Explanation - Why are IAS 9i and an RDBMS both needed ?

Question

Why are IAS 9i and an RDBMS both needed ? After all, IAS 8I/9I does contain a "database" in it -- but Oracle calls it a "data cache" !!
Here's why ...
The IAS 8I/9I "data cache" is intended to be a "performance enhancment" mechanism to avoid network round trips to the back end rdbms (called the 'origin' database in IAS terminology) for "rarely changing" data or application code accessed/used in the IAS 8I/9I mid-tier.
The IAS "data cache" was initially extracted from rdbms 8.1.6 to use in IAS 8i (aka IAS 1.0.0 or 1.0.1) and now rdbms 8.1.7 to use in IAS 9i (formerly referred to as IAS 1.0.2).
This was because the complete architecture and functionality needed to provide the IAS 9i's "performance enhancing read only" cache functionality already exists in the oracle 8i rdbms.
(talk about o-o wanting to have high reusability !!)
How about a practical application of why would you do this ??
Think of the web site activity of a major online order system, for example, a ".com" that sells books. We can all think of the famous ones who would be ideal users of this type of design.
Most of the transaction activity in an online order system is customers "browsing" the product catalog, looking at the
descriptions of the books they might consider to buy. When a customer identifies a desired book, the customer can place an order.
This typical customer behavior looks at the description for each book which is "rarely changing" information that is normally accessed in a "read only" mode.
To improve performance for this online order system, the "rarely changing" information can be stored (or "cached") on the mid-tier in IAS 8i/9i's "data cache".
How do this improve performance ??
With the information available in the mid-tier "data cache", network roundtrips by IAS 8i/9I applications to the 'origin' rdbms are avoided, reducing the workload on the network and the 'origin' rdbms.
Why do i still need a back-end or 'origin' rdbms along with ias 9i ?
You still need the 'origin" database as the "master repository" for your books, their inventory system, and orders placed with your business.
You also have the other necessary business systems they may or may not take advantage of the IAS design -- like shipping, payroll, Human Resources, etc.
What happens if the data changes ?
I kept repeating "read only" -- so - the next question is what do you do with "new or changing" data - like placing an order or updating the inventory ?
Since the "master copy" of the information is retained on the origin rdbms, then all changes will occur there.
When a new book is added or an existing book's information is updated or a book is dropped from the inventory, these changes are applied to the origin database.
This information is then "refreshed" on the IAS 8I/9I "data cache" using the "management policies" available within IAS 8I/9I.
These policies controls how and when to "refresh" the IAS 8I/9I data cache.
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Answer 1

In the following document:
1) "Oracle9i Application Server Technical White Paper" located at :
http://technet.oracle.com/products/ias/pdf/9ias_102.pdf
don -- right
At the bottom of page 16 and the top of page 17 is the following....
'The Java engine inside Oracle9i AS is the Oracle JVM.'....
don -- right --- new name is Enterprise Java Engine (EJE)
'The Oracle JVM is integrated in Oracle9i AS, giving it the same advantages and benefits available to the Oracle Database ...'. '
don -- almost right -- you left the key phrase off of it ...
it is completed as follows : (CAPS - are mine for emphasis)
'The Oracle JVM is integrated in Oracle9i AS, giving it the same advantages and benefits available to the Oracle Database FOR EXECUTING JAVA BASED APPLICATIONS ON THE SERVER'. '
STEVE --
that's why i made the comment in the previous post which i've copied below :
I don't think of it as a "database" even though some literature might refer to it as one in IAS 9i standard edition !!
The term "database" has a lot of extra functions with it that are not in IAS 8i/9i!!
for example, most RDBMS's have :
1) updateable tables, etc.
2) backup and recovery of data requirements
3) etc.
That's what makes the EJE in IAS different from an RDBMS -- the extra rdbms functrions are not needed...
That's why I think of it as a "Java Code Container" that holds the Oracle Enterprise Java Engine(EJE) in it. I was stuck on this also - now i can mentally exclude all of that extra functionality by calling it a "java code container" and not thinking of it as a "database".
Since Oracle JVM is the common Java environment for both the Oracle database and Oracle9i AS,...'.
The above gave me the impression that 9i AS has a JVM independent of a database.
don -- 9i AS has a JVM independent of a database -- they are the same item -- a "stripped down" database or as i call it a "Java Code Container" that holds the Oracle Enterprise Java Engine(EJE) -- formerly called the oracle 8i jvm -- in it.
i think the term "database" in the literature is being used to emphasize where it came from (stable oracle 8i -- as opposed to totally new technology)
but
i personally think the term "database" implies to many people, it is a "fully functional rdbms" ... so they assume they don't need a back end -- or in ias terms -- an 'origin' rdbms.
However -- i think this is where the confusion is ..
as people understand the differences between ias and rdbms, they soon realize they must have an rdbms.
However, the administrative instructions (that deal with setting up OSE) seem to point that the JVM is in a database.
don -- right -- it is a "stripped down" database or a a "Java Code Container" as i call it.
you still need to deploy the java code (servlets, jsp's, ejb's, corba, and java stored procs) to it.
The command line functions that you use to do that with the 8.1.7 rdbms -- still apply.
Commands like :
loadjava, deployejb, dropjava, sess_sh, publishjsp, publishservlet, etc.
Note :
Obviously ias 8i "EJE" or ORACLE 8i JVM (the old name), is based upon the rdbms 816 functions (no OSE in it), so you can't deploy servlets and jsp's to the ias 8i EJE just like you can't to the 816 rdbms.
I do find this subject (where is the JVM located) very confusing.
don - right -- but you are picking it up -- hang in there !!
Steve you asked --
Don - is the EJE (OSE/OJVM) implemented through a database?
'The Java engine inside Oracle9i AS is the Oracle JVM.'....
don - right
keep in mind from a java perspective -- the EJE is a "Stripped down" database that acts like a java code container that you connect to -- just like in 817 --- so you can deploy your code to it.
it's also a jvm -- and you execute your deployed java code in it -- just like in 817.
i hope this helps and i didn't confuse this topic further for you ...