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• I finished coding my program. What's next? what are the steps I should take that would enable me to

  - by Luay

  Hi, I finished developing a program and would like to sell it online. However, I am not really sure of what to do next. Here is my current plan (in-order): 1- Add a 'deployment' project (i'm using visual studio) to my project so I can create a setup file for my program. 2- Use visual studio 'testing' add ons to test the program. I have no idea how to do it, but will teach myself. 3- When all is done, install the program on my wife's, parents and in-laws computer to further test it under different environments. 3- Setup a small Ltd. company. ( I might start this earlier as it might take a few weeks to complete). 4- Build / finish building a website (actually I started on this step a few weeks ago but haven't devoted enough time for it to complete yet). 5- Find a software / service to protect my program from piracy. I know it is impossible to protect the program from piracy. I understand that fully. But I still want to implement some sort of solution that wouldn't harm or deter honest customers. 6- Set up a business paypal account. 7- Find a software / service to handle payments on my website 8- Find a software / service to handle issuing license codes 9- Set up all of the above and go 'live'. However, I have zero experience in this sort of thing and would like your guidance on some points. 1- Is it necessary to setup a company? Can I sell as an individual? Will selling as an individual deter persons or companies from buying my software? 2- What is a decent choice for as a software / service to protect my program from my piracy. I have done a quick search and found something called Quick License Manager by Interactive Studios. Is this the sort of thing I am looking for? Is it any good? At which stage do I use or implement their service (or any similar service you might point me too? I guess I am really asking: how does this work? Would they give me a file I just add to my project, rebuild it and that's it? 3- What should I implement to handle payments online and how complicated is it? could you point me to any such services, please? 4- What should I implement to handle issuing license codes and how will that software / service coordinate with the software / service that handles the anti-piracy stuff? could you point me to such services, please? 5- In a different Stack Overflow question (by another user) someone suggested a cms system called Software Droid (http://www.softwaredroid.com). Is this what I am after. Will it help? 6- If the steps i'm following are incorrect in order or logic could you please advise me on what I should actually do? I guess these are question for those of you who have 'been there and done that'. So any guidance will be vary much appreciated. Many thanks in advance for your help.

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• Can a conforming C implementation #define NULL to be something wacky

  - by janks

  I'm asking because of the discussion that's been provoked in this thread: http://stackoverflow.com/questions/2597142/when-was-the-null-macro-not-0/2597232 Trying to have a serious back-and-forth discussion using comments under other people's replies is not easy or fun. So I'd like to hear what our C experts think without being restricted to 500 characters at a time. The C standard has precious few words to say about NULL and null pointer constants. There's only two relevant sections that I can find. First: 3.2.2.3 Pointers An integral constant expression with the value 0, or such an expression cast to type void * , is called a null pointer constant. If a null pointer constant is assigned to or compared for equality to a pointer, the constant is converted to a pointer of that type. Such a pointer, called a null pointer, is guaranteed to compare unequal to a pointer to any object or function. and second: 4.1.5 Common definitions <stddef.h> The macros are NULL which expands to an implementation-defined null pointer constant; The question is, can NULL expand to an implementation-defined null pointer constant that is different from the ones enumerated in 3.2.2.3? In particular, could it be defined as: #define NULL __builtin_magic_null_pointer Or even: #define NULL ((void*)-1) My reading of 3.2.2.3 is that it specifies that an integral constant expression of 0, and an integral constant expression of 0 cast to type void* must be among the forms of null pointer constant that the implementation recognizes, but that it isn't meant to be an exhaustive list. I believe that the implementation is free to recognize other source constructs as null pointer constants, so long as no other rules are broken. So for example, it is provable that #define NULL (-1) is not a legal definition, because in if (NULL) do_stuff(); do_stuff() must not be called, whereas with if (-1) do_stuff(); do_stuff() must be called; since they are equivalent, this cannot be a legal definition of NULL. But the standard says that integer-to-pointer conversions (and vice-versa) are implementation-defined, therefore it could define the conversion of -1 to a pointer as a conversion that produces a null pointer. In which case if ((void*)-1) would evaluate to false, and all would be well. So what do other people think? I'd ask for everybody to especially keep in mind the "as-if" rule described in 2.1.2.3 Program execution. It's huge and somewhat roundabout, so I won't paste it here, but it essentially says that an implementation merely has to produce the same observable side-effects as are required of the abstract machine described by the standard. It says that any optimizations, transformations, or whatever else the compiler wants to do to your program are perfectly legal so long as the observable side-effects of the program aren't changed by them. So if you are looking to prove that a particular definition of NULL cannot be legal, you'll need to come up with a program that can prove it. Either one like mine that blatantly breaks other clauses in the standard, or one that can legally detect whatever magic the compiler has to do to make the strange NULL definition work. Steve Jessop found an example of way for a program to detect that NULL isn't defined to be one of the two forms of null pointer constants in 3.2.2.3, which is to stringize the constant: #define stringize_helper(x) #x #define stringize(x) stringize_helper(x) Using this macro, one could puts(stringize(NULL)); and "detect" that NULL does not expand to one of the forms in 3.2.2.3. Is that enough to render other definitions illegal? I just don't know. Thanks!

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• What's the right way to do mutable data structures (e.g., skip lists, splay trees) in F#?

  - by dan

  What's a good way to implement mutable data structures in F#? The reason I’m asking is because I want to go back and implement the data structures I learned about in the algorithms class I took this semester (skip lists, splay trees, fusion trees, y-fast tries, van Emde Boas trees, etc.), which was a pure theory course with no coding whatsoever, and I figure I might as well try to learn F# while I’m doing it. I know that I “should” use finger trees to get splay tree functionality in a functional language, and that I should do something with laziness to get skip-list functionality, etc. , but I want to get the basics nailed down before I try playing with purely functional implementations. There are lots of examples of how to do functional data structures in F#, but there isn’t much on how to do mutable data structures, so I started by fixing up the doubly linked list here into something that allows inserts and deletes anywhere. My plan is to turn this into a skip list, and then use a similar structure (discriminated union of a record) for the tree structures I want to implement. Before I start on something more substantial, is there a better way to do mutable structures like this in F#? Should I just use records and not bother with the discriminated union? Should I use a class instead? Is this question "not even wrong"? Should I be doing the mutable structures in C#, and not dip into F# until I want to compare them to their purely functional counterparts? And, if a DU of records is what I want, could I have written the code below better or more idiomatically? It seems like there's a lot of redundancy here, but I'm not sure how to get rid of it. module DoublyLinkedList = type 'a ll = | None | Node of 'a ll_node and 'a ll_node = { mutable Prev: 'a ll; Element : 'a ; mutable Next: 'a ll; } let insert x l = match l with | None -> Node({ Prev=None; Element=x; Next=None }) | Node(node) -> match node.Prev with | None -> let new_node = { Prev=None; Element=x; Next=Node(node)} node.Prev <- Node(new_node) Node(new_node) | Node(prev_node) -> let new_node = { Prev=node.Prev; Element=x; Next=Node(node)} node.Prev <- Node(new_node) prev_node.Next <- Node(new_node) Node(prev_node) let rec nth n l = match n, l with | _,None -> None | _,Node(node) when n > 0 -> nth (n-1) node.Next | _,Node(node) when n < 0 -> nth (n+1) node.Prev | _,Node(node) -> Node(node) //hopefully only when n = 0 :-) let rec printLinkedList head = match head with | None -> () | Node(x) -> let prev = match x.Prev with | None -> "-" | Node(y) -> y.Element.ToString() let cur = x.Element.ToString() let next = match x.Next with | None -> "-" | Node(y) -> y.Element.ToString() printfn "%s, <- %s -> %s" prev cur next printLinkedList x.Next

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• Did I find a bug in PHP's `crypt()`?

  - by Nathan Long

  I think I may have found a bug in PHP's crypt() function under Windows. However: I recognize that it's probably my fault. PHP is used by millions and worked on by thousands; my code is used by tens and worked on by me. (This argument is best explained on Coding Horror.) So I'm asking for help: show me my fault. I've been trying to find it for a few days now, with no luck. The setup I'm using a Windows server installation with Apache 2.2.14 (Win32) and PHP 5.3.2. My development box runs Windows XP Professional; the 'production' server (this is an intranet setup) runs Windows Storage Server 2003. The problem happens on both. I don't see anything in php.ini related to crypt(), but will happily answer questions about my config. The problem Several scripts in my PHP app occasionally hang: the page sits there on 'waiting for localhost' and never finishes. Each of these scripts uses crypt to hash a user's password before storing it in the database, or, in the case of the login page, to hash the entered password before comparing it to the version stored in the database. Since the login page is the simplest, I focused on it for testing. I repeatedly logged in, and found that it would hang maybe 4 out of 10 times. As an experiment, I changed the login page to use the plain text password and changed my password in the database to its plain text version. The page stopped hanging. I saw that PHP's latest version lists this bugfix: Fixed bug #51059 (crypt crashes when invalid salt are [sic] given). So I created a very simple test script, as follows, using the same salt given in an official example: $foo = crypt('rasmuslerdorf','r1'); echo $foo; This page, too, will hang, if I reload it like crazy. I only see it hanging in Chrome, but regardless of browser, the effect on Apache is the same. Effect on Apache When these pages hang, Apache's server-status page (which I explained here, regarding a different problem) increments the number of requests being processed and decrements the number of idle workers. The requests being processed almost all have a status of 'Sending Reply,' though sometimes for a moment they will show either 'Reading request' or 'keepalive (read).' Eventually, Apache may crash. When it does, the Windows crash report looks like this: szAppName: httpd.exe szAppVer: 2.2.14.0 szModName: php5ts.dll szModVer: 5.3.1.0 // OK, this report was before I upgraded to PHP 5.3.2, // but that didn't fix it offset: 00a2615 Is it my fault? I'm tempted to file a bug report to PHP on this. The argument against it is, as stated above, that bugs are nearly always my fault. However, my argument in favor of 'it's PHP's fault' is: I'm using Windows, whereas most servers use Linux (I don't get to choose this), so the chances are greater that I've found an edge case There was recently a bug with crypt(), so maybe it still has issues I have made the simplest test case I can, and I still have the problem Can anyone duplicate this? Can you suggest where I've gone wrong? Should I file the bug after all? Thanks in advance for any help you may give.

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• Design Question - how do you break the dependency between classes using an interface?

  - by Seth Spearman

  Hello, I apologize in advance but this will be a long question. I'm stuck. I am trying to learn unit testing, C#, and design patterns - all at once. (Maybe that's my problem.) As such I am reading the Art of Unit Testing (Osherove), and Clean Code (Martin), and Head First Design Patterns (O'Reilly). I am just now beginning to understand delegates and events (which you would see if you were to troll my SO questions of recent). I still don't quite get lambdas. To contextualize all of this I have given myself a learning project I am calling goAlarms. I have an Alarm class with members you'd expect (NextAlarmTime, Name, AlarmGroup, Event Trigger etc.) I wanted the "Timer" of the alarm to be extensible so I created an IAlarmScheduler interface as follows... public interface AlarmScheduler { Dictionary<string,Alarm> AlarmList { get; } void Startup(); void Shutdown(); void AddTrigger(string triggerName, string groupName, Alarm alarm); void RemoveTrigger(string triggerName); void PauseTrigger(string triggerName); void ResumeTrigger(string triggerName); void PauseTriggerGroup(string groupName); void ResumeTriggerGroup(string groupName); void SetSnoozeTrigger(string triggerName, int duration); void SetNextOccurrence (string triggerName, DateTime nextOccurrence); } This IAlarmScheduler interface define a component that will RAISE an alarm (Trigger) which will bubble up to my Alarm class and raise the Trigger Event of the alarm itself. It is essentially the "Timer" component. I have found that the Quartz.net component is perfectly suited for this so I have created a QuartzAlarmScheduler class which implements IAlarmScheduler. All that is fine. My problem is that the Alarm class is abstract and I want to create a lot of different KINDS of alarm. For example, I already have a Heartbeat alarm (triggered every (int) interval of minutes), AppointmentAlarm (triggered on set date and time), Daily Alarm (triggered every day at X) and perhaps others. And Quartz.NET is perfectly suited to handle this. My problem is a design problem. I want to be able to instantiate an alarm of any kind without my Alarm class (or any derived classes) knowing anything about Quartz. The problem is that Quartz has awesome factories that return just the right setup for the Triggers that will be needed by my Alarm classes. So, for example, I can get a Quartz trigger by using TriggerUtils.MakeMinutelyTrigger to create a trigger for the heartbeat alarm described above. Or TriggerUtils.MakeDailyTrigger for the daily alarm. I guess I could sum it up this way. Indirectly or directly I want my alarm classes to be able to consume the TriggerUtils.Make* classes without knowing anything about them. I know that is a contradiction, but that is why I am asking the question. I thought about putting a delegate field into the alarm which would be assigned one of these Make method but by doing that I am creating a hard dependency between alarm and Quartz which I want to avoid for both unit testing purposes and design purposes. I thought of using a switch for the type in QuartzAlarmScheduler per here but I know it is bad design and I am trying to learn good design. If I may editorialize a bit. I've decided that coding (predefined) classes is easy. Design is HARD...in fact, really hard and I am really fighting feeling stupid right now. I guess I want to know if you really smart people took a while to really understand and master this stuff or should I feel stupid (as I do) because I haven't grasped it better in the couple of weeks/months I have been studying. You guys are awesome and thanks in advance for your answers. Seth

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• Hardware/Software inventory open source projects

  - by Dick dastardly

  Dear Stackoverflowers I would like to develop a Network Inventory application that works on any operating system. Reports on every possible resource attacehd to a network. Reports all pertinent details of hardware and software. Thats (and i hate to use the phrase) my "End Game". However I am running before i can crawl here. I have no experience of this type of development, e.g. discovering a computers hardware and software settings. I've spent almost two weeks googling and come up short! :-(. So I am turning to you to ask these questions:- My first step is to find an existing open source project i can incorporate into my own code that extracts the fine grained details i am after, e.g. EVERYTHING there is to know about the hardaware and software on a single machine. Does this project exist? or do i have to develop that first? Have i got to write all this in C? I am guessing getting this information about a computer is going to be easier than for printers, scanners, routers etc... e.g. everything else you would find attached to a network. Once i have access to a single computers details i then need to investigate how i can traverse an entire newtork of printers, scanners, routers, load balancers, switches, firewalls, workstations, servers, storeage devices, laptops, monitors, the list goes on and on One problem i have is i dont have a 1000 machine newtork to play on! Is there any such resource available on theinternet? (is that a silly question?) Anywho, if you dont ask you wont find out! One aspect iam really looking forward to finding out how to travers the entire network, should i be using TCP/IP for this? Whats a good site, blog, usergorup, book for TCP/IP development? How do i go about getting through firewalls? How many questions can i ask in one go? :-) My previous question on this topic ended up with PYTHON being championed as the language/script to go with to develop this application in. Having looked at a few PYTHON examples they all seemed to be related to WINDOWS networks and interrogating Windows Management Instrumentation (WMI). I had the feeling you cant rely on whats in WMI, and even if you can that s no good for UNIX netwrks. Surely there exist common code for extracting hardware and software details from a computer? Why cant i find it on the internet? Pease help? Theres no prizes though :-( Thanks in advance I would like to appologise if i have broken forum rules or not tried hard enough on my own before asking for assistance. I just would like to start moving forward with this as its one of the best projects i have been involved with. I am inspired by the many differnt number of challenges involved and that if i manage to produce a useful application at the end of it it would hopefully be extremely helpful to many people. That sit Thanks in advance DD

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• how to use ggplot conditional on data

  - by Andreas

  I asked this question and it seams ggplot2 currently has a bug with empty data.frames. Therefore I am trying to check if the dataframe is empty, before I make the plot. But what ever I come up with, it gets really ugly, and doesn't work. So I am asking for your help. example data: SOdata <- structure(list(id = 10:55, one = c(7L, 8L, 7L, NA, 7L, 8L, 5L, 7L, 7L, 8L, NA, 10L, 8L, NA, NA, NA, NA, 6L, 5L, 6L, 8L, 4L, 7L, 6L, 9L, 7L, 5L, 6L, 7L, 6L, 5L, 8L, 8L, 7L, 7L, 6L, 6L, 8L, 6L, 8L, 8L, 7L, 7L, 5L, 5L, 8L), two = c(7L, NA, 8L, NA, 10L, 10L, 8L, 9L, 4L, 10L, NA, 10L, 9L, NA, NA, NA, NA, 7L, 8L, 9L, 10L, 9L, 8L, 8L, 8L, 8L, 8L, 9L, 10L, 8L, 8L, 8L, 10L, 9L, 10L, 8L, 9L, 10L, 8L, 8L, 7L, 10L, 8L, 9L, 7L, 9L), three = c(7L, 10L, 7L, NA, 10L, 10L, NA, 10L, NA, NA, NA, NA, 10L, NA, NA, 4L, NA, 7L, 7L, 4L, 10L, 10L, 7L, 4L, 7L, NA, 10L, 4L, 7L, 7L, 7L, 10L, 10L, 7L, 10L, 4L, 10L, 10L, 10L, 4L, 10L, 10L, 10L, 10L, 7L, 10L), four = c(7L, 10L, 4L, NA, 10L, 7L, NA, 7L, NA, NA, NA, NA, 10L, NA, NA, 4L, NA, 10L, 10L, 7L, 10L, 10L, 7L, 7L, 7L, NA, 10L, 7L, 4L, 10L, 4L, 7L, 10L, 2L, 10L, 4L, 12L, 4L, 7L, 10L, 10L, 12L, 12L, 4L, 7L, 10L), five = c(7L, NA, 6L, NA, 8L, 8L, 7L, NA, 9L, NA, NA, NA, 9L, NA, NA, NA, NA, 7L, 8L, NA, NA, 7L, 7L, 4L, NA, NA, NA, NA, 5L, 6L, 5L, 7L, 7L, 6L, 9L, NA, 10L, 7L, 8L, 5L, 7L, 10L, 7L, 4L, 5L, 10L), six = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L), .Label = c("2010-05-25", "2010-05-27", "2010-06-07"), class = "factor"), seven = c(0.777777777777778, 0.833333333333333, 0.333333333333333, 0.888888888888889, 0.5, 0.888888888888889, 0.777777777777778, 0.722222222222222, 0.277777777777778, 0.611111111111111, 0.722222222222222, 1, 0.888888888888889, 0.722222222222222, 0.555555555555556, NA, 0, 0.666666666666667, 0.666666666666667, 0.833333333333333, 0.833333333333333, 0.833333333333333, 0.833333333333333, 0.722222222222222, 0.833333333333333, 0.888888888888889, 0.666666666666667, 1, 0.777777777777778, 0.722222222222222, 0.5, 0.833333333333333, 0.722222222222222, 0.388888888888889, 0.722222222222222, 1, 0.611111111111111, 0.777777777777778, 0.722222222222222, 0.944444444444444, 0.555555555555556, 0.666666666666667, 0.722222222222222, 0.444444444444444, 0.333333333333333, 0.777777777777778), eight = c(0.666666666666667, 0.333333333333333, 0.833333333333333, 0.666666666666667, 1, 1, 0.833333333333333, 0.166666666666667, 0.833333333333333, 0.833333333333333, 1, 1, 0.666666666666667, 0.666666666666667, 0.333333333333333, 0.5, 0, 0.666666666666667, 0.5, 1, 0.666666666666667, 0.5, 0.666666666666667, 0.666666666666667, 0.666666666666667, 0.333333333333333, 0.333333333333333, 1, 0.666666666666667, 0.833333333333333, 0.666666666666667, 0.666666666666667, 0.5, 0, 0.833333333333333, 1, 0.666666666666667, 0.5, 0.666666666666667, 0.666666666666667, 0.5, 1, 0.833333333333333, 0.666666666666667, 0.833333333333333, 0.666666666666667), nine = c(0.307692307692308, NA, 0.461538461538462, 0.538461538461538, 1, 0.769230769230769, 0.538461538461538, 0.692307692307692, 0, 0.153846153846154, 0.769230769230769, NA, 0.461538461538462, NA, NA, NA, NA, 0, 0.615384615384615, 0.615384615384615, 0.769230769230769, 0.384615384615385, 0.846153846153846, 0.923076923076923, 0.615384615384615, 0.692307692307692, 0.0769230769230769, 0.846153846153846, 0.384615384615385, 0.384615384615385, 0.461538461538462, 0.384615384615385, 0.461538461538462, NA, 0.923076923076923, 0.692307692307692, 0.615384615384615, 0.615384615384615, 0.769230769230769, 0.0769230769230769, 0.230769230769231, 0.692307692307692, 0.769230769230769, 0.230769230769231, 0.769230769230769, 0.615384615384615), ten = c(0.875, 0.625, 0.375, 0.75, 0.75, 0.75, 0.625, 0.875, 1, 0.125, 1, NA, 0.625, 0.75, 0.75, 0.375, NA, 0.625, 0.5, 0.75, 0.875, 0.625, 0.875, 0.75, 0.625, 0.875, 0.5, 0.75, 0, 0.5, 0.875, 1, 0.75, 0.125, 0.5, 0.5, 0.5, 0.625, 0.375, 0.625, 0.625, 0.75, 0.875, 0.375, 0, 0.875), elleven = c(1, 0.8, 0.7, 0.9, 0, 1, 0.9, 0.5, 0, 0.8, 0.8, NA, 0.8, NA, NA, 0.8, NA, 0.4, 0.8, 0.5, 1, 0.4, 0.5, 0.9, 0.8, 1, 0.8, 0.5, 0.3, 0.9, 0.2, 1, 0.8, 0.1, 1, 0.8, 0.5, 0.2, 0.7, 0.8, 1, 0.9, 0.6, 0.8, 0.2, 1), twelve = c(0.666666666666667, NA, 0.133333333333333, 1, 1, 0.8, 0.4, 0.733333333333333, NA, 0.933333333333333, NA, NA, 0.6, 0.533333333333333, NA, 0.533333333333333, NA, 0, 0.6, 0.533333333333333, 0.733333333333333, 0.6, 0.733333333333333, 0.666666666666667, 0.533333333333333, 0.733333333333333, 0.466666666666667, 0.733333333333333, 1, 0.733333333333333, 0.666666666666667, 0.533333333333333, NA, 0.533333333333333, 0.6, 0.866666666666667, 0.466666666666667, 0.533333333333333, 0.333333333333333, 0.6, 0.6, 0.866666666666667, 0.666666666666667, 0.6, 0.6, 0.533333333333333)), .Names = c("id", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "elleven", "twelve"), class = "data.frame", row.names = c(NA, -46L)) And the plot iqr <- function(x, ...) { qs <- quantile(as.numeric(x), c(0.25, 0.5, 0.75), na.rm = T) names(qs) <- c("ymin", "y", "ymax") qs } magic <- function(y, ...) { high <- median(SOdata[[y]], na.rm=T)+1.5*sd(SOdata[[y]],na.rm=T) low <- median(SOdata[[y]], na.rm=T)-1.5*sd(SOdata[[y]],na.rm=T) ggplot(SOdata, aes_string(x="six", y=y))+ stat_summary(fun.data="iqr", geom="crossbar", fill="grey", alpha=0.3)+ geom_point(data = SOdata[SOdata[[y]] > high,], position=position_jitter(w=0.1, h=0),col="green", alpha=0.5)+ geom_point(data = SOdata[SOdata[[y]] < low,], position=position_jitter(w=0.1, h=0),col="red", alpha=0.5)+ stat_summary(fun.y=median, geom="point",shape=18 ,size=4, col="orange") } for (i in names(SOdata)[-c(1,7)]) { p<- magic(i) ggsave(paste("magig_plot_",i,".png",sep=""), plot=p, height=3.5, width=5.5) } The problem is that sometimes in the call to geom_point the subset returns an empty dataframe, which sometimes (!) causes ggplot2 to plot all the data instead of none of the data. geom_point(data = SOdata[SOdata[[y]] > high,], position=position_jitter(w=0.1, h=0),col="green", alpha=0.5)+ This is kindda of important to me, and I am really stuck trying to find a solution. Any help that will get me started is much appreciated. Thanks in advance.

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• add an image in listview

  - by danish

  Hi I would like to add more images in my list view as this code below only displays image 1 and 2 continuously in each row. What I want to do is display a different image for each different row. Here is mycode below; Thanks for any help. I am not good at java please change the code where necessary and I can then refer to it. public class starters extends ListActivity { private static class EfficientAdapter extends BaseAdapter { private LayoutInflater mInflater; private Bitmap mIcon1; private Bitmap mIcon2; private Bitmap mIcon3; private Bitmap mIcon4; private Bitmap mIcon5; private Bitmap mIcon6; private Bitmap mIcon7; private Bitmap mIcon8; private Bitmap mIcon9; private Bitmap mIcon10; public EfficientAdapter(Context context) { // Cache the LayoutInflate to avoid asking for a new one each time. mInflater = LayoutInflater.from(context); // Icons bound to the rows. mIcon1 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters1); mIcon2 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters2); mIcon3 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters3); mIcon4 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters4); mIcon5 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters5); mIcon6 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters6); mIcon7 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters7); mIcon8 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters8); mIcon9 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters9); mIcon10 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters10); } public int getCount() { return DATA.length; } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { // A ViewHolder keeps references to children views to avoid unneccessary calls // to findViewById() on each row. ViewHolder holder; // When convertView is not null, we can reuse it directly, there is no need // to reinflate it. We only inflate a new View when the convertView supplied // by ListView is null. if (convertView == null) { convertView = mInflater.inflate(R.layout.starters, null); // Creates a ViewHolder and store references to the two children views // we want to bind data to. holder = new ViewHolder(); holder.text = (TextView) convertView.findViewById(R.id.text01); holder.text = (TextView) convertView.findViewById(R.id.secondLine); holder.icon = (ImageView) convertView.findViewById(R.id.icon01); convertView.setTag(holder); } else { // Get the ViewHolder back to get fast access to the TextView // and the ImageView. holder = (ViewHolder) convertView.getTag(); } // Bind the data efficiently with the holder. holder.text.setText(DATA[position]); holder.icon.setImageBitmap((position & 1) ==1 ? mIcon1 : mIcon2); return convertView; } static class ViewHolder { TextView text; ImageView icon; } } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setListAdapter(new EfficientAdapter(this)); } private static final String[] DATA = { "Original nachos", "Toasted chicken and cheese quesadillas", "Chicken, lime and coriander nachos", "Spicy bean and cheese quesadillas", "Tuna and corn quesadillas", "Cheesy bean and sweetcorn nachos", "Crispy chicken, avocado and lime salad", "Beef and baby corn tostada", "Spicy mexican rice with chicken and prawns", "Chilli potato boats"}; }

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• Help with specific Regex: need to match multiple instances of multiple formats in a single string.

  - by KevenK

  I apologize for the terrible title...it can be hard to try to summarize an entire situation into a single sentence. Let me start by saying that I'm asking because I'm just not a Regex expert. I've used it a bit here and there, but I just come up short with the correct way to meet the following requirements. The Regex that I'm attempting to write is for use in an XML schema for input validation, and used elsewhere in Javascript for the same purpose. There are two different possible formats that are supported. There is a literal string, which must be surrounded by quotation marks, and a Hex-value string which must be surrounded by braces. Some test cases: "this is a literal string" <-- Valid string, enclosed properly in "s "this should " still be correct" <-- Valid string, "s are allowed within (if possible, this requirement could be forgiven if necessary) "{00 11 22}" <-- Valid string, {}'s allow in strings. Another one that can be forgiven if necessary I am bad output <-- Invalid string, no "s "Some more problemss"you know <-- Invalid string, must be fully contained in "s {0A 68 4F 89 AC D2} <-- Valid string, hex characters enclosed in {}s {DDFF1234} <-- Valid string, spaces are ignored for Hex strings DEADBEEF <-- Invalid string, must be contained in either "s or {}s {0A 12 ZZ} <-- Invalid string, 'Z' is not a valid Hex character To satisfy these general requirements, I had come up with the following Regex that seems to work well enough. I'm still fairly new to Regex, so there could be a huge hole here that I'm missing.: &quot;.+&quot;|\{([0-9]|[a-f]|[A-F]| )+\} If I recall correctly, the XML Schema regex automatically assumes beginning and end of line (^ and $ respectively). So, essentially, this regex accepts any string that starts and ends with a ", or starts and ends with {}s and contains only valid Hexidecimal characters. This has worked well for me so far except that I had forgotten about another (although less common, and thus forgotten) input option that completely breaks my regex. Where I made my mistake: Valid input should also allow a user to separate valid strings (of either type, literal/hex) by a comma. This means that a single string should be able to contain more than one of the above valid strings, separated by commas. Luckily, however, a comma is not a supported character within a literal string (although I see that my existing regex does not care about commas). Example test cases: "some string",{0A F1} <-- Valid {1122},{face},"peanut butter" <-- Valid {0D 0A FF FE},"string",{FF FFAC19 85} <-- Valid (Spaces don't matter in Hex values) "Validation is allowed to break, if a comma is found not separating values",{0d 0a} <-- Invalid, comma is a delimiter, but "Validation is allowed to break" and "if a comma..." are not marked as separate strings with "s hi mom,"hello" <-- Invalid, String1 was not enclosed properly in "s or {}s My thoughts are that it is possible to use commas as a delimiter to check each "section" of the string to match a regex similar to the original, but I just am not that advanced in regex yet to come up with a solution on my own. Any help would be appreciated, but ultimately a final solution with an explanation would just stellar. Thanks for reading this huge wall of text!

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• ssh login fails for user with empty password

  - by Reid

  How do you enable ssh login on OS X 10.8 (Mountain Lion) for a user with an empty password? I've seen others asking this question, and like me it's for the same reason: a parent who can't deal with passwords. So "set a password" is not an option. I found references to adding "nullok" to various PAM config files. Didn't work. Found sshd config "PermitEmptyPasswords yes". Didn't work. I've done a diff on "ssh -vvv" between a successful ssh with a password-enabled account and the one with no password. 54,55c54,55 < debug2: dh_gen_key: priv key bits set: 133/256 < debug2: bits set: 533/1024 --- > debug2: dh_gen_key: priv key bits set: 140/256 > debug2: bits set: 508/1024 67c67 < debug2: bits set: 509/1024 --- > debug2: bits set: 516/1024 79c79 < debug2: key: /Users/rae/.ssh/rae (0x7f9a0241e2c0) --- > debug2: key: /Users/rae/.ssh/rae (0x7f81e0c1e2c0) 90,116c90,224 < debug1: Authentications that can continue: publickey,keyboard-interactive < debug2: we did not send a packet, disable method < debug3: authmethod_lookup keyboard-interactive < debug3: remaining preferred: password < debug3: authmethod_is_enabled keyboard-interactive < debug1: Next authentication method: keyboard-interactive < debug2: userauth_kbdint < debug2: we sent a keyboard-interactive packet, wait for reply < debug2: input_userauth_info_req < debug2: input_userauth_info_req: num_prompts 1 < debug3: packet_send2: adding 32 (len 14 padlen 18 extra_pad 64) < debug1: Authentications that can continue: publickey,keyboard-interactive < debug2: userauth_kbdint < debug2: we sent a keyboard-interactive packet, wait for reply < debug2: input_userauth_info_req < debug2: input_userauth_info_req: num_prompts 1 < debug3: packet_send2: adding 32 (len 14 padlen 18 extra_pad 64) < debug1: Authentications that can continue: publickey,keyboard-interactive < debug2: userauth_kbdint < debug2: we sent a keyboard-interactive packet, wait for reply < debug2: input_userauth_info_req < debug2: input_userauth_info_req: num_prompts 1 < debug3: packet_send2: adding 32 (len 14 padlen 18 extra_pad 64) < debug1: Authentications that can continue: publickey,keyboard-interactive < debug2: we did not send a packet, disable method < debug1: No more authentication methods to try. < Permission denied (publickey,keyboard-interactive). --- > debug1: Server accepts key: pkalg ssh-dss blen 433 > debug2: input_userauth_pk_ok: fp 6e:02:20:63:48:6a:08:99:b8:5f:12:d8:d5:3d:e1:fb > debug3: sign_and_send_pubkey: DSA 6e:02:20:63:48:6a:08:99:b8:5f:12:d8:d5:3d:e1:fb > debug1: read PEM private key done: type DSA > debug1: Authentication succeeded (publickey). > Authenticated to cme-mini.local ([192.168.1.5]:22). > debug2: fd 7 setting O_NONBLOCK > debug3: fd 8 is O_NONBLOCK > debug1: channel 0: new [client-session] > debug3: ssh_session2_open: channel_new: 0 > debug2: channel 0: send open > debug1: Requesting [email protected] > debug1: Entering interactive session. > debug2: callback start > debug2: client_session2_setup: id 0 > debug2: fd 5 setting TCP_NODELAY > debug2: channel 0: request pty-req confirm 1 > debug1: Sending environment.

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• Languages and VMs: Features that are hard to optimize and why

  - by mrjoltcola

  I'm doing a survey of features in preparation for a research project. Name a mainstream language or language feature that is hard to optimize, and why the feature is or isn't worth the price paid, or instead, just debunk my theories below with anecdotal evidence. Before anyone flags this as subjective, I am asking for specific examples of languages or features, and ideas for optimization of these features, or important features that I haven't considered. Also, any references to implementations that prove my theories right or wrong. Top on my list of hard to optimize features and my theories (some of my theories are untested and are based on thought experiments): 1) Runtime method overloading (aka multi-method dispatch or signature based dispatch). Is it hard to optimize when combined with features that allow runtime recompilation or method addition. Or is it just hard, anyway? Call site caching is a common optimization for many runtime systems, but multi-methods add additional complexity as well as making it less practical to inline methods. 2) Type morphing / variants (aka value based typing as opposed to variable based) Traditional optimizations simply cannot be applied when you don't know if the type of someting can change in a basic block. Combined with multi-methods, inlining must be done carefully if at all, and probably only for a given threshold of size of the callee. ie. it is easy to consider inlining simple property fetches (getters / setters) but inlining complex methods may result in code bloat. The other issue is I cannot just assign a variant to a register and JIT it to the native instructions because I have to carry around the type info, or every variable needs 2 registers instead of 1. On IA-32 this is inconvenient, even if improved with x64's extra registers. This is probably my favorite feature of dynamic languages, as it simplifies so many things from the programmer's perspective. 3) First class continuations - There are multiple ways to implement them, and I have done so in both of the most common approaches, one being stack copying and the other as implementing the runtime to use continuation passing style, cactus stacks, copy-on-write stack frames, and garbage collection. First class continuations have resource management issues, ie. we must save everything, in case the continuation is resumed, and I'm not aware if any languages support leaving a continuation with "intent" (ie. "I am not coming back here, so you may discard this copy of the world"). Having programmed in the threading model and the contination model, I know both can accomplish the same thing, but continuations' elegance imposes considerable complexity on the runtime and also may affect cache efficienty (locality of stack changes more with use of continuations and co-routines). The other issue is they just don't map to hardware. Optimizing continuations is optimizing for the less-common case, and as we know, the common case should be fast, and the less-common cases should be correct. 4) Pointer arithmetic and ability to mask pointers (storing in integers, etc.) Had to throw this in, but I could actually live without this quite easily. My feelings are that many of the high-level features, particularly in dynamic languages just don't map to hardware. Microprocessor implementations have billions of dollars of research behind the optimizations on the chip, yet the choice of language feature(s) may marginalize many of these features (features like caching, aliasing top of stack to register, instruction parallelism, return address buffers, loop buffers and branch prediction). Macro-applications of micro-features don't necessarily pan out like some developers like to think, and implementing many languages in a VM ends up mapping native ops into function calls (ie. the more dynamic a language is the more we must lookup/cache at runtime, nothing can be assumed, so our instruction mix is made up of a higher percentage of non-local branching than traditional, statically compiled code) and the only thing we can really JIT well is expression evaluation of non-dynamic types and operations on constant or immediate types. It is my gut feeling that bytecode virtual machines and JIT cores are perhaps not always justified for certain languages because of this. I welcome your answers.

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• com.sun.org.apache.xerces.internal.dom.DocumentImpl cannot be cast to org.codehaus.plexus.util.xml.X

  - by Random

  Afetr using the Model library (see this) for my Maven pom.xml during this weeks I jumped on this error while attempting to write a ConfiguratonContainer into the pom.xml. The javadoc for Model says: public void setConfiguration(Object configuration) Set the configuration as DOM object. Parameters: configuration - So I made some xml with Document (org.w3c.dom.Document) and the xml parser standar javax library. You know the code (it's through all the net) but I paste it here... DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder parser = factory.newDocumentBuilder(); Document doc =parser.newDocument(); And then you fill the code with Element declaration,a lot of appendChild and such. And tried to make it work. Doesn't seem to do well. First tried using plugin.setConfiguration(doc); But it didn't work. Then I tried Obejct obj = doc; plugin.setConfiguration(obj); But it didn't work. Then I searched the net for answers, and guess... It didn't work. There are like 0 people using this library (maven.model) in all the net. So here am I again, asking the senseis for help. Where is my error? I have downloaded the source code of the library trying to see where is the error, but it seems to be ok (as should). I add the stackrace for reference java.lang.ClassCastException: com.sun.org.apache.xerces.internal.dom.DocumentImpl cannot be cast to org.codehaus.plexus.util.xml.Xpp3Dom at org.apache.maven.model.io.xpp3.MavenXpp3Writer.writePlugin(MavenXpp3Writer.java:1472) at org.apache.maven.model.io.xpp3.MavenXpp3Writer.writeBuild(MavenXpp3Writer.java:326) at org.apache.maven.model.io.xpp3.MavenXpp3Writer.writeModel(MavenXpp3Writer.java:1093) at org.apache.maven.model.io.xpp3.MavenXpp3Writer.write(MavenXpp3Writer.java:102) at com.mapfre.mutua.PDA.model.GeneratePOM.createPOM(GeneratePOM.java:28) at com.mapfre.mutua.PDA.prueba.MavenPOM.generatePOMWAR(MavenPOM.java:681) at com.mapfre.mutua.PDA.prueba.GenerarPOMMapfreAction.execute(GenerarPOMMapfreAction.java:36) at org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58) at org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67) at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51) at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191) at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305) at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191) at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913) at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462) at javax.servlet.http.HttpServlet.service(HttpServlet.java:647) at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:873) at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665) at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528) at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689) at java.lang.Thread.run(Unknown Source)

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• Use component id in Castle Windsor generic object configuration

  - by ChoccyButton

  2 questions in one, but very much related. Is it possible with Castle Windsor to resolve a configuration entry such as - Assembly.Namespace.Object1`2[[${ComponentId1}],[${ComponentId2}]], Assembly Where ComponentId1 and ComponentId2 are defined as components. Castle Windsor doesn't seem to be resolving the ComponentId, it is just looking for ComponentId1 in the Castle.Windsor assembly. The second question comes in to play if you can't do the first question. If you have to use a full assembly reference instead of a ComponentId, how can you pass any parameters to the object being created? eg to set ComponentId1.Field1 = "blah", or pass something to the constructor of ComponentId1 Hope that makes sense Update - Following the request for code I've knocked together the following - Objects public class Wrapper<T, T1> where T : ICollector where T1:IProcessor { private T _collector; private T1 _processor; public Wrapper(T collector, T1 processor) { _collector = collector; _processor = processor; } public void GetData() { _collector.CollectData(); _processor.ProcessData(); } } public class Collector1 : ICollector { public void CollectData() { Console.WriteLine("Collecting data from Collector1 ..."); } } public class Processor1 : IProcessor { public void ProcessData() { Console.WriteLine("Processing data from Processor1 ..."); } } repeated so 3 of each type of object in the example Config <components> <component id="Collector1" service="CastleWindsorPlay.ICollector, CastleWindsorPlay" type="CastleWindsorPlay.Collector1, CastleWindsorPlay"/> <component id="Collector2" service="CastleWindsorPlay.ICollector, CastleWindsorPlay" type="CastleWindsorPlay.Collector2, CastleWindsorPlay"/> <component id="Collector3" service="CastleWindsorPlay.ICollector, CastleWindsorPlay" type="CastleWindsorPlay.Collector3, CastleWindsorPlay"/> <component id="Processor1" service="CastleWindsorPlay.IProcessor, CastleWindsorPlay" type="CastleWindsorPlay.Processor1, CastleWindsorPlay"/> <component id="Processor2" service="CastleWindsorPlay.IProcessor, CastleWindsorPlay" type="CastleWindsorPlay.Processor2, CastleWindsorPlay"/> <component id="Processor3" service="CastleWindsorPlay.IProcessor, CastleWindsorPlay" type="CastleWindsorPlay.Processor3, CastleWindsorPlay"/> <component id="Wrapper1" type="CastleWindsorPlay.Wrapper`2[[CastleWindsorPlay.Collector1, CastleWindsorPlay],[CastleWindsorPlay.Processor3, CastleWindsorPlay]], CastleWindsorPlay" /> </components> Instantiation var wrapper = (Wrapper<ICollector, IProcessor>) container.Resolve("Wrapper1"); wrapper.GetData(); This brief example errors with this error message though - Can't create component 'Wrapper1' as it has dependencies to be satisfied. Wrapper1 is waiting for the following dependencies: Services: - CastleWindsorPlay.Collector1 which was not registered. - CastleWindsorPlay.Processor3 which was not registered. The curious part about this is that I can get it to resolve Collector1 and Processor3 individually before the call to the wrapper, but the wrapper still can't see them. This is a basic example, the next thing I'd like to be able to do is when instantiating the Wrapper, set a property on the collector and/or processor. So it could be something like Collector.Id = 10, but set in the config where the wrapper is defined. Setting against the Collector component definition wouldn't work as I'd want to be able to instantiate multiple copies of each Collector, using different Id's Update 2 What I'm actually trying to do is have - <components> <component id="Wrapper1" type="CastleWindsorPlay.Wrapper`2[${Collector1}(id=1)],[${Processor3}]], CastleWindsorPlay" /> <component id="Wrapper2" type="CastleWindsorPlay.Wrapper`2[${Collector1}(id=3)],[${Processor3}]], CastleWindsorPlay" /> </components> Then have another object defined as <component id="Manager" type="CastleWindsorPlay.Manager,CastleWindsorPlay"> <parameters> <wrappers> <array> <item>${Wrapper1}</item> <item>${Wrapper2}</item> </array> </wrappers> </parameters> Then finally in code just be able to call - var manager = (Manager)container.Resolve("Manager"); This should return the manager object, with an array of wrappers populated and the wrappers configured with the correct Collector and Convertor. I know there are errors in the Castle config here, that's why I'm asking the question, I don't know how to set the config up to do what I'm after, or even if it's possible to do it in Castle Windsor

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• c# send recive object over network?

  - by Data-Base

  Hello, I'm working on a server/client project the client will be asking the server for info and the server will send them back to the client the info may be string,number, array, list, arraylist or any other object I found allot of examples but I faced issues!!!! the solution I found so far is to serialize the object (data) and send it then de-serialize it to process here is the server code public void RunServer(string SrvIP,int SrvPort) { try { var ipAd = IPAddress.Parse(SrvIP); /* Initializes the Listener */ if (ipAd != null) { var myList = new TcpListener(ipAd, SrvPort); /* Start Listeneting at the specified port */ myList.Start(); Console.WriteLine("The server is running at port "+SrvPort+"..."); Console.WriteLine("The local End point is :" + myList.LocalEndpoint); Console.WriteLine("Waiting for a connection....."); while (true) { Socket s = myList.AcceptSocket(); Console.WriteLine("Connection accepted from " + s.RemoteEndPoint); var b = new byte[100]; int k = s.Receive(b); Console.WriteLine("Recieved..."); for (int i = 0; i < k; i++) Console.Write(Convert.ToChar(b[i])); string cmd = Encoding.ASCII.GetString(b); if (cmd.Contains("CLOSE-CONNECTION")) break; var asen = new ASCIIEncoding(); // sending text s.Send(asen.GetBytes("The string was received by the server.")); // the line bove to be modified to send serialized object? Console.WriteLine("\nSent Acknowledgement"); s.Close(); Console.ReadLine(); } /* clean up */ myList.Stop(); } } catch (Exception e) { Console.WriteLine("Error..... " + e.StackTrace); } } here is the client code that should return an object public object runClient(string SrvIP, int SrvPort) { object obj = null; try { var tcpclnt = new TcpClient(); Console.WriteLine("Connecting....."); tcpclnt.Connect(SrvIP, SrvPort); // use the ipaddress as in the server program Console.WriteLine("Connected"); Console.Write("Enter the string to be transmitted : "); var str = Console.ReadLine(); Stream stm = tcpclnt.GetStream(); var asen = new ASCIIEncoding(); if (str != null) { var ba = asen.GetBytes(str); Console.WriteLine("Transmitting....."); stm.Write(ba, 0, ba.Length); } var bb = new byte[2000]; var k = stm.Read(bb, 0, bb.Length); string data = null; for (var i = 0; i < k; i++) Console.Write(Convert.ToChar(bb[i])); //convert to object code ?????? Console.ReadLine(); tcpclnt.Close(); } catch (Exception e) { Console.WriteLine("Error..... " + e.StackTrace); } return obj; } I need to know a good serialize/serialize and how to integrate it into the solution above :-( I would be really thankful for any help cheers

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• Decentralized synchronized secure data storage

  - by Alberich

  Introduction Hi, I am going to ask a question which seems utopic for me, but I need to know if there is a way to achieve what I need. And if not, I need to know why not. The idea Suppose I have a database structure, in MySql. I want to create some solution to allow anyone (no matter who, no matter where) to have a synchronized copy (updated clone) of this database (with its content) Well, and it is not going to be just one synchronized copy, it could (and should) be a multiple replication (supposing the basic, this means, for example, ten copies all over the world) And, the most important thing: It must be secure. By secure I mean only real-accepted transactions will be synchronized with all the others (no matter how many) database copies/clones. Note: Since it would be quite difficult to make the synchronization in real-time, I will design everything to make this feature dispensable. So it is not required. My auto-suggestion This is how I am thinking to manage it: Time identifiers and Updates checking: Every action (insert, update, delete...) will be stored as the action instruction itself, associated to the time identifier. [I think better than a DATETIME field, it'll be an INT one, with the number of miliseconds passed from 1st january 2013 on, for example]. So each copy is going to ask to the "neighbour copy" for new actions done since last update, and execute them after checking they are allowed. Problem 1: the "neighbour copy" could be outdated too. Solution 1: do not ask just one neighbour, create a random list with some of the copies/clones and ask them for news (I could avoid the list and ask ALL the clones for updates, but this will be inefficient if clones number ascends too much). Problem 2: Real-time global synchronization is not active. What if... Someone at CLONE_ENTERPRISING inserts a row into TABLE. ... this row goes to every clone ... Someone at CLONE_FIXEMALL deletes this row. ... and at the same time, somewhere in an outdated clone ... Someone at CLONE_DROPOUT edits this row (now inexistent at the other clones) Solution 2: easy stuff, force a GLOBAL synchronization before doing any new "depending-on-third-data action" (edit, for example). This global synch. will be unnecessary when making an INSERT, for instance. Note: Well, someone could have some fun, and make the same insert in two clones... since they're not getting updated in real-time, this row will exist twice. But, it's the same as when we have one single database, in some needed cases we check if there is an existing same-row before doing the final action. Not a problem. Problem 3: It is possible to edit the code and do not filter actions, so someone could spread instructions to delete everything, or just make some trolling activity. This is not a problem, since good clones will always be somewhere. Those who got bad won't interest anymore. I really appreciate if you read. I know this is not the perfect solution, it has possibly hundred of holes, but it is my basic start. I will now appreciate anything you can teach me now. Thanks a lot. PS.: It could be that all this I am trying already exists and has its own name. Sorry for asking then (I'd anyway thank this name, if it exists)

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• How to handle recurring dates (dates only) in .NET?

  - by Wayne M

  I am trying to figure out a good way to handle recurring events in .NET, specifically for an ASP.NET MVC application. The idea is that a user can create an event and specify that the event can occur repeatedly after a specific interval (e.g. "every two weeks", "once a month" and so on). What would be the best way to tackle this? My brainstorming right now is to have two tables: Job and RecurringJob. Job is the "master" record and has the description of the job as well a key to what customer it's for, while RecurringJob links back to Job and has additional info on what the occurrence frequency is (e.g. 1 for "once a month") as well as the timespan (e.g. "Weekly", "Monthly"). The issue is how to determine and set the next occurrence of the job since this will have to be something that's done regularly. I've seen two trains of thought with this: This logic should either be stored in a database column and periodically updated, or calculated on the fly in the code. Any thoughts or suggestions on tackling this? Edit: this is for a subscription based web app I'm creating to let service businesses schedule their common recurring jobs easily and track their customers. So a typical use might be to create a "Cut lawn" job for Mr Smith that occurs every month The exact date isn't important - it's the ability for the customer to see that Mr Smith gets his lawn cut every month and followup with him about it. Let me rephrase the above to better convey my idea. A sample use case for the application might be as follows: User pulls up the customer record for John Smith and clicks the Add Job link. The user fills out the form to create a job with a name of "Cut lawn", a start date of 11/15/2009, and selects a checkbox indicating that this job continually occurs. The user is presented with a secondary screen asking for the job frequency. The user indicates (haven't decided how at this point - let's assume select lists) that the job occurs once a month. User clicks save. Now, when the user views the record for John Smith, they can see that he has a job, "Cut lawn", that occurs every month starting from 11/15/2009. On the main dashboard when it's one week prior to the assumed start date, the user sees the job displayed with an indicator such as "12/15/2009 - Cut lawn (John Smith)". A week before the due date someone from the company calls him up to schedule and he says he's going to be out of town until 1/1/2010, so he wants his appointment rescheduled for that date. Our user can change the date for the job to be 1/1/2010, and now the recurrence will start one month from that date (e.g. next time will be 2/1/2010). The idea behind this is that the app is targeting businesses like lawn care, plumbers, carpet cleaners and the like where the exact date isn't as important (because it can and will change as people are busy), the key thing is to give the business an indicator that Mr. Smith's monthly service is coming up, and someone should give him a call to determine when exactly it can be scheduled for. In effect give these businesses a way to track repeat business and know when it's time to followup with a customer.

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• PostgreSQL triggers and passing parameters

  - by iandouglas

  This is a multi-part question. I have a table similar to this: CREATE TABLE sales_data ( Company character(50), Contract character(50), top_revenue_sum integer, top_revenue_sales integer, last_sale timestamp) ; I'd like to create a trigger for new inserts into this table, something like this: CREATE OR REPLACE FUNCTION add_contract() RETURNS VOID DECLARE myCompany character(50), myContract character(50), BEGIN myCompany = TG_ARGV[0]; myContract = TG_ARGV[1]; IF (TG_OP = 'INSERT') THEN EXECUTE 'CREATE TABLE salesdata_' || $myCompany || '_' || $myContract || ' ( sale_amount integer, updated TIMESTAMP not null, some_data varchar(32), country varchar(2) ) ;' EXECUTE 'CREATE TRIGGER update_sales_data BEFORE INSERT OR DELETE ON salesdata_' || $myCompany || '_' || $myContract || ' FOR EACH ROW EXECUTE update_sales_data( ' || $myCompany || ',' || $myContract || ', revenue);' ; END IF; END; $add_contract$ LANGUAGE plpgsql; CREATE TRIGGER add_contract AFTER INSERT ON sales_data FOR EACH ROW EXECUTE add_contract() ; Basically, every time I insert a new row into sales_data, I want to generate a new table where the name of the table will be defined as something like "salesdata_Company_Contract" So my first question is how can I pass the Company and Contract data to the trigger so it can be passed to the add_contract() stored procedure? From my stored procedure, you'll see that I also want to update the original sales_data table whenever new data is inserted into the salesdata_Company_Contract table. This trigger will do something like this: CREATE OR REPLACE FUNCTION update_sales_data() RETURNS trigger as $update_sales_data$ DECLARE myCompany character(50) NOT NULL, myContract character(50) NOT NULL, myRevenue integer NOT NULL BEGIN myCompany = TG_ARGV[0] ; myContract = TG_ARGV[1] ; myRevenue = TG_ARGV[2] ; IF (TG_OP = 'INSERT') THEN UPDATE sales_data SET top_revenue_sales = top_revenue_sales + 1, top_revenue_sum = top_revenue_sum + $myRevenue, updated = now() WHERE Company = $myCompany AND Contract = $myContract ; ELSIF (TG_OP = 'DELETE') THEN UPDATE sales_data SET top_revenue_sales = top_revenue_sales - 1, top_revenue_sum = top_revenue_sum - $myRevenue, updated = now() WHERE Company = $myCompany AND Contract = $myContract ; END IF; END; $update_sales_data$ LANGUAGE plpgsql; This will, of course, require that I pass several parameters around within these stored procedures and triggers, and I'm not sure (a) if this is even possible, or (b) practical, or (c) best practice and we should just put this logic into our other software instead of asking the database to do this work for us. To keep our table sizes down, as we'll have hundreds of thousands of transactions per day, we've decided to partition our data using the Company and Contract strings as part of the table names themselves so they're all very small in size; file IO for us is faster and we felt we'd get better performance. Thanks for any thoughts or direction. My thinking, now that I've written all of this out, is that maybe we need to write stored procedures where we pass our insert data as parameters, and call that from our other software, and have the stored procedure do the insert into "sales_data" then create the other table. Then, have a second stored procedure to insert new data into the salesdata_Company_Contract tables, where the table name is passed to the stored proc as a parameter, and again have that stored proc do the insert, then update the main sales_data table afterward. What approach would you take?

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• Read files from directory to create a ZIP hadoop

  - by Félix

  I'm looking for hadoop examples, something more complex than the wordcount example. What I want to do It's read the files in a directory in hadoop and get a zip, so I have thought to collect al the files in the map class and create the zip file in the reduce class. Can anyone give me a link to a tutorial or example than can help me to built it? I don't want anyone to do this for me, i'm asking for a link with better examples than the wordaccount. This is what I have, maybe it's useful for someone public class Testing { private static class MapClass extends MapReduceBase implements Mapper<LongWritable, Text, Text, BytesWritable> { // reuse objects to save overhead of object creation Logger log = Logger.getLogger("log_file"); public void map(LongWritable key, Text value, OutputCollector<Text, BytesWritable> output, Reporter reporter) throws IOException { String line = ((Text) value).toString(); log.info("Doing something ... " + line); BytesWritable b = new BytesWritable(); b.set(value.toString().getBytes() , 0, value.toString().getBytes() .length); output.collect(value, b); } } private static class ReduceClass extends MapReduceBase implements Reducer<Text, BytesWritable, Text, BytesWritable> { Logger log = Logger.getLogger("log_file"); ByteArrayOutputStream bout; ZipOutputStream out; @Override public void configure(JobConf job) { super.configure(job); log.setLevel(Level.INFO); bout = new ByteArrayOutputStream(); out = new ZipOutputStream(bout); } public void reduce(Text key, Iterator<BytesWritable> values, OutputCollector<Text, BytesWritable> output, Reporter reporter) throws IOException { while (values.hasNext()) { byte[] data = values.next().getBytes(); ZipEntry entry = new ZipEntry("entry"); out.putNextEntry(entry); out.write(data); out.closeEntry(); } BytesWritable b = new BytesWritable(); b.set(bout.toByteArray(), 0, bout.size()); output.collect(key, b); } @Override public void close() throws IOException { // TODO Auto-generated method stub super.close(); out.close(); } } /** * Runs the demo. */ public static void main(String[] args) throws IOException { int mapTasks = 20; int reduceTasks = 1; JobConf conf = new JobConf(Prue.class); conf.setJobName("testing"); conf.setNumMapTasks(mapTasks); conf.setNumReduceTasks(reduceTasks); MultipleInputs.addInputPath(conf, new Path("/messages"), TextInputFormat.class, MapClass.class); conf.setOutputKeyClass(Text.class); conf.setOutputValueClass(BytesWritable.class); FileOutputFormat.setOutputPath(conf, new Path("/czip")); conf.setMapperClass(MapClass.class); conf.setCombinerClass(ReduceClass.class); conf.setReducerClass(ReduceClass.class); // Delete the output directory if it exists already JobClient.runJob(conf); } }

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• Insane SmartGWT + GWT situation... Error on instantiating ListGridRecord?

  - by Xandel

  Hi all, I am asking this here in the hope that someone has maybe come across this situation too... I have posted this on the SmartGWT forum: I am having an issue when trying to instantiate a ListGridRecord object on my server side. I am using the ListGrid on the client side, I want to use GWT's RPC to pass back an array of ListGridRecord objects to populate the grid with. I know that SmartGWT is designed to link to a datasource but I want full control over when I populate the grid and this shouldn't be as much of a nightmare as it is to do. I have searched high and low and cannot find anyone complaining about the same thing. The exception however (listed below) has come up (in my search findings) as a possible memory error - where increasing the memory (-Xmx512m argument) has apparently solved the problem. It did not, however, sort out mine. If anyone can shed any light on this I would greatly appreciate it! Here are my details: Developing using Eclipse Galileo on Ubuntu 9.04 (Jaunty) and GWT 2.0.3, I built the initial GWT project using the webAppCreator bundled with the GWT 2.0.3 release and imported the project into Eclipse as described on the GWT Getting Started Page (as using the GWT Eclipse plugin caused even more nightmares when trying to connect to a database - this is apparently due to using the Google App Engine and turning it off as all the posts suggested only causes ClassNotFound exceptions). The line that causes the error is literally: ListGridRecord a = new ListGridRecord(); The error I get is the following: 00:00:25.916 [WARN] Exception while dispatching incoming RPC call com.google.gwt.user.server.rpc.UnexpectedException : Service method 'public abstract java.lang.String za.co.company.product.client.service.EmployeeServi ce.getAllEmployeeAsListGridRecord()' threw an unexpected exception: java.lang.UnsatisfiedLinkError: com.smartgwt.client.util.LogUtil.setJSNIErrorHandl er()V at com.google.gwt.user.server.rpc.RPC.encodeResponseF orFailure(RPC.java:378) at com.google.gwt.user.server.rpc.RPC.invokeAndEncode Response(RPC.java:581) at com.google.gwt.user.server.rpc.RemoteServiceServle t.processCall(RemoteServiceServlet.java:188) at com.google.gwt.user.server.rpc.RemoteServiceServle t.processPost(RemoteServiceServlet.java:224) at com.google.gwt.user.server.rpc.AbstractRemoteServi ceServlet.doPost(AbstractRemoteServiceServlet.java :62) at javax.servlet.http.HttpServlet.service(HttpServlet .java:637) at javax.servlet.http.HttpServlet.service(HttpServlet .java:717) at org.mortbay.jetty.servlet.ServletHolder.handle(Ser vletHolder.java:487) at org.mortbay.jetty.servlet.ServletHandler.handle(Se rvletHandler.java:362) at org.mortbay.jetty.security.SecurityHandler.handle( SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(Se ssionHandler.java:181) at org.mortbay.jetty.handler.ContextHandler.handle(Co ntextHandler.java:729) at org.mortbay.jetty.webapp.WebAppContext.handle(WebA ppContext.java:405) at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:152) at org.mortbay.jetty.handler.RequestLogHandler.handle (RequestLogHandler.java:49) at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:324) at org.mortbay.jetty.HttpConnection.handleRequest(Htt pConnection.java:505) at org.mortbay.jetty.HttpConnection$RequestHandler.co ntent(HttpConnection.java:843) at org.mortbay.jetty.HttpParser.parseNext(HttpParser. java:647) at org.mortbay.jetty.HttpParser.parseAvailable(HttpPa rser.java:211) at org.mortbay.jetty.HttpConnection.handle(HttpConnec tion.java:380) at org.mortbay.io.nio.SelectChannelEndPoint.run(Selec tChannelEndPoint.java:395) at org.mortbay.thread.QueuedThreadPool$PoolThread.run (QueuedThreadPool.java:488) Caused by: java.lang.UnsatisfiedLinkError: com.smartgwt.client.util.LogUtil.setJSNIErrorHandl er()V at com.smartgwt.client.util.LogUtil.setJSNIErrorHandl er(Native Method) at com.smartgwt.client.core.JsObject.(JsObjec t.java:30) at za.co.company.product.server.service.EmployeeServi ceImpl.getAllEmployeeAsListGridRecord(EmployeeServ iceImpl.java:83) at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Native MethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(De legatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.google.gwt.user.server.rpc.RPC.invokeAndEncode Response(RPC.java:562) at com.google.gwt.user.server.rpc.RemoteServiceServle t.processCall(RemoteServiceServlet.java:188) at com.google.gwt.user.server.rpc.RemoteServiceServle t.processPost(RemoteServiceServlet.java:224) at com.google.gwt.user.server.rpc.AbstractRemoteServi ceServlet.doPost(AbstractRemoteServiceServlet.java :62) at javax.servlet.http.HttpServlet.service(HttpServlet .java:637) at javax.servlet.http.HttpServlet.service(HttpServlet .java:717) at org.mortbay.jetty.servlet.ServletHolder.handle(Ser vletHolder.java:487) at org.mortbay.jetty.servlet.ServletHandler.handle(Se rvletHandler.java:362) at org.mortbay.jetty.security.SecurityHandler.handle( SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(Se ssionHandler.java:181) at org.mortbay.jetty.handler.ContextHandler.handle(Co ntextHandler.java:729) at org.mortbay.jetty.webapp.WebAppContext.handle(WebA ppContext.java:405) at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:152) at org.mortbay.jetty.handler.RequestLogHandler.handle (RequestLogHandler.java:49) at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:324) at org.mortbay.jetty.HttpConnection.handleRequest(Htt pConnection.java:505) at org.mortbay.jetty.HttpConnection$RequestHandler.co ntent(HttpConnection.java:843) at org.mortbay.jetty.HttpParser.parseNext(HttpParser. java:647) at org.mortbay.jetty.HttpParser.parseAvailable(HttpPa rser.java:211) at org.mortbay.jetty.HttpConnection.handle(HttpConnec tion.java:380) at org.mortbay.io.nio.SelectChannelEndPoint.run(Selec tChannelEndPoint.java:395) at org.mortbay.thread.QueuedThreadPool$PoolThread.run (QueuedThreadPool.java:488) Thanks in advance! Xandel

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• ASP.Net/C# File Upload Progress Display

  - by Ioxp

  I am having a hard time figuring out how to do a "Please wait while file is uploading" message when the user submits the following form. So far the application works to specification with regards to checking files and uploading to the server. You will see some java script below, this is there to allow me to fake out the style of the file up load buttons so that it matches the rest of the site. I have tried to use the ASP.Net Ajax controls to do this however the updateprogress panel would not show up. In further reading it was explained that this has something to do with the Asynchronous transfer that the file upload control uses when you issue a PostedFile.SaveAs("filename") command. I also found a site that refereed to using an iframe to do the job. I'm not really sure if that's the best way to go about doing this or not so I'm asking you the professionals of stackoverflow for help to try and resolve this issue. I will be more than happy to post any spinets you need from my code to help me expedite a solution for this. <table border="0"> <tr> <td>File 1:&nbsp;</td> <td><div class="fileinputs"><input type="file" class="file" size="37" id="f1" runat="server" /></div></td> </tr> <tr> <td>File 2:&nbsp;</td> <td><div class="fileinputs"><input type="file" class="file" size="37" id="f2" runat="server" /></div></td> </tr> <tr> <td colspan="2" style="text-align:right;"><asp:ImageButton ID="ImageButton1" runat="server" ImageUrl="~/Images/Buttons/Upload_Files.gif" OnClick="Submit_Form" /></td> </tr> </table> <asp:Label ID="lblError" runat="server" Text=""></asp:Label> <script type="text/javascript"> var fakeFileUpload = document.createElement('div'); fakeFileUpload.className = 'fakefile'; var fakeInput = document.createElement('input'); fakeInput.style.width = '200px'; fakeFileUpload.appendChild(fakeInput); var image = document.createElement('img'); image.src='../Images/Buttons/Browse.gif'; fakeFileUpload.appendChild(image); var x = document.getElementsByTagName('input'); for (var i=0;i<x.length;i++) { if (x[i].type != 'file') continue; if (x[i].parentNode.className != 'fileinputs') continue; x[i].className = 'file hidden'; var clone = fakeFileUpload.cloneNode(true); x[i].parentNode.appendChild(clone); x[i].relatedElement = clone.getElementsByTagName('input')[0]; x[i].onchange = x[i].onmouseout = function () { this.relatedElement.value = this.value; } } </script>

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• Having a problem inserting a foreign key data into a table using a PHP form

  - by Gideon

  I am newbee with PHP and MySQL and need help... I have two tables (Staff and Position) in the database. The Staff table (StaffId, Name, PositionID (fk)). The Position table is populated with different positions (Manager, Supervisor, and so on). The two tables are linked with a PositionID foreign key in the Staff table. I have a staff registration form with textfields asking for the relevant attributes and a dynamically populated drop down list to choose the position. I need to insert the user's entry into the staff table along with the selected position. However, when inserting the data, I get the following error (Cannot add or update a child row: a foreign key constraint fails). How do I insert the position selected by the user into the staff table? Here is some of my code... ... echo "<tr>"; echo "<td>"; echo "*Position:"; echo "</td>"; echo "<td>"; //dynamically populate the staff position drop down list from the position table $position="SELECT PositionId, PositionName FROM Position ORDER BY PositionId"; $exeposition = mysql_query ($position) or die (mysql_error()); echo "<select name=position value=''>Select Position</option>"; while($positionarray=mysql_fetch_array($exeposition)) { echo "<option value=$positionarray[PositionId]>$positionarray[PositionName]</option>"; } echo "</select>"; echo "</td>"; echo "</tr>" //the form is processed with the code below $FirstName = $_POST['firstname']; $LastName = $_POST['lastname']; $Address = $_POST['address']; $City = $_POST['city']; $PostCode = $_POST['postcode']; $Country = $_POST['country']; $Email = $_POST['email']; $Password = $_POST['password']; $ConfirmPass = $_POST['confirmpass']; $Mobile = $_POST['mobile']; $NI = $_POST['nationalinsurance']; $PositionId = $_POST[$positionarray['PositionId']]; //format the dob for the database $dobpart = explode("/", $_POST['dob']); $formatdob = $dobpart[2]."-".$dobpart[1]."-".$dobpart[0]; $DOB = date("Y-m-d", strtotime($formatdob)); $newReg = "INSERT INTO Staff (FirstName, LastName, Address, City, PostCode, Country, Email, Password, Mobile, DOB, NI, PositionId) VALUES ('".$FirstName."', '".$LastName."', '".$Address."', '".$City."', '".$PostCode."', '".$Country."', '".$Email."', '".$Password."', ".$Mobile.", '".$DOB."', '".$NI."', '".$PostionId."')"; Your time and help is surely appreciated.

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• Create / build / generate a web form that can be on my server and has modern looks and could be impl

  - by Luay

  I have a small web site and would like to add a 'contact us' form and a 'feedback' form. i would like the forms to satisfy the following: 1- be modern looking (with beautiful css effects) 2- the form fields are validated properly and 'inline'. What I mean is once a user skips a required field or enters an email address incorrectly some kind of tooltip or icon is displayed to ask him to cerrect the error (as opposed to a message box that appears after the user clicks 'submit') 3- once the submit button is clicked the form contents are emailed to me. 4- the whole thing can be setup by a noob like myself. 5- no ads on the form I have been searching for at least 5 days for a solution but I can't seem to find anything the would satisfy the above 5 conditions. I don't mind paying for a solution as long as it is hosted on my site and it is a one off payment and not a monthly payment. So far my search has lead me to the following: 1 wufoo. The good: the generated forms seem to look okay but not the best there is. The bad: the free service is limited to 100 submissions. ads on the form. it is not hosted on my server. Paid service requires monthly payments 2- emailmeform: almost same as above except the generated form looks old. They do have an offer where you pay only $4 to get the form and set it up on your own site but that doesn't solve the fact that the forms look old. 3- formAssembly: same as above with minor variations (the generated form looks better) 4- formchamp, formthis, kontaktr,... And other similar online services: the same problem. either the form generated looks outdated or require monthly payments or they put ads...they don't satisfy my conditions. 5- coffeecup form builder. a desktop software. The problem is the generated forms look too old and use flash. 6- simfatic. Another software. Much better than coffeecup. almost satisfies my conditions but the forms not as good as I like. 7- many, many php scripts or html templates that look so outdated or fail when tested (probably because they are too old). Seriously guys, how hard is this. At least 90%+ of website contain at least a 'contact us' form. Why aren't there better solutions? if there is I can't seem to find them. In terms of looks I want something similar to this: http://web-kreation.com/articles/lightform-free-ajaxphp-contact-form/ It is called lightform. And this is a perfect example of what I mean by 'inline' validation. the only problem: there is no script to handle sending the mail. Even if I find one, I don't know how to modify it for my needs. So could you please help me out. I really can't search anymore. I reached rock bottom with this issue. I need a complete solution. If nothing exists then at least a: 1- form template (html) that looks nice and can easily be modified 2- a validation script that does 'inline' validation like the example above (or similar to it) and can be easily implemented by a noob like me to work with the html form. 3- a php script that will handle sending the email and can be easily implemented (all three working in harmony). I hope there is a complete solution but am I asking for too much? Pretty please...help...

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• PHP script causes segmentation fault then the browser asks me to download the .php file with nothing in it?

  - by John

  I've noticed an unusual problem with some of my php programs. Sometimes when visiting a page like profile.edit.php, the browser throws a dialogue box asking to download profile.edit.php page. When I download it, there's nothing in the file. profile.edit.php is supposed to be a web form that edits user information. I've noticed this on some of my other php pages as well. I look in my apache error logs, and I see a segmentation fault message: [Mon Mar 08 15:40:10 2010] [notice] child pid 480 exit signal Segmentation fault (11) And also, the issue may or may not appear depending on which server I deploy my application too. Additonal Details This doesn't happen all the time though. It only happens sometimes. For example, profile.edit.php will load properly. But as soon as I hit the save button (form action="profile.edit.php?save=true"), then the page asks me to download profile.edit.php. Could it be that sometimes my php scripts consume too much resources? Sample code Upon save action, my profile.edit.php includes a data_access_object.php file. I traced the code in data_access_object.php to this line here if($params[$this->primaryKey]) { $q = "UPDATE $this->tableName SET ".implode(', ', $fields)." WHERE ".$this->primaryKey." = ?$this->primaryKey"; $this->bind($this->primaryKey, $params[$this->primaryKey], $this->tblFields[$this->primaryKey]['mysqlitype']); } else { $q = "INSERT $this->tableName SET ".implode(', ', $fields); } // Code executes perfectly up to this point // echo 'print this'; exit; // if i uncomment this line, profile.edit.php will actually show 'print this'. If I leave it commented, the browser will ask me to download profile.edit.php if(!$this->execute($q)){ $this->errorSave = -3; return false;} // When I jumped into the function execute(), every line executed as expected, right up to the return statement. And if it helps, here's the function execute($sql) in data_access_object.php function execute($sql) { // find all list types and explode them // eg. turn ?listId into ?listId0,?listId1,?listId2 $arrListParam = array_bubble_up('arrayName', $this->arrBind); foreach($arrListParam as $listName) if($listName) { $explodeParam = array(); $arrList = $this->arrBind[$listName]['value']; foreach($arrList as $key=>$val) { $newParamName = $listName.$key; $this->bind($newParamName,$val,$this->arrBind[$listName]['type']); $explodeParam[] = '?'.$newParamName; } $sql = str_replace("?$listName", implode(',',$explodeParam), $sql); } // replace all ?varName with ? for syntax compliance $sqlParsed = preg_replace('/\?[\w\d_\.]+/', '?', $sql); $this->stmt->prepare($sqlParsed); // grab all the parameters from the sql to create bind conditions preg_match_all('/\?[\w\d_\.]+/', $sql, $matches); $matches = $matches[0]; // store bind conditions $types = ''; $params = array(); foreach($matches as $paramName) { $types .= $this->arrBind[str_replace('?', '', $paramName)]['type']; $params[] = $this->arrBind[str_replace('?', '', $paramName)]['value']; } $input = array('types'=>$types) + $params; // bind it if(!empty($types)) call_user_func_array(array($this->stmt, 'bind_param'), $input); $stat = $this->stmt->execute(); if($GLOBALS['DEBUG_SQL']) echo '<p style="font-weight:bold;">SQL error after execution:</p> ' . $this->stmt->error.'<p>&nbsp;</p>'; $this->arrBind = array(); return $stat; }

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• Resumable upload from Java client to Grails web application?

  - by dersteps

  After almost 2 workdays of Googling and trying several different possibilities I found throughout the web, I'm asking this question here, hoping that I might finally get an answer. First of all, here's what I want to do: I'm developing a client and a server application with the purpose of exchanging a lot of large files between multiple clients on a single server. The client is developed in pure Java (JDK 1.6), while the web application is done in Grails (2.0.0). As the purpose of the client is to allow users to exchange a lot of large files (usually about 2GB each), I have to implement it in a way, so that the uploads are resumable, i.e. the users are able to stop and resume uploads at any time. Here's what I did so far: I actually managed to do what I wanted to do and stream large files to the server while still being able to pause and resume uploads using raw sockets. I would send a regular request to the server (using Apache's HttpClient library) to get the server to send me a port that was free for me to use, then open a ServerSocket on the server and connect to that particular socket from the client. Here's the problem with that: Actually, there are at least two problems with that: I open those ports myself, so I have to manage open and used ports myself. This is quite error-prone. I actually circumvent Grails' ability to manage a huge amount of (concurrent) connections. Finally, here's what I'm supposed to do now and the problem: As the problems I mentioned above are unacceptable, I am now supposed to use Java's URLConnection/HttpURLConnection classes, while still sticking to Grails. Connecting to the server and sending simple requests is no problem at all, everything worked fine. The problems started when I tried to use the streams (the connection's OutputStream in the client and the request's InputStream in the server). Opening the client's OutputStream and writing data to it is as easy as it gets. But reading from the request's InputStream seems impossible to me, as that stream is always empty, as it seems. Example Code Here's an example of the server side (Groovy controller): def test() { InputStream inStream = request.inputStream if(inStream != null) { int read = 0; byte[] buffer = new byte[4096]; long total = 0; println "Start reading" while((read = inStream.read(buffer)) != -1) { println "Read " + read + " bytes from input stream buffer" //<-- this is NEVER called } println "Reading finished" println "Read a total of " + total + " bytes" // <-- 'total' will always be 0 (zero) } else { println "Input Stream is null" // <-- This is NEVER called } } This is what I did on the client side (Java class): public void connect() { final URL url = new URL("myserveraddress"); final byte[] message = "someMessage".getBytes(); // Any byte[] - will be a file one day HttpURLConnection connection = url.openConnection(); connection.setRequestMethod("GET"); // other methods - same result // Write message DataOutputStream out = new DataOutputStream(connection.getOutputStream()); out.writeBytes(message); out.flush(); out.close(); // Actually connect connection.connect(); // is this placed correctly? // Get response BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream())); String line = null; while((line = in.readLine()) != null) { System.out.println(line); // Prints the whole server response as expected } in.close(); } As I mentioned, the problem is that request.inputStream always yields an empty InputStream, so I am never able to read anything from it (of course). But as that is exactly what I'm trying to do (so I can stream the file to be uploaded to the server, read from the InputStream and save it to a file), this is rather disappointing. I tried different HTTP methods, different data payloads, and also rearranged the code over and over again, but did not seem to be able to solve the problem. What I hope to find I hope to find a solution to my problem, of course. Anything is highly appreciated: hints, code snippets, library suggestions and so on. Maybe I'm even having it all wrong and need to go in a totally different direction. So, how can I implement resumable file uploads for rather large (binary) files from a Java client to a Grails web application without manually opening ports on the server side?

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• Rogue PropertyChanged notifications from ViewModel

  - by user1886323

  The following simple program is causing me a Databinding headache. I'm new to this which is why I suspect it has a simple answer. Basically, I have two text boxes bound to the same property myString. I have not set up the ViewModel (simply a class with one property, myString) to provide any notifications to the View for when myString is changed, so even although both text boxes operate a two way binding there should be no way that the text boxes update when myString is changed, am I right? Except... In most circumstances this is true - I use the 'change value' button at the bottom of the window to change the value of myString to whatever the user types into the adjacent text box, and the two text boxes at the top, even although they are bound to myString, do not change. Fine. However, if I edit the text in TextBox1, thus changing the value of myString (although only when the text box loses focus due to the default UpdateSourceTrigger property, see reference), TextBox2 should NOT update as it shouldn't receive any updates that myString has changed. However, as soon as TextBox1 loses focus (say click inside TextBox2) TextBox2 is updated with the new value of myString. My best guess so far is that because the TextBoxes are bound to the same property, something to do with TextBox1 updating myString gives TextBox2 a notification that it has changed. Very confusing as I haven't used INotifyPropertyChanged or anything like that. To clarify, I am not asking how to fix this. I know I could just change the binding mode to a oneway option. I am wondering if anyone can come up with an explanation for this strange behaviour? ViewModel: namespace WpfApplication1 { class ViewModel { public ViewModel() { _myString = "initial message"; } private string _myString; public string myString { get { return _myString; } set { if (_myString != value) { _myString = value; } } } } } View: <Window x:Class="WpfApplication1.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:WpfApplication1" Title="MainWindow" Height="350" Width="525"> <Window.DataContext> <local:ViewModel /> </Window.DataContext> <Grid> <!-- The culprit text boxes --> <TextBox Height="23" HorizontalAlignment="Left" Margin="166,70,0,0" Name="textBox1" VerticalAlignment="Top" Width="120" Text="{Binding Path=myString, Mode=TwoWay}" /> <TextBox Height="23" HorizontalAlignment="Left" Margin="166,120,0,0" Name="textBox2" VerticalAlignment="Top" Width="120" Text="{Binding Path=myString, Mode=TwoWay}"/> <!--The buttons allowing manual change of myString--> <Button Name="changevaluebutton" Content="change value" Click="ButtonUpdateArtist_Click" Margin="12,245,416,43" Width="75" /> <Button Content="Show value" Height="23" HorizontalAlignment="Left" Margin="12,216,0,0" Name="showvaluebutton" VerticalAlignment="Top" Width="75" Click="showvaluebutton_Click" /> <Label Content="" Height="23" HorizontalAlignment="Left" Margin="116,216,0,0" Name="showvaluebox" VerticalAlignment="Top" Width="128" /> <TextBox Height="23" HorizontalAlignment="Left" Margin="116,245,0,0" Name="changevaluebox" VerticalAlignment="Top" Width="128" /> <!--simply some text--> <Label Content="TexBox1" Height="23" HorizontalAlignment="Left" Margin="99,70,0,0" Name="label1" VerticalAlignment="Top" Width="61" /> <Label Content="TexBox2" Height="23" HorizontalAlignment="Left" Margin="99,118,0,0" Name="label2" VerticalAlignment="Top" Width="61" /> </Grid> </Window> Code behind for view: namespace WpfApplication1 { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { ViewModel viewModel; public MainWindow() { InitializeComponent(); viewModel = (ViewModel)this.DataContext; } private void showvaluebutton_Click(object sender, RoutedEventArgs e) { showvaluebox.Content = viewModel.myString; } private void ButtonUpdateArtist_Click(object sender, RoutedEventArgs e) { viewModel.myString = changevaluebox.Text; } } }

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