In the example I gave, I mean the whole thing is loaded once, then every session can use it. Basically it is like a cache, only it is available cross sessions. Clearly one can use DB to store data to do that, however, (1)there are things that are not suitable to store in a DB; (2)DB is over-killed for some application and performance penalty -- in the given sample, a DB query could be several times slower than a memory lookup -- but of course that will depend on how it is implemented as well. a.f. "Joe Wollard" <joe.wollard@xxxxxxxxx> wrote in message news:A4875584-1D60-4DB2-A94B-F89ABDD1A2A7@xxxxxxxxxxxx > Aiguo, > > > > To achieve good performance, I want to load the > > whole dictionary into memory when the "application" starts (e.g., > > when > > the web server starts... > > I'm not sure how ASP works, but in PHP you can't load something into > memory when the web server starts and keep it there. PHP 'compiles' > each script upon request and then frees up the memory it occupied. > I'd think that this would be counter productive if your looking to > achieve good performance because you'll be re-building the dictionary > on every page load. > > > It might be better to let another application load the data into > memory and hold it there instead of making PHP load the whole thing > every time a user requests the page/data. If it were me I think I'd > simply load the dictionary into a database and build a simple library > or class to perform queries and calculations against the dictionary. > > Assuming your class definition takes care of connecting to the > database server you could lookup a word in almost the exact way you > demonstrated. > e.g. > $dict = new dictionary; > $definition = $dict->lookup($word); > > > If you'll need this object to be available on every page the user > sees you could always make a 'common.php' (or whatever) which would > create the object and then include that at the top of each page. > > > > For a complete solution, it should support object locking/exclusive > > access as well. > > Maybe I've been a spoiled PHP programmer for too long. ;-) I'm not > sure what object locking/ exclusive access is but from the sounds of > it, there isn't a way to do this in PHP that I'm aware of. This is > assuming that you want to be able to basically remove the object from > the global scope. In PHP objects are globally accessible from the > moment they're created to the moment they're destroyed. > > Good luck! > -Joe > > > On Jul 27, 2005, at 8:40 PM, Aiguo Fei wrote: > > > In ASP.Net there is the concept of "application" which is a virtual > > directory on a Web server. An application can have application-wide > > shared data/objects, which can be accessed by any script of that > > application (i.e., scripts under the virtual directory). I have gone > > through several PHP books, haven't seen it mentioned anywhere that PHP > > has similar facility. I don't know if anyone has written an extention > > to do something similar. Or any experience/suggestion on this matter. > > > > To make it clear, consider the following example. I want to do > > web-based dictionary. To achieve good performance, I want to load the > > whole dictionary into memory when the "application" starts (e.g., when > > the web server starts, or triggered when the first script under a > > certain directory is requested), and build a lookup table; then create > > a globally-accessible object, let's say, Application["my_dict"]; and > > it provides a function to do the dictionary lookup. In a script, one > > could do something like: > > $definition=Application["my_dict"]->lookup( $word ); > > > > For a complete solution, it should support object locking/exclusive > > access as well. > > > > -- > > PHP General Mailing List (http://www.php.net/) > > To unsubscribe, visit: http://www.php.net/unsub.php > > > > -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
