WildFly Domain Mode Concepts
Internal
Domain Mode
Details about configuring WildFly in domain mode are available here:
Domain
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Domain Controller
Also see:
High-Availability Domain Controller
Definition.
For more details, see:
Host Controller
Subordinate Host Controller
Also see:
Domain Controller/Host Controller Communication
Host controllers connect to the domain controller's management interface native API endpoint to get domain configuration, so the domain controller management functions have to be externally accessible over the management interface, hence the management interface has to be visible on the management (internal) network. A subordinate host controller does not have to expose its management interface.
Process Controller
Server Group
A server group is a set of WildFly server nodes that share a common configuration, described in a domain profile, a set of port values, described in a domain socket binding group and a set of deployments. Optionally, the servers of a server group may share a JVM configuration. It can be said that the servers of a server group are configured and managed as one, via the domain controller. Server groups allow to apply common management policies, deploy applications to all servers belonging to the server group. The servers of a server group can be subjected to group-wide management operations: all servers can be started or stopped at the same time, in one operation.
The servers belonging to a server group may run on one or multiple VMs. The association between servers, server groups and the VM they run is described here: relationship between servers and server groups.
The server groups are defined and configured in domain.xml.
In domain mode, each server instance belongs to a server group, even if that server group has just one single instance.
Server Groups and Rolling Upgrades
Different server groups can also have the same profile and deployments. This can allow for rolling application upgrades where the application is upgraded on one server group and then updated on a second server group, avoiding a complete service outage.
Server
The association between servers, server groups and the VM they run is described here: relationship between servers and server groups.
Server Node Networking
The actual values for the server node network interfaces are host-dependent, so the host controller defines them, in its configuration. Also see host controller networking.
Relationship Between Servers and Server Groups
The association between server instances and the hosts they run is defined by the host controller running on each host: the host controller reads its host.xml configuration file and instantiates the server nodes defined in its <servers> section, During start-up, the host controller determines what server group a specific server instance is part of, and pulls the profile configuration, port definitions and jvm configuration associated with that server group from the domain controller.
If more than one server instance is required on a specific host, the port offset that allows multiple server instance to run on the same host is specified in the host.xml's <server> definition as socket-bindings port-offset. For more details, see host.xml <servers> section.
Profile
See: