Pegasus
Enhancement
Proposal
(PEP)
PEP#:
363
PEP
Type: Functional
Title:
Latest ICU Version
Support for Open Pegasus
Status:
draft
Version
History:
| Version |
Date |
Author |
Change Description |
| 0.1 |
11
Aug
2011
|
Ajay.N.Rao
|
Initial
Submission |
| 0.2 |
10 Nov 2011
|
Ajay.N.Rao
|
Updated with the draft implementation
details for the Latest ICU Support.
|
|
|
|
|
Abstract:
Add Support of Latest ICU Version for Open Pegasus.
Definition of
the Problem
The
Pegasus
Currently
uses 3.2 version of the ICU.
According to the newer versions of the ICU Old Style of the data
packing is deprecated.This PEP tries to address the following problems:
- Pegasus Code does not support New
Style of data packing used in the
later versions above 3.6.
- ICU Currently uses the resource
bundle approach which is not very
efficient.
- Resource bundle approach uses
config properties , Environment
variables and User Defined paths (PEG_MSG_HOME, messageDir etc...)to
locate ICU Bundles. This causes several issues w.r.t Installation
and Configuration of the pegasus with ICU.
Proposed
Solution
This
PEP
proposes
following
line
items
to
solve
these problems:
- Pegasus Code should support New Style of data packing as well as the
old one(provide back ward compatibility).
- Making Use of the Shared library model of data packaging in order to
remove the issues with respect to Environment and configuration.
- Provide CMPI Interface support for the Messageloader to remove
compatibility concerns for Shared Library model.
Support for all ICU
Versions:
The
ICU
uses
icu-config command to get the version
details as follows:
icu-config --version
This Command gives the information
about the version number in the
format X.Y.Z . where X is the major version number Y is minor version
number.
eg:
ICUVERSION:=$(shell icu-config
--version)
ICUVERSION:=$(subst ., $(ICUVERSION))
ICUVERSIONMAJOR:=$(word
1,$(ICUVERSION))
ICUVERSIONMINOR:=$(word
2,$(ICUVERSION))
Using this information the Pegasus
environment obtains the version
number of ICU and provides the latest ICU Support for the version
>=3.6 and backward compatibility for the versions <3.6.Pegasus
will package data with the shared library model for ICU versions higher
than 3.6. For the ICU Version below the 3.6 the older resource bundle
approach for data packing will be used.
Variable
ICUSHAREDOBJVERSIONSUPPORT
is
set
to
true
if
the version of the ICU is greater than or equal to the 3.6.Pegasus uses
the variable set by this command to
bifurcate the flow for the Latest ICU and the old ICU with the package
options.A new environment variable
PEGASUS_ICUSHAREDOBJ_SUPPORT is introduced to user to set the bundling
approach to shared object or resource bundle model.if variable is set
to true then shared object model
is used, else the resource bundle approach is used.Shared object
support is rightly validated against
the old ICU versions as only resource bundle approach is supported by
them.
eg:
#if
PEGASUS_ICUSHAREDOBJ_SUPPORT == true
....
icu data handled by Shared Object Approach
....
#else
....
icu data handled by Resource Bundle Approach
....
#endif
ifneq
($(ICUSHAREDOBJVERSIONSUPPORT),true)
ifeq
($(PEGASUS_SHAREDOBJ_SUPPORT),true)
$(error
PEGASUS_SHAREDOBJ_SUPPORT
($(PEGASUS_SHAREDOBJ_SUPPORT))
\
is
not
valid
for ICU versions less than 3.6)
endif
endif
Support for
Resource
Bundle Model with the Latest ICU:
The
genrb
command
which is used to compile the resource text file into a
bundle has deprecated use of the option -p.This option specified the
package name of the resource bundle output file. Hence the resource txt
files are built without this option producing the resource bundle file
of the specific locale.
eg:
$(MSG_DIR)/%.res: %.txt $(ERROR)
$(MKDIRHIER)
$(MSG_DIR)
$(MSG_COMPILE) -d
$(MSG_DIR) $(MSG_FLAGS) $*.txt
@ $(ECHO)
Since
in
the newer versions of ICU the resource
bundle has to be of the format <locale>.res the target directory
of the resource bundle is modified to separate for each module in a
hierarchical format.
eg:
The default target directory for the
module pegasus/pegasusCLI is
$(PEGASUS_HOME)/msg/pegasus/pegasusCLI_en.res
This would be changed to
$(PEGASUS_HOME)/msg/pegasus/pegasusCLI/en.res
The complete msg_src_path is used for
the message bundle target
directory
hierarchy.
Resource
Management :
The directory from which the resource
bundle files have to be loaded
can be set from the u_setDataDirectory(char *path) API which accepts
the path of the resource bundle directory. The resource bundle files
can be found in these directory and opened by ures_open API . This
function returns
U_ZERO_ERROR status on success, U_USING_FALLBACK_WARNING
or
U_USING_DEFAULT_WARNING
status
when
a more general resource bundle
is returned if no exact match is found.
UResourceBundle*
ures_open(const char* package, const char*
locale, UErrorCode* status)
ures_openDirect API also used to open
message but will fail if the
exact match of the locale is not returned.
UResourceBundle*
ures_openDirect(const char* package, const char* locale, UErrorCode*
status)
Shared Library Model:
The
Pegasus install scripts have to be modified to
compile the ICU data into Shared Libraries. The Pkgdata tool is used to
achieve the same. The LD_LIBRARY_PATH would be updated with the path
related information of the Pegasus library path to which resource data
shared libraries are built.
eg:
$(ICU_INSTALL)/bin/pkgdata
-r
$(ICUVERSIONMAJOR)$(ICUVERSIONMINOR)
-d $(LIB_DIR) -s $(MSG_DIR)
--name $(MSG_PACKAGE)
--libname \
$(MSG_PACKAGE)Msg
--mode dll $(MSG_DIR)/list.txt
$(RM)
$(LIB_DIR)/$(MSG_PACKAGE).dat
$(LIB_DIR)/$(MSG_PACKAGE)_dat.o \
$(LIB_DIR)/$(MSG_PACKAGE)_dll.lst
$(LIB_DIR)/$(MSG_PACKAGE)_dll.mak
The
library generated by the pkgdata tool is then loaded to the memory by
using the Dynamic Library interface, which provides the handle of the
package data in the library.This is used to load the resource data of
the given
package which is achieved in pegasus by using ICU API udata_setAppData.
udata_setAppData function loads the resource
data specific to the package passed as argument.
void udata_setAppData (const char *packageName,
const void *data, UErrorCode
*err);
The
required package
specific data is opened by using ures_open API.
CMPI Compatibility:
The
CMPI Interface accepts the message source path as argument for loading
the messages, which is not used by shared object model to extract the
ICU Message,but it instead uses the package Id. Pegasus internal
implementation of CMPI obtains the package id from the message source
path which comes in as an argument in CMPI Interface. The Message
Source path consists of the path or relative path of the resource file
with the package id, the packageid is parsed from it removing the
string after the last path delimiter.
Update to BuildAndReleaseOptions.html
PEGASUS_ICUSHAREDOBJ_SUPPORT
Description:
Builds the Pegasus with the Shared Object support
for the ICU data for the Pegasus messages. If this option is set, the
value can be
one of the either true or false.
Default
Value: Not set
Recommended
Value
(Development
Build): Not set
Recommended
Value
(Release
Build): Not set
Required: No
Considerations:
This Build options has no effect without the
PEGASUS_HAS_ICU option enabled. If this option is set true then the
Pegasus Messages are bundled as shared objects else if set to false it
is bundled as Resource Bundles.
Rationale
Schedule
Available
with 2.12.0 OpenPegasus.
Discussion
Copyright
IBM,
2011
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