You can package servlets and JSPs into a .WAR file.
You can generate .WAR files from the Tasks page of the Generation dialog box ().
There is no constraint over the generation of one WAR per package. Only packages with the <<archive>> stereotype will generate a WAR when they (or one of their descendant package not stereotyped <<archive>>) contain one servlet, or one JSP.
The newly created archive contains the package and all of its non-stereotyped descendants. The root package (that is the model) is always considered as being stereotyped <<archive>>.
For example, if a model contains several Web components in different sub-packages but that none of these packages is stereotyped <<archive>>, a single WAR is created encompassing all packages.
For more information on generating WARs, see Selecting Java Generation Tasks.