Are PHP libraries linked dynamically or statically?

[Martin Larsen]

Hi,

When a PHP program links to a library using include or require (or their
_once variations), is the library then linked dynamically or statically?

While it might seem irrelevant from a technical point of view, the
linking method is important when it comes to licencing issues as some
licences, like GPL, differ between those kinds of linking when it comes
to viewing the library as a derivative work of the main program.

Therefore it is quite important to know what kind of linking is in
effect when including libraries, and I hope someone in this group can
shed some light on this matter.

Thank you very much in advance,
Martin

[NC]

Re: Are PHP libraries linked dynamically or statically?

On Jul 19, 4:14 pm, Martin Larsen <martin+spamfre e+lar...@bigfoo t.com>
wrote:

>
When a PHP program links to a library using include
or require (or their _once variations), is the library
then linked dynamically or statically?

Neither. include/require is not a linking mechanism; it is a way to
assemble a complete block of source code prior to its interpretation.
Any static linking takes place at the server process start-up (i.e.,
before any include/require can happen); dynamic linking (if any)
occurs during execution (i.e., after the source code has been
interpreted, and, therefore, after any include/require).

it is quite important to know what kind of linking is in
effect when including libraries,

Only if the libraries are true libraries (i.e., those compiled into
native executable code). With PHP "libraries" , using include/require
does not imply any linking...

Cheers,
NC

[Toby A Inkster]

Re: Are PHP libraries linked dynamically or statically?

Martin Larsen wrote:

When a PHP program links to a library using include or require (or their
_once variations), is the library then linked dynamically or statically?

Dynamically.

--
Toby A Inkster BSc (Hons) ARCS
[Geek of HTML/SQL/Perl/PHP/Python/Apache/Linux]
[OS: Linux 2.6.12-12mdksmp, up 29 days, 14:30.]

Parsing an HTML Table with PEAR's XML_HTTPSax3

http://tobyinkster.co.uk/blog/2007/07/20/html-table-parsing/

[Martin Larsen]

Re: Are PHP libraries linked dynamically or statically?

Thanks NC,

I understand that PHP is very different than say a Windows executable,
and perhaps linking is not the right term for what happens.

Anyway, in your opinion, does the mechanism rememble dynamic or static
linking most?

Btw, if I were to get an "official" statement, do you by chance know who
I should contact?

Martin

[NC]

Re: Are PHP libraries linked dynamically or statically?

On Jul 20, 12:34 pm, Jerry Stuckle <jstuck...@attg lobal.netwrote:

>

I understand that PHP is very different than say a Windows
executable,

>

PHP isn't (it can be a Windows executable). PHP scripts are.

>
Not quite true. The PHP interpreter (php.exe) itself is executable.

My point exactly. I guess I should have written "PHP interpreter"
rather than just "PHP"... :)

Cheers,
NC

[Martin Larsen]

Re: Are PHP libraries linked dynamically or statically?

NC wrote:

>Btw, if I were to get an "official" statement, do you by
>chance know who I should contact?

>
The PHP group: http://www.php.net/contact.php

Thanks for link. However, that page actually refers to this newsgroup or
the webmaster for website related comments.

Is there a way to contact the PHP Group directly?

Thanks again,
Martin

[Martin Larsen]

Re: Are PHP libraries linked dynamically or statically?

Hi Henk,

This may be true from a strict technical definition, but juridical
reasoning may not be that strict.

Thank you for making clear what I was trying to say. It is in fact a
juridical matter.

If we agree that the term linking might not be entirely irrelevant,
which kind of linking would you say is in effect when a PHP program
links to a script: dynamically or statically.

The reason why this is important is that dynamically linking is often
seen as a licence boundary
(http://en.wikipedia.org/wiki/Library...ynamic_linking)

Regards,
Martin

[Jerry Stuckle]

Re: Are PHP libraries linked dynamically or statically?

Martin Larsen wrote:

Hi Henk,
>

>This may be true from a strict technical definition, but juridical
>reasoning may not be that strict.

>
Thank you for making clear what I was trying to say. It is in fact a
juridical matter.
>
If we agree that the term linking might not be entirely irrelevant,
which kind of linking would you say is in effect when a PHP program
links to a script: dynamically or statically.
>
The reason why this is important is that dynamically linking is often
seen as a licence boundary
(http://en.wikipedia.org/wiki/Library...ynamic_linking)
>
Regards,
Martin

And despite what Henk posted, has absolutely nothing to do with PHP.

NC is correct in his discussion. You need to paying attention to what
he is saying.


--
=============== ===
Remove the "x" from my email address
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jstucklex@attgl obal.net
=============== ===

[Jerry Stuckle]

Re: Are PHP libraries linked dynamically or statically?

Martin Larsen wrote:

NC wrote:
>

>>Btw, if I were to get an "official" statement, do you by
>>chance know who I should contact?

>>
>The PHP group: http://www.php.net/contact.php

>
Thanks for link. However, that page actually refers to this newsgroup or
the webmaster for website related comments.
>
Is there a way to contact the PHP Group directly?
>
Thanks again,
Martin

Why?

If you understood the technology, the answer would be clear. Rather, I
suggest you visit your local library or bookstore and find out how
interpreters work.

--
=============== ===
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attgl obal.net
=============== ===

[Toby A Inkster]

Re: Are PHP libraries linked dynamically or statically?

Jerry Stuckle wrote:

Unless you have implemented a PHP optimizer, every PHP file is
interpreted every time you load the file. There is no intermediate code.

There normally *is* an intermediate form, but it's discarded after each
execution unless you have a PHP cache, such as eAccelerator.

That is, on each execution, the PHP interpreter:

1. Opens up the file;
2. Tokenises it, storing the token stream in memory;
3. Parses it into a form of byte code, storing that in
memory too; then
4. Executes the byte code.

Most smart interpreters (and I assume PHP is included here) will also
perform a bit of code optimisation around stage 3 too. Code optimisation
trades off execution time for parsing time, so interpreters (optimise once,
run once) tend not to optimise as much as compilers (optimise once, run
many) do.

--
Toby A Inkster BSc (Hons) ARCS
[Geek of HTML/SQL/Perl/PHP/Python/Apache/Linux]
[OS: Linux 2.6.12-12mdksmp, up 30 days, 12:01.]

Parsing an HTML Table with PEAR's XML_HTTPSax3

http://tobyinkster.co.uk/blog/2007/07/20/html-table-parsing/

[Rami Elomaa]

Re: Are PHP libraries linked dynamically or statically?

Martin Larsen kirjoitti:

Hi Henk,
>

>This may be true from a strict technical definition, but juridical
>reasoning may not be that strict.

>
Thank you for making clear what I was trying to say. It is in fact a
juridical matter.
>
If we agree that the term linking might not be entirely irrelevant,
which kind of linking would you say is in effect when a PHP program
links to a script: dynamically or statically.
>
The reason why this is important is that dynamically linking is often
seen as a licence boundary
(http://en.wikipedia.org/wiki/Library...ynamic_linking)

Looking at this definition:

"Dynamic linking means that the subroutines of a library are loaded into
an application program at runtime, rather than being linked in at
compile time, and remain as separate files on disk."

Based on that I'd say php "linking" resembles more dynamic linking than
static linking, since there is no separate "compile time" per se, a
script is each time recompiled at runtime. Plus the included scripts are
separate files on disk, they are not "built" into one executable.

And the reason I say it _resembles more_ is the basic problem that
neither of these terms can really be applied to php scripts, what you
need is a new term: call it including.

--
Rami.Elomaa@gma il.com

"Wikipedia on vähän niinq internetin raamattu, kukaan ei pohjimmiltaan
usko siihen ja kukaan ei tiedä mikä pitää paikkansa." -- z00ze

[Andy Hassall]

Re: Are PHP libraries linked dynamically or statically?

On Fri, 20 Jul 2007 01:14:02 +0200, Martin Larsen
<martin+spamfre e+larsen@bigfoo t.comwrote:

>When a PHP program links to a library using include or require (or their
>_once variations), is the library then linked dynamically or statically?
>
>While it might seem irrelevant from a technical point of view, the
>linking method is important when it comes to licencing issues as some
>licences, like GPL, differ between those kinds of linking when it comes
>to viewing the library as a derivative work of the main program.
>
>Therefore it is quite important to know what kind of linking is in
>effect when including libraries, and I hope someone in this group can
>shed some light on this matter.

Have you seen the following - not sure if it helps, or muddies the waters
further:

http://www.gnu.org/licenses/gpl-faq.html#IfInterpreterIsGPL

In particular the final two paragraphs:

"Another similar and very common case is to provide libraries with the
interpreter which are themselves interpreted. For instance, Perl comes with
many Perl modules, and a Java implementation comes with many Java classes.
These libraries and the programs that call them are always dynamically linked
together.

A consequence is that if you choose to use GPL'd Perl modules or Java classes
in your program, you must release the program in a GPL-compatible way,
regardless of the license used in the Perl or Java interpreter that the
combined Perl or Java program will run on. "


The implication appears to be that loading Perl modules is treated as "dynamic
linking" for the purposes of the license (pure technical definitions aside).
Perl modules are often "pure-Perl" and so very closely match "require/include"
for PHP libraries.

--
Andy Hassall :: andy@andyh.co.u k :: http://www.andyh.co.uk
http://www.andyhsoftware.co.uk/space :: disk and FTP usage analysis tool

[Toby A Inkster]

Re: Are PHP libraries linked dynamically or statically?

Jerry Stuckle wrote:

Ah, but OpenOffice is not MS Word. And just because OpenOffice
implements something one way doesn't mean Word does.

No, no -- the quotes from the OpenOffice.org developers were regarding
the MS Word ".doc" file format -- which they had to reverse engineer --
they were not on the subject of OpenOffice.org' s behaviour.

--
Toby A Inkster BSc (Hons) ARCS
[Geek of HTML/SQL/Perl/PHP/Python/Apache/Linux]
[OS: Linux 2.6.12-12mdksmp, up 32 days, 4:23.]

Parsing an HTML Table with PEAR's XML_HTTPSax3

http://tobyinkster.co.uk/blog/2007/07/20/html-table-parsing/

[Martin Larsen]

Re: Are PHP libraries linked dynamically or statically?

Jerry Stuckle wrote:

Martin Larsen wrote:

>Is there a way to contact the PHP Group directly?

Why?
>
If you understood the technology, the answer would be clear. Rather, I
suggest you visit your local library or bookstore and find out how
interpreters work.

Ok, I will tell you why. I had hoped it was not necessary, but here it is...

I do in fact know how interpreters work. I have actually written one
myself. Being a professional windows programmer for ages, I have also
learned the hard way the distinct difference between dynamic and static
libraries: missing DLL files on the end user's computer preventing the
programs from even starting.

I deliberately asked the question in a simple minded manner as I did not
want my own view of the matter to bias the replies. The thing is that
the core team behind a major CMS (Joomla) has recently changed their
mind about non-GPL plugins (or scripts, if you like). Until then they
accepted and welcomed proprietary plugins, but now they say that since
the CMS is GPL, the plugins must also be GPL to comply.

Now, I don't wish this thread to be for or against GPL. I only want to
discuss the reasoning behind their claims. The point is that they argue
that most extensions are *derivative work* of the CMS (even though they
normally don't include a single line of code from it) because they are
statically linked to the CMS. If they were dynamically linked, the
matter would be different.

Yep, that is what they say. While you and I can agree that it doesn't
make much sense to talk about linking for interpreters, they
nevertheless use it in their argumentation. And that is why I asked the
question: Are PHP libraries linked dynamically or statically?

In my opinion they make two mistakes: the first is to talk about linking
at all, the second is to claim that the plugins are statically linked.

As I see it, even when we are not really talking linking, the
characteristics of the processes involved in the INCLUDE more closely
resembles dynamic linking than static linking. Which means that their
argumentation is wrong no matter what.

As it happens, we (third-party developers for Joomla) have tried hard to
make them see that their arguments are wrong. But they keep claiming
that the scripts are statically linked and thus derivative works of the CMS.

And now to my question: Is there a way to contact the PHP Group directly?

I have an idea that if we could get a "official" statement of the
linking or non-linking involved, they might be more prone to listening.

And again, I certainly don't want the PHP Group or any other to comment
on the good or bad of plugins being GPL because that is entirely
irrelevant. I just sincerely believe that their technical resoning is
entirely wrong.

Thanks,
Martin

[Jerry Stuckle]

Re: Are PHP libraries linked dynamically or statically?

Martin Larsen wrote:

Jerry Stuckle wrote:
>

>Martin Larsen wrote:

>>Is there a way to contact the PHP Group directly?

>

>Why?
>>
>If you understood the technology, the answer would be clear. Rather,
>I suggest you visit your local library or bookstore and find out how
>interpreters work.

>
Ok, I will tell you why. I had hoped it was not necessary, but here it
is...
>
I do in fact know how interpreters work. I have actually written one
myself. Being a professional windows programmer for ages, I have also
learned the hard way the distinct difference between dynamic and static
libraries: missing DLL files on the end user's computer preventing the
programs from even starting.
>

Wow. A WINDOWS programmer. So you've been programming for what - 15
years, maybe? And you've programmed for ONE OS? Wow.

And you wrote an interpreter? Golly, Gee, Batman. I guess that makes
you an expert on everything! ROFLMAO!

I deliberately asked the question in a simple minded manner as I did not
want my own view of the matter to bias the replies. The thing is that
the core team behind a major CMS (Joomla) has recently changed their
mind about non-GPL plugins (or scripts, if you like). Until then they
accepted and welcomed proprietary plugins, but now they say that since
the CMS is GPL, the plugins must also be GPL to comply.
>

You got answers to the question you asked.

Now, I don't wish this thread to be for or against GPL. I only want to
discuss the reasoning behind their claims. The point is that they argue
that most extensions are *derivative work* of the CMS (even though they
normally don't include a single line of code from it) because they are
statically linked to the CMS. If they were dynamically linked, the
matter would be different.
>

This has nothing to do with PHP programming. I suggest you take it over
to the Joomla newsgroup.

Yep, that is what they say. While you and I can agree that it doesn't
make much sense to talk about linking for interpreters, they
nevertheless use it in their argumentation. And that is why I asked the
question: Are PHP libraries linked dynamically or statically?
>

That's their problem. If you understood as well as you say, you would
have the answer to your question.

In my opinion they make two mistakes: the first is to talk about linking
at all, the second is to claim that the plugins are statically linked.
>

That could be. But it's not a topic for this newsgroup.

As I see it, even when we are not really talking linking, the
characteristics of the processes involved in the INCLUDE more closely
resembles dynamic linking than static linking. Which means that their
argumentation is wrong no matter what.
>

It resembles INCLUDES. It has nothing to do with linking.

As it happens, we (third-party developers for Joomla) have tried hard to
make them see that their arguments are wrong. But they keep claiming
that the scripts are statically linked and thus derivative works of the
CMS.
>

Then build your own CMS.

And now to my question: Is there a way to contact the PHP Group directly?
>

Why? They can't change Joomla's mind, either. Nor are they going to
change Joomla's terminology.

I have an idea that if we could get a "official" statement of the
linking or non-linking involved, they might be more prone to listening.
>

This has nothing to do with their use of terminology. It is a licensing
issue, and they have a write to require licenses for their CMS to follow
their rules.

And again, I certainly don't want the PHP Group or any other to comment
on the good or bad of plugins being GPL because that is entirely
irrelevant. I just sincerely believe that their technical resoning is
entirely wrong.
>

You're discussing legal issues, and should be talking to an attorney.
But historically Joomla is on solid legal ground. The terminology they
use is not important. The fact your tools ARE derivative works is.

Thanks,
Martin

Please don't bring your argument over here. We're not interested.


--
=============== ===
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Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attgl obal.net
=============== ===