As I know many Java EE application servers are written in Java. (JBoss, Tomcat...)
Is Websphere also written in Java?
I found that Websphere's performance is dramatic high, I guess that Websphere is written in C++. I couldn't imagine that the 'heavy' server is able to run so fast in JVM.
Is it true?
Yes, WebSphere is written in Java. Typically application servers used to have components orineted towards high performance (like the HTTP listeners) written in C/C++, and compiled against the various supported platforms. Nowadays, fewer application servers employ this approach and are almost always written entirely in Java (I'm not sure whether this is truly the case with WebSphere, but most of it is surely written in Java).
As for the performance of relatively better performance of WebSphere, most of it can be attributed to the performance of the IBM J9 JVM, which in contrast to the JVMs derived from Sun, is more oriented towards the server-side applications (atleast thats what some people claim, although I havent noticed a huge amount of difference).
It's written in Java and in consequence portable across a wide variety of platforms including mainframes as well as Unixes and Windows.
The gap between native code and modern JVMs with JIT etc is quite small.
around 97, initially was written in plain C and Perl (for the Enterprise Java Bean container EJB1 then EJB2).. Not in Java and Not in C++ and Not in PL/1 and Not in Smalltalk. Before being commercialized, v1 and v2 run on RS6000 AIX, and one had to customize the Makefile to compile the product... there is a mix up on the original product name.. some confusion (even on Wiki) as some think it was a continuation of IBM failing product "IBM San Francisco". Well, it is not... finally, the name "WEBSPHERE" I believe was used as an Apple product early 80's, but there is no trace of it on Google and anywhere else; don't recall if it was a product put by a third company to do backup...
