ASP.NET rdlc with external images not displaying images in PDF

Question

I'm using the Microsoft ReportViewer that comes with ASP.NET and have a report parameter that should be setting the value (path) of an image in my report. I'm providing the path as a complete URL right now, starting with http:// but have also tried this as an app relative path, site rooted path, etc. and for some reason the image is always showing as the red X when it exports to PDF. I'm just creating an instance of a control in code, setting the properties and exporting directly to the response stream so it acts a download.

I'm just not sure what the problem could be with the image not showing up, so if anyone has any ideas please let me know.

UPDATE 1

I've determined that I can embed the image with a URL if it is on my public web server but when I'm running in localhost the image won't embed. I have confirmed for localhost that if I paste the same URL into my browser the image will open fine. As far as I know, I don't have a proxy. So I can work around my issue, but I still don't understand what the problem is with localhost.

UPDATE 2

Forgot to mention that when the URL to the image is opened from a browser it works fine.

Answer 1

It is not possible for a PDF to contain a reference an external image (at least from my understanding). In order for an image to appear in the PDF, it must be embedded into the document. Therefore, to use an external image, your app must retrieve the image and store it in the document. The report viewer will try to do this for you.

Two possible answers:

First, in order for your app to package the image into the PDF, it must be able to retrieve the image from the URL you are specifying. If that URL is behind a proxy (from the perspective of your app server) and/or requires credentials to access, this will present a challenge with the default configuration of the report viewer.

If a proxy server is the issue, please see the settings to your web.config you can add below. You may also need to supply network credentials, so your app can authenticate to the proxy. There are lots of ways to solve this, but one of the easiest is to run your application as a service account on your domain that has rights to traverse your proxy. You can test this by running the site as you temporarily (should be temporary because this is a horrible security practice).

The image you are using could require credentials to access (try pulling up the image in Firefox with empty cookies and verifying whether credentials were required to access it). If it requires Windows authentication, the same solution to proxy security may apply to authentication required on the remote image. If it requires some other form of authentication, you may be better off downloading and embedding the image into your project.

It is also possible to download the image using other means in your code and convert it to a byte array for inclusion in the report. There are lots of examples of this on the web, including a Stack Overflow here.

Second, take a look at the following page:

http://msdn.microsoft.com/en-us/library/ms251715%28VS.80%29.aspx

Using external images in a ReportViewer report is not enabled by default. To use an external image, you must set the EnableExternalImages property in your code. Depending on your network configuration, you might also need to bypass proxy settings to allow the external image to appear. You can add the following settings to the Web.config file to bypass the local proxy. When modifying your Web.config file, be sure to specify the name of the proxy server that is used in your network:

<system.net>
<defaultProxy>
<proxy usesystemdefault = "false" bypassonlocal = "true" proxyaddress = "http://< proxyservername >:80/" />
<defaultProxy>
</system.net>

Hope one or both of these helps.

Jerry

Answer 2

When passing external image filenames to ReportViewer parameters, pass the format like this: file://C:\app\images\pic.jpg. Anything else usually doesn't work well when deployed.

Answer 3

Okay, so this was our solution. The web server did not recognize its own qualified DNS name as a URL, so we had to edit the Hosts file in the C:\Windows\System32\drivers\etc folder and add the host name as localhost. The line we added to the file was:

ourserver.ourdomain.com 127.0.0.1