A computer system implementing a first content publisher addressable by a first domain name, the computer system comprising: at least one processor; and a storage medium storing code implemented by the at least one processor to: set one or more tokens under a first domain name in a client device connected over a network to the first content publisher in response to a request for content from the client device, the or each token specifying state data for a communication session between the client device and a first content publisher addressable by the first domain name, the communication session utilizing a stateless communication protocol; generate a redirection resource locator, the redirection resource locator including a uniform resource locator for a web object hosted by a second content publisher including a representation of the or each token, the generated uniform resource locator being embedded in content provided by the first content publisher in response to the request from the client device; and communicate the content with the embedded uniform resource locator to the client device, the uniform resource locator being selectable by a user to cause the client device to send a web object request for the web object to the second content publisher, the web object request including the representation of the or each token, wherein the web object causes the second content publisher to set a token in the client device under the second domain name and having a value representing the or each token. at least one processor; and a storage medium storing code implemented by the at least one processor to: set one or more tokens under a first domain name in a client device connected over a network to the first content publisher in response to a request for content from the client device, the or each token specifying state data for a communication session between the client device and a first content publisher addressable by the first domain name, the communication session utilizing a stateless communication protocol; generate a redirection resource locator, the redirection resource locator including a uniform resource locator for a web object hosted by a second content publisher including a representation of the or each token, the generated uniform resource locator being embedded in content provided by the first content publisher in response to the request from the client device; and communicate the content with the embedded uniform resource locator to the client device, the uniform resource locator being selectable by a user to cause the client device to send a web object request for the web object to the second content publisher, the web object request including the representation of the or each token, wherein the web object causes the second content publisher to set a token in the client device under the second domain name and having a value representing the or each token. set one or more tokens under a first domain name in a client device connected over a network to the first content publisher in response to a request for content from the client device, the or each token specifying state data for a communication session between the client device and a first content publisher addressable by the first domain name, the communication session utilizing a stateless communication protocol; generate a redirection resource locator, the redirection resource locator including a uniform resource locator for a web object hosted by a second content publisher including a representation of the or each token, the generated uniform resource locator being embedded in content provided by the first content publisher in response to the request from the client device; and communicate the content with the embedded uniform resource locator to the client device, the uniform resource locator being selectable by a user to cause the client device to send a web object request for the web object to the second content publisher, the web object request including the representation of the or each token, wherein the web object causes the second content publisher to set a token in the client device under the second domain name and having a value representing the or each token.