Create an APPS READONLY user:

There are 2 ways to achieve this:

1) Create a user and grant select option to that user.
This will have to be done individually for all users that you want to have as read only.

2) Create a readonly role and assign users this role.
This will have to be done once and then assign this role to the users.

1. Create a user and grant select option to that user.

Step 1: Connect as sysdba and create the database user to be used for apps read only schema.

$sqlplus / as sysdba
SQL> create user appsro identified by appsro default tablespace APPS_TS_TX_DATA;
User created.
SQL> grant connect to appsro;
Grant succeeded.
SQL> grant select any table to appsro;
Grant succeeded.

Step 2: Connect with the appsro user and run the SQL commands:
SQL> conn appsro
Enter password:
Connected.
SQL> show user
USER is "APPSRO"

Step 3: Try to access an apps schema table
SQL> select count(*) from apps.po_headers_all;
COUNT(*)
----------
132206

Step 4: Try to update an apps schema table
SQL> update apps.po_headers_all set attribute1 = '1' where po_header_id = 126;
update apps.po_headers_all set attribute1 = '1' where po_header_id = 126
*
ERROR at line 1:
ORA-01031: insufficient privileges

2. Create a read only role and assign to users this role.
Step 1: Connect as sysdba and create the database user to be used for apps read only schema.

SQL> create user appsro identified by appsro default tablespace APPS_TS_TX_DATA;
User created.
SQL> grant connect to appsro;
Grant succeeded.
SQL> create role role_readonly;
Role created.
SQL> grant select any table to role_readonly;
Grant succeeded.
SQL> grant role_readonly to appsro;
Grant succeeded.

Step 2: Connect with the appsro user and run the SQL commands:
SQL> conn appsro
Enter password:
Connected.
SQL> show user
USER is "APPSRO"

Step 3: Try to access an apps schema table
SQL> select count(*) from apps.po_headers_all;
COUNT(*)
----------
132206

Step 4: Try to update an apps schema table
SQL> update apps.po_headers_all set attribute1 = '1' where po_header_id = 126;
update apps.po_headers_all set attribute1 = '1' where po_header_id = 126
*
ERROR at line 1:
ORA-01031: insufficient privileges

Example: Grant another user the 'read only' role

SQL> create user apps_readonly identified by apps_readonly;
User created.
SQL> grant connect to apps_readonly;
Grant succeeded.
SQL> grant role_readonly to apps_readonly;
Grant succeeded.
SQL> conn apps_readonly
Enter password:
Connected.
SQL> show user
USER is "APPS_READONLY"
SQL> select count(*) from apps.fnd_concurrent_requests;
COUNT(*)
----------
75724
SQL> select count(*) from apps.po_headers_all;
COUNT(*)
----------
132206
SQL> update apps.po_headers_all set attribute1 = '1' where po_header_id = 126;
update apps.po_headers_all set attribute1 = '1' where po_header_id = 126
*
ERROR at line 1:
ORA-01031: insufficient privileges

SQL> exit;

You are done. Now your users can use “appsro” schema to have the read only access to Apps Data.