Skip to Content

There is a new book on Programming in SAP APO. You might want to check that out.

http://www.flipkart.com/programming-sap-apo-1st/p/itmdgt9hbdh6auzu?pid=9781259028441&ref=bc49ea80-1a9b-403b-b9b7-9cf00d7f05db&srno=s_1&otracker=from-search&query=ankush%20agrawal

also please read this :-

LiveCache is a program for high performance management of objects used by APO

application programs (COM Routines). These objects called OMS objects contain

application data whose meaning is unknown to LiveCache. All objects ideally are

located in main memory in the global data cache of the LiveCache -in the global

data cache -of the LiveCache, but may be swapped out to disk in case of memory

shortage.

COM routines run as stored procedures in the address space of LiveCache and are

called from APO ABAP programs which run on the APO application servers. Due to

the fact that COM routines run in the address space of LiveCache , they have direct

access to OMS objects, and navigation over networks of OMS objects is very fast.

Typical access time is less than 10 microseconds per object.

LiveCache provides classes and class methods to the COM routines to administer

their objects. Technically: COM routines inherit class methods from the LiveCache

base classes to create, read, store and delete OMS objects.

LiveCache relieves the application programs of implementing their own transaction

and lock management. The application program is able either to commit or rollback

all changes made on several objects in a business transaction.

LiveCache ensures the existence of OMS objects beyond the lifetime of COM

routines. That’s why LiveCache uses the term persistent OMS objects. When

LiveCache is stopped or when a checkpoint is requested, all objects are stored on

hard disks. The APO application uses a complex object orientated application

model. This model is easier to implement by an object oriented programming than

with the relational structures of a relational database. Therefore, LiveCache

supports object oriented programming through providing adequate C++

methods/functions.

LiveCache provides the application with the concept of consistent views to isolate

the data of an application from simultaneous updates by other users (reader

isolation). COM routines are implemented in LiveCache as stored procedure.

Therefore the call of a COM routine from ABAP is quite simple through using EXEC

SQL.

ABAP Programs and the APO optimizers use native SQL for communicating

through the standard SAP DB interface to LiveCache. LiveCache has an SQL

interface that is used to communicate with the SAP instances. With native SQL,

ABAP programs call stored procedures in the LiveCache that point to Component

Object Model (COM) routines written in C++. An SQL class provides SQL methods

to access the SQL data through the COM routines.

To report this post you need to login first.

1 Comment

You must be Logged on to comment or reply to a post.

  1. Kunal Patel

    Hi Ankush,

    Excellent article on the complex topic of SCM/livecache. I have one question. Livecache is similar to SAP HANA in the sense that it stores data in memory and when livecache is down it stores data in persistent memory. It seems that HANA is using the same basic technology of livecache. Hence, what is the difference between the two?

    (0) 

Leave a Reply