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Hi there, I'm in the process of writing a multi-threaded webcrawler using VC++ 6 and MFC. I've got the basics down, but I can't help feeling like I'm going about it the wrong way.
I've got a Doc/View set up and when the user chooses some options (base URL / how many threads to launch), the document launches the first thread. To do that, it sends a message (using postthreadmessage) to the worker. The worker then goes and downloads the first page, parses it for links and sends a message back to the document via the view as I wasn't able to send them directly to the document...
As a side note, that process feels a little clunky. It seems logical that you'd probably not want to send messages direct to the document, but I couldn't see where else to do it; afterall, the document's storing all the links the workers download.
...anyway, once the document knows there's an idle worker, it gets all the links from the worker (calls a member function on it to retrieve the data - should be safe as the worker is idling now?) and adds them onto the (end of) master list. Since the document knows there's now a free worker, it pulls off the next link on the master link and launches the worker off again.
Does this sound like a reasonable way of doing things? I'm not sure quite why, but it feels a little in-elegant, and I can't help feeling there's probably a better way of doing it?
Any suggestions / comments would be most welcome!
Cheers, Jon
Success is 99% failure
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If I were you I'd consider writing/using a thread-pool.
have the first thread start running with a job of downloading the first page. then perform your default processing on it which is to parse for links .
then, fill the thread-pool's job-list with jobs per each url, and so on.
add a depth count to each job so that you can limit them.
before a thread fills up the thread-pool's job-list with more urls to investigate, have it post some data into another list the doc/view is incharge of so that the user can get a sense of 'whats happening'.
p.s. - a thread pool is a simple structure of X threads that wait for 'jobs' to handle. they share a single 'list of pending jobs' and whenever a job exists in the list, an event is set and the first thread to catch it will be the one to remove that job from the list and handle it. it requiers some synchronization (locking list, waiting for input, waiting for all threads to destroy themselves, etc) but if you do it generalized it's worth it.
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hello friends!
I am writing an editor for indian languages
using Unicode.for this what i am doing is
1.i choosen mfc appwizard in vc
2.i am overriding onchar method for view class(CEditView)
3.i am setting the text to window using setwindowtext fn
4.i am not getting when coming to next line it is not coming and i am not
able to get the caret to the end of text
pls any of u can help
thanks in advance
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why don't you download a good hindi font like 'shusha' and create a CFont and set the font of CEditView.
C makes it easy to shoot yourself in the foot; C++ makes it harder, but when you do, it blows away your whole leg
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I can use.But any process is same.
I am writing editor to type with help of english keyboards.
that's why i have map ascii to corresponding font or unicode
then i have to display.
I am tracking kbinputs with onchar and storing as unicode in
an array.i am displaying that with setwindowtext.i am trying
move the caret that's not moving.it's at the starting pos
only
anyway thanks
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Does anybody know how you can insert your application to be by default in winodows shorcut menu. That you can right-click on your file and select to do something with it.
Something like WinZip: That you can right-click on the file and select for instance to compress the file. Thanks
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u will have to write shell extensions shell
greatest thing is to do wot others think you cant
suhredayan@omniquad.com>
messenger :suhredayan@hotmail.com
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Click Click[^]
MSN Messenger.
prakashnadar@msn.com
Tip of the day of visual C++ IDE.
"We use it before you do! Visual C++ was developed using Visual C++"
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I have a requirement to create MS Excel workbook files as part of a reporting application I am developing. I need to produce these files from within a Windows service. I cannot use automation so I need to create the files directly. I have been looking on the web for open-source, or commercial Excel file creation library and have come across a few possibilities. I am evaluating a couple options right now, but before I dive too deep into this, can anyone suggest a decent Excel file creation library for C++. (Again, commercial or open-source.)
PS. I must write to a native Excel format that supports multiple worksheets. BIFF8 or better I believe.
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Excel files can function as an ODBC (and JET) data source, so could it be that you can write an Excel file by using the same procedure, only reversed ?
Is there are reason on why you can't use automation ? It can be kept simple and efficient, with a minimal overhead, if that's a problem..
-Antti Keskinen
----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.
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I really hope to do that also, so I'm hoping you get a good response. I've used the alxBase classes I found on this site for .dbf's that writes directly to the file and is super-fast. I have to give the user an option though between .xls and .dbf (for import). I'm using the automation for excel and it's about 10 times as slow as the alxBase classes which are writing directly to the file with the correct offsets.
If it's broken, I probably did it
bdiamond
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I want to write to an Access(*.mdb) file from a form(Record View) and capability to read this access file.
I did like MSDN and i have created a Recordset class and Record View class i have connect record view to Recordset but it does not work. how can i do this?
Mehdi Hosseinpour
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For all database functionality on MFC, I first suggest you read the article by Stefan Chekanov found here[^].
The Access file acts as a data source, and by using Chekanov's article and the classes introduced there, you can execute plain SQL-queries to retrieve custom data sets, and then use a by-index or by-name methods to retrieve the data from the resulting set. After you have the data in a local variable (CString or similar), you can use Dialog Data Exchange implemented by a CFormView-derived class to move data into the form's controls and vice versa.
To write data into the database, use the Field function to get a reference to the CDBField, then use the overloaded assignment '=' operator in CDBField class. Remember to prepare the database for updates first, and then flush the update operations when finished. Otherwise an assertion might occur.
-Antti Keskinen
----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.
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Mehdi_Hosseinpour wrote:
...but it does not work.
Which means what? Are you getting compiler, linker, or runtime errors? Please elaborate.
"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)
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We can't help you if you don't give details!
Don't try it, just do it! 
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What is the difference between platform SDK and service pack for visual C++?
which one should i choose for what ?
Thanx.
MSN Messenger.
prakashnadar@msn.com
Tip of the day of visual C++ IDE.
"We use it before you do! Visual C++ was developed using Visual C++"
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As far as i know
Platform SDK is a set of header files, lib and other such stuff for developing windows application without any MFC or ATL.
Service Packs (for VC++) are generally for MFC, VB and data access(DAO,ADO)
C makes it easy to shoot yourself in the foot; C++ makes it harder, but when you do, it blows away your whole leg
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servicepack is a cumulative fixes for known bugs and problems.
sdk is a downloadable platform for developers. 
greatest thing is to do wot others think you cant
suhredayan@omniquad.com>
messenger :suhredayan@hotmail.com
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Suhredayan P wrote:
servicepack is a cumulative fixes for known bugs and problems.
so microsoft is still fixing bugs in VC6 
MSN Messenger.
prakashnadar@msn.com
Tip of the day of visual C++ IDE.
"We use it before you do! Visual C++ was developed using Visual C++"
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Well, SP5 is not that old. It's safe to say that they would only be concerned with critical issues (e.g., security, data integrity) at this point.
"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)
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Mr.Prakash wrote:
so microsoft is still fixing bugs in VC6
Nope, they barely support it anymore, as articles keep disappearing from MSDN. VS6SP5 was the last service pack released, and there won't be any more. The PSDK, however, gets a facelift every once in a while, and adds a huge list of functionality missing from the libraries shipped with VS6. Get both.
[EDIT]
I just scrolled down and discovered that SP6 was released yesterday. Yippee! Downloading now...
[/EDIT]
Will Build Nuclear Missile For Food - No Target Too Small
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Uh oh, the service pack contains a few VSS related fixes only. 
<edit>
Ah, it's VSS SP6, not VC++ SP6. That would explain it!
</edit>
/ravi
My new year's resolution: 2048 x 1536
Home | Articles | Freeware | Music
ravib@ravib.com
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Now that's confusing. You're right, the trail leads to a vss6sp6enu download from one path, but to vs6sp6 from another. The latter is 62MB, and is recommended for anyone using VC++6 with VSS, or VB6. I can't believe the fixes for VSS take up 62MB! Usually I like to check what fixes are included in a download, but the documentation links lead only to info about the VSS SP, not the one I just downloaded. Oh well, if it follows tradition there will be about 42 separate README files after I extract it. That should keep me entertained for a while.
Will Build Nuclear Missile For Food - No Target Too Small
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i was pegging away at the keyboard and accidently wrote something like this
int i;
int j=0;
CRect rc;
rc.left = j,i;
(notice the , between j and i)
compiler shows no errors or warnings 
VC6, No service Packs
never seen or heard anything about this before
C makes it easy to shoot yourself in the foot; C++ makes it harder, but when you do, it blows away your whole leg
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mailMonty wrote:
(notice the , between j and i)
compiler shows no errors or warnings
Hey, that ',' is the comma-operator, and you did use it in a syntactically correct way. About what sould the compiler complain?
"We trained hard, but it seemed that every time we were beginning to form up into teams we would be reorganised. I was to learn later in life that we tend to meet any new situation by reorganising: and a wonderful method it can be for creating the illusion of progress, while producing confusion, inefficiency and demoralisation."
-- Caius Petronius, Roman Consul, 66 A.D.
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