Setting up this functionality is actually very simple. To illustrate, I'll refer to two types of E-Business suite Users:

1) MANAGER - This is the User who will delegate responsibility to perform transactions on their behalf to the Administrator user.
……………………….In my examples, this user name is TESTMGR.

2) ADMINISTRATOR - This is the user who will sign on to the E-Business suite and assume the responsibilities of the Manager user.
……………………….…………In my examples, this user name is TESTADMIN.

STEP 1
- Connect to the R12 E-Business Suite as ANY User (e.g. SYSADMIN) with the responsibility 'User Management' and open the 'Users' form.
- Search for the user name of the MANAGER. In this case, the user name is TESTMGR.
- Assign the role 'Manage Proxies' to this user name e.g.

STEP 2
Now connect as the MANAGER user e.g. TESTMGR and navigate to the 'Preferences' form:

Click on the 'Manage Proxies' option and then, the 'Add People' button.

This will allow you to add the User Names of those Users that you wish to perform actions on your behalf:

STEP 3
Now, add the user names of all Users that you wish to assume your responsibilities.
In my example, I add the user name of my ADMINISTRATOR TESTADMIN:
Apply the changes and exit the E-Business suite.

STEP 4
OK - now comes the fun stuff.

Connect as the ADMINISTRATOR TESTADMIN:

Note - the new options 'Switch User' and 'Return to Self' available:

As its name suggest 'Switch User' is the magic button that allows you to 'become' the other User without having to enter their password i.e. TESTADMIN can become TESTMGR and access their responsibility list.

STEP 5
Select the 'People Icon' to switch your user to that of TESTMGR:

STEP 6
As if by magic, you are navigated to the home page of the proxied user, can access any of their current responsibilities and can perform action on their behalf in the E-Business that they themself are allowed to perform:

Note - the label 'Logged in As TESTADMIN Proxy For TESTMGR':

STEP 7
OK - to return to the original user session, select the option 'Return to Self'

Oracle Site Hub is a location mastering solution that enables organizations to centralize site and location specific information from heterogeneous systems, creating a single view of site information that can be leveraged across all functional departments and analytical systems. Site Hub has integrations to Property Manager, Assets Management and few other modules. Oracle Site Hub module is available from R12.1.1 version.

Site Hub Objects

Site - A site is defined as a place of business interest.
Hierarchy - Hierarchy provides a classification of relationships needed for the business.
Cluster - A group of Sites forms the Cluster.
Trade Area

Site Hub has two new responsibilites

Setup (Site Management Administrator)
The Site Administrator responsibility is mainly used for setting up the Attributes for all the Site Hub objects.Other set ups include Associating the UDA with Purpose and Pages, creating Results Format,Search Criteria,Value Sets for Attributes , Import/Export formats etc.

For capturing any data for Site/Hierarchy/Cluster the first step is to create the UDA ( User Defined Attributes). The UDA can be created by using the Site Administrator responsibility.Attribute groups can be single row or multi row. Every UDA needs to be assigned to a Purpose. Purpose can be of type Mail Box, Restaurant etc. It is an important step to be done before using it in Site or hierarchy.

Every AG will be associated to a Page. It can be added to a existing page or create  a new page and associate the AG to the page.

Site Home (Site Management User)

Site Management User responsibility is used for creating the Site Hub objects, Perform Advanced Search and manage the objects.After the UDA set up for the objects, the UDA's can be viewed while creating or viewing or updating the Site or any other object. The objects needs to be added to the same purpose where the AG is. Only then the UDA's are visible for the user.