diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/http.n | 79 |
1 files changed, 58 insertions, 21 deletions
@@ -1,11 +1,11 @@ '\" '\" Copyright (c) 1995-1997 Sun Microsystems, Inc. -'\" Copyright (c) 1999 by Scriptics Corporation. +'\" Copyright (c) 1998-2000 by Ajuba Solutions. '\" '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" -'\" RCS: @(#) $Id: http.n,v 1.10 2000/04/09 23:55:54 welch Exp $ +'\" RCS: @(#) $Id: http.n,v 1.11 2000/06/02 23:14:46 hobbs Exp $ '\" .so man.macros .TH "Http" n 8.3 Tcl "Tcl Built-In Commands" @@ -14,7 +14,7 @@ .SH NAME Http \- Client-side implementation of the HTTP/1.0 protocol. .SH SYNOPSIS -\fBpackage require http ?2.2?\fP +\fBpackage require http ?2.3?\fP .sp \fB::http::config \fI?options?\fR .sp @@ -32,8 +32,12 @@ Http \- Client-side implementation of the HTTP/1.0 protocol. .sp \fB::http::code \fItoken\fR .sp +\fB::http::ncode \fItoken\fR +.sp \fB::http::data \fItoken\fR .sp +\fB::http::error \fItoken\fR +.sp \fB::http::cleanup \fItoken\fR .sp \fB::http::register \fIproto port command\fR @@ -57,9 +61,8 @@ Its \fIoptions \fR determine whether a GET, POST, or HEAD transaction is performed. The return value of \fB::http::geturl\fR is a token for the transaction. The value is also the name of an array in the ::http namespace - that contains state -information about the transaction. The elements of this array are -described in the STATE ARRAY section. +that contains state information about the transaction. The elements +of this array are described in the STATE ARRAY section. .PP If the \fB-command\fP option is specified, then the HTTP operation is done in the background. @@ -262,12 +265,20 @@ any. This sets the \fBstate(status)\fP value to \fIwhy\fP, which defaults to \f \fB::http::wait\fP \fItoken\fP This is a convenience procedure that blocks and waits for the transaction to complete. This only works in trusted code because it -uses \fBvwait\fR. +uses \fBvwait\fR. Also, it's not useful for the case where +\fB::http::geturl\fP is called \fIwithout\fP the \fB-command\fP option +because in this case the \fB::http::geturl\fP call doesn't return +until the HTTP transaction is complete, and thus there's nothing to +wait for. .TP \fB::http::data\fP \fItoken\fP This is a convenience procedure that returns the \fBbody\fP element (i.e., the URL data) of the state array. .TP +\fB::http::error\fP \fItoken\fP +This is a convenience procedure that returns the \fBerror\fP element +of the state array. +.TP \fB::http::status\fP \fItoken\fP This is a convenience procedure that returns the \fBstatus\fP element of the state array. @@ -276,15 +287,24 @@ the state array. This is a convenience procedure that returns the \fBhttp\fP element of the state array. .TP +\fB::http::ncode\fP \fItoken\fP +This is a convenience procedure that returns just the numeric return +code (200, 404, etc.) from the \fBhttp\fP element of the state array. +.TP \fB::http::size\fP \fItoken\fP This is a convenience procedure that returns the \fBcurrentsize\fP -element of the state array. +element of the state array, which represents the number of bytes +received from the URL in the \fB::http::geturl\fP call. .TP \fB::http::cleanup\fP \fItoken\fP This procedure cleans up the state associated with the connection identified by \fItoken\fP. After this call, the procedures like \fB::http::data\fP cannot be used to get information -about the operation. +about the operation. It is \fIstrongly\fP recommended that you call +this function after you're done with a given HTTP request. Not doing +so will result in memory not being freed, and if your app calls +\fB::http::geturl\fP enough times, the memory leak could cause a +performance hit...or worse. .TP \fB::http::register\fP \fIproto port command\fP This procedure allows one to provide custom HTTP transport types @@ -309,19 +329,36 @@ registered via \fBhttp::register\fR. The \fBhttp::geturl\fP procedure will raise errors in the following cases: invalid command line options, an invalid URL, -or a URL on a non-existent host, +a URL on a non-existent host, +or a URL at a bad port on an existing host. These errors mean that it cannot even start the network transaction. It will also raise an error if it gets an I/O error while writing out the HTTP request header. +For synchronous \fB::http::geturl\fP calls (where \fB-command\fP is +not specified), it will raise an error if it gets an I/O error while +reading the HTTP reply headers or data. Because \fB::http::geturl\fP +doesn't return a token in these cases, it does all the required +cleanup and there's no issue of your app having to call +\fB::http::cleanup\fP. +.PP +For asynchronous \fB::http::geturl\fP calls, all of the above error +situations apply, except that if there's any error while +reading the +HTTP reply headers or data, no exception is thrown. This is because +after writing the HTTP headers, \fB::http::geturl\fP returns, and the +rest of the HTTP transaction occurs in the background. The command +callback can check if any error occurred during the read by calling +\fB::http::status\fP to check the status and if it's \fIerror\fP, +calling \fB::http::error\fP to get the error message. +.PP +Alternatively, if the main program flow reaches a point where it needs +to know the result of the asynchronous HTTP request, it can call +\fB::http::wait\fP and then check status and error, just as the +callback does. .PP -The \fBhttp::wait\fP procedure will raise errors if an I/O error -occurs while reading the HTTP reply headers or data. If the -\fB-command\fP flag is not passed to \fBhttp::geturl\fP, -then it will call \fBhttp::wait\fP and so these errors will -occur in \fBhttp::geturl\fP. -If you get an error from \fBhttp::wait\fP, you must still call -\fBhttp::cleanup\fP to delete the state array. +In any case, you must still call +\fBhttp::cleanup\fP to delete the state array when you're done. .PP There are other possible results of the HTTP transaction determined by examining the status from \fBhttp::status\fP. @@ -336,12 +373,11 @@ procedure returns a value like "HTTP 404 File not found". .TP eof If the server closes the socket without replying, then no error -is rasied, but the status of the transaction will be \fBeof\fP. +is raised, but the status of the transaction will be \fBeof\fP. .TP error -In this case \fBhttp::wait\fP should have raised an error. The error message will also be stored in the \fBerror\fP status -array element. +array element, accessible via \fB::http::error\fP. .PP Another error possibility is that \fBhttp::geturl\fP is unable to write all the post query data to the server before the server @@ -424,7 +460,8 @@ the post query data to the server. .TP \fBstatus\fR Either \fBok\fR, for successful completion, \fBreset\fR for -user-reset, or \fBerror\fR for an error condition. During the +user-reset, \fBtimeout\fP if a timeout occurred before the transaction +could complete, or \fBerror\fR for an error condition. During the transaction this value is the empty string. .TP \fBtotalsize\fR |