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  • PyGTK/GIO: monitor directory for changes recursively

    - by detly
    Take the following demo code (from the GIO answer to this question), which uses a GIO FileMonitor to monitor a directory for changes: import gio def directory_changed(monitor, file1, file2, evt_type): print "Changed:", file1, file2, evt_type gfile = gio.File(".") monitor = gfile.monitor_directory(gio.FILE_MONITOR_NONE, None) monitor.connect("changed", directory_changed) import glib ml = glib.MainLoop() ml.run() After running this code, I can then create and modify child nodes and be notified of the changes. However, this only works for immediate children (I am aware that the docs don't say otherwise). The last of the following shell commands will not result in a notification: touch one mkdir two touch two/three Is there an easy way to make it recursive? I'd rather not manually code something that looks for directory creation and adds a monitor, removing them on deletion, etc. The intended use is for a VCS file browser extension, to be able to cache the statuses of files in a working copy and update them individually on changes. So there might by anywhere from tens to thousands (or more) directories to monitor. I'd like to just find the root of the working copy and add the file monitor there. I know about pyinotify, but I'm avoiding it so that this works under non-Linux kernels such as FreeBSD or... others. As far as I'm aware, the GIO FileMonitor uses inotify underneath where available, and I can understand not emphasising the implementation to maintain some degree of abstraction, but it suggested to me that it should be possible. (In case it matters, I originally posted this on the PyGTK mailing list.)

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  • Defining Light Coordinates

    - by Zachary
    I took a Computer Graphics exam a couple of days ago which had extra credit question like the following: A light can be defined in one of two ways. It can be defined in world coordinates, e.g. a street light, or in the viewer (eye coordinates), e.g., a head-lamp worn by a miner. In either case the viewpoint can freely change. Describe how the light should be transformed different in these two cases. Since I won't get to see the results of this until after spring break, I thought I would ask here. It seems like the analogies being used are misleading - could you not define a light source that is located at the viewers eye in world coordinates just as well as you could in eye coordinates? I've been doing some research on how OpenGL handles light, and it seems as though it always uses eye coordinates - the ModelView matrix would be applied to any light in world coordinates. In that case the answer may just be that you would have to transform light defined in world coordinates into eye coordinates using something like the ModelView matrix, while light defined in eye coordinates would only need to be transformed by the projection matrix. Then again I could be totally under thinking (or over thinking this). Another thought I had is that it determines which way you render shadows, but that has more to do with the location of the light and its type (point, directional, emission, etc) than what coordinates it is represented in. Any ideas?

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  • tikz: set appropriate x value for a node

    - by basweber
    This question resulted from the question here I want to produce a curly brace which spans some lines of text. The problem is that I have to align the x coordinate manually, which is not a clean solution. Currently I use \begin{frame}{Example} \begin{itemize} \item The long Issue 1 \tikz[remember picture] \node[coordinate,yshift=0.7em] (n1) {}; \\ spanning 2 lines \item Issue 2 \tikz[remember picture] \node[coordinate, xshift=1.597cm] (n2) {}; \item Issue 3 \end{itemize} \visible<2->{ \begin{tikzpicture}[overlay,remember picture] \draw[thick,decorate,decoration={brace,amplitude=5pt}] (n1) -- (n2) node[midway, right=4pt] {One and two are cool}; \end{tikzpicture} } % end visible \end{frame} which produces the desired result: The unsatisfying thing is, that I had to figure out the xshift value of 1.597cm by trial and error (more or less) Without xshift argument the result is: I guess there is an elegant way to avoid the explicit xshift value. The best way would it imho be to calculate the maximum x value of two nodes and use this, (as already suggested by Geoff) But it would already be very handy to be able to explicitly define the absolute xvalues of both nodes while keeping their current y values. This would avoid the fiddly procedure of adapting the third post decimal position to ensure that the brace looks vertical.

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  • Handling Incoming Mail to Multiple Recipients in PHP

    - by Navarr
    Alright, this may take a moment or two to explain: I'm working on creating an Email<SMS Bridge (like Teleflip). I have a few set parameters to work in: Dreamhost Webhosting PHP 5 (without PEAR) Postfix What I have right now, is a catch-all email address that forwards the email sent to a shell account. The shell account in turn forwards it to my PHP script. The PHP script reads it, strips a few Email Headers in an effort to make sure it sends properly, then forwards it to the number specified as the recipient. [email protected] of course sends an SMS to +1 (555) 123-4567. This works really well, as I am parsing the To field and grabbing just the email address it is sending to. However, what I realized that I did not account for is multiple recipients. For example, an email sent to both 5551234567 and 1235554567 (using the To line, the CC line, or any combination of those). The way email works of course, is I get two emails received, end up parsing each of them separately, and 5551234567 ends up getting the same message twice. What is the best way to handle this situation, so that each number specified in TO and CC can get one copy of the message. In addition, though I doubt its possible: Is there a way to handle BCC the same way?

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  • How do I use Linq-to-sql to iterate db records?

    - by Seth Spearman
    I asked on SO a few days ago what was the simplest quickest way to build a wrapper around a recently completed database. I took the advice and used sqlmetal to build linq classes around my database design. Now I am having two problems. One, I don't know LINQ. And, two, I have been shocked to realize how hard it is to learn. I have a book on LINQ (Linq In Action by Manning) and it has helped some but at the end of the day it is going to take me a couple of weeks to get traction and I need to make some progress on my project today. So, I am looking for some help getting started. Click HERE To see my simple database schema. Click HERE to see the vb class that was generated for the schema. My needs are simple. I have a console app. The main table is the SupplyModel table. Most of the other tables are child tables of the SupplyModel table. I want to iterate through each of Supply Model records. I want to grab the data for a supply model and then DoStuff with the data. And I also need to iterate through the child records, for each supply model, for example the NumberedInventories and DoStuff with that as well. I need help doing this in VB rather than C# if possible. I am not looking for the whole solution...if you can supply a couple of code-snippets to get me on my way that would be great. Thanks for your help. Seth

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  • Most efficient way to send images across processes

    - by Heinrich Ulbricht
    Goal Pass images generated by one process efficiently and at very high speed to another process. The two processes run on the same machine and on the same desktop. The operating system may be WinXP, Vista and Win7. Detailled description The first process is solely for controlling the communication with a device which produces the images. These images are about 500x300px in size and may be updated up to several hundred times per second. The second process needs these images to display them. The first process uses a third party API to paint the images from the device to a HDC. This HDC has to be provided by me. Note: There is already a connection open between the two processes. They are communicating via anonymous pipes and share memory mapped file views. Thoughts How would I achieve this goal with as little work as possible? And I mean both work for me and the computer. I am using Delphi, so maybe there is some component available for doing this? I think I could always paint to any image component's HDC, save the content to memory stream, copy the contents via the memory mapped file, unpack it on the other side and paint it there to the destination HDC. I also read about a IPicture interface which can be used to marshall images. What are your ideas? I appreciate every thought on this!

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  • faster way to draw an image

    - by iHorse
    im trying to combine two images into a single image. unfortunately this has to be done very quickly in response to a user sliding a UISlider. i can combine the two images into a single image no problem. but the way I'm doing it is horribly slow. the sliders stick and jump rather frustratingly. i don't think i can throw the code into a background thread because i would run out of threads to quickly. i haven't actually tired that yet. below is my code. any ideas on how to speed it up would be helpful. UIGraphicsBeginImageContext(CGSizeMake(bodyImage.theImage.image.size.width * 1.2, bodyImage.theImage.image.size.height * 1.2)); [bodyImage.theImage.image drawInRect: CGRectMake(-2 + ((bodyImage.theImage.image.size.width * 1.2) - bodyImage.theImage.image.size.width)/2, kHeadAdjust, bodyImage.theImage.image.size.width * bodyImage.currentScale, bodyImage.theImage.image.size.height * bodyImage.currentScale)]; if(isCustHead) { [Head.theImage.image drawInRect: CGRectMake((bodyImage.theImage.image.size.width * 1.2 - headWidth)/2 - 11, 0, headWidth * 0.92, headWidth * (Head.theImage.image.size.height/Head.theImage.image.size.width) * 0.92)]; } else { [Head.theImage.image drawInRect: CGRectMake((bodyImage.theImage.image.size.width * 1.2 - (headWidth * defaultHeadAdjust))/2 - 10, 0, (headWidth * defaultHeadAdjust * 0.92), (headWidth * defaultHeadAdjust) * (Head.theImage.image.size.height/Head.theImage.image.size.width) * 0.92)]; } drawSurface.theImage.image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext();

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  • How to Find Intersections with Ellipses in PGF/TikZ

    - by infblnpf
    Hello, I am trying to display a sphere in PGF/TikZ to illustrate the idea of great circles. The code for my current result is: \begin{tikzpicture} \tikzfading[name=fade right, left color=transparent!20, right color=transparent!90] \tikzfading[name=fade out, inner color=transparent!100, outer color=transparent!10] \tikzfading[name=fade right gc, left color=transparent!0, right color=transparent!70] \draw [<->, dashed] (0,-5) -- (0,5); % y-axis \draw [->, dashed] (0, 0) -- (20:5); % x-axis \draw [->, dashed] (0, 0) -- (200:5); % x-axis \draw [->, dashed] (0, 0) -- (340:5); % z-axis \draw [->, dashed] (0, 0) -- (160:5); % z-axis \fill [color=cyan, opacity=0.15, path fading=fade out] (0,0) circle (4cm); % bounding circle \fill [color=cyan, opacity=0.25, path fading=fade right, fading angle=90] (0,0) ellipse (4cm and 1cm); % x-y-axis area % great circle 1 \draw [rotate=-40, color=red, path fading=fade right gc, fading angle=40] (0,0) ellipse (4cm and 1cm); % great circle 2 \draw[rotate=5, color=red, path fading=fade right gc, fading angle=5] (0,0) ellipse (1.5cm and 4cm); \end{tikzpicture} How do I find the two points of intersection of the two red ellipses (commented as great circle 1 and 2), find the point of intersection of a line (originating at the center (0,0)) with a ellipse, and place a little circle or rectangle there? Placing a little circle or rectangle there is not an issue. Thank you very much!

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  • Best way to enforce inter-table constraints inside database

    - by FerranB
    I looking for the best way to check for inter-table constraints an step forward of foreing keys. For instance, to check if a date child record value is between a range date on two parent rows columns. For instance: Parent table ID DATE_MIN DATE_MAX ----- ---------- ---------- 1 01/01/2009 01/03/2009 ... Child table PARENT_ID DATE ---------- ---------- 1 01/02/2009 1 01/12/2009 <--- HAVE TO FAIL! ... I see two approaches: Create materialized views on-commit as shown in this article (or other equivalent on other RDBMS). Use stored-procedures and triggers. Any other approach? Which is the best option? UPDATE: The motivation of this question is not about "putting the constraints on database or on application". I think this is a tired question and anyone does the way she loves. And, I'm sorry for detractors, I'm developing with constraints on database. From here, the question is "which is the best option to manage inter-table constraints on database?". I'm added "inside database" on the question title. UPDATE 2: Some one added the "oracle" tag. Of course materialized views are oracle-tools but I'm interested on any option regardless it's on oracle or others RDBMSs.

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  • Small-o(n^2) implementation of Polynomial Multiplication

    - by AlanTuring
    I'm having a little trouble with this problem that is listed at the back of my book, i'm currently in the middle of test prep but i can't seem to locate anything regarding this in the book. Anyone got an idea? A real polynomial of degree n is a function of the form f(x)=a(n)x^n+?+a1x+a0, where an,…,a1,a0 are real numbers. In computational situations, such a polynomial is represented by a sequence of its coefficients (a0,a1,…,an). Assuming that any two real numbers can be added/multiplied in O(1) time, design an o(n^2)-time algorithm to compute, given two real polynomials f(x) and g(x) both of degree n, the product h(x)=f(x)g(x). Your algorithm should **not** be based on the Fast Fourier Transform (FFT) technique. Please note it needs to be small-o(n^2), which means it complexity must be sub-quadratic. The obvious solution that i have been finding is indeed the FFT, but of course i can't use that. There is another method that i have found called convolution, where if you take polynomial A to be a signal and polynomial B to be a filter. A passed through B yields a shifted signal that has been "smoothed" by A and the resultant is A*B. This is supposed to work in O(n log n) time. Of course i am completely unsure of implementation. If anyone has any ideas of how to achieve a small-o(n^2) implementation please do share, thanks.

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  • MySQL & PHP - Creating Multiple Parent Child Relations

    - by Ashok
    Hi, I'm trying to build a navigation system using categories table with hierarchies. Normally, the table would be defined as follows: id (int) - Primary key name (varchar) - Name of the Category parentid (int) - Parent ID of this Category referenced to same table (Self Join) But the catch is that I require that a category can be child to multiple parent categories.. Just like a Has and Belongs to Many (HABTM) relation. I know that if there are two tables, categories & items, we use a join table categories_items to list the HABTM relations. But here i'm not having two tables but only table but should somehow show HABTM relations to itself. Is this be possible using a single table? If yes, How? If not possible, what rules (table naming, fields) should I follow while creating the additional join table? I'm trying to achieve this using CakePHP, If someone can provide CakePHP solution for this problem, that would be awesome. Even if that's not possible, any solution about creating join table is appreciated. Thanks for your time.

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  • Design pattern to use instead of multiple inheritance

    - by mizipzor
    Coming from a C++ background, Im used to multiple inheritance. I like the feeling of a shotgun squarely aimed at my foot. Nowadays, I work more in C# and Java, where you can only inherit one baseclass but implement any number of interfaces (did I get the terminology right?). For example, lets consider two classes that implement a common interface but different (yet required) baseclasses: public class TypeA : CustomButtonUserControl, IMagician { public void DoMagic() { // ... } } public class TypeB : CustomTextUserControl, IMagician { public void DoMagic() { // ... } } Both classes are UserControls so I cant substitute the base class. Both needs to implement the DoMagic function. My problem now is that both implementations of the function are identical. And I hate copy-and-paste code. The (possible) solutions: I naturally want TypeA and TypeB to share a common baseclass, where I can write that identical function definition just once. However, due to having the limit of just one baseclass, I cant find a place along the hierarchy where it fits. One could also try to implement a sort of composite pattern. Putting the DoMagic function in a separate helper class, but the function here needs (and modifies) quite a lot of internal variables/fields. Sending them all as (reference) parameters would just look bad. My gut tells me that the adapter pattern could have a place here, some class to convert between the two when necessery. But it also feels hacky. I tagged this with language-agnostic since it applies to all languages that use this one-baseclass-many-interfaces approach. Also, please point out if I seem to have misunderstood any of the patterns I named. In C++ I would just make a class with the private fields, that function implementation and put it in the inheritance list. Whats the proper approach in C#/Java and the like?

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  • How to Deserialize Missing Fields To Nulls

    - by Nathan
    I am working on a .NET project where several versions of the same type of object have been created over the life of the project - most new versions add a field or two. However, now I am looking to mitigate problems for users with an old version. My goal is that when a user tries to open an old version of the serialized object with the new program, the program will automatically assign default values to the fields that are missing from the depreciated version of the file. For example, say I had a class with two boolean fields - RepeatSound and RepeatForever. The first version of the program doesn't know how to repeat forever, so it only saved RepeatSound: <anyType xsi:type="Sound"> <RepeatSound>true</RepeatSound> </anyType> but the new files look like this: <anyType xsi:type="Sound"> <RepeatSound>true</RepeatSound> <RepeatForever>true</RepeatForever> </anyType> My goal is that when I deserialize the first file in the new program that it will create the Sound object but simply default the value of RepeatForever to false. Right now trying to deserialize the first object would throw an exception. Thank you in advance for any responses

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  • High-concurrency counters without sharding

    - by dound
    This question concerns two implementations of counters which are intended to scale without sharding (with a tradeoff that they might under-count in some situations): http://appengine-cookbook.appspot.com/recipe/high-concurrency-counters-without-sharding/ (the code in the comments) http://blog.notdot.net/2010/04/High-concurrency-counters-without-sharding My questions: With respect to #1: Running memcache.decr() in a deferred, transactional task seems like overkill. If memcache.decr() is done outside the transaction, I think the worst-case is the transaction fails and we miss counting whatever we decremented. Am I overlooking some other problem that could occur by doing this? What are the significiant tradeoffs between the two implementations? Here are the tradeoffs I see: #2 does not require datastore transactions. To get the counter's value, #2 requires a datastore fetch while with #1 typically only needs to do a memcache.get() and memcache.add(). When incrementing a counter, both call memcache.incr(). Periodically, #2 adds a task to the task queue while #1 transactionally performs a datastore get and put. #1 also always performs memcache.add() (to test whether it is time to persist the counter to the datastore). Conclusions (without actually running any performance tests): #1 should typically be faster at retrieving a counter (#1 memcache vs #2 datastore). Though #1 has to perform an extra memcache.add() too. However, #2 should be faster when updating counters (#1 datastore get+put vs #2 enqueue a task). On the other hand, with #1 you have to be a bit more careful with the update interval since the task queue quota is almost 100x smaller than either the datastore or memcahce APIs.

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  • Call by Reference Function in C

    - by Chad
    Hello everyone, I would just like a push in the right direction here with my homework assignment. Here is the question: (1) Write a C function called input which returns void, this function prompts the user for input of two integers followed by a double precision value. This function reads these values from the keyboard and finds the product of the two integers entered. The function uses call by reference to communicate the values of the three values read and the product calculated back to the main program. The main program then prints the three values read and the product calculated. Provide test results for the input: 3 5 23.5. Do not use arrays or global variables in your program. And here is my code: #include <stdio.h> #include <stdlib.h> void input(int *day, int *month, double *k, double *pro); int main(void){ int i,j; double k, pro; input(&i, &j, &k, &pro); printf("%f\n", pro); return 0; } void input(int *i, int *j, double *k, double *pro){ int x,y; double z; double product; scanf("%d", &x); scanf("%d", &y); scanf("%f", &z); *pro += (x * y * z); } I can't figure out how to reference the variables with pointers really, it is just not working out for me. Any help would be great!

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  • Inserting new <TD> elements into a table row.

    - by Hunter S. Smythe
    I have created a small application written in XHTML, JavaScript/JQuery and PHP. The PHP reads and writes to a small SQLite database. How would i go about inserting cells into a pre-scripted table. The cells would need to be configured using some information from my database. For example, below are two cells with their data retrieved from my database: Cell One Starts: 120px; Finishes: 180px; Background: Blue; Cell Two Starts: 240px; Finishes: 300px; Background: Green; On my table row, it is 500px in width. How would I insert the cells above into the row. In this example, the first cell would start 120px into the row and have a width of 180px. The second cell would start 240px into the row and have a width of 300px. I just cant seem to work out a way of doing this, any ideas would be very helpful. Thank you for any input, all is appreciated. Hunter.

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  • C# Regex stops after first line matched

    - by JD Guzman
    Ok so I have a regex and I need it to find matches in a multiline string. This is the string I am using: Device Identifier: disk0 Device Node: /dev/disk0 Part of Whole: disk0 Device / Media Name: OCZ-VERTEX2 Media Volume Name: Not applicable (no file system) Mounted: Not applicable (no file system) File System: None Content (IOContent): GUID_partition_scheme OS Can Be Installed: No Media Type: Generic Protocol: SATA SMART Status: Verified Total Size: 240.1 GB (240057409536 Bytes) (exactly 468862128 512-Byte-Blocks) Volume Free Space: Not applicable (no file system) Device Block Size: 512 Bytes Read-Only Media: No Read-Only Volume: Not applicable (no file system) Ejectable: No Whole: Yes Internal: Yes Solid State: Yes OS 9 Drivers: No Low Level Format: Not supported Basically I need to separate each line into two groups with the colon as the separator. The regex I am using is: @"([A-Za-z0-9\(\) \-\/]+):([A-Za-z0-9\(\) \-\/]+).*" It does work but only picks up the first line and separates it into the two groups like I want but it stops at that point. I have tried the Multiline option but it doesn't make any difference. I must admit I am new to the regex world. Any help is appreciated.

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  • MS Access Interop - How to set print filename?

    - by Ryan
    Hi all, I'm using Delphi 2009 and the MS Access Interop COM API. I'm trying to figure out two things, but one is more important than the other right now. I need to know how to set the file name when sending the print job to the spooler. Right now it's defaulting to the Access DB's name, which can be something different than the file's name. I need to just ensure that when this is printed it enters the print spool using the same filename as the actual file itself - not the DB's name. My printer spool is actually a virtual print driver that converts documents to an image. That's my main issue. The second issue is how to specify which printer to use. This is less important at the moment because I'm just using the default printer for now. It would be nice if I could specify the printer to use, though. Does anyone know either of these two issues? Thank you in advance. I'll go ahead and paste my code: unit Converter.Handlers.Office.Access; interface uses sysutils, variants, Converter.Printer, Office_TLB, Access_TLB, UDC_TLB; procedure ToTiff(p_Printer: PrinterDriver; p_InputFile, p_OutputFile: String); implementation procedure ToTiff(p_Printer: PrinterDriver; p_InputFile, p_OutputFile: String); var AccessApp : AccessApplication; begin AccessApp := CoAccessApplication.Create; AccessApp.Visible := False; try AccessApp.OpenCurrentDatabase(p_InputFile, True, ''); AccessApp.RunCommand(acCmdQuickPrint); AccessApp.CloseCurrentDatabase; finally AccessApp.Quit(acQuitSaveNone); end; end; end.

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  • Building a many-to-many db schema using only an unpredictable number of foreign keys

    - by user1449855
    Good afternoon (at least around here), I have a many-to-many relationship schema that I'm having trouble building. The main problem is that I'm only working with primary and foreign keys (no varchars or enums to simplify things) and the number of many-to-many relationships is not predictable and can increase at any time. I looked around at various questions and couldn't find something that directly addressed this issue. I split the problem in half, so I now have two one-to-many schemas. One is solved but the other is giving me fits. Let's assume table FOO is a standard, boring table that has a simple primary key. It's the one in the one-to-many relationship. Table BAR can relate to multiple keys of FOO. The number of related keys is not known beforehand. An example: From a query FOO returns ids 3, 4, 5. BAR needs a unique key that relates to 3, 4, 5 (though there could be any number of ids returned) The usual join table does not work: Table FOO_BAR primary_key | foo_id | bar_id | Since FOO returns 3 unique keys and here bar_id has a one-to-one relationship with foo_id. Having two join tables does not seem to work either, as it still can't map foo_ids 3, 4, 5 to a single bar_id. Table FOO_TO_BAR primary_key | foo_id | bar_to_foo_id | Table BAR_TO_FOO primary_key | foo_to_bar_id | bar_id | What am I doing wrong? Am I making things more complicated than they are? How should I approach the problem? Thanks a lot for the help.

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  • Libraries for developing NCPDP SCRIPT based systems (a standard for e-prescribing)

    - by Kaveh Shahbazian
    What are (based on experiences) best (commercial or open source) libraries for developing NCPDP-based systems? Background: NCPDP (National Council for Prescription Drug Programs) is a not-for-profit, ANSI-accredited, standards development organization. One of it's standards is the SCRIPT Standard for Electronic Prescribing, which allows PHARMACY, PRESCRIBER (i.e. Physician) and PAYERS (patient or more often insurer) communicate. So the SCRIPT standard is about data transmission. Problem: One step in implementing such systems is to develop models for data based on SCRIPT standard. These models should have utilities for serializing/deserializing to/from SCRIPT binary format and SCRIPT XML format (there are two distinct formats here; both must be supported). Here rises the problem (for me at least). To develop this subsystem for handling the model, implementing serializing and deserializing facilities and keep it uptodate with the SCRIPT standard specifications is a lot of work; it needs it's own team and team management issues (to support a standard implementation). So I am looking for a solution to this problem; to keep standard implementation out of the way and focusing on main problems. Thanks to all (Thankyou Freiheit for your hints!) Edit 2: Thanks to all for help! NCPDP (National Council for Prescription Drug Programs) is an standard for e-prescribing. It defines two formats for message transmission: binary and XML. Implementing XML is somehow easier because it is a standard format which in turn gives us more tooling options. The binary format has a very big specification and time-consuming to implement. I did not find an open source solution to work with. So I am looking for commercial alternatives. Edit 1: Please guide me; what's wrong with this question?

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  • ASP.NET lock thread method

    - by Peter
    Hello, I'm developing an ASP.NET forms webapplication using C#. I have a method which creates a new Order for a customer. It looks similar to this; private string CreateOrder(string userName) { // Fetch current order Order order = FetchOrder(userName); if (order.OrderId == 0) { // Has no order yet, create a new one order.OrderNumber = Utility.GenerateOrderNumber(); order.Save(); } return order; } The problem here is, it is possible that 1 customer in two requests (threads) could cause this method to be called twice while another thread is also inside this method. This can cause two orders to be created. How can I properly lock this method, so it can only be executed by one thread at a time per customer? I tried; Mutex mutex = null; private string CreateOrder(string userName) { if (mutex == null) { mutex = new Mutex(true, userName); } mutex.WaitOne(); // Code from above mutex.ReleaseMutex(); mutex = null; return order; } This works, but on some occasions it hangs on WaitOne and I don't know why. Is there an error, or should I use another method to lock? Thanks

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  • Splitting an image in GWT results in unwanted white space

    - by rancidfishbreath
    I am using GWT 2.03 and am have an image that I want to place partially in an area with a background and partially above a background. I am using a FlexTable to try to accomplish this and have used GIMP to cut the image into two sections. I am trying to load the top part of the image into row 0 and the bottom part of the image into row 1. I set the alignment of the top image to ALIGN_BOTTOM but there is a bit of space at the bottom of cell and so the two parts of the picture don't touch. Here is an image showing what I am talking about. I set the background of the cell to be yellow show where the cell boundaries are. The bottom image and background are rendering correctly. Here is the relevant code snippet: FlexTable table = new FlexTable(); table.setCellSpacing(0); table.setCellPadding(0); table.setBorderWidth(0); FlexCellFormatter formatter = table.getFlexCellFormatter(); table.setWidget(0, 0, topImage); formatter.setStyleName(0, 0, "topImageStyle"); formatter.setVerticalAlignment(0, 0, HasVerticalAlignment.ALIGN_BOTTOM); table.setWidget(1, 0, bottomImage); formatter.setStyleName(1, 0, "bottomImageStyle"); How can I get rid of that space between my image and the cell boundary?

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  • ExecutorService - scaling

    - by Stanciu Alexandru-Marian
    I am trying to write a program in Java using ExecutorService and it's function invokeAll. My question is: does the invokeAll functions solve the tasks simultaneously? I mean, if i have two processors, there will be two workers in the same time? Because a can't make it to scale correct. It takes the same time to complete the problem if i give newFixedThreadPool(2) or 1. List<Future<PartialSolution>> list = new ArrayList<Future<PartialSolution>>(); Collection<Callable<PartialSolution>> tasks = new ArrayList<Callable<PartialSolution>>(); for(PartialSolution ps : wp) { tasks.add(new Map(ps, keyWords)); } list = executor.invokeAll(tasks); Map is a class that implements Callable and wp is a vector of Partial Solutions, a class that holds some informations in different times. Why doesn't it scale? What could be the problem? Thank you, Alex

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  • Optimizing MySQL update query

    - by Jernej Jerin
    This is currently my MySQL UPDATE query, which is called from program written in Java: String query = "UPDATE maxday SET DatePressureREL = (SELECT Date FROM ws3600 WHERE PressureREL = (SELECT MAX" + "(PressureREL) FROM ws3600 WHERE Date >= '" + Date + "') AND Date >= '" + Date + "' ORDER BY Date DESC LIMIT 1), " + "PressureREL = (SELECT PressureREL FROM ws3600 WHERE PressureREL = (SELECT MAX(PressureREL) FROM ws3600 " + "WHERE Date >= '" + Date + "') AND Date >= '" + Date + "' ORDER BY Date DESC LIMIT 1), ..."; try { s.execute(query); } catch (SQLException e) { System.out.println("SQL error"); } catch(Exception e) { e.printStackTrace(); } Let me explain first, what does it do. I have two tables, first is ws3600, which holds columns (Date, PressureREL, TemperatureOUT, Dewpoint, ...). Then I have second table, called maxday, which holds columns like DatePressureREL, PressureREL, DateTemperatureOUT, TemperatureOUT,... Now as you can see from an example, I update each column, the question is, is there a faster way? I am asking this, because I am calling MAX twice, first to find the Date for that value and secondly to find the actual value. Now I know that I could write like that: SELECT Date, PressureREL FROM ws3600 WHERE PressureREL = (SELECT MAX(PressureREL) FROM ws3600 WHERE Date >= '" + Date + "') AND Date >= '" + Date + "' ORDER BY Date DESC LIMIT 1 That way I get the Date of the max and the max value at the same time and then update with those values the data in maxday table. But the problem of this solution is, that I have to execute many queries, which as I understand takes alot more time compared to executing one long mysql query because of overhead in sending each query to the server. If there is no better way, which solution beetwen this two should I choose. The first, which only takes one query but is very unoptimized or the second which is beter in terms of optimization, but needs alot more queries which probably means that the preformance gain is lost because of overhead in sending each query to the server?

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  • Java inheritance question

    - by Milos
    I have an abstract class Airplane, and two classes PassengerAirplane and CargoAirplane, which extend class Airplane. I also have an interface Measurable, and two classes that implement it - People and Containers. So, Airplane can do many things on its own, and there is a method which allows measurable things to be added to the airplane (called addAMeasurableThing). The only difference between PassengerAirplane/CargoAirplane and just an Airplane is that addAMeasurableThing should only accept People / Containers, and not any kind Measurable things. How do I implement this? I tried doing: Airplane class: public abstract Airplane addAMeasurableThing (Measurable m, int position); PassengerAirplane class: public Airplane addAMeasurableThing (Measurable m, int position) { if (m instanceof People)... CargoAirplane class: public Airplane addAMeasurableThing (Measurable m, int position) { if (m instanceof Containers)... But when I was debugging it, I've noticed that addAMeasurableThing in the CargoAirplane class never gets called, because both methods have the same signature. So how can the appropriate PassengerAirplane/CargoAirplane's addAMeasurableThing be called, depending on the type of Measurable thing that is being passed on? Thanks!

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