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Thread Trying to separate UI and data
Fri, Dec 23 2016 5:50 AMPermanent Link

Uli Becker

Hi,

for performance reasons I tried to run an EWB application from a linux
webspace. The data are served from a Windows host with an EWB server.

The MainForm of the app loads, then nothing seems to happen.

Debugging the app with Chrome shows, that the data-requests work, but
are very slow (querying a small table needs about 20 seconds).
Executing the same request by typing the url manually in the browser,
results in a very quick response (<10 ms).

What can be the reason for such a delay? Since I am separating data and
UI the first time: maybe this construction doesn't work generally?

Thanks for any hints.

Uli
Fri, Dec 23 2016 7:59 AMPermanent Link

Matthew Jones

Uli Becker <johnmuller54@googlemail.com> wrote:
> Hi,
>
> for performance reasons I tried to run an EWB application from a linux
> webspace. The data are served from a Windows host with an EWB server.
>
> The MainForm of the app loads, then nothing seems to happen.
>
> Debugging the app with Chrome shows, that the data-requests work, but
> are very slow (querying a small table needs about 20 seconds).
> Executing the same request by typing the url manually in the browser,
> results in a very quick response (<10 ms).
>
> What can be the reason for such a delay? Since I am separating data and
> UI the first time: maybe this construction doesn't work generally?
>
> Thanks for any hints.
>
> Uli
>

Chrome can lie. I had one query that seemed to take ages but it was
actually including the processing of the data on receipt which was taking
ages. The debugger should show you what is happening though.

--
Matthew Jones
Fri, Dec 23 2016 8:39 AMPermanent Link

Uli Becker

Matthew,

> Chrome can lie. I had one query that seemed to take ages but it was
> actually including the processing of the data on receipt which was taking
> ages. The debugger should show you what is happening though.

I used the debugger:

it just says OPTIONS (pending) and after a long time OPTIONS 200
No Error.

What else can I do? Sorry, no experience in debugging with Chrome.

BTW: same issue when I run the app on localhost fetching the data from
EWB Server.

Uli

Fri, Dec 23 2016 8:42 AMPermanent Link

Raul

Globestar Systems

Team Elevate Team Elevate

On 12/23/2016 5:50 AM, Uli Becker wrote:
> What can be the reason for such a delay? Since I am separating data and
> UI the first time: maybe this construction doesn't work generally?

Generally speaking there is really no difference where the EWB app is
hosted/loaded from since it's downloaded and executed in your browser.

I agree with Matthew in regards to timings - confirm. I assume you're
just monitoring timings using Chrome debug tools on "Network" tab and
not doing actual debugging (breakpoints etc) ?

Common issue usually is cross origin resource sharing - (have to be
enabled in EWB server Content tab) but sounds like you do get data.

I'd suggest start with simple query only EWB app and then see if you can
figure out where the delay comes from

Raul
Fri, Dec 23 2016 8:45 AMPermanent Link

Raul

Globestar Systems

Team Elevate Team Elevate

On 12/23/2016 8:39 AM, Uli Becker wrote:
> it just says OPTIONS (pending) and after a long time OPTIONS 200
> No Error.
>
> What else can I do? Sorry, no experience in debugging with Chrome.
>
> BTW: same issue when I run the app on localhost fetching the data from
> EWB Server.

It's probably this (CORS pre-flight):

http://www.elevatesoft.com/forums?action=view&category=ewb&id=ewb_general&page=1&msg=11039#11039



Raul
Fri, Dec 23 2016 8:53 AMPermanent Link

Uli Becker

Raul,

> It's probably this (CORS pre-flight):
>
> http://www.elevatesoft.com/forums?action=view&category=ewb&id=ewb_general&page=1&msg=11039#11039

Yes, looks like that (see the attached screenshot - method = OPTIONS).

So, what can I do using EWB Server?

thanks Uli
Fri, Dec 23 2016 8:55 AMPermanent Link

Uli Becker

Raul,

> I agree with Matthew in regards to timings - confirm. I assume you're
> just monitoring timings using Chrome debug tools on "Network" tab and
> not doing actual debugging (breakpoints etc) ?

That's correct.

> Common issue usually is cross origin resource sharing - (have to be
> enabled in EWB server Content tab) but sounds like you do get data.


Yes, that's enabled.

> I'd suggest start with simple query only EWB app and then see if you can
> figure out where the delay comes from

OK. Starting right now.

Thanks Uli
Fri, Dec 23 2016 8:56 AMPermanent Link

Uli Becker

Forgot the screenshot - here it is:



Attachments: Clip4.png
Fri, Dec 23 2016 9:25 AMPermanent Link

Uli Becker

Raul,

> It's probably this (CORS pre-flight):

I tried it with a very simple and small query: same issue.

Interesting: I wrote an app for a mobile phone with the same
construction (fetching data from EWB server) with EWB 2.04. That works
without issues.
Probably something was changed in EWB Server.

Uli


Fri, Dec 23 2016 9:46 AMPermanent Link

Raul

Globestar Systems

Team Elevate Team Elevate

On 12/23/2016 9:25 AM, Uli Becker wrote:
> I tried it with a very simple and small query: same issue.

Yes - it's a Chrome issue.

> Interesting: I wrote an app for a mobile phone with the same
> construction (fetching data from EWB server) with EWB 2.04. That works
> without issues.
> Probably something was changed in EWB Server.

No - where is your mobile app running from? If you load the html direct
(or use Cordova/Phonegap) then there is a CORS.

Long term solution i think is for Tim to have EWB web server respond to
OPTIONS query.

For now you could just host the EWB app and data from EWB web server as
a work around - the issue only happens when app and data are loaded from
different URL's (i.e. CORS)

Raul
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