Common Metadata Repository (CMR)

What is CMR?

The Common Metadata Repository (CMR) is a high-performance, high-quality, continuously evolving metadata system that merges all existing capabilities and metadata from EOS Clearing House (ECHO) and the Global Change Master Directory (GCMD) systems. Once fully operational, CMR will serve as the authoritative management system for all EOSDIS metadata.

The CMR system is composed of:

  • CMR itself (formerly the [ECHO])
  • GCMD
  • International Data Network (IDN)
  • Earth Science Data and Information System (ESDIS) Metrics System (EMS)
  • All related tools (internal and external)
  • All metadata — including the Unified Metadata Model (UMM) concepts, the GCMD Keywords Controlled Vocabulary, and other controlled vocabularies.

High Level Architecture Diagram of the Common Metadata Repository (CMR)
High Level Architecture Diagram

Why CMR?

Why CMR?

NASA's Earth Science Data Information Systems (ESDIS) program is responsible for providing access to Earth Observation data and services to an ever-growing user community including — but not limited to — Earth Scientists, Educators, other government agencies, decision makers, and the general public. As data archives grow and more data becomes accessible online — cataloging, searching, and extracting relevant data from these archives becomes a critical part of Earth Science research.

Currently, NASA metadata providers are required to contend with multiple, disparate systems; each requiring different formats and different mechanisms for submitting and updating data entries. As an end user or application developer, this inconsistency reduces the value of the metadata and complicates finding and using earth science data.

In response to these challenges, NASA set out to design a system that would:

  • Reduce the burden on metadata providers
  • Improve the metadata quality, consistency, and usability for end users.

Thus — CMR was born!

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How does CMR do that?

How does CMR do that?

The CMR is designed to handle metadata at the Concept level. Collections and Granules are common metadata concepts, but this can be extended out to Visualizations, Variable Parameters, Documentation, Services, and more. The CMR provides a flexible ingest system with pluggable adapters that can handle multiple metadata record formats, multiple metadata record concepts, and relationships and validations between them. As new formats are introduced, new ingest adapters can be written for the CMR to provide ingest, validation and search support and response adapters provide format conversions for backward compatibility.

Unified Metadata Model Diagram for the Common Metadata Repository (CMR)
Unified Metadata Model Diagram

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Benefits of CMR

Benefits of CMR

Enhanced Performance

Modern Earth Science applications strive to provide end users with nearly immediate access and interactivity across massive stores of Earth Science data. That data is discovered, navigated, and often interrogated through science metadata. As the range of applications grow and more and more information moves from the underlying science data to metadata, the challenges of navigating even just the metadata increases. CMR is designed to handle hundreds of millions of metadata records; making them available through high-speed performance, standards compliant, temporal, spatial, and faceted search.

The CMR builds on the work done by ECHO and the GCMD to provide a unified, authoritative repository for NASA's Earth Science metadata.

End-User Interface Diagram for the Common Metadata Repository (CMR)
End-User Interface Diagram

Quality Assurance

High performance access to metadata is only part of the problem. To be useful to a broad range of Earth Science applications, the metadata must be of high quality, complete, and consistent. The CMR incorporates both human and machine metadata assessment features that work to ensure the highest quality metadata possible. During ingest, automated metadata scoring rubrics are applied giving data providers insight into how to make their data more discoverable or usable by end users. Science Coordinators and review teams can review metadata that fails verification or lacks required information to help providers make their metadata more consistent and complete.

Metadata Quality Assurance Diagram for the Common Metadata Repository (CMR)
Metadata Quality Assurance Diagram

Consistent Metadata Representation

  1. The CMR's ingest adapter framework supports pluggable adapters which validate distinct metadata formats such as ECHO10, GCMD DIF, and ISO19115 against a common set of core metadata requirements, the Unified Metadata Model (UMM).
  2. The CMR will be able to take multiple metadata records associated with a common core concept, such as a Collection, and merge the disparate information into a robust and standards compliant ISO19115 representation for interested clients.
  3. As additional metadata concepts are introduced to the CMR, new ingest adapters will provide verification and search indexing capabilities across diverse metadata such as visualization and parameter information.

Working toward NASA's ISO 19115 Recommendations (Common Metadata Repository)
Working toward NASA's ISO 19115 Recommendations

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Additional Information

For more technical information regarding the CMR, see the CMR Wiki. You must register for an Earthdata Login profile to access the wiki.

Contact Earthdata Support for questions, comments or technical issues.

Last Updated: May 2, 2019 at 1:33 PM EDT