Along with expectations for the database to be updated online, users do not want to experience downtime for a new version of an application to be deployed. PAS for OpenEdge provides fault-tolerant and persistent ABL and SQL application sessions. These enhancements provide online capabilities to enable updates and troubleshooting without forcing users to disconnect from the instance.

Deploy your application while online

OpenEdge system administrators can securely deploy new ABL applications to production PAS for OpenEdge instances without having users experience any downtime. Secure ABL application deployment to a production instance requires a securely deployed Tomcat Manager, and other security considerations.

For example, as an e-commerce enterprise you want to set up your ABL applications to support microservices using PAS for OpenEdege. You need to update your applications frequently to keep your services competitive; however, your previous application architecture required a server restart when installing new microservices. Restarting your instance disrupted your other services because they rely on one another. To combat this disruption, you can choose to use PAS for OpenEdge to help build your architecture and to be able to install new versions of microservices without requiring a restart.

Main steps: Deploy applications while online

  1. Create a production PAS for OpenEdge instance.
  2. Deploy the Tomcat Manager web application.
  3. Enable the remote IP address valve.
  4. Deploy your initial web application.
  5. Deploy your service to an online instance of PAS for OpenEdge..

For more information about deploying your application while online, see Secure online deployment of a new ABL application.

Update PROPATH while online

Similar to using the PAS for OpenEdge capability to deploy a new application while online, you can dynamically update applications by enabling live PROPATH updates in production instances without restarting the server.

This feature allows system administrators to:
  • Deploy new application r-code to a running server instance.
  • Change the PROPATH by using the OEPROP utility or by deploying an updated application to include the new r-code location.

Consider the following scenario. As an enterprise, you have an application running on a deployed instance of PAS for OpenEdge and need to push an update to that application. The application is configured as modules using procedure libraries with a versioned directory structure. To push that update using PROPATH, you can deploy a new procedure library and update the instance PROPATH, making the update available while your application is running. However, after you push the update, you realize that there is now a bug in your application. To fix this bug, you can deploy an r-code file as a hotfix to address the bug in the update you just deployed, without ever restarting the server.

For more information, see Update PROPATH in a production instance with zero downtime.

Refresh agents in an ABL application

To prevent your application architecture going down from memory growth due to application leaks, you can refresh agents in ABL applications on a PAS for OpenEdge server. Using the refresh agents API you can return memory to the operating system and free memory currently used in the agents so that it can be reused by new ABL sessions. You might notice that the refresh agents API provides operations similar to the PAS for OpenEdge's ability to update PROPATH while online, however, the API does not require a change to the PROPATH or for run-time updates to be enabled.

The refreshagents API works by terminating all sessions within the agent of an ABL application, which causes the multi-session agent to refresh so that changes to the application can be picked up by a new agent. When you use this API, the ABL sessions that are running in the application complete before they are terminated. New sessions are started on the next session as needed, per the minAvailableABLSessions setting. The refreshagents API allows new sessions to use the updated persistent procedures, static objects, or online schema changes, and start running sessions against the new code. The following video introduces the refresh agents API in PAS for OpenEdge:

Enhanced ABL session management

In OpenEdge, the PAS for OpenEdge multi-session agent self-manages its ABL session pool to guarantee that an ABL Session is ready and available before it receives a request to process. The PAS for OpenEdge ability to self-manage supports continuous operations of ABL applications by addressing an unexpected failure due to resource unavailability. For example, creation of an ABL session may fail if the database it is connecting to runs out of capacity. The ABL session automatically reconnects to a session pool that has available resources. For more information, see Enhanced ABL session management.