1 karl  1.1.2.2 Title: The OpenPegasus memory-resident repository

  2 karl  1.1.2.1 Date: 1 November 2007

  3 karl  1.1.2.2 Reference: PEP 307
  4               Status: Draft

  5 karl  1.1.2.1 

  6 karl  1.1.2.2 Overview of the Memory-Resident Repository

  7 karl  1.1.2.1 

  8 karl  1.1.2.2     The memory-resident repository is an implementation of the
  9                   OpenPegasus CIM Class and Instance repository that operate
 10                   completely in memory and was designed to be used primarily by
 11                   embedded systems.  It has the following characteristics.

 12 karl  1.1.2.1         

 13 karl  1.1.2.2         1. The class repository is read-only and must be built and installed
 14                          as part of the server startup.  There is no capability to add,
 15                          modify, delete classes or qualifiers once the OpenPegasus server
 16                          has been built.

 17 karl  1.1.2.1         

 18 karl  1.1.2.2         2. The instance repository is maintained in core and is fully
 19                          read/write. The persistence of the instance repository is
 20                          maintained through a set of callbacks that the system creator must
 21                          create to save and restore the instance repository.

 22 karl  1.1.2.1 

 23 karl  1.1.2.2 How to Build the Memory-Resident Class Repository

 24 karl  1.1.2.1 

 25 karl  1.1.2.2     Thisepository is built with the Pegasus compiler cimmofl.  Note that in
 26                   the memory-resident repository there is no capability to modify the class
 27                   repository subsequent to building the system so the complete class 
 28                   repository must be compiled prior to building the system.

 29 karl  1.1.2.1 

 30 karl  1.1.2.2     To build the memory-resident repository, first determine the CIM namespaces
 31                   to be used and the classes that will be included in each namespace.  

 32 karl  1.1.2.1 

 33 karl  1.1.2.2     The complete set of classes and qualifiers for a single namespace must be
 34                   compiled with the OpenPegasus cimmofl compiler in a single call using
 35                   the -m option on the cimmofl MOF compiler to generate the C++ source
 36                   output that represents the classes/qualifiers to be compiled into the
 37                   target namespace.

 38 karl  1.1.2.1 

 39 karl  1.1.2.2     Typically this means building a single mof file that represents the
 40                   include of all of classes and qualifiers for the target namespace.
 41                   The following is an example of such a mof file, the 
 42                   root_PG_Internal-namespace.mof file

 43 karl  1.1.2.1 

 44 karl  1.1.2.2         #pragma include("CIM2131/Core_Qualifiers.mof")
 45                       #pragma include("Pegasus/Internal/VER20/PG_InternalSchema20.mof")

 46 karl  1.1.2.1 

 47 karl  1.1.2.2     The c++ source for that namespace is built with cimmofl using the -m option
 48                   to generate the c++ source file defining the namespace and its
 49                   contents..

 50 karl  1.1.2.1 

 51 karl  1.1.2.2     Within a Makefile the repository compile this can be defined as:

 52 karl  1.1.2.1 

 53 karl  1.1.2.2         SCHEMAS=$(PEGASUS_ROOT)/Schemas
 54                       CIMMOFL=cimmofl -d -W -m

 55 karl  1.1.2.1 

 56 karl  1.1.2.2         repository:
 57                       @ $(CIMMOFL) root/PG_Internal -I $(SCHEMAS) \
 58                           root_PG_Internal_namespace.mof

 59 karl  1.1.2.1 

 60 karl  1.1.2.2    -m - Generate memory-resident repository source files for the class and

 61 karl  1.1.2.1         qualifier definitions.

 62 karl  1.1.2.2    -d - Discard Description qualifiers

 63 karl  1.1.2.1    -W - Bypass the warning that you are using the cimmofl compiler
 64               

 65 karl  1.1.2.2     This builds all of the classes and qualifiers for the root/PG_Internal
 66                   namespace and outputs the result to the file root_PG_Internal_namespace.h
 67                   and .cpp files for installation into the embedded system.  
 68               
 69                   The input mof is contained in root_PG_Internal_namespace.mof.  It is the
 70                   responsibility of the developer to encapsulate all of the mof required
 71                   for this namespace into the single input file.

 72 karl  1.1.2.1 

 73 karl  1.1.2.2     NOTE: There is a working example of this build mechanism for VxWorks in
 74                   the directory

 75 karl  1.1.2.1 
 76                       pegasus/vxworks/cimserver
 77               

 78 karl  1.1.2.2 Building Repositories with Filterd Sets of Classes
 79               
 80                   Normally an OpenPegasus system does not require the complete DMTF class
 81                   hiearchy for any selected profile or set of providers. However,
 82                   the task of manually reducing the full set of DMTF and user
 83                   classes to the required subset is both error prone and tedious.
 84                   Each leaf class implemented in a provider requires a set of
 85                   additional classes in the repository that represent the class
 86                   hiearchy for this target class and association and associated
 87                   classes that may be used by this class.
 88               
 89                   Therefore, the cimmofl compiler includes a mechanism that will aid
 90                   in the filtering of classes to be compiled.  The compiler accepts
 91                   a supplementary file with a commandline option (NOTE: today the
 92                   option is -c but that is temporary) that defines a supplementary
 93                   file containing a list of classes.  The compiler will filter the
 94                   classes to be compiled from the input mof to those classes on this
 95                   list and classes that are associated with these classes as:
 96               
 97                   * superclasses in the assiearchy
 98                   * Association and associated classes directly associated with the
 99 karl  1.1.2.2     classes in this list.
100               
101                   Thus, the user should be able to define the required classes for
102                   any namespace as the list of classes defined in the profiles to be
103                   incuded in the namespace.
104                   
105                   Note that there are some classes required by OpenPegasus and these
106                   classes must also be in this list.
107               
108               The Description Qualifiers in the Repository
109                   
110                   Typically, the Description Qualifiers take a significant
111                   percentage of the space for Class and Qualifier declaractions. It
112                   appears that with the memory resident repository, about 666666 the
113                   total space usage for the repository in memory is the Description
114                   Qualifiers.  Therefore, to provide for an absolutely minimal class
115                   repository, an option has been added to the cimmofl compiler to
116                   discard the Description qualifiers and the MOF is compiled.  
117                   This is option -d and the only effect is that any Description
118                   Qualifiers in the input MOF are discarded from the class and
119                   qualifier objects as they are compiled.
120 karl  1.1.2.2 
121               Memory-Resident Repository Size
122               
123                   The key resource parameter for the memory-resident class
124                   repository is the size. Typically, the size of the repository is
125                   about 5% to 10% of the corresponding disk repository.  As an
126                   example, the compile of the complete 2.15 repository yields a
127                   repository that is used about 1.2 MB of memory with the Descripton
128                   qualifiers and about .5 MB without the Description Qualifiers
129               
130                   The actual size of the class repository for each namespace can be
131                   determined by TBD.
132               
133               Persistence of the Memory-Resident Repository Instance Repository
134               
135                   The instance repository is maintained completely in memory and it
136                   is the responsibility of the final implementor of the system to
137                   provide a set of functions that will provide persistence of the
138                   instances in this repository by implementing a set of callback
139                   functions for saving and restoring the repository. The functions
140                   required to be implemented to accomplish this are defined in PEP
141 karl  1.1.2.2     307 and an example of these callback functions is provided in the
142                   sample embedded server define in the file
143               
144                       pegasus/vxworks/cimserver/cimserver.cpp
145               
146                   If the embedded system implementor does not chose to implement
147                   these functions, the instance repository is considered transient
148                   and is started empty upon each startup of the server.
149               

150 karl  1.1.2.1 
151               
152