Use a calcout record and -field references in the format. +redirection to fields.
@@ -128,7 +128,7 @@ record (calcout, "$(RECORD)") {
-Use record references in the format. +Use redirection to records.
@@ -216,7 +216,7 @@ Any non-matching input is ignored by record B.
-Use record references in the format. +Use redirection to records. To avoid record names in protocol files, use protocol arguments.
@@ -244,11 +244,11 @@ processes record B. -
Use a @mismatch
exception handler and
-record references in the format.
+redirection to records.
To avoid record names in protocol files, use
protocol arguments.
+First you have to send a correctly formatted HTML request.
+Note that this request must contain the full URL like
+"http://server/page" and must be terminated with two newlines.
+The server should be the same as in the
+drvAsynIPPortConfigure
+command (if not using a http proxy).
+
+The web page you get often contains much more information than you need.
+Regular expressions are great
+to find what you are looking for.
+
+Read the title of a web page. +
+
+
+get_title {
+
+ extrainput = ignore;
+ replyTimeout = 1000;
+ out "GET http://\$1\n\n";
+ in "%+.1/(?im)<title>(.*)<\/title>/";
+}
+
+Terminate the request with two newlines, either explicit like here
+or using an
+outTerminator.
+The URI (without http:// but including the web server host name)
+is passed as argument 1 to \$1.
+Note that web servers may be slow, so allow some
+replyTimeout.
+
+If you don't use an inTerminator then the whole page is
+read as one "line" to the in command and can be parsed easily
+with a regular expression.
+We want to see the string between <title> and
+</title>, so we put it into a subexpression in
+() and request the first subexpression with .1.
+Note that the / in the closing tag has be be escaped
+to avoid a misinterpretation as the closing / of the regular
+expression.
+
+The tags may be upper or lower case like <TITLE> or
+<Title>, so we ask for case insensitive matching with
+(?i).
+
+The string should be terminated with the first closing
+</title>, not the last one in the file.
+(There should not be more than one title but you never know.)
+Thus we ask not to be greedy with (?m).
+(?i) and (?m) can be combined to (?im).
+See the PCRE documentation for more regexp syntax.
+
+The regular expression matcher ignores and discards any content before the
+matching section.
+Content after the match is discarded with extrainput = ignore
+so that it does not trigger errors reporting "surplus input".
+
+Finally, the title may be too long for the record.
+The + tells the format matcher not to fail in this case
+but to truncate the string instead.
+You can read the string with a stringin record or for longer strings with
+a waveform record with data type CHAR.
+
+
+record (stringin, "$(DEVICE):title") {
+
+ field (DTYP, "stream")
+ field (INP, "@$(DEVICETYPE).proto get_title($(PAGE)) $(BUS)")
+}
+record (waveform, "$(DEVICE):longtitle") {
+ field (DTYP, "stream")
+ field (INP, "@$(DEVICETYPE).proto get_title($(PAGE)) $(BUS)")
+ field (FTVL, "CHAR")
+ field (NELM, "100")
+}
+
+Read a number from a web page. First we have to locate the number.
+For that we match against any known string right before the number
+(and discard the match with *).
+Then we read the number.
+
+get_title {
+ extrainput = ignore;
+ replyTimeout = 1000;
+ out "GET http://\$1\n\n";
+ in "%*/Interesting value:/%f more text";
+}
+
+
+When using extrainput = ignore;, it is always a good idea to
+match a few bytes after the value, too.
+This catches errors where loading of the page is interrupted in the middle
+of the number. (You don't want to miss the exponent from something like 1.23E-14).
+
+You can read more than one value from a file with successive regular expressions +and redirections. +But this only works if the order of the values is predictible. +StreamDevice is not an XML parser! It always reads sequentially. +
Dirk Zimoch, 2007
+Dirk Zimoch, 2012