Error loading RadChart image: Showing Red "X" and error message popup

[mukund katpatal]

Hi,
I am using Licensed version of telerik controls. I am using rad chart in my asp.net user control.
My application will  get deployed on web farm and we have orcle database as backend tool so we are not using any asp .net session .
I am getting below error when I deploy my application to development server ( it is single server), but on my local machine it is working fine.

---------------------------
Microsoft Internet Explorer
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Error loading RadChart image.
You may also wish to check the ASP.NET Trace for further details.
Display stack trace?

Below is the setting  I did in my asp usercontrol on development server

 

<telerik:RadChart ID="ComplianceScoreChart" runat="server" ChartImageFormat="Jpeg" SeriesOrientation="Horizontal"

 

 

Height="100px" Width="200px" UseSession="false">

 

Web.config :
under httphandler I have below setting

<

add path="ChartImage.axd" type="Telerik.Web.UI.ChartHttpHandler" verb="*" validate="false" />

 

Also I have Temporary image folder path set. And i am seeing images created and getting deleted immediately.
What can be the reason and how can I fix it? And also What I have to do in QA Test sever (having web farm) so there also It should not break?

Thanks & Regards
Mukund Katpatal.

[Ves]

Hi mukund,

This is my reply to the bug report you have open:

The httphandler registration is different for IIS6 and IIS7. For IIS7 you need to add an additional registration in <system.webServer> section in your web.config file. You can fine more details in this help topic. We recommend removing the chart httphandler registration completely and using the link in the VisualStudio smart tag (check the second image in this help topic) -- it will register the httphandler correctly for both IIS6 and IIS7.

As for the web farm -- RadChart will work in web farm environment under certain conditions. It would be an issue if the page is served  and therefore the chart image is generated by one machine and the next request for the image itself is served by another machine. Then this second machine will not be able to find the image. You will need to be sure that the chart httphandler is served by the same machine, which served the page.

Please, keep the correspondence in a single thread, so it easier for both you and us to follow it. Thanks.

Sincerely,
Ves
the Telerik team

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[John Giblin]

I am getting the same message..  But i am using IIS 6 and developing in VS.net 2010

Also, I added page caching to the page.  I have 2 charts that are in usercontrols within that page.  Do you think the page caching would cause this.

[Ves]

Hello John,

Indeed, page caching might cause such issues. Here is how RadChart works: When the page is processed the image is created and stored in the session. Later, when the image is requested the HttpHandler moves the image from the session to the cache (expiration time is 5 minutes, not configurable) with a unique ID (GUID).

In case you have enabled output caching, it is possible that the cached html contains the last generated GUID, but 5 minutes later the cache no longer holds the image, the session has been removed, hence - no image at all. If you disable the output caching for the chart you will be sure that the image is generated with a valid GUID on each request.

Sincerely,
Ves
the Telerik team

[John Giblin]

Is there plans in later releases to be able to use page caching or to have control over the rad chart cache?

I guess for now I can cache the datasource

thanks.

[Ves]

Hello John,

I agree the point you set forth is valid, so I will make sure our developers are aware of this scenario, so they will consider allowing the user to control the cache validity period.

Thanks and regards,
Ves
the Telerik team

[K]

Hi,

Can I ask whether the mechanism to move from session[] to cache[] is still valid in 2013.1.xxxxx version?

Wouldn't this be a problem in a load balanced environment without a sticky session even if I was using a state server/session sql server?

I stumble upon this post cause I am facing a problem when I am in a load balanced environment where http works but not https.

Trying to figure out why.


I am using a state server for session.


Thanks.

[K]

Hi,

after further troubleshooting this is my findings.

The load balancer is configured for sticky for http but not https. Due to https encrypting. This needs to be explicitly set.

However I feel is a design flaw in the charting caching mechanism.

If I have 2 graphs in a single page.


time 1: test.aspx (server 1)
time 2: chart.axd (server 1) -> this moves 2 charts from session[] to cache[] of server 1
time 3: 1st chart loads
time 4: chart.axd (server 2 - due to load balancing non sticky) -> chart cannot be found in cache[] of server 2

Anyone from telerik can comment?

Thanks.

[Ves]

Hi,

I would agree that there are scenarios in which the httphandler approach, used in RadChart might suffer. Still, I would like to point you to our new charting control RadHtmlChart, which is ready to meet such scenarios.

Best regards,
Ves
Telerik