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diff --git a/docs/manual/developer/layeredio.html b/docs/manual/developer/layeredio.html deleted file mode 100644 index a4d1f5cda4..0000000000 --- a/docs/manual/developer/layeredio.html +++ /dev/null @@ -1,85 +0,0 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" - "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> - -<html xmlns="http://www.w3.org/1999/xhtml"> - <head> - <meta name="generator" content="HTML Tidy, see www.w3.org" /> - - <title>Apache 2.0 Layered I/O</title> - </head> - <!-- Background white, links blue (unvisited), navy (visited), red (active) --> - - <body bgcolor="#FFFFFF" text="#000000" link="#0000FF" - vlink="#000080" alink="#FF0000"> - <h1 align="center">Apache Layered I/O</h1> - - <p>Layered I/O has been the holy grail of Apache module writers - for years. With Apache 2.0, module writers can finally take - advantage of layered I/O in their modules.</p> - - <p>In all previous versions of Apache, only one handler was - allowed to modify the data stream that was sent to the client. - With Apache 2.0, one module can modify the data and then - specify that other modules can modify the data if they would - like.</p> - - <h2>Taking advantage of layered I/O</h2> - - <p>In order to make a module use layered I/O, there are some - modifications needed. A new return value has been added for - modules, RERUN_HANDLERS. When a handler returns this value, the - core searches through the list of handlers looking for another - module that wants to try the request.</p> - - <p>When a module returns RERUN_HANDLERS, it must modify two - fields of the request_rec, the handler and content_type fields. - Most modules will set the handler field to NULL, and allow the - core to choose the which module gets run next. If these two - fields are not modified, then the server will loop forever - calling the same module's handler.</p> - - <p>Most modules should not write out to the network if they - want to take advantage of layered I/O. Two BUFF structures have - been added to the request_rec, one for input and one for - output. The module should read and write to these BUFFs. The - module will also have to setup the input field for the next - module in the list. A new function has been added, - ap_setup_input, which all modules should call before they do - any reading to get data to modify. This function checks to - determine if the previous module set the input field, if so, - that input is used, if not the file is opened and that data - source is used. The output field is used basically the same - way. The module must set this field before they call ap_r* in - order to take advantage of layered I/O. If this field is not - set, ap_r* will write directly to the client. Usually at the - end of a handler, the input (for the next module) will be the - read side of a pipe, and the output will be the write side of - the same pipe.</p> - - <h3>An Example of Layered I/O.</h3> - - <p>This example is the most basic layered I/O example possible. - It is basically CGIs generated by mod_cgi and sent to the - network via http_core.</p> - - <p>mod_cgi executes the cgi script, and then sets - request_rec->input to the output pipe of the CGI. It then - NULLs out request_rec->handler, and sets - request_rec->content_type to whatever the CGI writes out (in - this case, text/html). Finally, mod_cgi returns - RERUN_HANDLERS.</p> - - <p>ap_invoke_handlers() then loops back to the top of the - handler list and searches for a handler that can deal with this - content_type. In this case the correct module is the - default_handler from http_core.</p> - - <p>When default handler starts, it calls ap_setup_input, which - has found a valid request_rec->input, so that is used for - all inputs. The output field in the request_rec is NULL, so - when default_handler calls an output primitive it gets sent out - over the network.</p> - <i>Ryan Bloom, 25th March 2000</i> - </body> -</html> - |