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Comment: Updated description of figure 2 - but diagram needs updating

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Figure 1: OMRS Connector Patterns

A

The Local Atlas OMRS Connector is hosted in the Apache Atlas server and calls the local internal metadata repository API. Every Atlas server will have one of these connectors.
BThe OMRS REST Connector translates calls to its repository interface to calls the OMRS REST API of a remote open metadata repository.  Apache Atlas servers support the OMRS REST API, and other Open Metadata native metadata repositories may also implement this interface too.
CMetadata repositories that have their own API can create a connector to translate OMRS calls to call to their API.  The IGC OMRS Repository Connector is an example of this type OMRS connector written to support a specific metadata repository that is not Apache Atlas.  This OMRS Connector will be included in the Apache Atlas build so it can be called directly from and OMAS API, the Enterprise OMRS Connector or the OMAG Repository Proxyrather than via a remote REST call.
DThe Enterprise OMRS Connector (see here for more details) converts each call to its repository connector interface to a call to each of the OMRS connectors that it is configured to work with (see OMRS Enterprise Connector Manager).  It then aggregates the results together for to form the response to its call.

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Figure 2: Using the OMRS Repository Connectors to access metadata in a an open metadata repository clustercohort

 

The notes below correspond to the numbers on the diagram in figure 2.

  1. There are many OMAS APIs, each designed for a different type of consumer.  Each OMAS API has a simple, bean-like Java interface for applications to call (or the application may use the OMAS REST API directly).
  2. The OMAS REST APIs provide JSON versions of the objects supported in the OMAS APIs.  The OMAS Java Server classes implement the server side of the REST APIs.  Each Java Server Class uses the connector broker to acquire an the Enterprise OMRS Repository Connector.
  3. The Local Atlas OMRS Repository Connector provides optimized local access to the local Apache Atlas metadata repository.
  4. This local repository includes a graphDB accessed through TinkerPop.
  5. The Enterprise OMRS Repository Connector is able to aggregate metadata from multiple metadata repositories in response to a single request for metadata.  It does this by replicating the request across multiple downstream OMRS Repository Connectors and then aggregating and correlating the results.
  6. The Enterprise OMRS Repository Connector is typically configured to call the local Atlas Repository repository for creates.  Updates go to the repository where the metadata entity was created.
  7. In addition, the Enterprise OMRS Repository Connector may be configured to call other metadata repositories using OMRS Repository Connector implementations that have been built into the Atlas runtime.  In this example,  (7) shows an OMRS connector that can call IBM’s Information Governance Catalog (IGC).
  8. The IGC OMRS Repository Connector will translate OMRS calls into IGC REST calls.
  9. For calls to remote Atlas Open Metadata Servers, and other servers that have OMRS connectors that are not included into the Atlas runtime, the Enterprise OMRS Connector will use the OMRS REST Repository Connector.  This connector translates OMRS connector requests into remote OMRS REST calls. 
  10. The OMRS REST Repository Connector may also be called from the OMAS Java Server classes to pass-through metadata requests to a remote metadata server.
  11. Every Atlas runtime supports the OMRS REST APIs.
  12. When an Atlas runtime received an OMRS REST call, it is passed to the local Atlas local  OMRS repository connector and is executed against the local metadata repository.
  13. The OMRS REST Repository Connector can be used to connect to an Repository Proxy for other types of metadata repositories.  
  14. The Repository Proxy would host an OMRS Repository Connector to the metadata repository.  This provides a solution for OMRS Connector implementations that are not (yet) integrated into the Atlas build.  The downside of this approach is the additional network hop that the adapter introduces.
  15. An OMRS REST Repository Connector can be incorporated into other metadata repositories to enable them to query Atlas open metadata.  Typically the repository will use the Enterprise OMRS Repository Connector to ensure it is reaching as much metadata as possible.
  16. This includes IBM’s Information Governance Catalog (IGC).

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