ACE+TAO Subsetting

Contents

1. Motivation for Splitting ACE into Multiple Libraries
2. Configuration Management
3. Classes in Each ACE Library Subset
4. Current ACE Subsetting Status
5. ACE Library Size Breakdown
6. Building ACE Subsets
7. ACE_OS Adaptation Layer
8. Minimum TAO
9. POSIX ACE (PACE)

Motivation for Splitting ACE into Multiple Libraries

• Principle of parsimony -- i.e., developers should incur time/space overhead for components they use, rather than for all the components in the ACE framework.

• Simplify the learning curve -- i.e., developers only need to learn how to program components that they actually use.

1. Support the original libACE as before. Thus, for users who want to use the existing ACE library as is, there will be no changes, i.e., just link with libACE as usual.

2. Allow ACE (and TAO) programmers to use smaller subsets of the entire libACE library. These subsets will include the following libraries:

   libACE_OS -- This library contains the OS adaptation layer and its supporting classes. All other ACE libraries will depend on libACE_OS and it will depend on no other ACE libraries.

   libACE_Utils -- This library contains the various ACE container classes and other miscellaneous classes, such as Singleton, auto_ptr, timers, etc. This library will depend only on libACE_OS.

   libACE_Logging -- This library contains the various ACE logging and tracing classes. This library will depend only on libACE_OS.

   libACE_Threads -- This library contains the ACE thread/process management and synchronization classes. This library will depend only on libACE_OS.

   libACE_Demux -- This library contains the ACE Reactor and Proactor classes. This library will depend on libACE_OS and libACE_Thread.

   libACE_Connection -- This library contains the ACE Connection components, i.e., Acceptor, Connector, and Svc_Handler. This library will depend on libACE_OS, libACE_Thread, and libACE_Demux.

   libACE_Sockets -- This library contains the ACE C++ wrappers for sockets. This library will depend on libACE_OS.

   libACE_IPC -- This library contains all the ACE C++ wrappers for the other types of IPC and FILE I/O other than sockets. This library will depend on libACE_OS and libACE_Sockets.

   libACE_Svcconf -- This library contains the ACE C++ wrappers for the Service Configurator. This library will depend on libACE_OS, libACE_Demux, libACE_Thread, and libACE_Sockets.

   libACE_Streams -- This library contains the ACE Streams classes. This library will depend on libACE_OS, libACE_Demux, and libACE_Thread.

   libACE_Memory -- This library contains the ACE C++ wrappers for shared memory and memory-mapped files. This library will depend on libACE_OS.

   libACE_Token -- This library contains the ACE C++ wrappers for token support. This library is not needed by TAO.

   libACE_Other -- This library contains miscellaneous code, primarily including a CORBA interface and naming support. It is not actively supported, and is not needed by TAO. Its functionality is included in TAO.

Note that the ACE library subsets described above are intended as a guideline, not a complete specification. The actual partitioning of files in the final ACE library subsets may differ somewhat to improve footprint and simplify common use-cases.

Configuration Management

1. A single source tree with a single "version" for the source tree.

2. Releases of libACE and its "subsets" will be atomic, i.e., all or nothing.

Classes in Each ACE Library Subset

libACE_OS

config.h
Basic_Types
OS
Sched_Params

libACE_Utils

ACE
Active_Map_Manager
Arg_Shifter
ARGV
Containers
Dirent
Dynamic
Filecache
Functor
Get_Opt
Hash_Map_Manager
High_Res_Timer
Method_Request
Object_Manager
Profile_Timer
Registry
SString
Stats
System_Time
Time_Request_Reply
Timeprobe
Timer_Hash
Timer_Heap
Timer_List
Timer_Queue
Timer_Wheel

libACE_Logging

Dump
Log_Msg
Log_Record
Trace

libACE_Threads

Activation_Queue
Process
Process_Manager
Synch
Synch_Options
Thread
Thread_Manager
Token

libACE_Demux

Event_Handler
Handle_Set
POSIX_Proactor
Priority_Reactor
Proactor
Reactor
Select_Reactor
Select_Reactor_Base
WFMO_Reactor

libACE_Connection

Asynch_IO
Asynch_IO_Impl
POSIX_Asynch_IO
Strategies

libACE_Sockets

IPC_SAP
LSOCK
LSOCK_Acceptor
LSOCK_CODgram
LSOCK_Connector
LSOCK_Dgram
LSOCK_Stream
SOCK
SOCK_Acceptor
SOCK_CODgram
SOCK_Connector
SOCK_Dgram
SOCK_Dgram_Bcast
SOCK_Dgram_Mcast
SOCK_IO
SOCK_Stream

libACE_IPC

Addr
DEV
DEV_Addr
DEV_Connector
DEV_IO
FIFO
FIFO_Recv
FIFO_Recv_Msg
FIFO_Send
FIFO_Send_Msg
FILE_Addr
FILE
FILE_Connector
FILE_IO
INET_Addr
IO_SAP
IOStream
Pipe
Signal
SPIPE_Addr
SPIPE
SPIPE_Acceptor
SPIPE_Connector
SPIPE_Stream
SV_Message
SV_Message_Queue
SV_Semaphore_Complex
SV_Semaphore_Simple
SV_Shared_Memory
TLI
TLI_Acceptor
TLI_Connector
TLI_Stream
TTY_IO
UNIX_Addr
UPIPE_Acceptor
UPIPE_Connector
UPIPE_Stream

libACE_Svcconf

DLL
Parse_Node
Service_Config
Service_Manager
Service_Object
Service_Repository
Service_Types
Shared_Object
Svc_Conf_l
Svc_Conf_y

libACE_Streams

CDR_Stream
Message_Block
Message_Queue
Task

libACE_Memory

Malloc
Mem_Map
Memory_Pool
Obstack
Read_Buffer
Shared_Memory
Shared_Memory_MM
Shared_Memory_SV

libACE_Token

Local_Tokens
Remote_Tokens
Token_Collection
Token_Invariants
Token_Manager
Token_Request_Reply

libACE_Other

CORBA_Handler
CORBA_Ref
Local_Name_Space
Msg_WFMO_Reactor
Name_Proxy
Name_Request_Reply
Name_Space
Naming_Context
Registry_Name_Space
Remote_Name_Space
TP_Reactor
XtReactor

Current ACE Subsetting Status

• Log_Msg cleanup: We have a good start on this, but it needs work to finish. It might be easiest to make an abstract base class, then have ACE_Log_Msg derive from it. That way we could remove the exposure of all the #includes in Log_Msg.cpp to applications that don't need it. Another alternative would be to disable compilation of Log_Msg.cpp when ACE_NLOGGING is enabled.

• Higher layer interdependencies: we haven't exhaustively tested all possible combinations of subsets. It's possible that there are interdependencies between some layers that we haven't yet identified.

• Remove use of multiple inheritance: its only used in a few places, in one of the SOCK classes and Service Config. This isn't really a subsetting problem, but is necessary to support Embedded C++.

ACE Library Size Breakdown

    debug=0 optimize=1 static_libs_only=1 DEFFLAGS=-DACE_USE_RCSID=0

These options translate into:

(a) No debugging,
(b) Optimization is set to -O2,
(c) Static ACE and TAO libraries, and
(d) Use of RCS Ids is turned off.

To build an ACE static library, if shared libraries are the default, use make static_libs_only=1. If you're using recent versions of GNU GCC, you can use the -frepo option, which typically reduces the footprint by another 25 percent.

Building ACE Subsets

1. In your $(ACE_ROOT)/include/makeinclude/platform_macros.GNU file, e.g., add:

   ACE_COMPONENTS = OS

   or

2. On the make command line, e.g.,

   make ACE_COMPONENTS=OS

   or

3. Set (and export) the ACE_COMPONENTS environment variable to contain the components that you want to build.

A special value of ACE_COMPONENTS can be used to build an ACE library that supports TAO. The special value is FOR_TAO. So, for example, you can add this to your $(ACE_ROOT)/include/makeinclude/platform_macros.GNU to restrict ACE support to just that which is needed for TAO:

ACE_COMPONENTS = FOR_TAO

Please note the current limitations:

1. We currently don't check for interdependencies between components. For example, if you build any component beside OS, you must explicitly include OS in your ACE_COMPONENTS.
   
   
2. We currently don't check this macro in other ACE or TAO Makefiles, or in their tests. We'll add those checks as time allows.
   
   
3. This is only supported by the gmake Makefiles. For example, the MSVC projects on Win32 do not support the specification of components.
   
   

ACE_OS Adaptation Layer

To create the ACE_OS adaptation layer, build your libACE with ACE_COMPONENTS set to OS. In addition, add #include "ace/config-minimal.h" to your ACE_wrappers/ace/config.h file.

When using the ACE_OS adaptation layer, you'll be limited to the the ACE_OS member functions, ACE's Basic_Types and Sched_Params, and macros defined in ace/OS.h. See ACE's Basic_Types_Test.cpp for an example of usage.

The POSIX ACE (PACE) project is an OS abstraction layer designed for lightweight and/or verified systems. When complete, it will offer these benefits:

1. A strict POSIX.1-like, low-level interface. Its interface is ``POSIX compatible'' by that we mean as close to POSIX.1 as it can be, given that PACE is not an operating system. And, to avoid name conflicts with OS APIs, all low-level PACE function names have the pace_ prefix.
2. The low-level interface is a C file, so that it can be used in both C and C++ programs.
3. The low-level interface is partitioned into multiple files, one per POSIX.1 section, which will help linkers reduce the footprint for statically linked applications.

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