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The "TomcatGridDiscussion" page has been changed by markt: https://wiki.apache.org/tomcat/TomcatGridDiscussion?action=diff&rev1=10&rev2=11 Comment: Add some initial comments The Grid Agents are Java processes installed and running on each machine that listen (on a configured port) for commands from a Grid Manager application (Web or CLI) and act upon them by interacting with the local Tomcat instances. No encryption is envisioned on the network channels, since all these machines are considered to be installed on a secured network segment (at least in prod). [Maybe we should reconsider this] + ''markt: I think this needs to be reconsidered.'' + - All Tomcat instances (including the Web Grid Managers), as well as the Grid Agents, are installed manually. The primary grid manager and all the agents are started manually too. + All Tomcat instances (including the Web Grid Managers), as well as the Grid Agents, are installed manually. The primary grid manager and all the agents are started manually too. - Once the Web Grid Manager is started up, machines and instances can be registered in it, so they can become manageable. No centralized (comprehensive) provisioning is envisioned until later versions of Tomcat Grid (see below). + Once the Web Grid Manager is started up, machines and instances can be registered in it, so they can become manageable. No centralized (comprehensive) provisioning is envisioned until later versions of Tomcat Grid (see below). The Grid Agents are processes that can also be managed. In particular, status can be obtained (and showed) from them, and basic operations (start/stop/kill) can be triggered on them. These operations are, however, heavily dependent on OS and OS capabilities (configuration, installed tools, etc.) and the infrastructure architecture (fire-walled machines, network VLans, etc). Collectively, Tomcat instances and Grid Agents are "services" since both can be managed. + ''markt: Managing the agents strikes me as making this significantly more complex. Operating systems have tools to ensure particular services are running and are restarted if they fail. What is the benefit of pulling this into this tool?'' + Later versions of the Grid include "collection" management. This allows to group subsets of services (Tomcat instances and Grid Agents), so they can be operated as whole. Each collection can include plain services, or other collections (recursively). Considering all the above, the following phases could be considered as a base line for the road map of the Tomcat Grid. + + ''markt: I'd like to see a little more high level architecture to steer development. For example, is there a common core of management functionality that we then wrap with a web-based GUI and a CLI? That would allow others to write other wrappers to plug this into other tools.'' == Phase 1 - Core Grid Operation == The first phase includes the most basic features, in order to provide a functioning and useful first version of the Grid. In particular, no Tomcat instances or Grid Agents automatic provisioning is considered, no configuration GUI (only pre-configured XML config files), no WAR deployments, no command-line interface, no complex grid operations, no secondary managers, and no collections. + + ''markt: This raises another architectural question. Wouldn't this be more scalable if agents were configured with the location of the primary manager and registered themselves? The manager could persist that registration so an agent would have to be explicitly removed if it was taken off-line permanently.'' Included features are: @@ -51, +59 @@ * '''trigger-start''': sends a start request to the Tomcat instance using the corresponding Grid Agent * '''trigger-stop''': sends a stop request to the Tomcat instance using the corresponding Grid Agent * '''trigger-kill''': sends a kill request to the Tomcat instance using the corresponding Grid Agent + * ''markt: A small thing. I think I'd prefer start/stop/kill/'' 1. A simple configuration file lists all the machines and their instances so the Grid knows where each instance resides. [This configuration file is probably in XML format] @@ -61, +70 @@ * OS calls for any OS related need. 1. It's assumed that a port will be accessible from each Grid Manager to each machine where the Grid Agents are serving. The firewall, if present must allow active server-type sockets on that port. + * ''markt: Another architectural question. Which end opens the connection, does it stay open and which protocol is used? For example, agents connect to Manager via WebSocket.'' 1. Multiple Grids (and Grid Agents) can be running on the same set (or subset) of machines. If that's the case, Tomcat instances, and Grid Agents run on different ports for each grid. When multiple grids use the same machines they don't interfere with each other and can be operated simultaneously. --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@tomcat.apache.org For additional commands, e-mail: dev-h...@tomcat.apache.org
