Table 17 defines the parameters for the Service.

Table 17 – ActivateSession Service Parameters







Common request parameters. The type RequestHeader is defined in 7.28.



This is a signature generated with the private key associated with the clientCertificate. This parameter is calculated by appending the serverNonce to the serverCertificate and signing the resulting sequence of bytes.

If the serverCertificate contains a chain, the signature calculation shall be done only with the leaf Certificate. For backward compatibility a Server shall check the signature with the full chain if the check with the leaf Certificate fails.

The SignatureAlgorithm shall be the AsymmetricSignatureAlgorithm specified in the SecurityPolicy for the Endpoint.

The SignatureData type is defined in 7.32.

clientSoftwareCertificates []


Reserved for future use.

The SignedSoftwareCertificate type is defined in 7.33.

localeIds []


List of locale ids in priority order for localized strings. The first LocaleId in the list has the highest priority. If the Server returns a localized string to the Client, the Server shall return the translation with the highest priority that it can. If it does not have a translation for any of the locales identified in this list, then it shall return the string value that it has and include the locale id with the string. See OPC 10000-3 for more detail on locale ids. If the Client fails to specify at least one locale id, the Server shall use any that it has.

This parameter only needs to be specified during the first call to ActivateSession during a single application Session. If it is not specified the Server shall keep using the current localeIds for the Session.


Extensible Parameter


The credentials of the user associated with the Client application. The Server uses these credentials to determine whether the Client should be allowed to activate a Session and what resources the Client has access to during this Session.

The UserIdentityToken is an extensible parameter type defined in 7.36.

The EndpointDescription specifies what UserIdentityTokens the Server shall accept.

Null or empty user token shall always be interpreted as anonymous.



If the Client specified a user identity token that supports digital signatures, then it shall create a signature and pass it as this parameter. Otherwise the parameter is null.

The SignatureAlgorithm depends on the identity token type.

The SignatureData type is defined in 7.32.




Common response parameters (see 7.29 for ResponseHeader definition).



A random number that should never be used in any other request.

This number shall have a minimum length of 32 bytes.

The Client shall use this value to prove possession of its Application Instance Certificate in the next call to ActivateSession request.

results []


List of validation results for the SoftwareCertificates (see 7.34 for StatusCode definition).

diagnosticInfos []


List of diagnostic information associated with SoftwareCertificate validation errors (see 7.8 for DiagnosticInfo definition). This list is empty if diagnostics information was not requested in the request header or if no diagnostic information was encountered in processing of the request.