Serialization of DOMDocument...in order to put it in session

wha___

Hey, sorry for posting something that has been covered before, but I've gone through the examplee that have already been posted to no avail...

Here's my problem....
I've got an enormous XML file which is loaded and then parsed w/ DOMDocument ect. since the xml file is 2+ megs i'd like to only load it once. i then call a function that displays a given range of the xml entries. everything looks like this...

code:
if ( !isset($SESSION['day'])) {
$obj = new DOMDocument();
$obj->load( 'WeeklySample.xml' );
$serialized = serialize($obj);
$SESSION["ser"] = $serialized;

$start = 1;
$end = 100;

}else{
$obj = unserialize( $_SESSION['ser'] );
}

function( $obj, $start, $end );

ideally i'd like to reload the page when the link is clicked, reset the variables $start and $end and display entries 200 - 300.

XML takes a bit of time to load the first time, and i'd like to only have to do it once, i know there's a way it just hasn't clicked yet.

Thanks in advance for the help.

devinemke

the XML data is in a file
the SESSION data is in a file
either way you are reading the data from a file, and with the session you are incurring the extra overhead of serialzing/unserializing.

depending on the logic flow of your app, if you only need to work with part of the XML data on numerous page requests then yes stick just that portion of the XML into a session so you do not need to grab the whole file on each page request.

wha___

There is no common part of the xml, there are thousands of
<entry><data>...</data></entry>
elements. i'd like to have links which'll modify the start/end range of the entries to be displayed.

but you're basically saying that i might as well reload the XML on each page b/c i've got the over head of serializing, then sessionizing (i love making up words), then unserializing the object.

if it's not too much trouble could you give me an example of how i could do this serializing, sessionizing, and unserializing just for my piece of mind

Thanks again

devinemke

Originally posted by wha???
...if it's not too much trouble could you give me an example of how i could do this serializing, sessionizing, and unserializing just for my piece of mind

you already did it in your initial post

wha___

right...I realize that it looks like it works, but doesn't really. The object is unserialized but then i get the following errors complaining about the object not being what was expected.

Warning: Couldn't fetch DOMDocument in /home/jamesr/test_apache/htdocs/oat/dom/readNdisplay.php on line 66

Warning: Couldn't fetch DOMDocument in /home/jamesr/test_apache/htdocs/oat/dom/readNdisplay.php on line 68

Fatal error: Call to a member function item() on a non-object in /home/jamesr/test_apache/htdocs/oat/dom/readNdisplay.php on line 69

Thanks, sorry for not being clear.

devinemke

when working with OOP and sessions, the class definition must come before the session initialization.

wha___

sorry, i'm still not getting it...

this is what i've got

$obj = new DOMDocument();
$obj->load( 'WeeklySample.xml' );
session_start();

if ( !isset($SESSION['ser'])) {
$serialized = serialize($obj);
$SESSION["ser"] = $serialized;
}else{
$obj = unserialize( $_SESSION['ser'] );

}

ecksPath( $obj, $start, $end );

ecksPath expects $obj to be a DOMDocument object.

Thanks for your patience:bemused:

rehfeld


require_once 'your_class.php';

// THEN 
session_start():

wha___

There's no 'my_class.php' i'm making an object that is in the php framework

www.php.net/dom

that's the object i need to persist. i appologize. i understand the require_once call when applicable, but it's not in this case...

sorry 🙁

Roger_Ramjet

Originally posted by wha???
then sessionizing (i love making up words),

But why make up UGLY words: sessioning would sound so much nicer. 🆒

So you want to speed up access to the contents of the file, eh. Try thinking outside the box, or in this case the box-file. XML and Databases

wha___

ok...i do like sessioning

yeah...i'm using databases to hold absurd amounds of xml files that describe events over time periods...

i just need to figure out how to persist the object so that i can make the calls to XPath to get the needed data. all the while only getting a chunk @ a time. i just want to do it so that i can see the speed advantages/disadavntages between persisting the object between pages and loading the xml file at every subsequent page.

Thanks

rehfeld

i just noticed your serializing your object twice. php automatically serializes all data put into a session. so no need to use serialize() if your putting it into a session.

try this


session_start();

$obj =& $_SESSION['obj'];
if (!is_object($obj)) {
    $obj = new DOMDocument();
}

wha___

session_start();

$obj = $_SESSION['obj'];
if (!is_object($obj)) {
    $obj = new DOMDocument();
    $obj->load( 'WeeklySample.xml' );
}

ecksPath( $obj, 1, 100 );

ecksPath just does some xpath filtering on the xml that it gets and then displays entries accordingly in a table. The errors occur when the obj isn't an object

this gave me the same problem, for some reason the object's not being passed over properly. Thanks, i didn't know sessions serialized everything for you. Thanks

rehfeld

when you do

$var1 = $var2;

php by default will pass a COPY of the value to the new variable.

when working with objects, this is the same until php5, then objects are passed by reference by default, and other variables are still passed as a copy.

same goes for functions. by default they pass a COPY of the value into the function. you can change that though when you define the function.

function foo(&$var) {
    // $var will be passed by reference into the function now
}

i noticed you removed the =& from the code example i posted, which makes me think your not familiar with references yet.

have a read

http://www.php.net/references

Roger_Ramjet

Originally posted by wha???
ok...i do like sessioning

yeah...i'm using databases to hold absurd amounds of xml files that describe events over time periods...

i just need to figure out how to persist the object so that i can make the calls to XPath to get the needed data. all the while only getting a chunk @ a time. i just want to do it so that i can see the speed advantages/disadavntages between persisting the object between pages and loading the xml file at every subsequent page.

Thanks

And I was hinting that a better idea might be to just use a 'real' database engine if search-and-retrieval is your bottleneck. To my knowledge, making objects persist in Apache/PHP is a non-starter; though I'm sure someone will correct me in this. Seems to be altogether the wrong toolset for the job, hence the performance problems.

wha___

I wouldn't say there's a performance bottleneck, and as of right now i'm remaking the object on all subsequent page loads, i'd just like to get this working for comparison and for my personal sanity.

Also the design's out of my hands, There is XML and it is stored in the db. a user requests a time interval, they then get that interval. however if they request a week's data, there'll be thousands of entries, all of which can't be viewed on the same page. so i'm trying to parse the xml show 100 at a time. it really wouldn't make sense to me to break up a user's query further and save that in the db.

Thanks