Did you ever noticed that after restart of the IIS ASP.Net page which has Crystal Reports Viewer would take much longer to come up?
Some of it is expected since on initial start up, a number of Crystal assemblies and objects need to be created and this does take time.
I want to emphasize that discussion below is related to the first run of any reports. We have to actually restart/reset IIS to see problem again.
Note: There was a question about IIS’ Application Pools recycling which could cause similar effect. Make sure your application pool is set properly.
Setting up a playground
Let’s assume ASP.Net pages were already migrated to use .Net 3.x and look at what happen behind the scene.
Remember that after restart IIS starts from ground up. This means several things in respect to our page content:
- .Net assemblies need to be preloaded and validated if necessary.
Since Crystal Reports 2008 comes as .Net 2.0-based core and we may already moved to .Net 3.x, CR2008 Engine and some additional files need to be loaded and validated aside from one which already used by any previously loaded pages.
- For each session engine would create a cached version of RPT file in temp folder.
- Some code would have to be brought to the client machine for Viewer to operate properly.
- Database connection established, data retrieved, processed, paged and sent to the client Viewer.
That about it, now we ready to work with reports. Please notice that after that initial load, any other reports would come up faster. We could even close the browser or use another browser (ex. go from IE to FF) and it would be still faster than the first time, so there is something important about the first step above…
Combing the sand
Let’s try to break the IIS initialization process to get more detailed view.
Since we already had some ASP.Net pages loaded before coming to CR related page, we could disregard .Net core initialization procedure. It is there on IIS side: used and ready.
Ok, next thing is CR engine related stuff. There is some 5Mb of files in crystalreportviewers12 folder to support CR Viewer in ASP.Net and we need to send some of them over the network. In addition to that there is Crystal Reports Engine assemblies which need to be loaded by IIS at the time of the first use. And this is our spot to dig.
If we try and trace what exactly going on we would notice that aside from IIS loading a few dozen assemblies, there is also process associated with trying connect to CRL.VERISIGN.NET.
What is it?
“Problem” is that assemblies are Authenticode signed and therefore need to be verified or it technical terms they need to be checked against Certificate Revocation List (CRL) by Publisher for Code Access Security (CAS).
Default behavior is that they need to be verified by the certificate authority. If certificate is not present on the same machine (I have my doubts that SAP doing anything about that, but I could be wrong), validation need to be done via central repository mentioned above, or if machine does not have network/internet access the .NET thread might timeout waiting to connect.
Yes, by performing strong name signing of assemblies or placing the CA certificate on the same machine issue would be avoided, but it seems not being a case.
Building the castle
Since assemblies are provided by SAP, we cannot remove digital signature and it is a hassle to keep certificates current by obtaining them from CA every time they expire. Let’s concentrate on the Publisher mentioned above and turn it off.
It is all-or-nothing solution since it would require turning off CRC for the entire IIS.
When working with regular .Net apps, it can be done on the app level (assuming we already have fix for .Net 2.0) by adding the following section in <Application>.exe.config
<configuration> <runtime> <generatePublisherEvidence enabled="false"/> </runtime> </configuration>
This new element described in this MSDN article. Interesting note there (why not to turn it then by default? Oh, security concerns… UAC anyone?):
We recommend that services use the <generatePublisherEvidence> element to improve startup performance. Using this element can also help avoid delays that can cause a time-out and the cancellation of the service startup.
Since there is no such config file for our ASP.Net app (web.config would not work here, because it defines settings that are only AppDomain wide and we need process wide for aspnet_isapi.dll being the hosting environment for the runtime), we would have to turn code access security (CAS) publisher policy off for the entire IIS.
There are two options:
- Create a file called w3wp.exe.config (for IIS6, or aspnet_wp.exe.config for IIS5). This will affect all .NET based web applications on the system.
- Or to specify this in machine.config, but then this affects every .NET application on the machine and is not available for override in individual Apps.
Adding the summer cabin
There is one more step which could be taken to improve performance by preloading some of the core assemblies while site visitor is doing something else.
I wouldn’t go into much details here, since it is implementation/application environment specific, but just give a hint:
- some other place in application, create a background process which would create CR document object, load some not essential report file, retrieve some data and then disapear without the trace. This would allow Crystal Reports Engine being initialized in the background offsetting time needed for the actual CR related page load. Don’t force garbage collection though, this may cancel desired effect.
In some situation I observed 50% to 70% drop in start-up time…