Web Portal and Application Integration

We're building a web portal which hosts number of applications. Even though there are number of Open Source solutions but we think it would be better fit to our requirements if we build our own one.

Some options:

1. Web Portal is a standalone application which has a application container. To display the application content:

   a. Following some standards like JSR 168 or WSRP

   b. AJAX pulling HTML contents from the target application

   c. Using IFRAME with proxy pass to the target application (to avoid cross-domain issues)

2. Web Portal only provides navigation/header/footer "include" and the overall content is hosted in individual Application infrastructure

Most open source solutions provide 1.a and support 1.c (maybe 1.b).

What do you think about 2. ?