ILOG CPLEX 11.0 User's Manual

Controlling Message ChannelsIn both the Interactive Optimizer and the Callable Library, there are message channels thatenable you to direct output from your application as you prefer. In the Interactive Optimizer,these channels are defined by the command set output channel with its options aslisted in Table 6.2. In the Callable Library, there are routines for managing messagechannels, in addition to parameters that you can set. In the C++ and Java APIs, the classIloCplex inherits methods from the Concert Technology class IloAlgorithm, methodsthat enable you to control input and output channels.The following sections offer more details about these ideas:◆ Parameter for Output Channels on page 150;◆ Callable Library Routines for Message Channels on page 151;◆ Example: Callable Library Message Channels on page 152;◆ Concert Technology Message Channels on page 154.Parameter for Output ChannelsBesides the log-file parameter, Interactive Optimizer and the Callable Library offer yououtput-channel parameters to give you finer control over when and where messages appearin the Interactive Optimizer. Output-channel parameters indicate whether output should orshould not appear on screen. They also allow you to designate log files for messagechannels. The output-channel parameters do not affect the log-file parameter, so it iscustomary to use the command set logfile before the commandset output channel value1 value2.In the output-channel command, you can specify a channel to be one of dialog, errors,logonly, results, or warnings. Table 6.2 summarizes the information carried over eachchannel.Table 6.2 Options for the Output-Channel CommandChanneldialogerrorslogonlyresultswarningsInformationmessages related to interactive use; e.g., prompts, help messages, greetingsmessages to inform user that operation could not be performed and whymessage to record only in file (not on screen) e.g., multiline messagesinformation explicitly requested by user; state, change, progress informationmessages to inform user request was performed but unexpected conditionmay result150 ILOG CPLEX 11.0 — USER’ S MANUAL