API`_ is available for developers.

.. _Java API: ./api/index.html

Metacat Features

----------------

Metacat is a repository for data and metadata (documentation about data), that 

helps scientists find, understand and effectively use the data sets they manage or 

that have been created by others. Specifically,

* Metacat is an open source web application, which can run on Linux, MacOS, and Windows operating systems and is written in Java

* Metacat's Web interface facilitates the input and retrieval of data 

* Metacat's optional mapping functionality enables you to query and visualize the geographic coverage of stored data sets

* Metacat's replication feature ensures that all Metacat data and metadata is stored safely on multiple Metacat servers

* The Metacat interface can be easily extended and customized via Web forms, themes, and/or user-developed client tools in Java and other languages

* The Metacat harvester automates the process of retrieving and storing EML documents from one or more sites

* Metacat can be customized to use Life Sciences Identifiers (LSIDs), uniquely identifying every data record

* Metacat has a built-in logging system for tracking events such as document insertions, updates, deletes, and reads

* The appearance of Metacat's Web interface can be customized via themes. 

* Metacat fully supports the DataONE Member Node interface, allowing Metacat deployments to easily participate in the DataONE federation

.. figure:: images/screenshots/image007.png

   Metacat's default home page. Users can customize the appearance using themes.