is there any difference between iAS and EBS?
iAS: stands for Internet Application Server and generally we call it as Application Server. This is the middle tier of the EBS architecture. He acts as an intermediary between Client and the Database. Please refer doc:
EBS: EBS is a complete ERP solution. This is a fully integrated solution which compromise of Database, iAS and Application. This is an end to end solution from Oracle.
Hope this helps!
For example, I found 1.3.19, this is exactly the version of Apache Struts? is there any difference between iAS and EBS?
According to http://struts.apache.org/
The Apache Struts web framework is a free open-source solution for creating Java web applications
EBS uses it's own Java web framework, Oracle Applications Framework (OAF) so does not use Struts. So far as I understand, there are no Struts libraries shipped with EBS
If you are trying to do customization within EBS, you should be using JDeveloper for EBS, see "OA Framework - How to find the correct version of JDeveloper to use with eBusiness Suite 11i or Release 12.x" (Doc ID 416708.1)
For customization outside of EBS, you can use whatever coding framework you wish, but would be advised to install your choice outside of the EBS technology stack (in it's own Apache, for example)
Hope this helps