Develop Reference

How to have only one instance of the CHM file opened?

I want to set up only one instance of the CHM file when clicking on "Help" in the menubar and stopping it from opening twice when clicked again - therefore how do I code it?
I've tried to use it with process.isAlive(), but after I close it I want a counter set to zero, which only opens another CHM file when the counter is 0.
helpMenu.addMouseListener(new MouseAdapter() {
// do this after clicked
openCHM();
});
So MouseEvent is fired once.
openCHM() {
Process p;
if(cnt == 0) {
p = Runtime.getRuntime().exec("hh.exe Help.chm");
cnt++;
if(!p.isAlive()) {
cnt = 0;
}
}
I expected the counter to be 0, but then came to the conclusion that MouseEvent already fired once and the code got already executed, therefore it never goes to the second if-statement and sets my counter to 0.
EDIT
There is no correct answer how to open a CHM file once, but there is a workaround that makes it possible, we just need to look if the file is renamable or not.
protected void openCHM() {
try {
File file = new File("YOURNAME.chm");
boolean renamable = file.renameTo(file); // can't rename if file is already open, returns true if renaming is possible
if(renamable) {
Runtime.getRuntime().exec("hh.exe YOURNAME.chm");
} else if(!file.exists() ){
// message: file doesn't exist (in path)
} else {
// file is already open
}
} catch () {
}
}

I'm not a Java programmer but the short story - not possible (AFAIK).
You know, hh.exe is the HTMLHelp executable and associated with *.CHM files. It's just a shell that uses the HTML Help API and is really just hosting a browser window.
HH.EXE is not single instance, if you open a CHM or another file three times using HH.EXE, then three help windows will appear. Try it using PowerShell:
PS D:\_working> hh.exe C:\Windows\Help\htmlhelp.chm
Several client-side command line switches are available to help authors that are part of the HTML Help executable program (hh.exe) and therefore work when HTML Help Workshop is not set up.
KeyHH.exe was running years ago with special parameters.
If you call the HH API directly from your application, and not via a second helper program like HH.EXE or KEYHH.EXE, then you MUST close any open help windows before shutting down the application or you will probably crash Windows.
For some information related to the problem you maybe interested in Open CHM File Once.
Some quoted info from the link above:
When you do that you are just calling the help viewer again and again from the command line, you're not using the HTML Help API which is what you need to access the CHM once it is open. You need to check whether your flavors of Java and Smalltalk support calls to the HTML Help API. This API is documented in detail in the help file of Microsoft HTML Help Workshop, which is the compiler package you installed to be able to generate CHMs.

CommandExecuteIn Background throws a "Not an (encodable) value" error

I am currently trying to implement file exports in background so that the user can do some actions while the file is downloading.
I used the apache isis CommandExexuteIn:Background action attribute. However, I got an error
"Not an (encodable) value", this is an error thrown by the ScalarValueRenderer class.
This is how my method looks like:
#Action(semantics = SemanticsOf.SAFE,
command = CommandReification.ENABLED)
commandExecuteIn = CommandExecuteIn.BACKGROUND)
public Blob exportViewAsPdf() {
final Contact contact = this;
final String filename = this.businessName + " Contact Details";
final Map<String, Object> parameters = new HashMap<>();
parameters.put("contact", contact);
final String template = templateLoader.buildFromTemplate(Contact.class, "ContactViewTemplate", parameters);
return pdfExporter.exportAsPdf(filename, template);
}
I think the error has something to do with the command not actually invoking the action but returns the persisted background command.
This implementation actually worked on the method where there is no return type. Did I miss something? Or is there a way to implement background command and get the expected results?

interesting use case, but it's not one I anticipated when that part of the framework was implemented, so I'm not surprised it doesn't work. Obviously the error message you are getting here is pretty obscure, so I've raised a
JIRA ticket to see if we could at least improve that.
I'm interested to know in what user experience you think the framework should provide here?
In the Estatio application that we work on (that has driven out many of the features added to the framework over the last few years) we have a somewhat similar requirement to obtain PDFs from a reporting server (which takes 5 to 10 seconds) and then download them. This is for all the tenants in a shopping centre, so there could be 5 to 50 of these to generate in a single go. The design we went with was to move the rendering into a background command (similar to the templateLoader.buildFromTemplate(...) and pdfExporter.exportAsPdf(...) method calls in your code fragment, and to capture the output as a Document, via the document module. We then use the pdfbox addon to stitch all the document PDFs together as a single downloadable PDF for printing.
Hopefully that gives you some ideas of a different way to support your use case
Thx
Dan

start and stop stream consumption in php script from my java frontend

i am trying to make a project where the user inputs a couple of brands and receives feedback of their mentioned times in twitter.. so far i ve made/found/tweaked the basic frontend in java, the php scripts for consuming the twitter streaming api plus a database to save the incoming tweets,, the last two in a xaamp server locally. Its working perfectly but i must run the scripts manually through my browser.
what i need is
php scripts to run in the backround (as their creator insists )
start and stop scripts at will to change and renew requested keywords
and i need this to be done from my frontend.
i thought of this..
since in the first place i send user inputs to the scripts through my database (java arrayOfBrands => db table => php requests and gets a column as array ) i could do smth like a flag in mysql database changable by my frontend and critical in the execution of my script.
then i looked at this question
Starting / Stopping php script running in background from browser
but the guy here proposes to do it as a cronjob... the other guy who made the scripts says about a thousand times in the instructions "DONT DO IT AS A CRONJOB" but as a procedure in the backround... and they both seem good and pro(Adam Green 140dev and Aziz Saleh 1763 fame here ) and i dont know which way to go..
here is "my" code
<?php
/**
* get_tweets.php
* Collect tweets from the Twitter streaming API
* This must be run as a continuous background process
* Latest copy of this code: http://140dev.com/free-twitter-api-source-code-library/
* #author Adam Green <140dev#gmail.com>
* #license GNU Public License
* #version BETA 0.30
*/
ini_set('display_errors', true);
require_once('140dev_config.php');
require_once('brands.php');
require_once('../libraries/phirehose/Phirehose.php');
require_once('../libraries/phirehose/OauthPhirehose.php');
class Consumer extends OauthPhirehose
{
// A database connection is established at launch and kept open permanently
public $oDB;
public function db_connect() {
require_once('db_lib.php');
$this->oDB = new db;
}
// This function is called automatically by the Phirehose class
// when a new tweet is received with the JSON data in $status
public function enqueueStatus($status) {
$tweet_object = json_decode($status);
// Ignore tweets without a properly formed tweet id value
if (!(isset($tweet_object->id_str))) { return;}
$tweet_id = $tweet_object->id_str;
// If there's a ", ', :, or ; in object elements, serialize() gets corrupted
// You should also use base64_encode() before saving this
$raw_tweet = base64_encode(serialize($tweet_object));
$field_values = 'raw_tweet = "' . $raw_tweet . '", ' .
'tweet_id = ' . $tweet_id;
$this->oDB->insert('json_cache',$field_values);
}
}
// Open a persistent connection to the Twitter streaming API
$stream = new Consumer(OAUTH_TOKEN, OAUTH_SECRET, Phirehose::METHOD_FILTER);
// Establish a MySQL database connection
$stream->db_connect();
// The keywords for tweet collection are entered here as an array
// More keywords can be added as array elements
// For example: array('recipe','food','cook','restaurant','great meal')
$stream->setTrack($mybrands);
// Start collecting tweets
// Automatically call enqueueStatus($status) with each tweet's JSON data
$stream->consume();
this is the script i need to run/not run
plz help me in any way possible either code or advice or just a tip are valuable for me.
thanks in advance.

shared SQl Lite db between phonegap app and native java app

I have two android apps (one written in js(using phonegap) the other in java). Both need to access one SQLite DB. Yes it's possible.
In my js file I use Cordova-sqlite-storage to create and insert data into a db:
var db = window.sqlitePlugin.openDatabase({name: "CAC.db", location: 1});
db = sqlitePlugin.openDatabase({name: "CAC.db", location: 2, createFromLocation: 1});
db.transaction(function(tx) {
tx.executeSql('DROP TABLE IF EXISTS test_table');
tx.executeSql('CREATE TABLE IF NOT EXISTS test_table (id integer primary key, data text, data_num integer)');
// demonstrate PRAGMA:
db.executeSql("pragma table_info (test_table);", [], function(res) {
console.log("PRAGMA res: " + JSON.stringify(res));
});
tx.executeSql("INSERT INTO test_table (data, data_num) VALUES (?,?)", ["MY ID", 100], function(tx, res) {
db.transaction(function(tx) {
tx.executeSql("select data as dt from test_table;", [], function(tx, res) {
var id = res.rows.item(0).dt;
console.log("res.rows.item(0).cnt: " + id);
});
});
}, function(e) {
console.log("ERROR: " + e.message);
});
});
Then I use this answer to try to connect the java app to my preexisting db:
Context sharedContext = null;
try {
sharedContext = this.createPackageContext("com.my.app", Context.CONTEXT_INCLUDE_CODE);
if (sharedContext == null) {
return;
}
} catch (Exception e) {
String error = e.getMessage();
return;
}
DbAdapter sharedDBadapter = new PerformerDbAdapter(sharedContext);
sharedDBadapter.open();
However I am required to use this code in my js app:
DBadapter hostDBAdapter = new DbAdapter(getApplicationContext());
performerDBadapter.open();
to try to get its context. (But obviously I can't because this code^ is java). So I tried to get the context using this answer.(Context context=this.cordova.getActivity().getApplicationContext();) But am not sure where to add this, and I am not even sure if this code would work anyways.
My questions are:
Where do I add this code in my application?
Am I on the right path?
What is the best way to connect a js app and Java app to the same SQLite Dtatabase on Android? (Examples would be very helpful)
INFO:
Android 5.1,
Cordova 5.0
UPDATE:
I already have android:sharedUserId="my.app" in both apps.

1) it depends from your application, please read some book on android and will able to put the code where you need. You can use also GreenDAO for a more simple access to sqlite
3) you can sign 2 different app with the same certificate, in this way the two apps are recognised as "same user id" and can share private data
2) this is a way, but a good way (the best way) is to expose data between two app on android is to use content provider
I hope this help you

Both are using different database, in this situation I recommend to use the following plug-in:
https://github.com/brodysoft/Cordova-SQLitePlugin
But, SQLite is a single-user database. If you go the "copy the database" route, then you risk losing data. If the desktop user added data and the iOS user added data, someone's data will be lost when you copy the file.
You can implement your own "syncing" algorithm that identifies changes between the databases and keeps them in sync. This can be a pain, but is a common solution and is what I would recommend. I've done it this way for a desktop/iOS app.
You can choose to use a database server, but this will require network access to connect to it.

Temporary URLs that expire after download

I'd like to create a launcher for a Java game I'm developing that will require the user to log in before the game itself can be downloaded. My idea was to have the launcher send the credentials to my webserver, and the webserver would output the location of a temporary file given the credentials were correct. However, this would be a bit tricky/inefficient, given:
The server would need to copy the game file every time someone updates, and
The webserver wouldn't know when the file was finished downloading.
Perhaps the launcher could send a request to a separate script to delete a file of the given temporary name? The problem with that is that the launcher could easily be decompiled and modified to not send the request, defeating the purpose of creating a new file.
Any suggestions as to this idea and its issues?

I would use a database, like this:
urlgenerator.php
<?php
// generate code
$code = uniqid();
// save code to database
db_save($code);
// write link
echo 'Download';
download.php
<?php
// get code from url
$single_use_code = $_GET['code'];
// check if the code is in the db
if(db_get_code($single_use_code)) {
// remove code from database as it is single use only
db_remove($single_use_code);
// start download
start_download();
} else {
// the code is not valid
die('BAD code');
}

Try something like this:
// Define a random key
$key = 'kgjiowtjiohgjiut09ig90im09yig90mi903i490ti209tgwgt';
$secondsValid = 300;
if($_GET['action'] == 'download')
{
$time = $_GET['time'];
if(time() - $time > $secondsValid)
die('Code has expired, please try again');
if($_GET['validation'] != md5($time.$key))
die('Invalid validation code');
DownloadFile();
die;
}
elseif(CredentialsAreCorrect())
{
$time = time();
header('Location: '.$_SERVER['REQUEST_URI'].'?action=download&time='.$time.'&validation='.md5($time.$key));
die;
}
else
die('Invalid credentials');
This is an easy way to give a validated user a timebombed URL (valid for 5 minutes in this case) without any nasty copying/symlinking/whatever involved, no databases, just using basic facilities that cannot be hacked as long as the key is secure. Just make sure your key has enough entropy (40+ random keypresses should do it) so no rainbow table or brute force attack is feasible.

Simple workaround: on a unix system, you can remove a file while it's in use without affecting currently-open file handles on that file. so
user requests download
script makes a symlink in the documentroot somewhere that points at wherever the file is really stored (somewhere outside of the document root)
URL to the symlink is send out as a parameter to the user.
User clicks on the donwload link, e.g. http://example.com?get=path/of/symlink
The download script fopen()'s the symlink and starts dishing out the file's contents
script REMOVES the symlink after it's been fopen()'d
Now the symlink is gone and can't be reused anymore, but the download script will still be sending data to the user because it opened the symlink/file before it was removed.