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  • Would hybrid drive work after SSD failure

    - by lulalala
    Hybrid hard drive combines SSD with traditional hard drives. I know that SSD can fail much often than traditional hard drives. So I want to ask that, when the SSD part of the hybrid drive fails, would I still be able to use the traditional hard drive? If it won't work like that, then I will consider add-in SATA cards instead, as it delegates risk much better. EDIT: I guess it differs from model to model, so if yes what models would work. (I am evaluating Seagate DX for now)

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  • MS Access (Jet) transactions, workspaces & scope

    - by Eric G
    I am having trouble with committing a transaction (using Access 2003 DAO). It's acting as if I never had called BeginTrans -- I get error 3034 on CommitTrans, "You tried to commit or rollback a transaction without first beginning a transaction"; and the changes are written to the database (presumably because they were never wrapped in a transaction). However, BeginTrans is run, if you step through it. I am running it within the Access environment using the DBEngine(0) workspace. The tables I'm updating are all opened via a Jet database connection (to the same database) and updated using DAO.Recordset.update. The connection is opened before starting BeforeTrans. I'm not doing anything weird in the middle of the transaction like closing/opening connections or multiple workspaces etc. There is one nested transaction level (basically it's wrapping multiple transacted updates in an outer transaction, so if any fail they all fail). The inner transactions run without errors, it's the outer transaction that doesn't work. Here are a few things I've looked into and ruled out: The transaction is spread across several methods and BeginTrans and CommitTrans (and Rollback) are all in different places. But when I tried a simple test of running a transaction this way, it doesn't seem like this should matter. I thought maybe the database connection gets closed when it goes out of local scope, even though I have another 'global' reference to it (I'm never sure what DAO does with dbase connections to be honest). But this seems not to be the case -- right before the commit, the connection and its recordsets are alive (I can check their properties, EOF = False, etc.) My CommitTrans and Rollback are done within event callbacks. (Very basically, a parser program is throwing an 'onLoad' or 'onLoadFail' event at the end of parsing, which I am handling by either committing or rolling back the inserts I made during processing.) However, again, trying a simple test, it doesn't seem like this should matter. Any ideas why this isn't working for me? Thanks.

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  • Can I use a cheap inverter for my laptop?

    - by Georg
    I'm going to travel in a car this summer. It would be very nice if I could charge my laptop using the cigarette lighter. Because my computer is from Apple, there's no way to directly connect the two, therefore I need an inverter that provides 120V alternating current. There are many different models, ranging from very cheap to really expensive. The wave forms are: (from most expensive to cheapest) sine modified sine trapezoid square Can I use just any inverter or does it have to be a sine inverter? If so, what happens to my computer in case I use the wrong one. The laptop is a MacBook witch needs 60W.

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  • How to send Bluetooth audio to non-Bluetooth speakers?

    - by wonsungi
    In short, I am looking for a Bluetooth-3.5 mini stereo converter. What is this type of device called, and what are some of the best models (is there a difference in audio quality/lag)? I wish to connect some speakers (Altec Lansing inMotion IM7), which does not support Bluetooth, to my laptop (Lenovo X301) wirelessly. Currently, I can connect my laptop's headphone jack to the AUX jack on my speakers via a mini stereo cable. How do I replace this cable with some type of Bluetooth setup? I am not sure what this Bluetooth device is called. I thought I found something, but it actually does the opposite of what I need (3.5 mini stereo-Bluetooth). (My OS is Vista Enterprise, if that matters)

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  • Using wifi router as bridge to increase signal?

    - by overtherainbow
    A friend of mine lives in an appartment building whose structure is such that wifi signal is very weak. Even a USB key won't work. I was thinking of buying an entry-level wifi router and reconfigure it as a bridge to act as repeater. Would that increase the chance of getting a good signal, or I shouldn't bother? If experience shows that it does improve things significantly, is their another router I should look at besides the Linux-based Linksys models? Thank you.

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  • Lenovo Thinkpad SL500 and Keyboard Flex problem.

    - by nitbuntu
    I was testing a Thinkpad SL500 system at a local store and found the flexing of the keyboard to be quite a deal breaker for me; it was flexing quite prominently with very little pressure applied. I find it hard to believe that a business grade laptop should have this problem as a consumer grade laptop that I own (Dell Inspiron 1526) has very little keyboard flex and one needs to apply a lot of pressure to notice it. Is this a common issue with the SL500 or SL510 models of Thinkpad laptops? What about the Thinkpad R500, does this also suffer from similar issues?

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  • select all values from a dimension for which there are facts in all other dimensions

    - by ideasculptor
    I've tried to simplify for the purposes of asking this question. Hopefully, this will be comprehensible. Basically, I have a fact table with a time dimension, another dimension, and a hierarchical dimension. For the purposes of the question, let's assume the hierarchical dimension is zip code and state. The other dimension is just descriptive. Let's call it 'customer' Let's assume there are 50 customers. I need to find the set of states for which there is at least one zip code in which EVERY customer has at least one fact row for each day in the time dimension. If a zip code has only 49 customers, I don't care about it. If even one of the 50 customers doesn't have a value for even 1 day in a zip code, I don't care about it. Finally, I also need to know which zip codes qualified the state for selection. Note, there is no requirement that every zip code have a full data set - only that at least one zip code does. I don't mind making multiple queries and doing some processing on the client side. This is a dataset that only needs to be generated once per day and can be cached. I don't even see a particularly clean way to do it with multiple queries short of simply brute-force iteration, and there are a heck of a lot of 'zip codes' in the data set (not actually zip codes, but the there are approximately 100,000 entries in the lower level of the hierarchy and several hundred in the top level, so zipcode-state is a reasonable analogy)

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  • How might I wrap the FindXFile-style APIs to the STL-style Iterator Pattern in C++?

    - by BillyONeal
    Hello everyone :) I'm working on wrapping up the ugly innards of the FindFirstFile/FindNextFile loop (though my question applies to other similar APIs, such as RegEnumKeyEx or RegEnumValue, etc.) inside iterators that work in a manner similar to the Standard Template Library's istream_iterators. I have two problems here. The first is with the termination condition of most "foreach" style loops. STL style iterators typically use operator!= inside the exit condition of the for, i.e. std::vector<int> test; for(std::vector<int>::iterator it = test.begin(); it != test.end(); it++) { //Do stuff } My problem is I'm unsure how to implement operator!= with such a directory enumeration, because I do not know when the enumeration is complete until I've actually finished with it. I have sort of a hack together solution in place now that enumerates the entire directory at once, where each iterator simply tracks a reference counted vector, but this seems like a kludge which can be done a better way. The second problem I have is that there are multiple pieces of data returned by the FindXFile APIs. For that reason, there's no obvious way to overload operator* as required for iterator semantics. When I overload that item, do I return the file name? The size? The modified date? How might I convey the multiple pieces of data to which such an iterator must refer to later in an ideomatic way? I've tried ripping off the C# style MoveNext design but I'm concerned about not following the standard idioms here. class SomeIterator { public: bool next(); //Advances the iterator and returns true if successful, false if the iterator is at the end. std::wstring fileName() const; //other kinds of data.... }; EDIT: And the caller would look like: SomeIterator x = ??; //Construct somehow while(x.next()) { //Do stuff } Thanks! Billy3

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  • Is it safe to assert a functions return type?

    - by wb
    This question is related to this question. I have several models stored in a collection. I loop through the collection and validate each field. Based on the input, a field can either be successful, have an error or a warning. Is it safe to unit test each decorator and assert that the type of object returned is what you would expect based on the given input? I could perhaps see this being an issue for a language with function return types since my validation function can return one of 3 types. This is the code I'm fiddling with: <!-- #include file = "../lib/Collection.asp" --> <style type="text/css"> td { padding: 4px; } td.error { background: #F00F00; } td.warning { background: #FC0; } </style> <% Class UserModel Private m_Name Private m_Age Private m_Height Public Property Let Name(value) m_Name = value End Property Public Property Get Name() Name = m_Name End Property Public Property Let Age(value) m_Age = value End Property Public Property Get Age() Age = m_Age End Property Public Property Let Height(value) m_Height = value End Property Public Property Get Height() Height = m_Height End Property End Class Class NameValidation Private m_Name Public Function Init(name) m_Name = name End Function Public Function Validate() Dim validationObject If Len(m_Name) < 5 Then Set validationObject = New ValidationError Else Set validationObject = New ValidationSuccess End If validationObject.CellValue = m_Name Set Validate = validationObject End Function End Class Class AgeValidation Private m_Age Public Function Init(age) m_Age = age End Function Public Function Validate() Dim validationObject If m_Age < 18 Then Set validationObject = New ValidationError ElseIf m_Age = 18 Then Set validationObject = New ValidationWarning Else Set validationObject = New ValidationSuccess End If validationObject.CellValue = m_Age Set Validate = validationObject End Function End Class Class HeightValidation Private m_Height Public Function Init(height) m_Height = height End Function Public Function Validate() Dim validationObject If m_Height > 400 Then Set validationObject = New ValidationError ElseIf m_Height = 324 Then Set validationObject = New ValidationWarning Else Set validationObject = New ValidationSuccess End If validationObject.CellValue = m_Height Set Validate = validationObject End Function End Class Class ValidationError Private m_CSSClass Private m_CellValue Public Property Get CSSClass() CSSClass = "error" End Property Public Property Let CellValue(value) m_CellValue = value End Property Public Property Get CellValue() CellValue = m_CellValue End Property End Class Class ValidationWarning Private m_CSSClass Private m_CellValue Public Property Get CSSClass() CSSClass = "warning" End Property Public Property Let CellValue(value) m_CellValue = value End Property Public Property Get CellValue() CellValue = m_CellValue End Property End Class Class ValidationSuccess Private m_CSSClass Private m_CellValue Public Property Get CSSClass() CSSClass = "" End Property Public Property Let CellValue(value) m_CellValue = value End Property Public Property Get CellValue() CellValue = m_CellValue End Property End Class Class ModelValidator Public Function ValidateModel(model) Dim modelValidation : Set modelValidation = New CollectionClass ' Validate name Dim name : Set name = New NameValidation name.Init model.Name modelValidation.Add name ' Validate age Dim age : Set age = New AgeValidation age.Init model.Age modelValidation.Add age ' Validate height Dim height : Set height = New HeightValidation height.Init model.Height modelValidation.Add height Dim validatedProperties : Set validatedProperties = New CollectionClass Dim modelVal For Each modelVal In modelValidation.Items() validatedProperties.Add modelVal.Validate() Next Set ValidateModel = validatedProperties End Function End Class Dim modelCollection : Set modelCollection = New CollectionClass Dim user1 : Set user1 = New UserModel user1.Name = "Mike" user1.Age = 12 user1.Height = 32 modelCollection.Add user1 Dim user2 : Set user2 = New UserModel user2.Name = "Phil" user2.Age = 18 user2.Height = 432 modelCollection.Add user2 Dim user3 : Set user3 = New UserModel user3.Name = "Michele" user3.Age = 32 user3.Height = 324 modelCollection.Add user3 ' Validate all models in the collection Dim modelValue Dim validatedModels : Set validatedModels = New CollectionClass For Each modelValue In modelCollection.Items() Dim objModelValidator : Set objModelValidator = New ModelValidator validatedModels.Add objModelValidator.ValidateModel(modelValue) Next %> <table> <tr> <td>Name</td> <td>Age</td> <td>Height</td> </tr> <% Dim r, c For Each r In validatedModels.Items() %><tr><% For Each c In r.Items() %><td class="<%= c.CSSClass %>"><%= c.CellValue %></td><% Next %></tr><% Next %> </table> Thank you.

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  • Dell V105 printer and OS X 10.6

    - by James
    I am trying to get a Dell V105 printer to work with my iMac. It is running 10.6 and I have installed all the drivers on the Snow Leopard disk. I believe there is no official Dell driver but I have also heard the Dell printers are made by third parties that may sell the same printer under different names. There a quite a few Lexmark models that seem to look very similar and I have tried setting the driver to the 2600 series that looks very similar but that has not enabled me to print. Although it claims to give me the supply levels correctly. Can anyone help? Thanks for your time

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  • Problem with linking in gcc

    - by chitra
    I am compiling a program in which a header file is defined in multiple places. Contents of each of the header file is different, though the variable names are the same internal members within the structures are different . Now at the linking time it is picking up from a library file which belongs to a different header not the one which is used during compilation. Due to this I get an error at link time. Since there are so many libraries with the same name I don't know which library is being picked up. I have lot of oems and other customized libraries which are part of this build. I checked out the options in gcc which talks about selecting different library files to be included. But no where I am able to see an option which talks about which libraries are being picked up the linker. If the linker is able to find more than one library file name, then which does the linker pick up is something which I am not able to understand. I don't want to specify any path, rather I want to understand how the linker is resolving the multiple libraries that it is able to locate. I tried putting -v option, but that doesn't list out the path from which the gcc picks up the library. I am using gcc on linux. Any help in this regard is highly appreciated. Regards, Chitra

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  • How to start with entity framework and service oriented architecture?

    - by citronas
    At work I need to create a new web application, that will connection to an MySql Database. (So far I only have expercience with Linq-To-Sql classes and MSSQL Servers.) My superior tells me to use the entity framework (he probably refers to Linq-To-Entity) and provide everything as a service based architecture. Unfortunatly nobody at work has experience with that framework and with a real nice server oriented architecture. (till now no customer wanted to pay for architecture that he can't see. This speficic project I'm leading will be long-term, meaning multiple years, so it would be best to design it the way, that multiple targetting plattforms like asp.net, c# wpf, ... could use it) For now, the main target plattform is ASP.net So I do have the following questions: 1) Where can I read best what's really behind service oriented architecture (but for now beginner tutorials work fine as well) and how to do it in best practise? 2) So far I can't seem a real difference between Linq-To-Sql classes and the information I've google so far on the 'entity framework'. So, whats the difference? Where do I find nice tutorials for it. 3) Is there any difference in the entity framework regarding the database server (MSSQL or MySQL). If not, does that mean that code snipperts I will stumble across will word database independent? 4) I do you Visual Studio 2010. Do I have to regard something specific?

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  • Resource mapping in a Ruby on Rails URL (RESTful API)

    - by randombits
    I'm having a bit of difficulty coming up with the right answer to this, so I will solicit my problem here. I'm working on a RESTFul API. Naturally, I have multiple resources, some of which consist of parent to child relationships, some of which are stand alone resources. Where I'm having a bit of difficulty is figuring out how to make things easier for the folks who will be building clients against my API. The situation is this. Hypothetically I have a 'Street' resource. Each street has multiple homes. So Street :has_many to Homes and Homes :belongs_to Street. If a user wants to request an HTTP GET on a specific home resource, the following should work: http://mymap/streets/5/homes/10 That allows a user to get information for a home with the id 10. Straight forward. My question is, am I breaking the rules of the book by giving the user access to: http://mymap/homes/10 Technically that home resource exists on its own without the street. It makes sense that it exists as its own entity without an encapsulating street, even though business logic says otherwise. What's the best way to handle this?

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  • How do I pick a motherboard?

    - by EpsilonVector
    When building your own computer one part was always a mystery to me: the motherboard. Picking a CPU/GPU/memory is easy- you just figure out where the various chips are in the low end to high end scale, do a little market research on what current games demand, and pick the parts from their respective continuums of low-to-high-end models. A mother board is more complicated though. Its features are not as obvious as "this motherboard is faster than that motherboard". Now you need to deal with part compatibilities, bus speeds, maybe power management stuff, etc. I'm interested in a short guide for selecting a motherboard, especially- what pitfalls to avoid (for example, can bus speed become a bottleneck?). To clarify: I'm not looking for motherboard recommendations. I'm looking for guidance regarding how to evaluate the fitness of a motherboard given the rest of the computer parts.

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  • Escape whitespace in paths using nautilus script

    - by Tommy Brunn
    I didn't think this would be as tricky as it turned out to be, but here I am. I'm trying to write a Nautilus script in Python to upload one or more images to Imgur just by selecting and right clicking them. It works well enough with both single images and multiple images - as long as they don't contain any whitespace. In fact, you can upload a single image containing whitespace, just not multiple ones. The problem is that NAUTILUS_SCRIPT_SELECTED_FILE_PATHS returns all the selected files and directories as a space separated string. So for example, it could look like this: print os.environment['NAUTILUS_SCRIPT_SELECTED_FILE_PATHS'] /home/nevon/Desktop/test image.png /home/nevon/Desktop/test.jpg What I need is a way to -either in bash or Python- escape the spaces in the path - but not the spaces that delimit different items. Either that, or a way to put quotation marks around each item. The ultimate solution would be if I could do that in bash and then send the items as separate arguments to my python script. Something like: python uploader.py /home/nevon/Desktop/test\ image.png /home/nevon/Desktop/test.jpg I've tried RTFM'ing, but there doesn't seem to be a lot of good solutions for this. At least not that I've found. Any ideas?

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  • Why would certain browsers request all pages on my ASP.Net Web site twice?

    - by Deane
    Firefox is issuing duplicate requests to my ASP.Net web site. It will request a page, get the response, then immediately issue the same request again (well, almost the same -- see below). This happens on every page of this particular Web site (but not any others). IE does not do this, but Chrome also does this. I have confirmed that there is no Location header in the response, and no Javascript or meta tag in the page which would cause the page to be re-requested (if any of these were true, IE would be re-requesting pages as well). I have confirmed this behavior on multiple Firefox installs on multiple machines. Versions vary, but all are 3.x. The only difference between the two requests is the Accepts header. For the first request, it looks like this: Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 For the second request, it looks like this: Accept: */* The Content-Type response header in all cases is: Content-Type: text/html; charset=utf-8 Something else odd -- even though Firefox requests the page twice, it uses the first response and discards the second. I put a counter on a page that increments with every request. I can watch the responses come back (via the Charles proxy). Firefox will get a "1" the first time, and a "2" the second time. Yet it will display the "1," for some reason. Chrome exhibits this exact same behavior. I suspect it's a protocol-level issue, given the difference in Accepts header, but I've never seen this before.

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  • MVC design in Cocoa - are all 3 always necessary? Also: naming conventions, where to put Controller

    - by Nektarios
    I'm new to MVC although I've read a lot of papers and information on the web. I know it's somewhat ambiguous and there are many different interpretations of MVC patterns.. but the differences seem somewhat minimal My main question is - are M, V, and C always going to be necessary to be doing this right? I haven't seen anyone address this in anything I've read. Examples (I'm working in Cocoa/Obj-c although that shouldn't much matter).. 1) If I have a simple image on my GUI, or a text entry field that is just for a user's convenience and isn't saved or modified, these both would be V (view) but there's no M (no data and no domain processing going on), and no C to bridge them. So I just have some aspects that are "V" - seems fine 2) I have 2 different and visible windows that each have a button on them labeled as "ACTIVATE FOO" - when a user clicks the button on either, both buttons press in and change to say "DEACTIVATE FOO" and a third window appears with label "FOO". Clicking the button again will change the button on both windows to "ACTIVATE FOO" and will remove the third "FOO" window. In this case, my V consists of the buttons on both windows, and I guess also the third window (maybe all 3 windows). I definitely have a C, my Controller object will know about these buttons and windows and will get their clicks and hold generic states regarding windows and buttons. However, whether I have 1 button or 10 button, my window is called "FOO" or my window is called "BAR", this doesn't matter. There's no domain knowledge or data here - just control of views. So in this example, I really have "V" and "C" but no "M" - is that ok? 3) Final example, which I am running in to the most. I have a text entry field as my View. When I enter text in this, say a number representing gravity, I keep it in a Model that may do things like compute physics of a ball while taking in to account my gravity parameter. Here I have a V and an M, but I don't understand why I would need to add a C - a controller would just accept the signals from the View and pass it along to the Model, and vice versa. Being as the C is just a pure passthrough, it's really "junk" code and isn't making things any more reusable in my opinion. In most situations, when something changes I will need to change the C and M both in nearly identical ways. I realize it's probably an MVC beginner's mistake to think most situations call for only V and M.. leads me in to next subject 4) In Cocoa / Xcode / IB, I guess my Controllers should always be an instantiated object in IB? That is, I lay all of my "V" components in IB, and for each collection of View objects (things that are related) I should have an instantiated Controller? And then perhaps my Models should NOT be found in IB, and instead only found as classes in Xcode that tie in with Controller code found there. Is this accurate? This could explain why you'd have a Controller that is not really adding value - because you are keeping consistent.. 5) What about naming these things - for my above example about FOO / BAR maybe something that ends in Controller would be the C, like FancyWindowOpeningController, etc? And for models - should I suffix them with like GravityBallPhysicsModel etc, or should I just name those whatever I like? I haven't seen enough code to know what's out there in the wild and I want to get on the right track early on Thank you in advance for setting me straight or letting me know I'm on the right track. I feel like I'm starting to get it and most of what I say here makes sense, but validation of my guessing would help me feel confident..

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  • Mercurial CLI is slow in C#?

    - by pATCheS
    I'm writing a utility in C# that will make managing multiple Mercurial repositories easier for the way my team is using it. However, it seems that there is always about a 300 to 400 millisecond delay before I get anything back from hg.exe. I'm using the code below to run hg.exe and hgtk.exe (TortoiseHg's GUI). The code currently includes a Stopwatch and some variables for timing purposes. The delay is roughly the same on multiple runs within the same session. I have also tried specifying the exact path of hg.exe, and got the same result. static string RunCommand(string executable, string path, string arguments) { var psi = new ProcessStartInfo() { FileName = executable, Arguments = arguments, WorkingDirectory = path, UseShellExecute = false, RedirectStandardError = true, RedirectStandardInput = true, RedirectStandardOutput = true, WindowStyle = ProcessWindowStyle.Maximized, CreateNoWindow = true }; var sbOut = new StringBuilder(); var sbErr = new StringBuilder(); var sw = new Stopwatch(); sw.Start(); var process = Process.Start(psi); TimeSpan firstRead = TimeSpan.Zero; process.OutputDataReceived += (s, e) => { if (firstRead == TimeSpan.Zero) { firstRead = sw.Elapsed; } sbOut.Append(e.Data); }; process.ErrorDataReceived += (s, e) => sbErr.Append(e.Data); process.BeginOutputReadLine(); process.BeginErrorReadLine(); var eventsStarted = sw.Elapsed; process.WaitForExit(); var processExited = sw.Elapsed; sw.Reset(); if (process.ExitCode != 0 || sbErr.Length > 0) { Error.Mercurial(process.ExitCode, sbOut.ToString(), sbErr.ToString()); } return sbOut.ToString(); } Any ideas on how I can speed things up? As it is, I'm going to have to do a lot of caching in addition to threading to keep the UI snappy.

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  • Entity Framework and WCf

    - by Nihilist
    Hi I am little confused on designing WCf services with EF. When using WCf and EF, where do we draw this line on what properties to return and what not to with the entity. Here is my scenario I have User. Here are the relations. User [1 to many] Address, User [ 1 to many] Email, User [ 1 to many] Phone So now on the webform, on page1 I can edit user information. say I can edit few properties on the user entity and can also edit address, phone, email entities[ like add / delete and update any] On page2, i can only update user properties and nothing related to navigation properties [ address, email, phone]. So when I return the User Entity [ OR DTO] should i be returning the navigation properties too? Or should the client make multiple calls to get navigation properites. Also, how does it go with Save? Like should the client make multiple calls to save user and related entites or just one call to save the graph? Lets say, if I just have a Save(User user) [ where user has all the related entities too] both page1 and page2 will call save and pass me the user. but one page1 i will need a lot more information. but on page2 i just need the user primitive properties. So my question is, where do we draw this line, how do we design theses services ? Is the WCF operation designed on the page and the fields it has ? I am hoping i explained my problem well enough.

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  • Multi-reader IPC solution?

    - by gct
    I'm working on a framework in C++ (just for fun for now), that lets the user write plugins that use a standard API to stream data between each other. There's going to be three basic transport mechanisms for the data: files, sockets, and some kind of IPC piping system. The system is set up so that for the non-file transport, each stream can have multiple readers. IE once a server socket it setup, multiple computers can connect and stream the data. I'm a little stuck at the multi-reader IPC system though. All my plugins run in threads so they live in the same address space, so some kind of shared memory system would work fine, I was thinking I'd write my own circular buffer with a write pointer and read pointers chassing it around the buffer, but I have my doubts that I can achieve the same performance as something like linux pipes. I'm curious what people would suggest for a multi-reader solution to something like this? Is the overhead for pipes or domain sockets low enough that I could just open a connection to each reader and issue separate writes to each reader? This is intended to be significant volumes of data (tens of mega-samples/sec), so performance is a must.

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  • What are the elegant ways to do MixIns in Python?

    - by Slava Vishnyakov
    I need to find an elegant way to do 2 kinds of MixIns. First: class A(object): def method1(self): do_something() Now, a MixInClass should make method1 do this: do_other() - A.method1() - do_smth_else() - i.e. basically "wrap" the older function. I'm pretty sure there must exist a good solution to this. Second: class B(object): def method1(self): do_something() do_more() In this case, I want MixInClass2 to be able to inject itself between do_something() and do_more(), i.e.: do_something() - MixIn.method1 - do_more(). I understand that probably this would require modifying class B - that's ok, just looking for simplest ways to achieve this. These are pretty trivial problems and I actually solved them, but my solution is tainted. Fisrt one by using self._old_method1 = self.method1(); self.method1() = self._new_method1(); and writing _new_method1() that calls to _old_method1(). Problem: multiple MixIns will all rename to _old_method1 and it is inelegant. Second MixIn one was solved by creating a dummy method call_mixin(self): pass and injecting it between calls and defining self.call_mixin(). Again inelegant and will break on multiple MixIns.. Any ideas?

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  • How to design data storage for partitioned tagging system?

    - by Morgan Cheng
    How to design data storage for huge tagging system (like digg or delicious)? There is already discussion about it, but it is about centralized database. Since the data is supposed to grow, we'll need to partition the data into multiple shards soon or later. So, the question turns to be: How to design data storage for partitioned tagging system? The tagging system basically has 3 tables: Item (item_id, item_content) Tag (tag_id, tag_title) TagMapping(map_id, tag_id, item_id) That works fine for finding all items for given tag and finding all tags for given item, if the table is stored in one database instance. If we need to partition the data into multiple database instances, it is not that easy. For table Item, we can partition its content with its key item_id. For table Tag, we can partition its content with its key tag_id. For example, we want to partition table Tag into K databases. We can simply choose number (tag_id % K) database to store given tag. But, how to partition table TagMapping? The TagMapping table represents the many-to-many relationship. I can only image to have duplication. That is, same content of TagMappping has two copies. One is partitioned with tag_id and the other is partitioned with item_id. In scenario to find tags for given item, we use partition with tag_id. If scenario to find items for given tag, we use partition with item_id. As a result, there is data redundancy. And, the application level should keep the consistency of all tables. It looks hard. Is there any better solution to solve this many-to-many partition problem?

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  • Sharing a COM port over TCP

    - by guinness
    What would be a simple design pattern for sharing a COM port over TCP to multiple clients? For example, a local GPS device that could transmit co-ordinates to remote hosts in realtime. So I need a program that would open the serial port and accept multiple TCP connections like: class Program { public static void Main(string[] args) { SerialPort sp = new SerialPort("COM4", 19200, Parity.None, 8, StopBits.One); Socket srv = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); srv.Bind(new IPEndPoint(IPAddress.Any, 8000)); srv.Listen(20); while (true) { Socket soc = srv.Accept(); new Connection(soc); } } } I would then need a class to handle the communication between connected clients, allowing them all to see the data and keeping it synchronized so client commands are received in sequence: class Connection { static object lck = new object(); static List<Connection> cons = new List<Connection>(); public Socket socket; public StreamReader reader; public StreamWriter writer; public Connection(Socket soc) { this.socket = soc; this.reader = new StreamReader(new NetworkStream(soc, false)); this.writer = new StreamWriter(new NetworkStream(soc, true)); new Thread(ClientLoop).Start(); } void ClientLoop() { lock (lck) { connections.Add(this); } while (true) { lock (lck) { string line = reader.ReadLine(); if (String.IsNullOrEmpty(line)) break; foreach (Connection con in cons) con.writer.WriteLine(line); } } lock (lck) { cons.Remove(this); socket.Close(); } } } The problem I'm struggling to resolve is how to facilitate communication between the SerialPort instance and the threads. I'm not certain that the above code is the best way forward, so does anybody have another solution (the simpler the better)?

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  • Django sub-applications & module structure

    - by Rob Golding
    I am developing a Django application, which is a large system that requires multiple sub-applications to keep things neat. Therefore, I have a top level directory that is a Django app (as it has an empty models.py file), and multiple subdirectories, which are also applications in themselves. The reason I have laid my application out in this way is because the sub-applications are separated, but they would never be used on their own, outside the parent application. It therefore makes no sense to distribute them separately. When installing my application, the settings file has to include something like this: INSTALLED_APPS = ( ... 'myapp', 'myapp.subapp1', 'myapp.subapp2', ... ) ...which is obviously suboptimal. This also has the slightly nasty result of requiring that all the sub-applications are referred to by their "inner" name (i.e. subapp1, subapp2 etc.). For example, if I want to reset the database tables for subapp1, I have to type: python manage.py reset subapp1 This is annoying, especially because I have a sub-app called core - which is likely to conflict with another application's name when my application is installed in a user's project. Am I doing this completely wrongly, or is there away to force these "inner" apps to be referred to by their full name?

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  • Safari Web Inspector is not updating when I update an element with ajax

    - by Ashley
    I have a checkout page http://www.oipolloi.com/oipolloi/shop/viewbasket.php with multiple ajax calls after certain items update (EG look up postage cost when country is changed, then update discount boxes etc). I've asked for help in the past about the best method of making sure ALL calls have returned before allowing the form to be submitted for payment processing: http://stackoverflow.com/questions/2290372/how-do-i-prevent-form-submission-until-multiple-ajax-calls-have-finished-jquery I was fairly happy that the logic in the finished solution was correct, but I have still been receiving reports that people using Safari are able to submit the form without the ajax calls returning properly. I have tried using the Safari Web Inspector to debug but it seems that when you Inspect Element, then update an element with an ajax call, the Inspector doesn't seem to update. I am updating hidden fields, so it's hard to be able to know whether the problem lies with the DOM not being updated properly, or the Inspector itself. I'm using Safari 4.0.5 on PC and you can reproduce the problem above by looking for a div id="countryFieldsBilling" with Web Inspector. It should contain three hidden fields that are initially empty. You can try to make it update (or not) by choosing a country from the select menu at the bottom of 'Shipping Address' box, and then clicking the 'click to use Shipping Address' link at the top of the 'Billing Address' just below. The behaviour I am seeing is that the country chosen in the shipping select gets copied correctly to the country in the billing select, but the hidden inputs in the Web Inspector do not get updated. When these hidden inputs do not get updated, this causes the problem that Mac Safari users report. If you can let me know either how to get Web Inspector to work properly, or something else I may have missed in the behaviour of Mac Safari that may cause these problems, that would be great. Thanks in advance

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