What is a Registry?
Registry in essence is a storage space in which data and configuration relating to a product can be persisted and referred from. The Registry uses a database for data persistence and it can be mounted to any type of Relational DB. Registry is a Carbon Kernel component hence all WSO2 products have a registry space built into the product.
Each registry can be divided into 3 spaces.
- Local Registry space
Local Registry space is specific to each WSO2 product and is not shared with other products in the deployment. Local registry stores artifacts that are local to that particular server.
- Config Registry space
Config Registry is shared between similar products in the cluster. For example all ESB nodes in the cluster would share a single Config Registry space. All product specific artifacts are stored inside this Registry.
- Governance Registry space
The governance registry space is a common space that is shared by all WSO2 products in the deployment. This registry space will store all artifacts that are common to all WSO2 products in the deployment. Governance Registry space should not be confused with the WSO2 Governance Registry.
Registry spaces are conceptual and all 3 spaces can mount to a single location. In the vanilla distribution of a WSO2 product, all these 3 spaces are pointed to the local H2 Database.
What is Registry mounting?
Registry mounting refers to a concept of linking the registry to a database. By Default the registry is mounted to the local H2 Database. It is possible to mount different Registry spaces of the same registry to different databases. For example the Local Registry space can be mounted to the H2 database whilst other spaces can be mounted to a remote database. In a production system it is recommend to mount the Config and Governance spaces of the Registry to a remote database.
Governance Registry Space != Governance Registry
Even though they sound similar, the Governance Registry space is not the same as WSO2 Governance Registry Product. Governance Registry simply refers to a registry space that is common to all WSO2 Products. Whereas the WSO2 Governance Registry product is a registry and a repository to store any type of data or metadata. It provides a rich set of features including SOA governance, lifecycle management, and a strong framework for governing anything.
What is remote Registry mounting
In a production deployment it is recommended to mount the Config and Governance space of the Registry to a remote database. This allows these registry spaces to be shared by the other products in the cluster or in the deployment. For example if you mount the Config space in a remote location all similar products in the cluster can use this remote location, where as if you mount the Governance space in a remote location all the WSO2 products in the deployment can use this remote Governance space.
How WSO2 Governance Registry comes into the picture
WSO2 governance registry can be used to manage the registry spaces of WSO2 products. This provides the capability to incorporate registry features to the registry spaces so that the registry can be managed better from a central point.