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From Emmanuel Lecharny <elecha...@gmail.com>
Subject Re: Implementing the PagedSearchControl
Date Thu, 04 Dec 2008 01:13:08 GMT
Norval Hope wrote:
> Hi,
>
> I don't know the core code like you, but given my current
> understanding (pardon me if my understanding is woefully inadequate
> :-) I'm not sure your option 2 is really viable. After the first page
> is returned, how are you going to initialize the cursor for the next
> page?
You have to store some session information in any case. So assuming we 
implement the second option, we just store the number of entries we 
already transmitted.
>  Wouldn't you have to remember where you were up to (using some
> sort of unique per-result key) and rerun the search, skipping results
> up to this key value (if so then it's unworkable no?). 
Yes, this is exactly what I have in mind :)
> BTW Is there
> guaranteed to be a stable sorting order for search results internally,
> and is the sort control supported by AD so that it may be posed
> externally etc.
>   
There are no such guarantee, either with option 1 or option 2, as stated 
by RFC 2696 :
"A client may safely assume that all entries that satisfy a given search 
query are returned once and only once during the set of paged Search 
requests/responses necessary to enumerate the entire result set, unless 
the result set for that query has changed since the searchRequest 
starting the request/response sequence was processed."
> At any rate I don't think keeping a cursor open is that big a deal,
> although there probably needs to be a server-side timeout so that if
> the cursor is not accessed for a long time (say an hour for argument)
> it is automatically closed. Well behaved clients should explicitly
> close their NamingEnumerations which I would hope would allow the
> cursor to be discarded immediately.
>   
The problem is certainly not well behaved client. but there are many 
case when even a well behaved client might be troublesome. Typically, 
Apache Studio (a well behaved client, that's for sure :), when it comes 
to load thousands of entries, uses this control to get the entries 
little by little. It present the entries in a list of N sub-entries, and 
when you open a block, then a new search is sent to the server. Another 
possibility is to design a cursored presentation of data, with, say, 20 
entries per page. The client click on 'next' or 'prev' to get the next 
20 entries. As it's interactive, we may have some long period of time 
between two interactions.

So sure, we will have to implement a timeout (but we already have a 
session timeout), which is a bit painfull, as you need a thread to 
manage it.

But anyway, I think this is the way to go too... It's just that it's 
painful ! :-]

-- 
--
cordialement, regards,
Emmanuel L├ęcharny
www.iktek.com
directory.apache.org



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