Note however that SURF will be slower than the old SG to handle traces with
a lots of variations (there is no trace integration anymore).
+\section faq_flexml_bypassing How could I have some C functions do what the platform and deployment files do?
+
+So you want to bypass the XML files parser, uh? Maybe doin some parameter
+sweep experiments on your simulations or so? This is possible, but it's not
+really easy. Here is how it goes.
+
+For this, you have to first remember that the XML parsing in SimGrid is done
+using a tool called FleXML. Given a DTD, this gives a flex-based parser. If
+you want to bypass the parser, you need to provide some code mimicking what
+it does and replacing it in its interactions with the SURF code. So, let's
+have a look at these interactions.
+
+FleXML parser are close to classical SAX parsers. It means that a
+well-formed SimGrid platform XML file might result in the following
+"events":
+
+ - start "platform_description"
+ - start "cpu" with attributes name="host1" power="1.0"
+ - end "cpu"
+ - start "cpu" with attributes name="host2" power="2.0"
+ - end "cpu"
+ - start "network_link" with ...
+ - end "network_link"
+ - start "route" with ...
+ - end "route"
+ - start "route" with ...
+ - end "route"
+ - end "platform_description"
+
+The communication from the parser to the SURF code uses two means:
+Attributes get copied into some global variables, and a surf-provided
+function gets called by the parser for each event. For example, the event
+ - start "cpu" with attributes name="host1" power="1.0"
+
+let the parser do the equivalent of:
+\verbatim
+ strcpy("host1",A_cpu_name);
+ A_cpu_power = 1.0;
+ (*STag_cpu_fun)();
+\endverbatim
+
+In SURF, we attach callbacks to the different events by initializing the
+pointer functions to some the right surf functions. Example in
+workstation_KCCFLN05.c (surf_parse_open() ends up calling surf_parse()):
+\verbatim
+ // Building the routes
+ surf_parse_reset_parser();
+ STag_route_fun=parse_route_set_endpoints;
+ ETag_route_element_fun=parse_route_elem;
+ ETag_route_fun=parse_route_set_route;
+ surf_parse_open(file);
+ xbt_assert1((!surf_parse()),"Parse error in %s",file);
+ surf_parse_close();
+\endverbatim
+
+So, to bypass the FleXML parser, you need to write your own version of the
+surf_parse function, which should do the following:
+ - Call the corresponding STag_<tag>_fun function to simulate tag start
+ - Fill the A_<tag>_<attribute> variables with the wanted values
+ - Call the corresponding ETag_<tag>_fun function to simulate tag end
+ - (do the same for the next set of values, and loop)
+
+Then, tell SimGrid that you want to use your own "parser" instead of the stock one:
+\verbatim
+ surf_parse = surf_parse_bypass;
+ MSG_create_environment(NULL);
+\endverbatim
+
+An example of this trick is distributed in the file examples/msg/msg_test_surfxml_bypassed.c
+
\section faq_flexml_limit I get the message "surf_parse_lex: Assertion `next<limit' failed."
This is because your platform file is too big for the parser.
this FAQ section to fit your taste if possible.
-
\author Arnaud Legrand (arnaud.legran::imag.fr)
\author Martin Quinson (martin.quinson::loria.fr)
