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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.
Table 1 below lists the OMRS Connectors are used in 4 places:
- They are called from the Open Metadata Access Services (OMAS). Because all OMRS connectors support the same API, the OMAS APIs can work with any OMRS Connector implementation. The OMAS API manages the connection information that identifies which OMRS Connector implementation plus the network address and user credentials it is using in its configuration.
- The OMRS event notification framework uses the OMRS Connector to store reference copies of metadata in a metadata repository.
- The Enterprise OMRS Connector (described below) uses multiple OMRS Connectors to federate calls to multiple metadata repositories and aggregate the responses.
- The OMRS Repository Proxy (part of the toolkit for integrating new metadata repositories into the open metadata ecosystem) uses an OMRS Connector to connect a metadata repository.
OMRS Connector Implementations
Repository Connectors that form part of the core open metadata capability:
Connector | Description |
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Enterprise OMRS Repository Connector | This 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 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 Connector | This connector wraps a "real" repository connector (see table 2) and manages events and validation for this connector. |
OMRS REST Repository Connector | 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 typically used by the Enterprise OMRS Connector described above. |
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 repositoriesInitially we plan 4 implementations of connectors with the OMRS Connector API. These connector implementations will be part of the Apache Atlas code base.
Connector | Description | JIRA | ||||||||||||||||||||
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Local Atlas OMRS Repository Connector | 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. |
| This 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. It is also used by the Enterprise OMRS Connector described below. |
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IGC OMRS IGC OMRS Repository Connector | This 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. |
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Enterprise In-memory OMRS Repository Connector | This 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 connectors.provides a simple in-memory repository for testing/demos or small-scale environments where metadata is being managed remotely and cached locally. |
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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. 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, ..., D) refer to the notes beside the diagram.
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Figure 1: OMRS Connector Patterns | A | The Local Atlas OMRS 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. |
B | The OMRS 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. | |
C | Metadata 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 OMRS Repository Proxyrather than via a remote REST call. | |
D | The 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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Together the OMRS Connectors provide a flexible way to make calls to many types of metadata repositories. Figure 2 illustrates these OMRS connectors in action. Since OMRS connectors are Java, those that are committed into the Atlas build can be hosted directly in the Atlas server. Additional connectors can be built by anyone and these can be assessed through the OMRS REST interface.
Figure 2: Using the OMRS Connectors to access metadata in a metadata repository cluster |
The notes below correspond to the numbers on the diagram in figure 2.
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types of metadata repositories.
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