...you need to write a handler for the (static) EasyUAClient.LogEntry event, and display or physically log the messages that this event provides. The LogEntry event has an argument of type LogEntryEventArgs, which carries the log entry data, such as the numerical category and event ID, entry type (Error, Warning, Information, SuccessAudit, or FailureAudit), the event source, and most importantly, the actual Message string. For OPC compliance, as a minimum, the Message should be logged or displayed.

• www.opclabs.com/files/onlinedocs/QuickOpc/5.30/Reference/Qui...807-6a37-b4d2-a7a27ed18832.htm
• www.opclabs.com/files/onlinedocs/QuickOpc/5.30/Reference/Qui...83d-388d-c5b7-8aaa1797b127.htm
• www.opclabs.com/files/onlinedocs/QuickOpc/5.30/Reference/Qui...5d4-d49b-41a9-093918cc60c0.htm

What assembly title are you talking about in the first paragraph? Is that TOP Server or our application?

I meant that if I look in the default location where the Data-UA certificates are stored, the file date is from May 2013. The error occurred last week and it was resolved by running the application as admin and then re-issuing the certificate. Although, we don't seem to be issuing a new certificate (according to the file date) so it does not seem to be a problem with the certificate itself.

• whether the dates/times of the problem correspond to when the component's engine is started (which will roughly correspond to when the Web app starts) - EventId 101 and some more
• The user credentials used - EventId 114
• client certificate parameters - EventId 121 - very important !

when checking the file dates on the certificates in the default folder (for QuickOPC UA) the date does not correspond to the last date that the error occurred. Therefore, we do not believe the server is reissuing the certificate.

OPC-UA requires that both parties (client and server) mutually identify themselves using application certificates. The certificates are supposed to be unique for each application (instance), and therefore cannot be a constant part of the "toolkit" (such as QuickOPC), and need to be generated. In order to make this process invisible (in common cases) to the developer, QuickOPC
a) determines the parameters of the certificate automatically, using values such as the EXE name or the calling assembly name,
b) attempts to look up the certificate in the certificate store,
c) if not found, it attempts to create it, and save it into the certificate store.

The algorithm described above does not, however fit well wit hosted environments such as IIS, for two reasons:
- It is difficult to automatically determine reasonable and unique parameters for the certificate, because the hosting process is the IIS service, not "your" own application EXE.
- The page processing code in IIS typically runs with low privileges that do not allow it to call the necessary CertificateGenerator utility, and even less to save the new certificate to the store.

For usage in such environments, the recommendation is:
- Pre-generate the application certificate manually, and save it to the certificate store. This will remove the need for the application to create and save the certificate.
- In your application, set your own parameters of the certificate. The application will then use these parameters to look up the certificate.

Application certificate can be generated using Opc.Ua.CertificateGenerator.exe utility, typically located (after QuickOPC installation) at C:\Program Files (x86)\Common Files\OPC Foundation\UA\v1.0\Bin. Run it with "/?" to obtain usage instructions.

Setting the certificate parameters is done by modifying properties in EasyUAClient.SharedParameters.Engine (EasyUAClient.SharedParameteres is a static property, and you need to set the values before creating the first instance EasyUAClient, in order for it to have the desired effect). The properties of interest are:
- ApplicationCertificateSubject
- ApplicationName
- ApplicationUriString
- ProductUriString

The values should match those used when the certificate was generated, because they (or at least some of them) are used to look up the certificate in the store.

I understand that the above instructions may need further details or explanation; let me know which parts need more attention and I will try to help.