is there a way to send input and receive output from console programs using Node Webkit?
I tried searching the net but couldn't find what I was looking for.
Basically, if you can do it in node.js, you should be able to do it in node-webkit. For example, to receive output from the 'ls' command and print it to console.log, you could do this:
exec('ls', function (err, stdout, stderr) {
console.log(stdout)
});
Of course, you'd want to do some error handling as well in real life.
Related
I'm new to nginx and I'm trying to develope a simple nginx module,a handler module specifically. Although it's not what I really wanna do,I try to finish this task first. I'm trying to get the socketfd when a browser(or a client) connects to nginx.And I have get it successfully.However, when I tried to output something using dup2(),the nginx is always pending and just outputs nothing.Sometimes I can get output after a long time and once I stop nginx like nginx -s stop,and the output appears immediately.
Like this:
reach http://100.100.60.199/nc?search=123456
get
search=123456 HTTP/1.l
HOST
output
I have read some blogs about nginx module and I found that handler module has its own pattern (to my understanding?).For example, the output should be nginx_chain_t,and I should construct that chain instead of using dup2 like a regular c code.So I wonder if it's feasible to get output like the function below.
Here is my handler function:
static ngx_int_t ngx_http_nc_handler(ngx_http_request_t *r){
//ngx_int_t rc;
ngx_socket_t connfd = r->connection->fd;
int nZero=0;
//if(setsockopt(connfd,SOL_SOCKET,SO_SNDBUF,(const void*)&nZero,sizeof(nZero))==0)
if(setsockopt(connfd,IPPROTO_TCP,TCP_NODELAY,(const void*)&nZero,sizeof(int))==0){
setbuf(stdout,NULL);
setbuf(stdin,NULL);
setbuf(stderr,NULL);
dup2(connfd,STDOUT_FILENO);
dup2(connfd,STDERR_FILENO);
dup2(connfd,STDIN_FILENO);
printf("%s\n", r->args.data);
//close(connfd);
}
return NGX_OK;
}
So I wonder if it's feasible,how can I get things right using the method above or can anybody just say it's impossible and construct a chain is the only way?
I finally solved this problem by trying to understand how exactly nginx works.In short,all I need to do is to add a http header to the output.But it's not that easy like what I described.
Working with Evernote IOS SDK 3.0
I would like to retrieve a specific resource from note using
fetchResourceByHashWith
This is how I am using it. Just for this example, to be 100% sure about the hash being correct I first download the note with a single resource using fetchNote and then request this resource using its unique hash using fetchResourceByHashWith (hash looks correct when I print it)
ENSession.shared.primaryNoteStore()?.fetchNote(withGuid: guid, includingContent: true, resourceOptions: ENResourceFetchOption.includeData, completion: { note, error in
if error != nil {
print(error)
seal.reject(error!)
} else {
let hash = note?.resources[0].data.bodyHash
ENSession.shared.primaryNoteStore()?.fetchResourceByHashWith(guid: guid, contentHash: hash, options: ENResourceFetchOption.includeData, completion: { res, error in
if error != nil {
print(error)
seal.reject(error!)
} else {
print("works")
seal.fulfill(res!)
}})
}
})
Call to fetchResourceByHashWith fails with
Optional(Error Domain=ENErrorDomain Code=0 "Unknown error" UserInfo={EDAMErrorCode=0, NSLocalizedDescription=Unknown error})
The equivalent setup works on Android SDK.
Everything else works so far in IOS SDK (chunkSync, auth, getting notebooks etc.. so this is not an issue with auth tokens)
would be great to know if this is an sdk bug or I am still doing something wrong.
Thanks
This is a bug in the SDK's "EDAM" Thrift client stub code. First the analysis and then your workarounds.
Evernote's underlying API transport uses a Thrift protocol with a documented schema. The SDK framework includes a layer of autogenerated stub code that is supposed to marshal input and output params correctly for each request and response. You are invoking the underlying getResourceByHash API method on the note store, which is defined per the docs to accept a string type for the contentHash argument. But it turns out the client is sending the hash value as a purely binary field. The service is failing to parse the request, so you're seeing a generic error on the client. This could reflect evolution in the API definition, but more likely this has always been broken in the iOS SDK (getResourceByHash probably doesn't see a lot of usage). If you dig into the more recent Python version of the SDK, or indeed also the Java/Android version, you can see a different pattern for this method: it says it's going to write a string-type field, and then actually emits a binary one. Weirdly, this works. And if you hack up the iOS SDK to do the same thing, it will work, too.
Workarounds:
Best advice is to report the bug and just avoid this method on the note store. You can get resource data in different ways: First of all, you actually got all the data you needed in the response to your fetchNote call, i.e. let resourceData = note?.resources[0].data.body and you're good! You can also pull individual resources by their own guid (not their hash), using fetchResource (use note?.resources[0].guid as the param). Of course, you may really want to use the access-by-hash pattern. In that case...
You can hack in the correct protocol behavior. In the SDK files, which you'll need to build as part of your project, find the ObjC file called ENTProtocol.m. Find the method +sendMessage:toProtocol:withArguments.
It has one line like this:
[outProtocol writeFieldBeginWithName:field.name type:field.type fieldID:field.index];
Replace that line with:
[outProtocol writeFieldBeginWithName:field.name type:(field.type == TType_BINARY ? TType_STRING : field.type) fieldID:field.index];
Rebuild the project and you should find that your code snippet works as expected. This is a massive hack however and although I don't think any other note store methods will be impacted adversely by it, it's possible that other internal user store or other calls will suddenly start acting funny. Also you'd have to maintain the hack through updates. Probably better to report the bug and don't use the method until Evernote publishes a proper fix.
As you may know, ZeroRPC documentation is sparse. I can't get Streaming between a Python server and a Node client to work.
Here is the Python method:
#zerorpc.stream
def PublishWhaterver(self, some_args):
yield "love"
yield "stack"
yield "overflow"
Here is the Node call:
export const tryStream = () => {
connectedZerorpcClient.invoke('PublishWhatever', (error, res, more) => {
console.log('STREAM', res, more);
});
};
This code will log "STREAM love", and then do nothing.
So here are my questions:
In the Python server code, am I supposed to call PublishWhatever with relevant args so that it yield additionnal values ?
In the Node client, should I call some recursive function when there is more data ?
What I am trying to implement is a Pub/Sub system but right now implementation seems to only exists for a Python server and a Python client, there are no Node example.
The example on the main page and tests are not relevant either, it shows how to stream an array that already exists when the invoke method is called.Here the messages are generated during some heavy computations, I want the server to be able to tell the client "here, some data are ready" and never disconnect.
Well, ZeroRPC actively promotes, that it is using its own python implementation code as a self-documentation how things work. In other words, no one has spent such additional efforts needed so as to publish a user-focused, the less a learning-process focused documentation.
Anyway, try to obey the few "visible" statements from the ZeroRPC description.
#zerorpc.stream
def PublishWhaterver(self, some_args):
yield ( "love", "stack", "overflow", ) # one, tuple-wrapped result-container
How do you read any arbitrary keypress in R (interactive-mode), such as cursor-up or shift, and return the actual key(s) pressed?
Ideally in a device-independent, OS-independent way (I'm on Mac OS 10.8.x)
I'm talking about reading any actual arbitrary keypress including cursor-keys or modifier-keys, so scan() and readline() won't do it - cursor-keys get intercepted by the interactive console. And not just waiting for a keypress.
It's not clear this is easy or device-independent. I looked at documentation:
interactive(), options('device'), R_INTERACTIVE_DEVICE, R_DEFAULT_DEVICE
I read R-internals, which says "a graphics device... can handle requests/opportunities to take action such as... wait for an event, for example a mouse click or keypress." but it doesn't say much more.
I tried grDevices::getGraphicsEvent() but got:
> getGraphicsEvent('waiting for cursor keys', onKeybd=function(key) { print(key) } )
Error in setGraphicsEventEnv(which, as.environment(list(...))) :
this graphics device does not support event handling
It seems like if you dig deep enough you could use a toolkit-specific and/or OS-specific hack, e.g. with Quartz. This guy suggests Sudoku::playSudoku(), which uses Quartz to handle mouse and key input. I have Quartz. But a Quartz-specific solution won't work on Windows. This all seems quite messy.
Can someone please demystify all this?
I have a GSM modem and a PLC. The PLC sees a modem (I use a *.lib and functional block "openPort"), but I don't understand how send an "AT command" to the modem, for example, "ate0".
First, to increase your understanding of AT commands in general, read the V.250 specification. That will go a long way in making you an AT command expert.
Then for the actual implementation, I do not know Codesys, so the following is pseudo code of the structure you should have for handling AT commands:
the_modem = openPort();
...
// Start sending ATE0
writePort(the_modem, "ATE0\r");
do {
line = readLinePort(the_modem);
} while (! is_final_result_code(line))
// Sending of ATE0 command finished (successfully or not)
...
closePort(the_modem);
Whatever you do, never, never use delay, sleep or similar as a substitute for waiting for the final result code. You can look at the code for atinout for an example for the is_final_result_code function (you can also compare to isFinalResponseError and isFinalResponseSuccess in ST-Ericsson's U300 RIL, although note that CONNECT is not a final result code. It is an intermediate result code, so the name isFinalResponseSuccess is not 100% correct).