Streaming data

[Anon]

I have created a script which creates pdf dynamically with PDFlib. This script runs through a lot of articles stored in a mySQL database. The problem with this script is that it could take a while to finish(up to several minutes).

What I'm looking for is a way to output data while this script is running, so that the user could know the status of the the the process. I want to print out a message after each article the script runs through.

As it is now, nothing is sent from the server until the script is finished parsed by PHP.

Is this "streaming-process" possible? And how?

[[deleted]]

Technically you could do it by calling 'flush()' to force output.

//do something
echo '10% done';
flush();
//do some more
echo '20% done';
flush();

etc...
but, if you wait too long between flushes, the browser will time out anyway.

A 'better' approach might be to see why your PDF takes so long to create. A few seconds is ok, several seconds is very very long.

[[deleted]]

"several seconds is very very long."

that should ofcourse be:

"several minutes is very very long."

[Anon]

Thanks for fast reply.

Anyway: the flush() method didn't help. Nothing is sent to the browser before the pdf is finished.

The reason why the pdf takes so long, is probably the method I use to create it. I create the pdf based on html and have to translate each character, ie: change font when a <b> tag comes, and create bullets when <ul><li> comes and so on. Therefore I check each character in every article. And if the total amount of articles and pictures reaches 400 pages(about 350Mb), the process could take som time(nearly 10 minutes when there's a lot of large images).

Do you have any other suggestions? We know that we have seen this done before, so it should be doable.

vincent wrote:

"several seconds is very very long."

that should ofcourse be:

"several minutes is very very long."

[Anon]

Could it be something in the php or Apache configuration which cause the problem?

[Anon]

I found a solution. It was related to the browser. The browser was keeping a buffer.

What I did to solve the problem was to add these lines before each output:

for($no=0;$no<300;$no++)
{
echo " ";
}

so that the browser got enought data in it's buffer to output data after each article.

[[deleted]]

My first suggestion would be: use google!

There are already scripts/executables that can convert HTML to PDF which are bound to be more efficient than your method (other people always think of better methods :-) )

If that doesn't help, I'd take out the most time-consuming bits.
First, take out the on-the-fly processing of the content. Instead, do the processing only when the content changes, and store the processed data in the database next to the original.
So instead of storing
&lt;b>this is bold text&lt/b> with some plaintext

just store:
bold:this is bold text
plain: with some plain text

Then when you need the data, you can load the pre-processed data and just bang it into PDF. The first word is the font type (you can add more info if required) and the rest is the actual content. That is much faster than doing it char-by-char every time.