Liberty Vs Websphere Full Profile for CLM

Authors: DineshKumar
Build basis: CLM 6.0.6.1, ELM 7.x

This article focuses on answering the curious question on if Liberty is the right choice for CLM Deployment. The article is a one-stop place for comparative study on Websphere vs Liberty for CLM/ELM. Read on for the experience share from our internal hosting and from Customer deployments..

Support for TWAS Deprecated from ELM 7.0.3

ELM 7.0.2 is the last version with support for Traditional WAS, starting ELM 7.0.3 Liberty is the only Supported Application Server.

What IBM Websphere Team says about Liberty

One of the frequent asks from Websphere deployments was the start times. Websphere Team says that "Application start is generally faster on Liberty."

Next common concern when comparing the two is performance, on which the Websphere Team says "The performance of request processing is very similar on the two profiles in most scenarios, because the application request paths are mostly common code (channels, transports, containers etc)."

The differences between the two profiles is touched upon at high-level in the below article, a whitepaper is referred inside gives in-depth details :
Traditional WebSphere or Liberty: how to choose?

Why Liberty, a word from CLM Development Team

CLM applications are typical J2EE applications and only require standard J2EE application server container. WebSphere Liberty is a standard J2EE application container.

Liberty is much lighter (200mb) than traditional WebSphere (1gb+) (as an example, we do not require EJB support, which is one of several features that make TWAS heavy). This makes Liberty more suitable for many of the modern use cases.

For example Clustering... RTC nodes should be light and fast... starting up a Liberty node takes two - four minutes, this could be much longer with the heavier Traditional Websphere.

With Cluster use cases, Liberty is much simpler to handle.. in terms of starting, stopping, upgrading, monitoring, and overall resource footprint.

Clustering requires Jazz Authorization Server (JAS) and JAS is supported only on Liberty. If you are looking to Scale your Deployments, its important to migrate to Liberty.

What we see in our Internal Hosting

Jazz.net, ClearObject runs on Liberty and haven't witnessed any performance degradation.

By Migrating to Liberty, Jazz.net Team found that it was much easier to administer and maintain due to :

• Relieved of the Thread Pool management. For more details, refer to Why you probably don’t need to tune Liberty Thread Pool
• Easier to stage the deployment for any testing purposes.
• Startup times are noticeably faster, which makes it easier for incorporating quick changes.

Jazz.net Team migrated to Liberty mid 2017, and now some of RTC instances have further been clustered, making them more scalable. During migration, some key things to take care of were Certificates, LDAP config and custom properties.

A link that helps with Certificates is here : Migrate from Traditional WebSphere to WebSphere Liberty

Some Websphere custom properties that had to be mapped are listed below :

• com.ibm.ws.webcontainer.channelwritetype to channelwritetype
• com.ibm.ws.webcontainer.extractHostHeaderPort to extractHostHeaderPort
• trusthostheaderport to trustHostHeaderPort
• HttpSessionIdReuse to idReuse

Properties that are valid for Liberty can be found here

A word of caution from them though, about changing the XML files. Liberty loads the files automatically, without necessitating a restart and that might catch you off-guard, test your changes well before updating anything on the XML configuration files.

ClearObject Team see that, with Liberty Performance is better with startup as well as during runtime. Like Jazz.net Team, even the ClearObject Team opines that Migration is simple, could be accounted for in person-hours rather than in person-days. For some CLM Instances, only few applications were migrated to Liberty while others continued to be on WAS Full Profile. Even with such mix, the interop between applications remains unaffected.

Admin/IT Team was well-versed with Full Profile and were skeptic of the learning curve involved in moving over to Liberty. However, they found that learning curve was short and post migration, Admin/IT Team is happy since they find it easier to administer and maintain a Liberty setup, a few examples mentioned include :

• editing User Roles to Group mappings, visiting each profile through the admin console is avoided
• enforcing TLS v1.2 is simpler

Some things to be cautious about before switching to Liberty though :

• verify if your integrations are covered
• any war file that is not CLM, needs to be investigated before
• test authentications before planning the migration

Overall experience with and/or post Migration has been positive and now, mostly the CLM instances that are older (v5.x and pre v6.0.1), continue to be on WAS Full Profile and they are looking forward to moving more and more instances to Liberty sooner.

What we have seen with our Customers

Several large Customers have migrated to Liberty.

Some of them were further able to Cluster RTC and were able to support over 900 concurrent user base on a single RTC instance, running as a 3-Node Cluster.

A number of customers have observed slow application restart times with WAS. IBM's experience has been that restart times with Liberty are faster and more consistent. Based on some customer data collected, we have further observed that Liberty restarts a mere fraction of WAS restarts. See the graphic showing restarts of a CCM server on WAS vs CCM server on Liberty.

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Related topics: Deployment web home,Migrate from Traditional WebSphere to WebSphere Liberty Migrate from Apache Tomcat to WebSphere Liberty, WebSphere Liberty threading (and why you probably don’t need to tune it)

External links:

• IBM