This post is part of a series exploring the unique aspects and capabilities of WebSphere Liberty when running on z/OS.
We'll also explore considerations when moving from WebSphere traditional on z/OS to Liberty on z/OS.
The next post in the series is here.
To start at the beginning, follow this link to the first post.
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There are several different ways to interact with a Liberty server that work everywhere. If you have configuration monitoring enabled (on by default), changes to the server config are seen and enacted pretty fast. You can also do some things via the ‘server’ shell script that you use to start the server. And there are an assortment of MBeans you can call to do various operations on the server. These are generally driven from within the server, but you can also use things like jconsole to call them.
But if you’re running on z/OS and you’ve started the server as a started task, you kind of expect it to be able to handle Modify commands issued from the z/OS console. Most ‘server’ things running on z/OS will have a thread waiting on the ECB that gets posted when a Modify command is issued for the address space. (Here’s a trivia question: the ECB posted for a Modify is not in key 8 storage, but a key 8 problem state program can wait on it. Waiting on an ECB changes the storage contents. How does this work?)
Ok, so Liberty added code to wait on the Modify ECB. There’s some magic to keep us from doing that when we’re running inside of CICS. Seems they wanted to wait on that ECB themselves….
What sorts of things do we allow you to do via Modify commands? Well, we’ll get to that in the coming posts. We started by looking at what we had supported in WAS traditional on z/OS. Those commands were about an even mix of commands to do something to the server (like change trace settings, collect doc, etc) and display commands to show you various things about what was going on in the server.
Of the display commands, much of the specifics didn’t really apply for Liberty (show all the servant regions…). But there are still some things that still make sense.
In the weeks to come we’ll look at commands relating to configuration changes, both ‘permanent’ (meaning you changed the server config itself) and temporary (just for this instance of the server because you issued the command). We’ll see a command to gather some doc and to display information about what is going on in the server.
There are also some Modify commands relating to the Angel, but we’ll save those until we’ve gotten around to discussing the Angel. The commands will hopefully make more sense then.