Common Metadata Repository (CMR)
What is CMR?
NASA's Common Metadata Repository (CMR) is a high-performance, high-quality, continuously evolving metadata system that catalogs all data and service metadata records for NASA's Earth Observing System Data and Information System (EOSDIS) system and will be the authoritative management system for all EOSDIS metadata. These metadata records are registered, modified, discovered, and accessed through programmatic interfaces leveraging standard protocols and APIs.
CMR tools and services include:
- CMR Application
- Metadata Management Tool (MMT)
- draft Metadata Management Tool (dMMT)
- Metadata Curation Dashboard
CMR is the backend behind the following data search and discovery services:
NASA's Earth Science Data Information System (ESDIS) Project 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.
Formerly, NASA metadata providers were 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 reduced the value of the metadata and complicated 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 and improve the metadata quality, consistency, and usability for end users by:
- Serving as a middleware replacement for GCMD’s backend. Note: Users of GCMD should see no impact as the GCMD frontend will remain as is.
- Handling metadata at the concept level; including collections, granules, visualizations, variables, documentation, services, and more.
- Managing hundreds of millions of metadata records; making them available through performing standards-based temporal, spatial, and faceted search.
- Incorporating both human and machine metadata assessment features that work to ensure the highest quality metadata possible.
- Supporting multiple metadata standards using an ever-evolving Unified Metadata Model (UMM).
How does CMR do that?
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, variables, documentation, services, and more. CMR provides a flexible ingest system with metadata libraries which can handle multiple metadata record formats, multiple metadata record concepts, and relationships and validations between them. As new formats are introduced, new translations can be written for CMR’s metadata libraries to provide ingest, validation and search support. The libraries also provide format conversions for backward compatibility.
Benefits of CMR
CMR provides a unified repository for NASA's Earth science metadata. This benefits providers by only needing to ingest their metadata into one system. It also benefits users by being able search one system and retrieve both EOSDIS and IDN data.
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; striving to make them available in under a second. CMR is able to do this by a using sophisticated data indexing and caching strategies built on top of a performance infrastructure.
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. 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.
Consistent Metadata Representation
- CMR's ingest framework supports services which validate distinct metadata standards such as ECHO10, GCMD DIF, and ISO19115 against a common set of core metadata elements described in UMM.
UMM describes the metadata related to key EOSDIS concepts (such as collection or granule) using UMM metadata “profiles” (such as UMM-C for collection and UMM-G for granule).
- CMR provides services for mapping metadata records to and from any of the CMR-supported metadata standards, through UMM. Thus, CMR is able take metadata records of various source formats, and convert non-ISO 19115 metadata into robust and standards compliant ISO 19115 representation for interested clients. This can be seen in the diagram below:
For example, for collection metadata records, a UMM-C record may be mapped to any other supported collection metadata standard such as ISO 19115-1, ISO 19115-2, ECHO 10, DIF 9, or DIF 10. Records created using any of those supported standards may be mapped to any other of those supported standards by first mapping to UMM-C.
- As additional metadata concepts are introduced to CMR, new ingest services will provide verification and search indexing capabilities across diverse metadata such as visualization and variable information.
There is a lot of excellent information available that can help get you off and running.
- The CMR Partner Guide is a wealth of information for users of any level
- The CMR Wiki houses the CMR and UMM administration documents as well as links to CMR related projects.
- Developers and interested parties should visit the Earthdata Developer Resource to view:
- General API information
- API documentation
- API reference information
- A Metadata Ingest API Overview
- OpenSearch documentation
- Collection CSW documentation
- UMM-C and UMM-S schema
- Metadata Management Tool User Guide
- Client-Partner User Guide
- Access the CMR Client Developer Forum
Visit this page to get details with examples on how to cite and reference NASA's discipline-specific data and services.
- EOSDIS Tools and Services
EOSDIS Tools and Service Portfolio was created to:
- Evaluate and update the existing inventory DAAC and EOSDIS tools and services to understand the current portfolio
- Identify tools and services with apparent overlapping functionality and evaluate to determine what, if any, efficiencies may be gained moving forward
- Create a framework for a governance process to apply to future tool and service development efforts
EOSDIS Tools Information
NASA's Distributed Active Archive Centers (DAACs) provide an extensive variety of tools that make it easy for users to discover, access, manipulate and use EOSDIS data products. Visit this page to learn more about the tools NASA has to offer.
- EOSDIS Tools and Service Portfolio was created to:
Page Last Updated: Jan 29, 2021 at 1:19 PM EST