Livecache Architecture

􀂄 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 (LCA) routines written in C++. An SQL class provides SQL methods to access the SQL data through the LCA routines.

􀂄 The LCA routines are part of a dynamic link library that runs in the process context of the
liveCache instance. In the Windows NT implementation of liveCache, LCA routines and their
interface are registered in the Windows NT Registry. For the Unix implementation, a registry
file is provided by liveCache. A persistent C++ class provides the LCA routines with access to
the corresponding Object Management System (OMS) data that is stored in the liveCache.

􀂄 LCA Routines in APO are delivered in DLL libraries as SAPXXX.DLL and SAPXXX.LST on NT or as shared libraries SAPXXX.ISO and SAPXXX.LST on UNIX . The application specific
knowledge is built into these LCA routines based on the concept of object orientation.

􀂄 liveCache is a hybrid of a relational and object-oriented database

􀂄 The relational part of the liveCache is available as the open source data base SAP DB (see http://www.sapdb.org/)

􀂄 The SQL part as well as the OMS part of the liveCache are based on the same DBMS basis
functionality which supplies services as for instance transaction management, logging, device handling and caching mechanisms

􀂄 Object and SQL data are stored on common devices

􀂄 All liveCache data is stored in the caches as well as on disks in 8 KB blocks called pages.

􀂄 liveCache stores the OMS objects in page chains, the pages in the chain being linked by
pointers. SQL table data are stored in the B*trees. SQL and OMS data reside together in the data cache and the data devices of the liveCache.

􀂄 liveCache, similar to the standard SAP RDBMS, can be administered within the SAP system.
The SAP transaction LC10 makes it possible to monitor, configure and administer liveCache.

􀂄 The LC10 applies the Database Manager CLI (DBMCLI) to administer the liveCache. Therefore, it is obvious that all functionalities of an SAP System are still available without the LC10 and could also be performed with the „native“ data base administration tool DBMCLI.

􀂄 In addition to the DBMCLI the administration tool DBMGUI is available, which is a graphical
user interface to the liveCache management client tool DBMCLI.

􀂄 While the DBMGUI works only on Windows NT/2000, running the WEB DBM requires only an internet browser and the DBM Web Server which can be installed anywhere in the net.

􀂄 DBMCLI, DBMGUI and WEB DBM should not be used for starting or stopping the liveCache,
even if LC10 itself calls DBMCLI for starting or stopping the liveCache. They should only be used for changing liveCache parameters, defining backup media and for liveCache monitoring. That is because the LC10 runs in addition to starting, stopping and initializing application specific reports. Moreover, it registers the LCA routines each time the liveCache is started.

The liveCache can be administered by
􀂄 Transaction LC10 in the SAPGUI
􀂄 Database Manager CLI (DBMCLI) command line interface
􀂄 Database Manager GUI (DBMGUI) graphical user interface for Windows NT/2000 only
􀂄 Web Database Manager (WEB DBM)