| Re: Output status during processing [message #179535 is a reply to message #179532] |
Mon, 05 November 2012 14:24   |
crankypuss
Messages: 147
Registered: March 2011
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Senior Member |
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On 11/04/2012 08:10 PM, Scott Johnson wrote:
> On 11/4/2012 5:21 PM, Jerry Stuckle wrote:
>> On 11/4/2012 4:52 PM, Scott Johnson wrote:
>>> On 11/4/2012 1:28 PM, M. Strobel wrote:
>>>> Am 04.11.2012 20:23, schrieb Scott Johnson:
>>>> > Hello
>>>> >
>>>> > I hate to come here with a question without any tried code but I
>>>> > really do not even
>>>> > know where to start, I have never attempted this before without a net.
>>>> >
>>>> > What I would like to do is provide an output to the browser during a
>>>> > long processing
>>>> > term.
>>>> >
>>>> > Exactly what I am doing is this.
>>>> >
>>>> > I am loading a csv file to update inventory.
>>>> >
>>>> > During this process I am flushing the current Table and then loading
>>>> > the new and then
>>>> > comparing the inventory table to a product table and would like to
>>>> > provide status of
>>>> > where we are in the process what items matched and changed and so
>>>> > forth in real time.
>>>> >
>>>> > I have done some similar tasks in JS but with minimal steps in the
>>>> > processing then
>>>> > what I am trying to accomplish.
>>>> >
>>>> > I did some binging and found that it may have to do with output
>>>> > buffering but nothing
>>>> > particular to my situation. (as far as I could find)
>>>> >
>>>> > If this is possible could someone point me in the right direction and
>>>> > I will do the
>>>> > leg work.
>>>>
>>>> Are you starting your long running job in the browser? Not good, the
>>>> whole setup is
>>>> designed for request-response, and not long running jobs.
>>>>
>>>> I would try to design the long running update-compare job as a
>>>> separate process,
>>>> writing status or progress information to a file/a db table. Then you
>>>> have a
>>>> corresponding script you call in your browser, showing you status and
>>>> progress. This
>>>> could be done with whole page refreshs or with ajax.
>>>>
>>>> /Str.
>>>>
>>>
>>> Ok that makes makes sense.
>>>
>>> And yes it was started in the browser on a file upload from a form
>>> field.
>>>
>>> I could use AJAX to load the file and then process it in the background
>>> sending status points as it goes through AJAX.
>>>
>>> I have done this is the past just not for so many steps to perform.
>>>
>>> The more I read about the PHP buffer functions, I could not find a way
>>> that would periodically send text without a header issue.
>>>
>>> Guess why they have different tools for the different needs.
>>>
>>> Thanks Str.
>>>
>>> Scotty
>>>
>>>
>>
>> Nope, but it has nothing to do with php. HTTP is a request/response
>> protocol; the client sends a request and expects a response within the
>> time specified by the browser's timeout value.
>>
>> But then this causes a problem also, because PHP has a buffer (for
>> efficiency), the server has a buffer (also for efficiency), routers
>> along the way may have buffers (again, for efficiency), and the client's
>> system may have a buffer (hmmm... efficiency?) and finally the browser
>> may have a buffer.
>>
>> The bottom line is - the HTTP protocol is pretty much useless for
>> long-running tasks. The time it takes to send data to the browser is
>> dependent on a lot of things, and the browser's timeout values are
>> independent of anything the server can control.
>>
>> If you need such processing, I suggest you look into other methods of
>> communications. Java applets, for instance, can work with non-http
>> protocols.
>>
>
> Yeah I can see there can be a bottle-neck/lag issue anywhere which would
> be useless for anything real time (which I use loosely).
>
> Thanks for the input.
>
> Scotty
You can also have the browser request a reload every few seconds, it
isn't exactly what you're asking for but it can give more or less the
same benefits.
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