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Comment: Added description of in-memory repository connector

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An OMRS A Connector is a Java class that supports the standard Open Connector Framework (OCF) APIs.   The Open Metadata Repository Services (OMRS) uses the following types of connectors:

  • OMRS Repository Connectors - providing a common interface to metadata repositories.
  • OMRS Audit Log Store - providing a common interface to an audit log destination.
  • OMRS Cohort Registry Store - providing a common interface to the cohort registry store that saves information about members of a cohort.
  • OMRS Archive Store - providing a common interface to Open Metadata Archives
  • OMRS Topic Connector - providing a common interface to an instance of the OMRS Topic.
  • OMRS Repository Event Mapper - providing a common API for specific implementations of OMRS Event Mappers to implement

 

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OMRS Repository Connector Implementations

The OMRS Repository Connector API.  This API defines a call interface to create, search, query, update and delete metadata stored in a metadata repository.  The implementation of a specific OMRS connector determines which type(s) of metadata repository it is able to access.

Initially we plan 4 implementations of connectors with the OMRS Connector API.  These connector implementations will be part of the Apache Atlas code base. 

 Table 1 below lists the OMRS Repository Connectors that form part of the core open metadata capability:

ConnectorDescriptionJIRA
Local Atlas Enterprise OMRS Repository ConnectorThis connector can issue calls to multiple OMRS connectors and aggregate the results as if the metadata was stored in a single repository.  This is the connector to a local Apache Atlas metadata repository.  It calls directly to Apache Atlas's internal interface for the metadata repository and as such is always deployed in an Apache Atlas Server.
Jira
serverASF JIRA
serverId5aa69414-a9e9-3523-82ec-879b028fb15b
keyATLAS-1773
how metadata queries are federated across open metadata repositories.   Since all implementations of OMRS connectors have the same API, the Enterprise OMRS Connector is able to work will a heterogeneous collection of OMRS connectors.  It uses its configuration to create the appropriate instances of the OMRS connectors.
Local OMRS Repository ConnectorThis connector wraps a "real" repository connector (see table 2) and manages events and validation for this connector.
OMRS REST Repository ConnectorOMRS REST ConnectorThis is a connector to a remote Apache Atlas repository (or any other metadata repository that supports the OMRS REST APIs).  This is the connector used by an open metadata repository to make a direct call to another open metadata repository through the OMRS REST API.  It is also typically used by the Enterprise OMRS Connector described belowabove.
Table 1: OMRS Repository Connectors providing core open metadata function

 

Table 2 shows the OMRS Repository Connectors that provide open metadata access to specific types of metadata repositories

 

ConnectorDescriptionJIRA
Atlas OMRS Repository ConnectorThis is the connector to a local Apache Atlas metadata repository.  It calls directly to Apache Atlas's internal interface for the metadata repository and as such is always deployed in an Apache Atlas Server.
Jira
serverASF JIRA
serverId5aa69414-a9e9-3523-82ec-879b028fb15b
keyATLAS-1773
IGC OMRS Repository ConnectorThis is the connector for retrieving metadata from IBM’s Information Governance Catalog.   This connector translates the calls to its OMRS Connector API to IGC's REST API and then translates the results of these calls to appropriate responses on its API.
Jira
serverASF JIRA
columnskey,summary,type,created,updated,due,assignee,reporter,priority,status,resolution
serverId5aa69414-a9e9-3523-82ec-879b028fb15b
keyATLAS-1774
Enterprise In-memory OMRS Repository ConnectorThis connector can issue calls to multiple OMRS connectors and aggregate the results as if the metadata was stored in a single repository.  This is how metadata queries are federated across the metadata repository cluster.   Since all implementations of OMRS connectors have the same API, the Enterprise OMRS Connector is able to work will a heterogeneous collection of OMRS connectors.  It uses its configuration to create the appropriate instances of the OMRS connectorsprovides a simple in-memory repository for testing/demos or small-scale environments where metadata is being managed remotely and cached locally.
Jira
serverASF JIRA
columnskey,summary,type,created,updated,due,assignee,reporter,priority,status,resolution
serverId5aa69414-a9e9-3523-82ec-879b028fb15b
keyATLAS-17752122
Table 2: OMRS Repository Connectors for specific metadata repositories

 

Every OMRS connector supports the Open Connector Framework (OCF).  This means that they use connections to define the network address and user credentials necessary to access a specific instance of a metadata repository. 

If an OMRS Connector is included in the Apache Atlas build, then it can be called directly from an OMAS API, or from the Enterprise OMRS Connector, or from the OMRS Adapter (more details in figure 1).   When the OMRS Connector is not included in the Atlas build, it can be called from the OMRS Adapter.

Figure 1 shows some potential patterns for the use of OMRS Connectors to access different types of metadata repositories.  The letters above each pattern (A, ..., GD) refer to the notes below beside the diagram.

 

Image Modified

Figure 1: OMRS Connector Patterns

A

The Local Atlas OMRS Local Repository 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 Enterprise OMRS Connector (see here for more details) converts each call to its interface to a call to each of the OMRS connectors that it is configured to work with.  It then aggregates the results together for form the response to its call.CThe OMRS REST REST Repository 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.
DThe OMRS REST Connector is calling the OMRS REST API that has been implemented by a non-Apache Atlas metadata repository.
EThe OMRS REST Connector is calling the OMRS REST API that is implemented by the OMRS adapter.  This is a standard OMRS component that runs is its own WAR file (ie outside of the Atlas server).   New connector implementations can be introduced into the OMRS Adapter from third parties.  The OMRS Adapter translates to OMRS REST API calls to a local OMRS Connector based on configuration.  This adapter pattern enables OMRS Connector implementations that are not part of the Atlas Build to be called from standard open metadata components.  In this example the OMRS Connector calls the proprietary interface of the XYZ repository.
FThis is an alternative adapter pattern where the adapter translates between the OMRS REST API and the repositories proprietary interface rather than going through a connector.  This adapter is not an open metadata component - it is provided by a third party.
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 GThe IGC OMRS Connector is an example of a special 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 OMRS Adapterthe Enterprise OMRS Connector rather 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 to form the response to its call.

 

Together the OMRS Connectors provide a flexible way to federate make calls to many types of metadata repositories. 

 

   

 

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