Ecological Metadata

1 Introduction

Ecological Metadata Language (EML) is a metadata specification developed by the ecology discipline and for the ecology discipline. It is based on prior work done by the ESA (Ecological Society of America) and associated efforts. At present, ESA will require data associated with submitted papers to be put into EML. Currently EML version 2.0.1 is implemented by US LTER sites.

The concept of “module” is a very important in EML. EML is implemented as a series of XML document types that can be used in a modular and extensible manner to document ecological data. Each EML module is designed to describe one logical part of the total metadata that should be included with any ecological dataset. EML module is a wrapper container that allows the inclusion of any metadata content in a single EML document. The EML module is used as a container to hold structured descriptions of ecological resources. In EML, the definition of a resource comes from the The Dublin Core Metadata Initiative, which describes a general element set used to describe "networked digital resources". The top-level structure of EML has been design to be compatible with the Dublin Core syntax. In general, dataset resources, literature resources, software resources, and protocol resources comprise the list of information that may be described in EML. EML is largely designed to desrcibe digital resources, however, it may also be used to describe non-digital resources such as paper maps and other non-digital media. In EML, the definition of a "Data Package" is the combination of both the data and metadata for a resource. So, data packages are built by using the wrapper, which will include all of the metadata, and optionally the data (or references to them). All EML packages must begin with the tag and end with the tag.

The eml module may be extended to describe other resources by means of it's optional sub-field, . This field is largely reserved for the inclusion of metadata that may be highly discipline specific and not covered in this version of EML, or it may be used to internally extend fields within the EML standard.

The following table lists some important modules by their functions:

Table1 Description of the EML Modules

2 Morpho and Metacat

2.1 Metacat

Metacat stands for "Metadata Catalog". Metacat servers allow ecologists to share their data and metadata via the Internet. A Metacat is essentially a server from which ecologists (through using Morpho) can upload, download, store, query and view relevant metadata and data on the KNB (Knowledge Network for Biocomplexity).

Metacat servers can also be accessed independently of Morpho, such as via a Web browser, or calls from a database, but this requires some specialized programming. Morpho is the easiest way for most ecologists to immediately access and store metadata and data on a Metacat server. We will describe Morpho in detail in the following section.

Metacat is implemented as a Java Servlet, and so communicates using basic HTTP protocol semantics. The figure below shows the basic structure of the Metacat architecture. A well defined interface for inserting, updating, deleting, querying, and transforming (using XSL) XML documents is presented. We would like to add the DOM API as an alternative supported mechanism for interacting with Metacat, but have not yet implemented this functionality.

Metacat's backend database stores the structure and data of any arbitrary XML document. The Metacat database uses the DOM approach to store XML documents as a hierarchy of nodes. All nodes are stored as records in database tables. The hierarchical relationship between the nodes is saved to preserve the structure of the documents.

The database Entity Relationship Diagram (ERD) currently looks like this:

Figure1. Database Entity Relationship Diagram

2.2 Morpho

Morpho is a client of Metcat server. It was created to provide an easy-to-use, cross-platform application for accessing and manipulating metadata (e.g. documentation) and data (both locally and on the network). Morpho allows ecologists to create metadata, (i.e. describe their data in a standardized format), and create a catalog of data and metadata upon which to query, edit and view data collections. In addition, Morpho provides the means to access network servers, in order to query, view and retrieve relevant, public ecological data.

Morpho can be used to perform the following basic operations:

• Create and Edit Metadata
• Search and Query Metadata Collections
• View Data and Data Collections
• Verify and Edit Data
• Provide Access Control

Many types of "data" can be used with Morpho, including data tables and images.

Figure2. A snapshot of login interface of Morho

Figure3. A snapshot of working interface of Morpho