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• best practice - loging events (general) and changes (database)

  - by b0x0rz

  need help with logging all activities on a site as well as database changes. requirements: * should be in database * should be easily searchable by initiator (user name / session id), event (activity type) and event parameters i can think of a database design but either it involves a lot of tables (one per event) so i can log each of the parameters of an event in a separate field OR it involves one table with generic fields (7 int numeric and 7 text types) and log everything in one table with event type field determining what parameter got written where (and hoping that i don't need more than 7 fields of a certain type, or 8 or 9 or whatever number i choose)... example of entries (the usual things): [username] login failed @datetime [username] login successful @datetime [username] changed password @datetime, estimated security of password [low/ok/high/perfect] @datetime [username] clicked result [result number] [result id] after searching for [search string] and got [number of results] @datetime [username] clicked result [result number] [result id] after searching for [search string] and got [number of results] @datetime [username] changed profile name from [old name] to [new name] @datetime [username] verified name with [credit card type] credit card @datetime datbase table [table name] purged of old entries @datetime etc... so anyone dealt with this before? any best practices / links you can share? i've seen it done with the generic solution mentioned above, but somehow that goes against what i learned from database design, but as you can see the sheer number of events that need to be trackable (each user will be able to see this info) is giving me headaches, BUT i do LOVE the one event per table solution more than the generic one. any thoughts? edit: also, is there maybe an authoritative list of such (likely) events somewhere? thnx stack overflow says: the question you're asking appears subjective and is likely to be closed. my answer: probably is subjective, but it is directly related to my issue i have with designing a database / writing my code, so i'd welcome any help. also i tried narrowing down the ideas to 2 so hopefully one of these will prevail, unless there already is an established solution for these kinds of things.

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• Encrypt a file base upon a pregenerated "key" C#

  - by Anubis

  Hello everyone. I'm trying to determine the best course of action to implement a simple "licensing" system with a partner of mine. The concept is: Generate an encrypted value based upon several internal hardware components. Have the customer send this value to us which we will implement into our key generator. Once we have that, we add any other restrictions on the license (user, expires, etc.). From there we generate a file which we send to the customer they can add to their installation and voila, happy people about. I have the first part all done. My next part is trying to figure out which encryption methodology I would need to use. I already know Symmetric Encryption is pretty much the only route I can take. Most of the information I have found involves .NET already creating a key from its own internal methods. That's a bit of background, my question is: "Which encryption method could I use which would allow me to encrypt the restrictions based upon the "id" I was given from the customer's computer?" I'm writing this in C# by the way. Any ideas would be greatly appreciated! Take Care!

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• Twitter api - no more than 150 requests per hour....

  - by RenegadeAndy

  Hi. I am writing a twitter app using jtwitter - and its running inside a server inside my work. Anyway - whenever i run it from work it returns the error below and I am only making a couple requests per hour: HTTP/1.1 400 Bad Request {"request":"/1/statuses/user_timeline.json?count=6&id=cicsdemo&","error":"Rate limit exceeded. Clients may not make more than 150 requests per hour."} ] 2010-06-03 18:44:49 zero.timer.TimerTask::run Thread-3 SEVERE [ CWPZA3100E: Exception during processing for timer task, "twitterTimer". Exception: java.lang.ClassCastException: winterwell.jtwitter.Twitter$Status incompatible with java.lang.String ] I run the same code from home - its fine. So obviously at some point twitter thinks our work is all coming from one direct IP - which is why its hitting a limit which it shouldnt. Do I have any choice or workaround - can i make the limit be counted from my direct machine IP - or to my account instead of IP? Can i use a proxy? Has any body else had this problem and solved it?! Before anyone asks the APP must live inside my work - it cannot run anywhere else! Cheers, Andy

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• From where to send mails in a MVC framework, so that there is no duplication of code?

  - by Sabya

  It's a MVC question. Here is the situation: I am writing an application where I have "groups". You can invite other persons to your groups by typing their email and clicking "invite". There are two ways this functionality can be called: a) web interface and b) API After the mail sending is over I want to report to the user which mails were sent successfully (i.e., if the SMTP send succeeded. Currently, I am not interested in reporting mail bounces). So, I am thinking how should I design so that there is no code duplication. That is, API and web-interface should share the bulk of the code. To do this, I can create the method "invite" inside the model "group". So, the API and and the Web-interface can just call: group-invite($emailList); This method can send the emails. But the, problem is, then I have to access the mail templates, create the views for the mails, and then send the mails. Which should actually be in the "View" part or at least in the "Controller" part. What is the most elegant design in this situation? Note: I am really thinking to write this in the Model. My only doubt is: previously I thought sending mails also as "presentation". Since it is may be considered as a different form of generating output.

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• Why doesn't my test run tearDownAfterTestClass when it fails

  - by Memor-X

  in a test i am writing the setUpBeforeTests creates a new customer in the database who is then used to perform the tests with so naturally when i finish the test i should get rid of this test customer in tearDownAfterTestClass so that i can create then anew when i rerun the test and not get any false positives how when the tests all run fine i have no problem but if a test fails and i go to rerun it my setUpBeforeTests fails because i check for mysql errors in it like this try { if(!mysqli_query($connection,$query)) { $this->assertTrue(false); } } catch (Exception $exc) { $msg = '[tearDownAfterTestClass] Exception Error' . PHP_EOL . PHP_EOL; $msg .= 'Could not run query - '.mysqli_error($connection). PHP_EOL;; $this->fail($msg); } the error i get is that there is a primary key violation which is expected cause i'm trying to create a new customer using the same data (primary key is on email which is also used to log in) however that means when the test failed it didn't run tearDownAfterTestClass now i could just move everything in tearDownAfterTestClass to the start of setUpBeforeTests however to me that seems like bad programming since it defeates the purpose of even have tearDownAfterTestClass so i am wondering, why isn't my tearDownAfterTestClass running when a test fails NOTE: the database is a fundamental part of the system i'm testing and the database and system are on a separate development environment not the live one, the backup files for the database are almost 2 GBs and takes almost 1/2 an hour to restore, the purpose of the tear down is to remove any data we have added because of the test so that we don't have to restore the database every time we run the tests

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• problem with fork()

  - by john

  I'm writing a shell which forks, with the parent reading the input and the child process parsing and executing it with execvp. pseudocode of main method: do{ pid = fork(); print pid; if (p<0) { error; exit; } if (p>0) { wait for child to finish; read input; } else { call function to parse input; exit; } }while condition return; what happens is that i never seem to enter the child process (pid printed is always positive, i never enter the else). however, if i don't call the parse function and just have else exit, i do correctly enter parent and child alternatingly. full code: int main(int argc, char *argv[]){ char input[500]; pid_t p; int firstrun = 1; do{ p = fork(); printf("PID: %d", p); if (p < 0) {printf("Error forking"); exit(-1);} if (p > 0){ wait(NULL); firstrun = 0; printf("\n> "); bzero(input, 500); fflush(stdout); read(0, input, 499); input[strlen(input)-1] = '\0'; } else exit(0); else { if (parse(input) != 0 && firstrun != 1) { printf("Error parsing"); exit(-1); } exit(0); } }while(strcmp(input, "exit") != 0); return 0; }

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• Trying to create XPath from this HTML snippet

  - by doneright

  I have played for a while writing XPath but am unable to come up with exactly what I want. I'm trying to write XPath for link(click1 and click2 in code snippet below) based on known text(myidentity in code snippet below). Can someone take a look into and suggest possible solution? HTML code snippet: <div class="abc"> <a onclick="mycontroller.goto('xx','yy'); return false;" href="#"> <img src="images/controls/inheritance.gif"/> </a> myidentity <span> <a onclick="mycontroller.goto('xx','yy'); return false;" href="#">click1</a> <a onclick="mycontroller.goto('xx','yy'); return false;" href="#">click2</a> </span> </div>

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• Extract domain from body of email

  - by iman453

  Hi, I was wondering if there is any way I could extract domain names from the body of email messages in python. I was thinking of using regular expressions, but I am not too great in writing them, and was wondering if someone could help me out. Here's a sample email body: <tr><td colspan="5"><font face="verdana" size="4" color="#999999"><b>Resource Links - </b></font><span class="snv"><a href="http://clk.about.com/?zi=4/RZ">Get Listed Here</a></span></td><td class="snv" valign="bottom" align="right"><a href="http://sprinks.about.com/faq/index.htm">What Is This?</a></td></tr><tr><td colspan="6" bgcolor="#999999"><img height="1" width="1"></td></tr><tr><td colspan="6"><map name="sgmap"><area href="http://x.about.com/sg/r/3412.htm?p=0&amp;ref=fooddrinksl_sg" shape="rect" coords="0, 0, 600, 20"><area href="http://x.about.com/sg/r/3412.htm?p=1&amp;ref=fooddrinksl_sg" shape="rect" coords="0, 55, 600, 75"><area href="http://x.about.com/sg/r/3412.htm?p=2&amp;ref=fooddrinksl_sg" shape="rect" coords="0, 110, 600, 130"></map><img border="0" src="http://z.about.com/sg/sg.gif?cuni=3412" usemap="#sgmap" width="600" height="160"></td></tr><tr><td colspan="6">&nbsp;</td></tr> <tr><td colspan="6"><a name="d"><font face="verdana" size="4" color="#cc0000"><b>Top Picks - </b></font></a><a href="http://slclk.about.com/?zi=1/BAO" class="srvb">Fun Gift Ideas</a><span class="snv"> from your <a href="http://chinesefood.about.com">Chinese Cuisine</a> Guide</span></td></tr><tr><td colspan="6" bgcolor="cc0000"><img height="1" width="1"></td></tr><tr><td colspan="6" class="snv"> So I would need "clk.about.com" etc. Thanks!

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• How do I ensure that a regex does not match an empty string?

  - by Dancrumb

  I'm using the Jison parser generator for Javascript and am having problems with my language specification. The program I'm writing will be a calculator that can handle feet, inches and sixteenths. In order to do this, I have the following specification: %% ([0-9]+\s*"'")?\s*([0-9]+\s*"\"")?\s*([0-9]+\s*"s")? {return 'FIS';} [0-9]+("."[0-9]+)?\b {return 'NUMBER';} \s+ {/* skip whitespace */} "*" {return '*';} "/" {return '/';} "-" {return '-';} "+" {return '+';} "(" {return '(';} ")" {return ')';} <<EOF>> {return 'EOF';} Most of these lines come from a basic calculator specification. I simply added the first line. The regex correctly matches feet, inch, sixteenths, such as 6'4" (six feet, 4 inches) or 4"5s (4 inches, 5 sixteenths) with any kind of whitespace between the numbers and indicators. The problem is that the regex also matches a null string. As a result, the lexical analysis always records a FIS at the start of the line and then the parsing fails. Here is my question: is there a way to modify this regex to guarantee that it will only match a non-zero length string?

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• C/C++: feedback in analyzing a code example

  - by KaiserJohaan

  Hello, I have a piece of code from an assignment I am uncertain about. I feel confident that I know the answer, but I just want to double-check with the community incase there's something I forgot. The title is basically secure coding and the question is just to explain the results. int main() { unsigned int i = 1; unsigned int c = 1; while (i > 0) { i = i*2; c++; } printf("%d\n", c); return 0; } My reasoning is this: At first glance you could imagine the code would run forever, considering it's initialized to a positive value and ever increasing. This of course is wrong because eventually the value will grow so large it will cause an integer overflow. This in turn is not entirely true either, because eventally it will force the variable 'i' to be signed by making the last bit to 1 and therefore regarded as a negative number, therefore terminating the loop. So it is not writing to unallocated memory and therefore cause integer overflow, but rather violating the data type and therefore causing the loop to terminate. I am quite sure this is the reason, but I just want to double check. Any opinions?

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• JavaME - LWUIT images eat up all the memory

  - by Marko

  Hi, I'm writing a MIDlet using LWUIT and images seem to eat up incredible amounts of memory. All the images I use are PNGs and are packed inside the JAR file. I load them using the standard Image.createImage(URL) method. The application has a number of forms and each has a couple of labels an buttons, however I am fairly certain that only the active form is kept in memory (I know it isn't very trustworthy, but Runtime.freeMemory() seems to confirm this). The application has worked well in 240x320 resolution, but moving it to 480x640 and using appropriately larger images for UI started causing out of memory errors to show up. What the application does, among other things, is download remote images. The application seems to work fine until it gets to this point. After downloading a couple of PNGs and returning to the main menu, the out of memory error is encountered. Naturally, I looked into the amount of memory the main menu uses and it was pretty shocking. It's just two labels with images and four buttons. Each button has three images used for style.setIcon, setPressedIcon and setRolloverIcon. Images range in size from 15 to 25KB but removing two of the three images used for every button (so 8 images in total), Runtime.freeMemory() showed a stunning 1MB decrease in memory usage. The way I see it, I either have a whole lot of memory leaks (which I don't think I do, but memory leaks aren't exactly known to be easily tracked down), I am doing something terribly wrong with image handling or there's really no problem involved and I just need to scale down. If anyone has any insight to offer, I would greatly appreciate it.

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• SQLite Databases and Grid Hosting

  - by jocull

  I'm considering moving my site from a GoDaddy shared hosting account to a Media Temple grid hosting account in anticipation of traffic. However, I first have some concerns with the grid hosting setup. My site stores a large personal set of data on a per-user basis (possibly 3-4MB per user). At this rate I was worried about blowing over a 1GB MySQL limit in no time. To deal with this I created distributed SQLite databases per user to store large data objects. It's worked wonderfully so far. SQLite is super fast and simple. I know that reading from and writing to files is different in a Grid Hosting environment. I need to know if this setup is going to cause serious problems. These databases are not (and will not be) highly trafficked. They are personal to the user and will only be touched maybe two locations at the same time (one updating the data hourly at the most, and one or more reading on demand). I'd like to keep this setup as getting additional space (beyond 4GB) on a MySQL database seems to be a real trouble point. Will Grid Hosting cause me serious problems? Thanks.

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• How do I use my own debugger visualiser to edit variables runtime?

  - by C Sharper

  I'm writing my own debugger visualiser. All works great to show up to visualiser with the data. Now I add the code for more clearness: public class MyVisualiserObjectSource : VisualizerObjectSource { public override void GetData(object target, Stream outgoingData) { string data= target as string; var writer = new StreamWriter(outgoingData); writer.Write(data); writer.Flush(); } } public class MyVirtualizer : DialogDebuggerVisualizer { protected override void Show(IDialogVisualizerService windowService, IVisualizerObjectProvider objectProvider) { var streamReader = new StreamReader(objectProvider.GetData()); string data = streamReader.ReadToEnd(); using (var form = new MyVirtualizerForm(data)) { windowService.ShowDialog(form); } } } The string here is passed to the visualizer and show my own form. It works. But now I want to pass back the modified data from the form to the variable. How do I do that? Edit: I found out that I need to override the TransferData method in VisualizerObjectSource. But in the MSDN is no detail information about how I implement this correctly. Can someone help me please?

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• Java equivalent of the VB Request.InputStream

  - by Android Addict

  I have a web service that I am re-writing from VB to a Java servlet. In the web service, I want to extract the body entity set on the client-side as such: StringEntity stringEntity = new StringEntity(xml, HTTP.UTF_8); stringEntity.setContentType("application/xml"); httppost.setEntity(stringEntity); In the VB web service, I get this data by using: Dim objReader As System.IO.StreamReader objReader = New System.IO.StreamReader(Request.InputStream) Dim strXML As String = objReader.ReadToEnd and this works great. But I am looking for the equivalent in Java. I have tried this: ServletInputStream dataStream = req.getInputStream(); byte[] data = new byte[dataStream.toString().length()]; dataStream.read(data); but all it gets me is an unintelligible string: data = [B@68514fec Please advise. Edit Per the answers, I have tried: ServletInputStream dataStream = req.getInputStream(); ByteArrayOutputStream buffer = new ByteArrayOutputStream(); int r; byte[] data = new byte[1024*1024]; while ((r = dataStream.read(data, 0, data.length)) != -1) { buffer.write(data, 0, r); } buffer.flush(); byte[] data2 = buffer.toByteArray(); System.out.println("DATA = "+Arrays.toString(data2)); whichs yields: DATA = [] and when I try: System.out.println("DATA = "+data2.toString()); I get: DATA = [B@15282c7f So what am I doing wrong? As stated earlier, the same call to my VB service gives me the xml that I pass in.

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• Building a ctypes-"based" C library with distutils

  - by Robie Basak

  Following this recommendation, I have written a native C extension library to optimise part of a Python module via ctypes. I chose ctypes over writing a CPython-native library because it was quicker and easier (just a few functions with all tight loops inside). I've now hit a snag. If I want my work to be easily installable using distutils using python setup.py install, then distutils needs to be able to build my shared library and install it (presumably into /usr/lib/myproject). However, this not a Python extension module, and so as far as I can tell, distutils cannot do this. I've found a few references to people other people with this problem: Someone on numpy-discussion with a hack back in 2006. Somebody asking on distutils-sig and not getting an answer. Somebody asking on the main python list and being pointed to the innards of an existing project. I am aware that I can do something native and not use distutils for the shared library, or indeed use my distribution's packaging system. My concern is that this will limit usability as not everyone will be able to install it easily. So my question is: what is the current best way of distributing a shared library with distutils that will be used by ctypes but otherwise is OS-native and not a Python extension module? Feel free to answer with one of the hacks linked to above if you can expand on it and justify why that is the best way. If there is nothing better, at least all the information will be in one place.

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• Generic callbacks

  - by bobobobo

  Extends So, I'm trying to learn template metaprogramming better and I figure this is a good exercise for it. I'm trying to write code that can callback a function with any number of arguments I like passed to it. // First function to call int add( int x, int y ) ; // Second function to call double square( double x ) ; // Third func to call void go() ; The callback creation code should look like: // Write a callback object that // will be executed after 42ms for "add" Callback<int, int, int> c1 ; c1.func = add ; c1.args.push_back( 2 ); // these are the 2 args c1.args.push_back( 5 ); // to pass to the "add" function // when it is called Callback<double, double> c2 ; c2.func = square ; c2.args.push_back( 52.2 ) ; What I'm thinking is, using template metaprogramming I want to be able to declare callbacks like, write a struct like this (please keep in mind this is VERY PSEUDOcode) <TEMPLATING ACTION <<ANY NUMBER OF TYPES GO HERE>> > struct Callback { double execTime ; // when to execute TYPE1 (*func)( TYPE2 a, TYPE3 b ) ; void* argList ; // a stored list of arguments // to plug in when it is time to call __func__ } ; So for when called with Callback<int, int, int> c1 ; You would automatically get constructed for you by < HARDCORE TEMPLATING ACTION > a struct like struct Callback { double execTime ; // when to execute int (*func)( int a, int b ) ; void* argList ; // this would still be void*, // but I somehow need to remember // the types of the args.. } ; Any pointers in the right direction to get started on writing this?

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• Counting entries in a list of dictionaries: for loop vs. list comprehension with map(itemgetter)

  - by Dennis Williamson

  In a Python program I'm writing I've compared using a for loop and increment variables versus list comprehension with map(itemgetter) and len() when counting entries in dictionaries which are in a list. It takes the same time using a each method. Am I doing something wrong or is there a better approach? Here is a greatly simplified and shortened data structure: list = [ {'key1': True, 'dontcare': False, 'ignoreme': False, 'key2': True, 'filenotfound': 'biscuits and gravy'}, {'key1': False, 'dontcare': False, 'ignoreme': False, 'key2': True, 'filenotfound': 'peaches and cream'}, {'key1': True, 'dontcare': False, 'ignoreme': False, 'key2': False, 'filenotfound': 'Abbott and Costello'}, {'key1': False, 'dontcare': False, 'ignoreme': True, 'key2': False, 'filenotfound': 'over and under'}, {'key1': True, 'dontcare': True, 'ignoreme': False, 'key2': True, 'filenotfound': 'Scotch and... well... neat, thanks'} ] Here is the for loop version: #!/usr/bin/env python # Python 2.6 # count the entries where key1 is True # keep a separate count for the subset that also have key2 True key1 = key2 = 0 for dictionary in list: if dictionary["key1"]: key1 += 1 if dictionary["key2"]: key2 += 1 print "Counts: key1: " + str(key1) + ", subset key2: " + str(key2) Output for the data above: Counts: key1: 3, subset key2: 2 Here is the other, perhaps more Pythonic, version: #!/usr/bin/env python # Python 2.6 # count the entries where key1 is True # keep a separate count for the subset that also have key2 True from operator import itemgetter KEY1 = 0 KEY2 = 1 getentries = itemgetter("key1", "key2") entries = map(getentries, list) key1 = len([x for x in entries if x[KEY1]]) key2 = len([x for x in entries if x[KEY1] and x[KEY2]]) print "Counts: key1: " + str(key1) + ", subset key2: " + str(key2) Output for the data above (same as before): Counts: key1: 3, subset key2: 2 I'm a tiny bit surprised these take the same amount of time. I wonder if there's something faster. I'm sure I'm overlooking something simple. One alternative I've considered is loading the data into a database and doing SQL queries, but the data doesn't need to persist and I'd have to profile the overhead of the data transfer, etc., and a database may not always be available. I have no control over the original form of the data. The code above is not going for style points.

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• Parsing data with Clojure, interval problem.

  - by Andrea Di Persio

  Hello! I'm writing a little parser in clojure for learning purpose. basically is a TSV file parser that need to be put in a database, but I added a complication. The complication itself is that in the same file there are more intervals. The file look like this: ###andreadipersio 2010-03-19 16:10:00### USER COMM PID PPID %CPU %MEM TIME root launchd 1 0 0.0 0.0 2:46.97 root DirectoryService 11 1 0.0 0.2 0:34.59 root notifyd 12 1 0.0 0.0 0:20.83 root diskarbitrationd 13 1 0.0 0.0 0:02.84` .... ###andreadipersio 2010-03-19 16:20:00### USER COMM PID PPID %CPU %MEM TIME root launchd 1 0 0.0 0.0 2:46.97 root DirectoryService 11 1 0.0 0.2 0:34.59 root notifyd 12 1 0.0 0.0 0:20.83 root diskarbitrationd 13 1 0.0 0.0 0:02.84 I ended up with this code: (defn is-header? "Return true if a line is header" [line] (> (count (re-find #"^\#{3}" line)) 0)) (defn extract-fields "Return regex matches" [line pattern] (rest (re-find pattern line))) (defn process-lines [lines] (map process-line lines)) (defn process-line [line] (if (is-header? line) (extract-fields line header-pattern)) (extract-fields line data-pattern)) My idea is that in 'process-line' interval need to be merged with data so I have something like this: ('andreadipersio', '2010-03-19', '16:10:00', 'root', 'launchd', 1, 0, 0.0, 0.0, '2:46.97') for every row till the next interval, but I can't figure how to make this happen. I tried with something like this: (def process-line [line] (if is-header? line) (def header-data (extract-fields line header-pattern))) (cons header-data (extract-fields line data-pattern))) But this doesn't work as excepted. Any hints? Thanks!

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• How to call a function from another class file

  - by Guy Parker

  I am very familiar with writing VB based applications but am new to Xcode (and Objective C). I have gone through numerous tutorials on the web and understand the basics and how to interact with Interface Builder etc. However, I am really struggling with some basic concepts of the C language and would be grateful for any help you can offer. Heres my problem… I have a simple iphone app which has a view controller (FirstViewController) and a subview (SecondViewController) with associated header and class files. In the FirstViewController.m have a function defined @implementation FirstViewController (void) writeToServer:(const uint8_t ) buf { [oStream write:buf maxLength:strlen((char)buf)]; } It doesn't really matter what the function is. I want to use this function in my SecondViewController, so in SecondViewController.m I import FirstViewController.h import "SecondViewController.h" import "FirstViewController.h" @implementation SecondViewController -(IBAction) SetButton: (id) sender { NSString *s = [@"Fill:" stringByAppendingString: FillLevelValue.text]; NSString *strToSend = [s stringByAppendingString: @":"]; const uint8_t *str = (uint8_t *) [strToSend cStringUsingEncoding:NSASCIIStringEncoding]; FillLevelValue.text = strToSend; [FirstViewController writeToServer:str]; } This last line is where my problem is. XCode tells me that FirstViewController may not respond to writeToServer. And when I try to run the application it crashes when this function is called. I guess I don't fully understand how to share functions and more importantly, the relationship between classes. In an ideal world I would create a global class to place my functions in and call them as required. Any advice gratefully received.

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• Tail recursion and memoization with C#

  - by Jay

  I'm writing a function that finds the full path of a directory based on a database table of entries. Each record contains a key, the directory's name, and the key of the parent directory (it's the Directory table in an MSI if you're familiar). I had an iterative solution, but it started looking a little nasty. I thought I could write an elegant tail recursive solution, but I'm not sure anymore. I'll show you my code and then explain the issues I'm facing. Dictionary<string, string> m_directoryKeyToFullPathDictionary = new Dictionary<string, string>(); ... private string ExpandDirectoryKey(Database database, string directoryKey) { // check for terminating condition string fullPath; if (m_directoryKeyToFullPathDictionary.TryGetValue(directoryKey, out fullPath)) { return fullPath; } // inductive step Record record = ExecuteQuery(database, "SELECT DefaultDir, Directory_Parent FROM Directory where Directory.Directory='{0}'", directoryKey); // null check string directoryName = record.GetString("DefaultDir"); string parentDirectoryKey = record.GetString("Directory_Parent"); return Path.Combine(ExpandDirectoryKey(database, parentDirectoryKey), directoryName); } This is how the code looked when I realized I had a problem (with some minor validation/massaging removed). I want to use memoization to short circuit whenever possible, but that requires me to make a function call to the dictionary to store the output of the recursive ExpandDirectoryKey call. I realize that I also have a Path.Combine call there, but I think that can be circumvented with a ... + Path.DirectorySeparatorChar + .... I thought about using a helper method that would memoize the directory and return the value so that I could call it like this at the end of the function above: return MemoizeHelper( m_directoryKeyToFullPathDictionary, Path.Combine(ExpandDirectoryKey(database, parentDirectoryKey)), directoryName); But I feel like that's cheating and not going to be optimized as tail recursion. Any ideas? Should I be using a completely different strategy? This doesn't need to be a super efficient algorithm at all, I'm just really curious. I'm using .NET 4.0, btw. Thanks!

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• Best practice - logging events (general) and changes (database)

  - by b0x0rz

  need help with logging all activities on a site as well as database changes. requirements: * should be in database * should be easily searchable by initiator (user name / session id), event (activity type) and event parameters i can think of a database design but either it involves a lot of tables (one per event) so i can log each of the parameters of an event in a separate field OR it involves one table with generic fields (7 int numeric and 7 text types) and log everything in one table with event type field determining what parameter got written where (and hoping that i don't need more than 7 fields of a certain type, or 8 or 9 or whatever number i choose)... example of entries (the usual things): [username] login failed @datetime [username] login successful @datetime [username] changed password @datetime, estimated security of password [low/ok/high/perfect] @datetime [username] clicked result [result number] [result id] after searching for [search string] and got [number of results] @datetime [username] clicked result [result number] [result id] after searching for [search string] and got [number of results] @datetime [username] changed profile name from [old name] to [new name] @datetime [username] verified name with [credit card type] credit card @datetime datbase table [table name] purged of old entries @datetime via automated process etc... so anyone dealt with this before? any best practices / links you can share? i've seen it done with the generic solution mentioned above, but somehow that goes against what i learned from database design, but as you can see the sheer number of events that need to be trackable (each user will be able to see this info) is giving me headaches, BUT i do LOVE the one event per table solution more than the generic one. any thoughts? edit: also, is there maybe an authoritative list of such (likely) events somewhere? thnx stack overflow says: the question you're asking appears subjective and is likely to be closed. my answer: probably is subjective, but it is directly related to my issue i have with designing a database / writing my code, so i'd welcome any help. also i tried narrowing down the ideas to 2 so hopefully one of these will prevail, unless there already is an established solution for these kinds of things.

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• PHP Socket Server vs node.js: Web Chat

  - by Eliasdx

  I want to program a HTTP WebChat using long-held HTTP requests (Comet), ajax and websockets (depending on the browser used). Userdatabase is in mysql. Chat is written in PHP except maybe the chat stream itself which could also be written in javascript (node.js): I don't want to start a php process per user as there is no good way to send the chat messages between these php childs. So I thought about writing an own socket server in either PHP or node.js which should be able to handle more then 1000 connections (chat users). As a purely web developer (php) I'm not much familiar with sockets as I usually let web server care about connections. The chat messages won't be saved on disk nor in mysql but in RAM as an array or object for best speed. As far as I know there is no way to handle multiple connections at the same time in a single php process (socket server), however you can accept a great amount of socket connections and process them successive in a loop (read and write; incoming message - write to all socket connections). The problem is that there will most-likely be a lag with ~1000 users and mysql operations could slow the whole thing down which will then affect all users. My question is: Can node.js handle a socket server with better performance? Node.js is event-based but I'm not sure if it can process multiple events at the same time (wouldn't that need multi-threading?) or if there is just an event queue. With an event queue it would be just like php: process user after user. I could also spawn a php process per chat room (much less users) but afaik there are singlethreaded IRC servers which are also capable to handle thousands of users. (written in c++ or whatever) so maybe it's also possible in php. I would prefer PHP over Node.js because then the project would be php-only and not a mixture of programming languages. However if Node can process connections simultaneously I'd probably choose it.

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• How to: Simulating keystroke inputs in shell to an app running in an embedded target

  - by fzkl

  I am writing an automation script that runs on an embedded linux target. A part of the script involves running an app on the target and obtaining some data from the stdout. Stdout here is the ssh terminal connection I have to the target. However, this data is available on the stdout only if certain keys are pressed and the key press has to be done on the keyboard connected to the embedded target and not on the host system from which I have ssh'd into the target. Is there any way to simulate this? Edit: Elaborating on what I need - I have an OpenGL app that I run on the embedded linux (works like regular linux) target. This displays some graphics on the embedded system's display device. Pressing f on the keyboard connected to the target outputs the fps data onto the ssh terminal from which I control the target. Since I am automating the process of running this OpenGL app and obtaining the fps scores, I can't expect a keyboard to be connected to the target let alone expect a user to input a keystroke on the embedded target keyboard. How do I go about this? Thanks.

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• Is there a way to programatically check dependencies of an EXE?

  - by Mason Wheeler

  I've got a certain project that I build and distribute to users. I have two build configurations, Debug and Release. Debug, obviously, is for my use in debugging, but there's an additional wrinkle: the Debug configuration uses a special debugging memory manager, with a dependency on an external DLL. There's been a few times when I've accidentally built and distributed an installer package with the Debug configuration, and it's then failed to run once installed because the users don't have the special DLL. I'd like to be able to keep that from happening in the future. I know I can get the dependencies in a program by running Dependency Walker, but I'm looking for a way to do it programatically. Specifically, I have a way to run scripts while creating the installer, and I want something I can put in the installer script to check the program and see if it has a dependency on this DLL, and if so, cause the installer-creation process to fail with an error. I know how to create a simple CLI program that would take two filenames as parameters, and could run a DependsOn function and create output based on the result of it, but I don't know what to put in the DependsOn function. Does anyone know how I'd go about writing it?

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• Testing ActionFilterAttributes with MSpec

  - by Tomas Lycken

  I'm currently trying to grasp MSpec, mainly to learn new ways of (T/B)DD to be able to make an educated decision on which technology to use. Previously, I've mostly (read: only) used the built-in MSTest framework with Moq, so BDD is quite new for me. I'm writing an ASP.NET MVC app, and I want to implement PRG. Last time I did this, I used action filters to export and import ModelState via TempData, so that I could return a RedirectResult and the validation errors would still be there when the user got the view. I tested that scenario by verifying two things: a) That the ExportModelStateAttribute I had written was applied (among tests for my controller) b) That the attribute worked (among tests for action filter attributes) However, in BDD I've understood I should be even more concerned with behavior, and even less with implementation. This means I should probably just verify that the model state is in tempdata when the action has finished executing - not necessarily that it's done via an attribute. To further complicate things, attributes are not run when calling the action directly in the test, so I can't just call the action and see if the job's been done. How should I spec/test this in MSpec?

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