Why would anyone use WSO2 Application Server instead of other application servers?
I rather encountered only problems with it, mainly due to class loading issues, so I would appreciate if someone could point out what are the advantages or the use cases when using WSO2-AS really makes a difference.
I can see the benefits of other standalone WSO2 products, but as far as the AS is concerned, I would rather rely on more lightweight servers and just package the libraries I need.
There are number of advantages on WSO2 Application Server.
1.) It provides in-built support for multi-tenancy, in case if you have isolated departments like organization there is no real need to have number of server instances you could simply create a new tenant.
2.) Automatic lazy loading support for tenants, web applications and web services. In a production system a particular tenant/web application/web service can be ideal for sometime it's a waste to allocate hardware resources continuously to such ideal applications specially if you use IaaS. WSO2 application server can detect such ideal tenant/web application/web service and release their resources and tenant/web application/web service will load again when a new request dispatch to the particular tenant/web application/web service.
3.) Wide range of deployment options, support to deploy on-premise, public or private IaaS , public or private PassS such as Apache Stratos. An an example one can deploy his application into WSO2 App Cloud (http://wso2.com/cloud/app-cloud/) instantly without downloading anything, later he can get same experience one of above platforms.
4.) Deployment synchronization feature, a clustered environment you may have very large number of nodes and upgrading application version and configuration changes across the cluster can be headache. Using Deployment synchronization feature you can modify only one node labeled as manger node and Deployment synchronization will take care about synchronize changes across the cluster automatically and consistently.
5.) When developing applications on WSO2 Application Server you can leverage carbon platform level features such as identity, registry, logging, distributed caching, multi-tenancy etc. As an example one can use identity features provided by the platform to mange users, roles permissions also for authentication and authorization without write something own.
6.) Inbuilt support for security standards such SSO among other WSO2 products.
7.) In-build monitoring capability for web services and web application through WSO2 BAM.
8.) Enhanced and rich dashboard for applications and services which facilitate to basic statistics, application management, security wizards, code generations, Try -It tools, run time logging configurations etc.
9.) Enhanced classloading mechanism (starting from AS 5.1.0), within one Application server instance you can have number of virtual server environments per application level. As an example one can specify an application run on minimal Tomcat mode or can assign to run Carbon mode which is ( Tomcat + Carbon platform).
When it come to your specific issue if you can specify your Application Server version and elaborate more on your classloading issue I can provide you more specific answer.
Having said above I want to mention that I'm from WSO2.