Easy creation of nodejs server (9): non-blocking operations, nodejs Server

Easy creation of nodejs server (9): non-blocking operations, nodejs Server

We need to pass the response object (obtained from the server's callback function onRequest () to the request handler through the request route. Then, the handler can use the functions on the object to respond to the request.

Modify server. js first:

Copy codeThe Code is as follows:
Var http = require ("http ");
Var url = require ("url ");
Function start (route, handle ){
Function onRequest (request, response ){
Var pathname = url. parse (request. url). pathname;
Console. log ("Request for" + pathname + "received .");
Route (handle, pathname, response );
}
Http. createServer (onRequest). listen (8888 );
Console. log ("Server has started .");
}
Exports. start = start;

We pass the response object to the route () function as the third parameter, and we remove all the response function calls in the onRequest () handler, because we want this part of work to be completed by the route () function.

Next, modify router. js:

Copy codeThe Code is as follows:
Function route (handle, pathname, response ){
Console. log ("About to route a request for" + pathname );
If (typeof handle [pathname] === 'function '){
Handle [pathname] (response );
} Else {
Console. log ("No request handler found for" + pathname );
Response. writeHead (404, {"Content-Type": "text/plain "});
Response. write ("404 Not found ");
Response. end ();
}
}
Exports. route = route;

In the same mode, the response object is directly transmitted instead of obtaining the return value from the request processing program. If no corresponding request processor is processed, We will directly return the "404" error.

Next, modify requestHandler. js:

Copy codeThe Code is as follows:
Var exec = require ("child_process" cmd.exe c;
Function start (response ){
Console. log ("Request handler 'start' was called .");
Exec ("ls-lah", function (error, stdout, stderr ){
Response. writeHead (200, {"Content-Type": "text/plain "});
Response. write (stdout );
Response. end ();
});
}
 
Function upload (response ){
Console. log ("Request handler 'upload' was called .");
Response. writeHead (200, {"Content-Type": "text/plain "});
Response. write ("Hello Upload ");
Response. end ();
}
 
Exports. start = start;
Exports. upload = upload;

Our handler functions need to receive the response Parameter in order to make a direct response to the request. The start handler performs the request response operation in the anonymous callback function of exec (), while the upload handler still simply replies "Hello World", but this time only uses the response object.

If you want to prove that time-consuming operations in the/start handler do not block the immediate response to the/upload request, you can change requestHandlers. js to the following format:

Copy codeThe Code is as follows:
Var exec = require ("child_process" cmd.exe c;
Function start (response ){
Console. log ("Request handler 'start' was called .");
Exec ("find /",
{Timeout: 10000, maxBuffer: 20000*1024 },
Function (error, stdout, stderr ){
Response. writeHead (200, {"Content-Type": "text/plain "});
Response. write (stdout );
Response. end ();
}
);
}
 
Function upload (response ){
Console. log ("Request handler 'upload' was called .");
Response. writeHead (200, {"Content-Type": "text/plain "});
Response. write ("Hello Upload ");
Response. end ();
}
 
Exports. start = start;
Exports. upload = upload;

In this way, when http: // localhost: 8888/start is requested, it takes 10 seconds to load the data. When http: // localhost: 8888/upload will immediately respond, even if the/start response is still being processed.