OMAG Server Platform¶
The OMAG Server Platform provides a runtime process for all of Egeria's services.
When the OMAG Server Platform is first started, all of its REST APIs are visible and callable by external clients. However, only the Administration Services and Platform Services are operational at this point. The other services will give an error response if called.
The other services are configured and activated in OMAG Servers using the administration services. The configuration operations of the administration services create configuration documents, one for each OMAG Server. Inside a configuration document is the definition of which services to activate for the server. These include:
- The Open Metadata Repository Services (OMRS) (any type of server),
- The Open Metadata Access Services (OMASs) (for metadata access servers),
- The Open Metadata Engine Services (OMESs) (for engine host servers),
- The Open Metadata Integration Services (OMISs) (for integration daemon servers) and
- The Open Metadata View Services (OMVSs) (for view servers).
Each server is configured to support specific set of Egeria services and connect to a specific set of metadata resources. When it runs, each server is isolated within the platform and so the OMAG Server Platform can be used to support multi-tenant operation for a cloud service, or host a variety of different OMAG Servers needed at a particular location.
Deployment of the OMAG Server Platform¶
Once a configuration document is defined, the OMAG Server can be started and stopped multiple times by the admin services server instance operations.
The OMAG Server Platform can host multiple OMAG Servers at any one time and a single server may be active on multiple platforms. The choices are as follows:
- A - Each OMAG Server has its own dedicated OMAG Server Platform - useful when only one server is needed in a deployment environment, or there is a desire to keep each server isolated in its own operating system process.
- B - Multiple OMAG Servers are hosted on the same OMAG Server Platform. The OMAG Server Platform routes inbound requests to the right server based on the server name specified in the request URL. The servers may all be of the same type offering the same services but to different groups of people or be a set of collaborating servers of different types consolidated onto the same platform.
- C - Multiple copies of same server instance each running on different platforms to provide high availability and distribution of workload (horizontal scalability).
Inside the OMAG Server platform¶
Figure 1 shows the OMAG Server platform when it first starts up.
Figure 1: OMAG Server Platform at start up
The platform origin service is operational at this point. It can be used by operational scripts to determine if the OMAG Server platform is still running.
The administration services are also active, while the open metadata and governance services will return an error if called since there are no OMAG Servers running.
The configuration services are used to create configuration documents. Each configuration document describes the open metadata and governance services that should be activated in a OMAG Server. Figure 2 shows the configuration services creating three configuration documents:
- one for the
- one for the
- one for the
Figure 2: Creating configuration documents for OMAG Servers
The Administration Guide provides detailed instructions on creating configuration documents.
Once a configuration document for an OMAG Server is used by the operational services initialize the requested services in the OMAG Server. The OMAG Server can be started in any OMAG Server platform. It does not have to be the same OMAG Server platform that created the configuration document.
Figure 3 shows an OMAG Server platform with the cdoMetadataRepository local OMAG Server running.
Figure 3: Starting a OMAG Server through the operational services
Once the OMAG Server has initialized successfully, the open metadata and governance services can route requests to it.
An OMAG Server platform can run multiple OMAG Servers at one time. Figure 4 shows an OMAG Server platform running multiple servers.
Figure 4: An OMAG Server platform running multiple OMAG Servers