WLST is a powerful scripting solution for managing and administering WebLogic Server and resources deployed on them. WLST is built on the Java implementation of the scripting language Python called as Jython. All the commands in WLST are implemented as Jython functions and they require a set of parentheses for passing any arguments. Even any commands that do not require any arguments are supposed to be suffixed with parentheses. For example the command “ls” is used to list all the child MBeans and/or attributes of the current MBean you are at.

ls() – lists all the child MBeans and attributes
ls(‘a’) – lists all the attribute names and values only
ls(‘c’) – lists all the child MBeans only

So even if you want to invoke “ls” with no arugments you must use “ls()“. This might not be an issue when you are building scripts that you might want to run many times. But while connected to a server and working with WLST in interactive mode, it might get a little frustated to type the parentheses everytime you want to run some simple commands with no arguments. To ease this pain there is a hidden option in WLST which can be used to ease the syntax for WLST commands – easeSyntax().

You can supply the “easeSyntax()” command to ease the syntax but this is not recommended for script mode and especially when using loop constructs. You can also use the regular Jython syntax with parentheses even after you enabled the easy syntax. To turn off the easy syntax mode simply issue the command again “easeSyntax“.

Bye Bye parentheses!

If you are using WebLogic Admin console frequently to configure resources or to manage the life cycle of the servers, you might have seen a confirmation prompt. This prompt will show not up when you are running the domain in development mode. When the domain is running in production mode they will ask confirmation for all the operations. There used to be no way to disable this confirmation page prior WebLogic Server 10.3. Now in WebLogic Server 10.3 and higher you can set a console user preference that can disable these confirmation pages.

Use the tool bar at the center (top) of the console to go to the “Preferences”. Under the “User Preferences” tab you will find an option called “Ask for confirmation in operations”. By default it will be enabled in production domains and you can disable it to avoid that annoying confirmation pages where will have to click either “Yes” or “No”. While you are there explore the other useful preferences like “Show Inline Help” and “Show Advanced Sections” which can buy some real-estate space in the console and save you some clicks.

When using HTTP Sessions with WebLogic Cluster, you can ensure high availability for your session by configuring HTTP Session Replication. For the replication strategy, you have many options to select from like In-memory, file, JDBC, Cookie etc. When you are using in-memory replication with a web server to front WebLogic Server Cluster, the proxy plug-in must be configured on the web servers. The proxy plug-ins are intelligent enough to stick the request from a client to the same server where the session is hosted. A secondary copy of the session will be sent to a backup server by the primary server. This information will be written to a cookie or encoded in the URL depending on the client’s configuration to support cookies.

In the past, during failure of the primary server, the proxy plug-in on the web server will redirect the request to the secondary/backup server. This resulted in increased traffic to the secondary/backup server. So somewhere during the Weblogic Server 9.x the plug-ins are updated to do a random routing incase of failures. The proxy server will randomly distribute all the requests from the failed server to different servers that are still running in the cluster. When the request from the existing clients (with valid session id) gets redirected to servers that are not secondary server then that server will connect to the secondary server for that client and will pull the session to become primary server. This ensures that one server will not get overloaded when a server in a cluster fails.

The same exact strategy was used when you front a WebLogic cluster with a load balancing hardware as not all the load balancing hardware understand the WebLogic cluster configuration. Now the same strategy is applied to the WebLogic Cluster front by a proxy plug-in hosted on a web server. This make the failover strategy consistent whether you have hardware or a software based proxy in front a WebLogic Cluster.

WebLogic Server documentation is still not updated to reflect this change under the “Proxy Failover Procedure” section. If you are running WebLogic Cluster with 9.x and you are not seeing this behavior then you can contact Oracle Support to find out whether there is a patch that can you can apply for your current WebLogic implementation.