php-java-bridge-users Mailing List for PHP/Java Bridge

Hi Verena,

> Why did I capture the top-level environment? 

java_closure() without any arguments captures the
top-level environment, creates and returns a Java
proxy for it.

Of cause you could use 

invocable.invokeMethod(engine.get(objectBinding),...)

to call a method[1]. But if you don't have more than
one PHP class per php file, this shouldn't be
necessary; you can capture the object directly, which
has the advantage that you don't need to keep a
dictionary of additional symbol->object bindings.


> thought with engine.get("obj") 
> I get the PHP object returned 

Yes. (you'll get a Java proxy for the PHP object).

> and so the method
> saySomething is invoked on 
> that object?

Yes.

> What is the correct syntax to invoke a method on
> MyClass()?
> 
> I tried this:
> PhpScriptEngine engine = new PhpScriptEngine();
> String s =  "<?php \n";
>    s +=	"require_once 'MyClass.php'; \n";
>    s += "java_context()->setAttribute( 'obj',
> java_closure(new MyClass()), 
> 100 ); \n";
>    s +=	"?>";
> engine.eval( new StringReader(s) );
> Invocable inv = (Invocable) engine;
> inv.invokeMethod( engine.get("obj"), "saySomething",
> new Object() );

The above script is not invocable. The last line of a
invocable PHP script must contain:

java_context()->call(java_closure());


> java.io.IOException: Bad file descriptor
> 	at java.io.FileOutputStream.writeBytes(Native

Well, PHP simply terminates after a PHP script is
executed. To keep it, you must suspend it and pass
control back to the Java continuation. 

The java_context()->call(kont) 

calls the Java continuation with the PHP continuation
as its argument, so that the Java continuation can
call back into the PHP continuation kont whenever
necessary:

  kont.call(scriptEngine.getContinuation());

Of course the above PHP<->Java continuation passing
style is hidden behind the JSR223 interfaces. But on
the PHP side the java_context()->call() must exist,
otherwise the PHP script cannot be called from a
(potentially) remote Java script engine interface.


> Yes, it sounds like, but actually I'm not sure how
> to do it. This faces things 
> are about the web framework, aren't they? 

In practice, yes.


> So how do
> I transform this to a 
> J2SE app?

Just create one public PHP class per PHP file. Example
file my/foo.php, my/bar.php

foo.php:
class my_Foo { function toString() {return "foo";} }
java_context()->call(java_closure(new myFoo());

bar.php:
class my_Bar { function toString() {return "bar";} }
java_context()->call(java_closure(new myBar());


Now you need a XML file which describes your PHP
"beans", or simply hard-code the names in your code:

ScriptEngineManager m = new ScriptEngineManager();
ScriptEngine foo = m.getEngineByName("php");
foo.eval(new FileReader("my/foo.php"));
ScriptEngine bar = m.getEngineByName("php");
bar.eval(new FileReader("my/bar.php"));

// now you can call methods from the foo and bar 
// PHP classes


> No, it instanciates a JavaSript object which has one
> method called hello.

Interesting. I thought that unlike PHP, the JavaScript
object hierarchy is not orthogonal to the Java object
hierarchy.


Regards,
Jost Boekemeier

[1] In the old JSR223 proposal the invokeMethod() and
invokeProcedure() methods where called "invoke()".



		
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Am Freitag, 17. November 2006 19:40 schrieb 
php...@li...:
> However, you'll get a warning that the instance of
> MyClass is not a Java object. Use
>
>   java_closure(new MyClass())
>
> instead.
OK, this is working now without the warning.

>
> > Invocable inv = (Invocable) engine;
> > inv.invokeMethod( engine.get("obj"), "saySomething",
> > new Object() );
>
> You will get a null pointer exception because obj is
> bound to null, see the warning above. Furthermore you
> have captured the top-level environment, but you
> probably want to invoke methods from MyClass().
Why did I capture the top-level environment? I thought with engine.get("obj") 
I get the PHP object returned and so the method saySomething is invoked on 
that object?
What is the correct syntax to invoke a method on MyClass()?

I tried this:
PhpScriptEngine engine = new PhpScriptEngine();
String s =  "<?php \n";
   s +=	"require_once 'MyClass.php'; \n";
   s += "java_context()->setAttribute( 'obj', java_closure(new MyClass()), 
100 ); \n";
   s +=	"?>";
engine.eval( new StringReader(s) );
Invocable inv = (Invocable) engine;
inv.invokeMethod( engine.get("obj"), "saySomething", new Object() );

and it results in this error message:
Nov 20 10:55:20 JavaBridge ERROR: An exception occured: java.io.IOException: 
Bad file descriptor
java.io.IOException: Bad file descriptor
	at java.io.FileOutputStream.writeBytes(Native Method)
	at java.io.FileOutputStream.write(FileOutputStream.java:260)
	at java.io.ByteArrayOutputStream.writeTo(ByteArrayOutputStream.java:109)
	at php.java.bridge.Response$Writer.flush(Response.java:125)
	at php.java.bridge.Response.flush(Response.java:671)
	at php.java.bridge.ClassicResponse.copyResponse(ClassicResponse.java:82)
	at php.java.bridge.Request.handleSubRequests(Request.java:607)
	at php.java.bridge.PhpProcedure.invoke(PhpProcedure.java:77)
	at php.java.bridge.PhpProcedure.invoke(PhpProcedure.java:95)
	at php.java.script.PhpScriptEngine.invokeMethod(PhpScriptEngine.java:204)
	at Bootstrap.main(Bootstrap.java:39)

Bootstrap.java, line 39 is the last one showed above.



> [...]
>
> return
> ((Invocable)((PhpFacesContext)FacesContext.getCurrentInstance()).getScriptE
>ngine(this, new URL(script))).invoke(name, args);
>
> I think this is exactly what you want. The only
> difference is that the above method calls out to a URL
> instead of a local script file.
Yes, it sounds like, but actually I'm not sure how to do it. This faces things 
are about the web framework, aren't they? So how do I transform this to a 
J2SE app?
In the code example I can't see how to call a method on a previously 
instanciated PHP object. It only uses the invoke Method with 2 parameters 
(invokeFunction).


> >         String script = "var obj = new Object();
> > obj.hello = function(name)
> > { print('Hello, ' + name); }";
> >
> > Any chance todo something similar with PHP?
>
> It is certainly possible to automatically call
> java_closure(), when a php object is passed to a Java
> procedure. But for several reasons we've decided to
> require java_closure(php_object). Furthermore, if I
> understand the above code correctly, the "new
> Object()" above instanciates a Java object, not an
> object from the js script interpreter.
No, it instanciates a JavaSript object which has one method called hello. But 
if the only difference to this snippet and the possibiblities of the php-java 
bridge is the automatic call to java_close(), it is similar enough for my 
project.

Regards,
Verena