The Alert Class

The Alert class defines a set of methods to be used by libwww to be used for passing prompts and message to a user. In order to maintain the Library core application independent and natural language independent, libwww does not know how to communicate with a user. Note here that a user is a somewhat abstract notion for  something that can receive a message or prompt from the Library. This can for example be a person, but is may also be handled automatically by a robot or a client receiving a response from a HTTP server.

Libwww has a set of opcodes that classifies the nature of the message, for example that it is a question that must be confirmed in order to continue a request or simply a progress notification. The application can register a method for any number of the defined opcodes - in case the Library has a message for an opcode that does not have a method associated, the message is ignored. You can also globally disable any message send from the Library.