Re: [Php-java-bridge-users] passing objects from PHP to JAVA

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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