Since tc Server is aimed at Tomcat usage, it's important to ask what customers running large Tomcat environments used before tc Server came to market? Well, some used Tomcat without support. Others used JBoss, Geronimo, GlassFish, and WAS Community Edition, which deliver Tomcat inside. Still others purchased Tomcat support from Covalent, OpenLogic, etc. For the most part, customers who have not purchased Tomcat support or management for five-plus years are not going to buy a product now. If customers were missing some of the management capabilities that tc Server provides, by now they would have built this capability in house. I know of several large Tomcat users that fall into this category. The customer now has to consider the sunk costs of their custom code versus the cost of acquiring a new product. Customers that have purchased Tomcat support are targets for tc Server, but they are also being targeted by JBoss, Geronimo, GlassFish, and WAS Community Edition. It's not yet clear that tc Server provides differentiated value that will allow it to win disproportionately against the other products. The important insight is that very few Tomcat users are using just Tomcat. They use other parts of a Java Enterprise Edition (JEE) stack, such as JMS messaging or Web Services. So the choice between tc Server with just Tomcat runtime features or a JEE product which includes Tomcat and other JEE APIs is not as cut and dry as SpringSource's marketing would suggest.
In the nearly 10 months since dm Server became generally available, I've frankly heard of virtually no customer usage. But don't take my word for it. Ask your neighborhood Java developer if they've heard of dm Server or if they've used dm Server. The key issue with dm Server is that it's proprietary. Developers and their managers were comfortable using the Spring Framework because while the framework was proprietary, they could easily move their applications across multiple standards-based JEE application servers. Protection from vendor lock-in was delivered by the runtime application server. Customers continue to expect this. If you build a dm Server application, there is exactly one runtime it will run on. Hence, dm Server fails the vendor lock-in test, and its adoption is a testament to this failure. This is, however, a fixable problem for VMware. dm Server could be evolved to meet the forthcoming JEE 6 Web Profile specification, which Geronimo, GlassFish, JBoss, WebLogic, and WebSphere are all expected to support.
VMware is going to find that broad usage of a framework or having a Build-Run-Manage story does not easily translate into customers migrating off their existing Java standards-compliant application server runtime to a proprietary runtime.