World: r3wp

I also added a little section on implementation specifics (directly 
in the host, as extension, embedded?, etc)

all the IPC I've done with rebol where TCP socket based, some per 
connection, others with persistent and fault-detection wrappers similar 
to ip packets.

Its actually quite fast when running on the same host.

one advantage to using TCP/ip is that users/admins have some control 
over them using standard firewall HW & software.  also, if one needs 
to he can use port 80 so messages can to through normal HTTP messaging 
routes.  This improves flexibility of the IPC, without it being a 
requirement.

One enterprise service I did used EDI formatted information and allowed 
queued message sending and receiving, with order detection and re-sending 
on time-outs or connection errors.


funny thing is that I had to throttle my REBOL app because it parsed/replied 
messages faster than the remote service could handle :-)

Has anyone tried to build a .NET DLL that can be used from Rebol? 
Is this possible? IMO it should be possible.

I dont know if we can used managed code from within an un-managed 
app.

That's possible.

until host-kit-a100, the extensions that I produced worked properly. 
With a102, the tests fail at a certain point (r3 found a problem 
...), even with the sample extension example produced by Carl. Any 
other experience on compatibility problems ?

I just built r3.exe from A102 and was able to load in the extensions 
I produced from A101 ...

windows or  linux ?

Windows 7

not tested with a101

Sample extension works just fine for me with (Linux) A102.

But as parts of the extension API have changed, I don't think that'll 
be the case in general.

I.e. as soon as you use any of the RXI_* functions, as almost any 
"real" extension will, you'll have to recompile against the A102 
headers

jocko, I had assumed you had recompiled them....


you must recompile them for A101 and up, many enums and offsets have 
changed, so they don't correspond anymore.

The external sample extension works partly (apart from several string 
and word functions, like t-word-map)I understand that I have to recompile, 
but  it's not so easy to find the proper headers. Furthermore, I 
am not sure that the old make-ext.r script which generates the init_block 
is still usable. It would be useful to actualize the external sample 
extension. By the way, where is the page giving the main changes 
from a101 (changes from char * to REBSER*, t-word-map etc) ? I am 
not able to find it out.

Having had a look to the extension pages of the R3 documentation, 
I see that the use of make-ext.r to generate the init_block is no 
more relevant.

The necessary headers are in src/include/: reb-c.h, reb-ext.h, and 
reb-ext-lib.h

(In the hostkit, that is.)

And I fear that some parts of the extension docs are currently outdated.

Regarding the changes, Carl's official docs are here: http://www.rebol.com/r3/changes.html

My personal summary for the extensions API:

- A100 is basically the same as the previous extensions-only API 
release (A77).

- A101 adds map_word, word_of_string, words_of_object, get_field, 
set_field

- A102 adds make_image and gc_protect, renames the constants used 
for series_info from RXI_INFO_* to RXI_SER_* and adds RXI_SER_DATA

Andreas: thanks? With A100+, it seems that we need some other headers: 
ext-types.h, reb-defs.h (also present in src/include ). However, 
although they compile, it seems that they cannot be opened under 
r3 ( access error: cannot open %xxx.dll ... reason: none). I suspect 
the absence of a given #define flag, but not easy to debug. Anyway, 
I think that it would be useful  to clarify. If anybody already succeded, 
please give us the set of files and the config used. If not, could 
somebody do the test ?

Jocko, here's an "add-mul" sample extension that works with A102: 
https://gist.github.com/bc820cc3eb301c79c1ef

Compiled with `gcc -shared -fpack-struct=4 -Isrc/include/ -o sample.so 
sample.c`.

You'll possibly want to adapt the -I, make sure it points to the 
A102 hostkit's src/include/ directory. For Win32, you'll also want 
"-o sample.dll".

thhanks, I will try. But my problem is not here. I have two concerns 
:  for the extensions dealing with strings (not the simple example 
where one reverse the order of chars), the compatibility is no more 
achieved (because of changes in the representation or processing 
of strings ?) Then I have to compile using the new headers. And when 
I do so, the extension is no more loadable (even a simple one like 
your example)

I dont't follow.

The example I have given above needs to be compiled with the "new" 
headers, the headers of the A102 hostkit, that is.

And as demonstrated: it compiles _and_ loads just fine.

Note that while my sample.c it may _look_ just like the example given 
in http://www.rebol.com/r3/docs/concepts/extensions-making.html#section-2, 
it differs in that `RX_Call` takes three arguments instead of two.

I added a second file, sample2.c, to demonstrate working with strings 
in A102: https://gist.github.com/bc820cc3eb301c79c1ef#file_sample2.c

Also compiles and loads fine for me.

thanks, ill have a look

Well, I had the same problem that some months ago :  

 in my application, I must compile in c++, and there is a difference 
 in labelling the function calls in c and c++.  
The simplest solution is to modify a line in reb-ext-lib.h:  
#define RXIEXT _declspec(dllexport) to
#define extern "C" RXIEXT _declspec(dllexport) 

One shoud definitly insert in this header a condition like  
#ifdef _cplusplus   
 #define extern "C" RXIEXT _declspec(dllexport)

This done, everything works correctly

So C++ name mangling was the issue?

yes

Good to know. Thank for posting!

Yes, that's a good note. Should be used. I forward it to Carl.

Done.

http://www.rebol.com/r3/docs/concepts/extensions-making.html#section-17
says it's out of date and I'm really having trouble including words 
as symbols in a result block of an extension command. 

It works fine with an *INIT_BLOCK defined as


 const char *init_block = "REBOL [\nTitle: {Power Management}\nName: 
 power\nType: extension\nExports: [power-status]\n]\n"

     "lib-boot:           does [map-words words] ;-- Is that a good idea?\n"

     "words:             [ac-line battery remains of high low critical 
     charging]\n"
	    "map-words:    command [words [block!]]\n"
	    "power-status: command []\n"
;

if after IMPORT %power.dll I call SYSTEM/MODULES/POWER/LIB-BOOT.


Is there a way to have IMPORT automatically execute the LIB-BOOT 
code with a simple extension not included into the host code with 
host-kit?

Sorry, don't get what you want to do. You can run some init code 
when the extension is loaded.

I'm trying to return a block containg a word not taken from a commands 
arguments. Say, I want to return a block like [BATTERY CHARGING]: 

That works with

	u32 *word_ids = 0; // used to hold word identifiers
	enum power_words {W_POWER_BATTERY = 1, W_POWER_CHARGING};

	RXIEXT int RX_Call(int cmd, RXIFRM *frm, void *data) {
		/* .... */

		v.int32a = word_ids[W_POWER_BATTERY];
		RXI_SET_VALUE(s, pos++, v, RXT_WORD); 
		v.int32a = word_ids[W_POWER_CHARGING];
		RXI_SET_VALUE(s, pos++, v, RXT_WORD);
	
		/* .... */
   	}


only after importing the DLL I "manually" init the words with a MAP-WORDS 
command. I was thinking that IMPORT eventually triggers LIB-BOOT 
init-code from the INIT_BLOCK. It seems like the init code is not 
executed.

That MAP-WORDS command only does:

	word_ids = RXI_MAP_WORDS(RXA_SERIES(frm, 1));
	return RXR_TRUE;

How does your RX_Init look like?

RXIEXT const char *RX_Init(int opts, RXILIB *lib) {
    RXI = lib;
    if (lib->version == RXI_VERSION) return init_block;
    return 0;
}

Straight from the samples, since I have about zero knowledge of C 
and only am exploring how extensions work.

Ok, you need to make a call to your lob-boot function out of this 
init function.