/* ** (c) COPYRIGHT MIT 1995. ** Please first read the full copyright statement in the file COPYRIGH. */
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.
Note: The library core does not define any message or dialog
methods - they are all considered part of the application. The library comes
with a default set of methods which can be initiated
using the function HTAlertInit() in HTInit
module
This module is implemented by HTAlert.c, and it is a part of the W3C Sample Code Library.
#ifndef HTALERT_H #define HTALERT_H #include "HTReq.h"
The callback functions are defined as a generic callback where the caller
can pass a set of input parameters and the callee can return a set of outptu
parameters. Also note that all the *_PROG_* opcodes are a subset
of HT_A_PROGRESS. This means that you easily can register a
callback for all progress reports.
typedef enum _HTAlertOpcode {
HT_PROG_DNS = 0x1, /* Doing DNS resolution */
HT_PROG_CONNECT = 0x2, /* Connecting Active */
HT_PROG_ACCEPT = 0x4, /* Connecting Passive */
HT_PROG_READ = 0x8, /* Read data */
HT_PROG_WRITE = 0x10, /* Write data */
HT_PROG_DONE = 0x20, /* Request finished */
HT_PROG_WAIT = 0x40, /* Wait for socket */
HT_PROG_GC = 0x80, /* Cache garbage collecting */
HT_A_PROGRESS = 0xFF, /* Send a progress report - no reply */
/* First word are reserved for progresss notifications */
HT_A_MESSAGE = 0x1<<8, /* Send a message - no reply */
HT_A_CONFIRM = 0x2<<8, /* Want YES or NO back */
HT_A_PROMPT = 0x4<<8, /* Want full dialog */
HT_A_SECRET = 0x8<<8, /* Secret dialog (e.g. password) */
HT_A_USER_PW = 0x10<<8 /* Atomic userid and password */
} HTAlertOpcode;
typedef struct _HTAlertPar HTAlertPar;
typedef BOOL HTAlertCallback (HTRequest * request, HTAlertOpcode op,
int msgnum, const char * dfault, void * input,
HTAlertPar * reply);
If you don't expect any return values then reply can be NULL.
The return value of the callback function can be used to indicate confirmation
on a prompt (Yes or No).
This is an enumerated list of messages that can be converted into a string table etc.
typedef enum _HTAlertMsg {
HT_MSG_NULL = -1,
HT_MSG_UID = 0,
HT_MSG_PROXY_UID,
HT_MSG_FTP_UID,
HT_MSG_PW,
HT_MSG_FILENAME,
HT_MSG_ACCOUNT,
HT_MSG_METHOD,
HT_MSG_MOVED,
HT_MSG_RULES,
HT_MSG_FILE_REPLACE,
HT_MSG_RETRY_AUTHENTICATION,
HT_MSG_RETRY_PROXY_AUTH,
HT_MSG_REDO,
HT_MSG_BIG_PUT,
HT_MSG_SOURCE_MOVED,
HT_MSG_DESTINATION_MOVED,
HT_MSG_REDIRECTION,
HT_MSG_PROXY,
HT_MSG_CACHE_LOCK,
HT_MSG_ELEMENTS /* This MUST be the last element */
} HTAlertMsg;
#define HT_MSG_ENGLISH_INITIALIZER \
"Please enter username:", \
"Please enter username for proxy authentication:", \
"Please enter username for this FTP server:", \
"Password:", \
"Please give name of file to save in:", \
"Plase enter account:", \
"You might not be allowed to use this method here, continue?", \
"Location has moved, continue?", \
"A new set of rules is requested to be added to your setup - continue?", \
"This file already exists - replace existing file?", \
"Authentication failed - retry?", \
"Proxy authentication failed - retry?", \
"This method has already been performed - repeat operation?", \
"This document is very big - continue operation?", \
"The source document for this operation has moved - continue operation \
with new location?", \
"The destination document for this operation has moved - continue \
operation with new location?", \
"A redirection may change the behavior of this method - proceed anyway?", \
"An automatic request for changing proxy has been encountered - continue?", \
"The persistent cache is already in use by another user. If this is not \
the case then you can manually delete this lock and restart."
If you really don't want the library to prompt for anything at all then enable this constant. The default value is Interactive.
extern void HTAlert_setInteractive (BOOL interative); extern BOOL HTAlert_interactive (void);
Message methods are registered in lists. By default a list is not enabled before you assign it as being active. This allows the application to maintain multiple lists of message handlers which can be swapped in and out as neeeded.
Register a call back function that is to be called when generating messages,
dialog, prompts, progress reports etc. The opcode signifies which call back
function to call depending of the type of the message. Opcode can be any
combination of the bitflags defined by HTAlertOpcode. If you
register one callback for HT_A_PROGRESS then this will get called
on all progress notifications.
extern BOOL HTAlertCall_add (HTList * list, HTAlertCallback * cbf, HTAlertOpcode opcode);
Unregister a call back function from a list
extern BOOL HTAlertCall_delete (HTList * list, HTAlertCallback * cbf);
Unregister all handlers registered for a given opcode.
extern BOOL HTAlertCall_deleteOpcode (HTList * list, HTAlertOpcode opcode);
Unregisters all call back functions
extern BOOL HTAlertCall_deleteAll (HTList * list);
Finds a callback function corresponding to the opcode. If none has been registered then NULL is returned.
extern HTAlertCallback * HTAlertCall_find(HTList * list, HTAlertOpcode opcode);
The reply object is used for communicating input from the user back to the Library. This is only required to use when for example the user is prompted for a file name etc. You can find several examples on how to use this in the default message and dialog module provided together with the Library.
extern HTAlertPar * HTAlert_newReply (void); extern void HTAlert_deleteReply (HTAlertPar * old);
These methods provide the API for handling the reply message. There are two ways of assigning a message to the reply message - either by copying the buffer or by reusing the same buffer. In the latter case, the caller must make sure not to free the reply message before it has been used.
extern BOOL HTAlert_setReplyMessage (HTAlertPar * me, const char *message); extern BOOL HTAlert_assignReplyMessage (HTAlertPar * me, char * message);
You can get the data back again by using this method:
extern char * HTAlert_replyMessage (HTAlertPar * me);
extern char * HTAlert_replySecret (HTAlertPar * me); extern BOOL HTAlert_setReplySecret (HTAlertPar * me, const char * secret); extern void * HTAlert_replyOutput (HTAlertPar * me); extern BOOL HTAlert_setReplyOutput (HTAlertPar * me, void * output);
A list can be assigned as being active in which case it is visible for libwww by assigning the list as the global alert list. Libwww does not know about inactive lists of alert handlers.
extern void HTAlert_setGlobal (HTList * list); extern HTList * HTAlert_global (void);
You can assign a callback directly to the global list in which case it becomes immediately available to libwww. In this case you do not need to worry about creating the list - it will be created as well as deleted automatically.
extern BOOL HTAlert_add (HTAlertCallback * cbf, HTAlertOpcode opcode);
You can either delete a handler by referring to its address or to the opcode that it has been registered for.
extern BOOL HTAlert_delete (HTAlertCallback * cbf); extern BOOL HTAlert_deleteOpcode (HTAlertOpcode opcode);
extern BOOL HTAlert_deleteAll (void);
extern HTAlertCallback * HTAlert_find (HTAlertOpcode opcode);
#endif