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  • Can parser combination be made efficient?

    - by Jon Harrop
    Around 6 years ago, I benchmarked my own parser combinators in OCaml and found that they were ~5× slower than the parser generators on offer at the time. I recently revisited this subject and benchmarked Haskell's Parsec vs a simple hand-rolled precedence climbing parser written in F# and was surprised to find the F# to be 25× faster than the Haskell. Here's the Haskell code I used to read a large mathematical expression from file, parse and evaluate it: import Control.Applicative import Text.Parsec hiding ((<|>)) expr = chainl1 term ((+) <$ char '+' <|> (-) <$ char '-') term = chainl1 fact ((*) <$ char '*' <|> div <$ char '/') fact = read <$> many1 digit <|> char '(' *> expr <* char ')' eval :: String -> Int eval = either (error . show) id . parse expr "" . filter (/= ' ') main :: IO () main = do file <- readFile "expr" putStr $ show $ eval file putStr "\n" and here's my self-contained precedence climbing parser in F#: let rec (|Expr|) (P(f, xs)) = Expr(loop (' ', f, xs)) and shift oop f op (P(g, xs)) = let h, xs = loop (op, g, xs) loop (oop, f h, xs) and loop = function | ' ' as oop, f, ('+' | '-' as op)::P(g, xs) | (' ' | '+' | '-' as oop), f, ('*' | '/' as op)::P(g, xs) | oop, f, ('^' as op)::P(g, xs) -> let h, xs = loop (op, g, xs) let op = match op with | '+' -> (+) | '-' -> (-) | '*' -> (*) | '/' -> (/) | '^' -> pown loop (oop, op f h, xs) | _, f, xs -> f, xs and (|P|) = function | '-'::P(f, xs) -> let f, xs = loop ('~', f, xs) P(-f, xs) | '('::Expr(f, ')'::xs) -> P(f, xs) | c::xs when '0' <= c && c <= '9' -> P(int(string c), xs) My impression is that even state-of-the-art parser combinators waste a lot of time back tracking. Is that correct? If so, is it possible to write parser combinators that generate state machines to obtain competitive performance or is it necessary to use code generation?

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  • Direct show video renderers suck?

    - by Daniel
    So I've been looking into the world of media playback for windows and I've started making a C# Media Player using DirectShow. I started off using the VRM-7 windowed video renderer and it was brilliant except it had a couple of small problems (multi monitors, fullscreen). But after some research I found that it's deprecated and I should be using VRM9. So I changed it to use VRM9 windowless then found out that was an old post rofl _< so finally I'm using Vista/Win7 (or XP .net 3) Enhanced Video Renderer (EVR) which is apparently the most up to date Microsoft video renderer and has all the flashy performance/quality things added to it. (tbh I haven't noticed any difference but maybe I need a blue-ray or HQ video to notice it). With using EVR everything is working fine except resizing the video. Its really laggy/choppy/teary and problem something to do with its frame queueing mechanism. To demonstrate my problem open up windows media player classic. View - Options - Playback - output Chose the "EVR" DirectShow Video renderer Now restart wmp class and play a video, while it's playing click and drag a corner to resize it. You'll notice its horribly laggy. This is the exact same problem i am having. But if you chose "EVR Custom Pres. *" or EVR Sync *" resizing works beautifully! So i tried googling around for anything about EVR resizing issues and how to fix it but i couldn't believe how little i could find. I'm guessing "Custom Pres." stands for "Custom Presenter" which sounds like they made their own. Also you'll notice on the right hand size when you swap between EVR and the other EVR's the Resizer drop down on the right greys out. So basically I wan't to know how I can fix this retarded resizing problem and is there any decent documentation out there? There is a fair bit for VMR7/9 but not much for EVR. I downloaded the DirectX SDK which apparently has samples but it was a waste of 500mb of bandwidth as it had nothing relevant. Perhaps there is some way to force it not queueing up frames if that is the problem? If you want code say the word and I'll paste some in. But it's really quite simple and nothing much happens, i'm convinced it's a problem with the EVR renderer. EDIT: Oh and one other thing, what does VLC use? If you go into vlc options and change the renderer to anything but default, they all suck. So is it using VMR7? Or its own?

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  • DirectShow EVR resizing window problem

    - by Daniel
    So I've been looking into the world of media playback for windows and I've started making a C# Media Player using DirectShow. I started off using the VRM-7 windowed video renderer and it was brilliant except it had a couple of small problems (multi monitors, fullscreen). But after some research I found that it's deprecated and I should be using VRM9. So I changed it to use VRM9 windowless then found out that was an old post rofl _< so finally I'm using Vista/Win7 (or XP .net 3) Enhanced Video Renderer (EVR) which is apparently the most up to date Microsoft video renderer and has all the flashy performance/quality things added to it. (tbh I haven't noticed any difference but maybe I need a blue-ray or HQ video to notice it). With using EVR everything is working fine except resizing the video. Its really laggy/choppy/teary and probably something to do with its frame queueing mechanism. To demonstrate my problem open up windows media player classic. View - Options - Playback - output Chose the "EVR" DirectShow Video renderer Now restart wmp class and play a video, while it's playing click and drag a corner to resize it. You'll notice its horribly laggy. This is the exact same problem i am having. But if you chose "EVR Custom Pres. *" or EVR Sync *" resizing works beautifully! So i tried googling around for anything about EVR resizing issues and how to fix it but i couldn't believe how little i could find. I'm guessing "Custom Pres." stands for "Custom Presenter" which sounds like they made their own. Also you'll notice on the right hand size when you swap between EVR and the other EVR's the Resizer drop down on the right greys out. So basically I wan't to know how I can fix this retarded resizing problem and is there any decent documentation out there? There is a fair bit for VMR7/9 but not much for EVR. I downloaded the DirectX SDK which apparently has samples but it was a waste of 500mb of bandwidth as it had nothing relevant. Perhaps there is some way to force it not queueing up frames if that is the problem? If you want code say the word and I'll paste some in. But it's really quite simple and nothing much happens, i'm convinced it's a problem with the EVR renderer. EDIT: Oh and one other thing, what does VLC use? If you go into vlc options and change the renderer to anything but default, they all suck. So is it using VMR7? Or its own?

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  • USB windows xp final USB access issues

    - by Lex Dean
    I basically understand you C++ people, Please do not get distracted because I'm writing in Delphi. I have a stable USB Listing method that accesses all my USB devices I get the devicepath, and this structure: TSPDevInfoData = packed record Size: DWORD; ClassGuid: TGUID; DevInst: DWORD; // DEVINST handle Reserved: DWord; end; I get my ProductID and VenderID successfully from my DevicePath Lists all USB devices connected to the computer at the time That enables me to access the registry data to each device in a stable way. What I'm lacking is a little direction Is friendly name able to be written inside the connected USB Micro chips by the firmware programmer? (I'm thinking of this to identify the device even further, or is this to help identify Bulk data transfer devices like memory sticks and camera's) Can I use SPDRP_REMOVAL_POLICY_OVERRIDE to some how reset these polices What else can I do with the registry details. Identifying when some one unplugs a device The program is using (in windows XP standard) I used a documented windows event that did not respond. Can I read a registry value to identify if its still connected? using CreateFileA (DevicePath) to send and receive data I have read when some one unplugs in the middle of a data transfer its difficult clearing resources. what can IoCreateDevice do for me and how does one use it for that task This two way point of connection status and system lock up situations is very concerning. Has some one read anything about this subject recently? My objectives are to 1. list connected USB devices identify a in development Micro Controller from everything else send and receive data in a stable and fast way to the limits of the controller No lock up's transferring data Note I'm not using any service packs I understand everything USB is in ANSI when windows xp is not and .Net is all about ANSI (what a waste of memory) I plan to continue this project into a .net at a later date as an addition. MSDN gives me Structures and Functions and what should link to what ok but say little to what they get used for. What is available in my language Delphi is way over priced that it needs a major price drop.

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  • Embedded "Smart" character LCD driver. Is this a good idea?

    - by chris12892
    I have an embedded project that I am working on, and I am currently coding the character LCD driver. At the moment, the LCD driver only supports "dumb" writing. For example, let's say line 1 has some text on it, and I make a call to the function that writes to the line. The function will simply seek to the beginning of the line and write the text (plus enough whitespace to erase whatever was last written). This is well and good, but I get the feeling it is horribly inefficient sometimes, since some lines are simply: "Some-reading: some-Value" Rather than "brute force" replacing the entire line, I wanted to develop some code that would figure out the best way to update the information on the LCD. (just as background, it takes 2 bytes to seek to any char position. I can then begin writing the string) My idea was to first have a loop. This loop would compare the input to the last write, and in doing so, it would cover two things: A: Collect all the differences between the last write and the input. For every contiguous segment (be it same or different) add two bytes to the byte count. This is referenced in B to determine if we are wasting serial bandwidth. B: The loop would determine if this is really a smart thing to do. If we end up using more bytes to update the line than to "brute force" the line, then we should just return and let the brute force method take over. We should exit the smart write function as soon as this condition is met to avoid wasting time. The next part of the function would take all the differences, seek to the required char on the LCD, and write them. Thus, if we have a string like this already on the LCD: "Current Temp: 80F" and we want to update it to "Current Temp: 79F" The function will go through and see that it would take less bandwidth to simply seek to the "8" and write "79". The "7" will cover the "8" and the "9" will cover the "0". That way, we don't waste time writing out the entire string. Does this seem like a practical idea?

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  • MSSQL 2005: Update rows in a specified order (like ORDER BY)?

    - by JMTyler
    I want to update rows of a table in a specific order, like one would expect if including an ORDER BY clause, but MS SQL does not support the ORDER BY clause in UPDATE queries. I have checked out this question which supplied a nice solution, but my query is a bit more complicated than the one specified there. UPDATE TableA AS Parent SET Parent.ColA = Parent.ColA + (SELECT TOP 1 Child.ColA FROM TableA AS Child WHERE Child.ParentColB = Parent.ColB ORDER BY Child.Priority) ORDER BY Parent.Depth DESC; So, what I'm hoping that you'll notice is that a single table (TableA) contains a hierarchy of rows, wherein one row can be the parent or child of any other row. The rows need to be updated in order from the deepest child up to the root parent. This is because TableA.ColA must contain an up-to-date concatenation of its own current value with the values of its children (I realize this query only concats with one child, but that is for the sake of simplicity - the purpose of the example in this question does not necessitate any more verbosity), therefore the query must update from the bottom up. The solution suggested in the question I noted above is as follows: UPDATE messages SET status=10 WHERE ID in (SELECT TOP (10) Id FROM Table WHERE status=0 ORDER BY priority DESC ); The reason that I don't think I can use this solution is because I am referencing column values from the parent table inside my subquery (see WHERE Child.ParentColB = Parent.ColB), and I don't think two sibling subqueries would have access to each others' data. So far I have only determined one way to merge that suggested solution with my current problem, and I don't think it works. UPDATE TableA AS Parent SET Parent.ColA = Parent.ColA + (SELECT TOP 1 Child.ColA FROM TableA AS Child WHERE Child.ParentColB = Parent.ColB ORDER BY Child.Priority) WHERE Parent.Id IN (SELECT Id FROM TableA ORDER BY Parent.Depth DESC); The WHERE..IN subquery will not actually return a subset of the rows, it will just return the full list of IDs in the order that I want. However (I don't know for sure - please tell me if I'm wrong) I think that the WHERE..IN clause will not care about the order of IDs within the parentheses - it will just check the ID of the row it currently wants to update to see if it's in that list (which, they all are) in whatever order it is already trying to update... Which would just be a total waste of cycles, because it wouldn't change anything. So, in conclusion, I have looked around and can't seem to figure out a way to update in a specified order (and included the reason I need to update in that order, because I am sure I would otherwise get the ever-so-useful "why?" answers) and I am now hitting up Stack Overflow to see if any of you gurus out there who know more about SQL than I do (which isn't saying much) know of an efficient way to do this. It's particularly important that I only use a single query to complete this action. A long question, but I wanted to cover my bases and give you guys as much info to feed off of as possible. :) Any thoughts?

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  • Which network protocol to use for lightweight notification of remote apps?

    - by Chris Thornton
    I have this situation.... Client-initiated SOAP 1.1 communication between one server and let's say, tens of thousands of clients. Clients are external, coming in through our firewall, authenticated by certificate, https, etc.. They can be anywhere, and usually have their own firewalls, NAT routers, etc... They're truely external, not just remote corporate offices. They could be in a corporate/campus network, DSL/Cable, even Dialup. Client uses Delphi (2005 + SOAP fixes from 2007), and the server is C#, but from an architecture/design standpoint, that shouldn't matter. Currently, clients push new data to the server and pull new data from the server on 15-minute polling loop. The server currently does not push data - the client hits the "messagecount" method, to see if there is new data to pull. If 0, it sleeps for another 15 min and checks again. We're trying to get that down to 7 seconds. If this were an internal app, with one or just a few dozen clients, we'd write a cilent "listener" soap service, and would push data to it. But since they're external, sit behind their own firewalls, and sometimes private networks behind NAT routers, this is not practical. So we're left with polling on a much quicker loop. 10K clients, each checking their messagecount every 10 seconds, is going to be 1000/sec messages that will mostly just waste bandwidth, server, firewall, and authenticator resources. So I'm trying to design something better than what would amount to a self-inflicted DoS attack. I don't think it's practical to have the server send soap messages to the client (push) as this would require too much configuration at the client end. But I think there are alternatives that I don't know about. Such as: 1) Is there a way for the client to make a request for GetMessageCount() via Soap 1.1, and get the response, and then perhaps, "stay on the line" for perhaps 5-10 minutes to get additional responses in case new data arrives? i.e the server says "0", then a minute later in response to some SQL trigger (the server is C# on Sql Server, btw), knows that this client is still "on the line" and sends the updated message count of "5"? 2) Is there some other protocol that we could use to "ping" the client, using information gathered from their last GetMessageCount() request? 3) I don't even know. I guess I'm looking for some magic protocol where the client can send a GetMessageCount() request, which would include info for "oh by the way, in case the answer changes in the next hour, ping me at this address...". Also, I'm assuming that any of these "keep the line open" schemes would seriously impact the server sizing, as it would need to keep many thousands of connections open, simultaneously. That would likely impact the firewalls too, I think. Is there anything out there like that? Or am I pretty much stuck with polling? TIA, Chris

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  • MySQL - Calculating fields on the fly vs storing calculated data

    - by Christian Varga
    Hi Everyone, I apologise if this has been asked before, but I can't seem to find an answer to a question that I have about calculating on the fly vs storing fields in a database. I read a few articles that suggested it was preferable to calculate when you can, but I would just like to know if that still applies to the following 2 examples. Example 1. Say you are storing data relating to a car. You store the fuel tank size in litres, and how many litres it uses per 100km. You also want to know how many KMs it can travel, which can be calculated from the tank size and economy. I see 2 ways of doing this: When a car is added or updated, calculate the amount of KMs and store this as a static field in the database. Every time a car is accessed, calculate the amount of KMs on the fly. Because the cars economy/tank size doesn't change (although it could be edited), the KMs is a pretty static value. I don't see why we would calculate it every single time the car is accessed. Wouldn't this waste cpu time as opposed to simply storing it in a separate field in the database and calculating only when a car is added or updated? My next example, which is almost an entirely different question (but on the same topic), relates to counting children. Let's say we have a app which has categories and items. We have a view where we display all the categories, and a count of all the items inside each category. Again, I'm wondering what's better. To perform a MySQL query to count all the items in each category every single time the page is accessed? Or store the count in a field in the categories table and update when an item is added / deleted? I know it is redundant to store anything that can be calculated, but I worry that calculating fields or counting records might be slow as opposed to storing the data in a field. If it's not then please let me know, I just want to learn about when to use either method. On a small scale I guess it wouldn't matter either way, but apps like Facebook, would they really count the amount of friends you have every time someone views your profile or would they just store it as a field? I'd appreciate any responses to both of these scenarios, and any resource that might explain the benefits of calculating vs storing. Thanks in advance, Christian

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  • SQL Server 2005: Update rows in a specified order (like ORDER BY)?

    - by JMTyler
    I want to update rows of a table in a specific order, like one would expect if including an ORDER BY clause, but SQL Server does not support the ORDER BY clause in UPDATE queries. I have checked out this question which supplied a nice solution, but my query is a bit more complicated than the one specified there. UPDATE TableA AS Parent SET Parent.ColA = Parent.ColA + (SELECT TOP 1 Child.ColA FROM TableA AS Child WHERE Child.ParentColB = Parent.ColB ORDER BY Child.Priority) ORDER BY Parent.Depth DESC; So, what I'm hoping that you'll notice is that a single table (TableA) contains a hierarchy of rows, wherein one row can be the parent or child of any other row. The rows need to be updated in order from the deepest child up to the root parent. This is because TableA.ColA must contain an up-to-date concatenation of its own current value with the values of its children (I realize this query only concats with one child, but that is for the sake of simplicity - the purpose of the example in this question does not necessitate any more verbosity), therefore the query must update from the bottom up. The solution suggested in the question I noted above is as follows: UPDATE messages SET status=10 WHERE ID in (SELECT TOP (10) Id FROM Table WHERE status=0 ORDER BY priority DESC ); The reason that I don't think I can use this solution is because I am referencing column values from the parent table inside my subquery (see WHERE Child.ParentColB = Parent.ColB), and I don't think two sibling subqueries would have access to each others' data. So far I have only determined one way to merge that suggested solution with my current problem, and I don't think it works. UPDATE TableA AS Parent SET Parent.ColA = Parent.ColA + (SELECT TOP 1 Child.ColA FROM TableA AS Child WHERE Child.ParentColB = Parent.ColB ORDER BY Child.Priority) WHERE Parent.Id IN (SELECT Id FROM TableA ORDER BY Parent.Depth DESC); The WHERE..IN subquery will not actually return a subset of the rows, it will just return the full list of IDs in the order that I want. However (I don't know for sure - please tell me if I'm wrong) I think that the WHERE..IN clause will not care about the order of IDs within the parentheses - it will just check the ID of the row it currently wants to update to see if it's in that list (which, they all are) in whatever order it is already trying to update... Which would just be a total waste of cycles, because it wouldn't change anything. So, in conclusion, I have looked around and can't seem to figure out a way to update in a specified order (and included the reason I need to update in that order, because I am sure I would otherwise get the ever-so-useful "why?" answers) and I am now hitting up Stack Overflow to see if any of you gurus out there who know more about SQL than I do (which isn't saying much) know of an efficient way to do this. It's particularly important that I only use a single query to complete this action. A long question, but I wanted to cover my bases and give you guys as much info to feed off of as possible. :) Any thoughts?

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  • Akka framework support for finding duplicate messages

    - by scala_is_awesome
    I'm trying to build a high-performance distributed system with Akka and Scala. If a message requesting an expensive (and side-effect-free) computation arrives, and the exact same computation has already been requested before, I want to avoid computing the result again. If the computation requested previously has already completed and the result is available, I can cache it and re-use it. However, the time window in which duplicate computation can be requested may be arbitrarily small. e.g. I could get a thousand or a million messages requesting the same expensive computation at the same instant for all practical purposes. There is a commercial product called Gigaspaces that supposedly handles this situation. However there seems to be no framework support for dealing with duplicate work requests in Akka at the moment. Given that the Akka framework already has access to all the messages being routed through the framework, it seems that a framework solution could make a lot of sense here. Here is what I am proposing for the Akka framework to do: 1. Create a trait to indicate a type of messages (say, "ExpensiveComputation" or something similar) that are to be subject to the following caching approach. 2. Smartly (hashing etc.) identify identical messages received by (the same or different) actors within a user-configurable time window. Other options: select a maximum buffer size of memory to be used for this purpose, subject to (say LRU) replacement etc. Akka can also choose to cache only the results of messages that were expensive to process; the messages that took very little time to process can be re-processed again if needed; no need to waste precious buffer space caching them and their results. 3. When identical messages (received within that time window, possibly "at the same time instant") are identified, avoid unnecessary duplicate computations. The framework would do this automatically, and essentially, the duplicate messages would never get received by a new actor for processing; they would silently vanish and the result from processing it once (whether that computation was already done in the past, or ongoing right then) would get sent to all appropriate recipients (immediately if already available, and upon completion of the computation if not). Note that messages should be considered identical even if the "reply" fields are different, as long as the semantics/computations they represent are identical in every other respect. Also note that the computation should be purely functional, i.e. free from side-effects, for the caching optimization suggested to work and not change the program semantics at all. If what I am suggesting is not compatible with the Akka way of doing things, and/or if you see some strong reasons why this is a very bad idea, please let me know. Thanks, Is Awesome, Scala

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  • Which network protocol to use for lightweight notification of remote apps (Delphi 2005)

    - by Chris Thornton
    I have this situation.... Client-initiated SOAP 1.1 communication between one server and let's say, tens of thousands of clients. Clients are external, coming in through our firewall, authenticated by certificate, https, etc.. They can be anywhere, and usually have their own firewalls, NAT routers, etc... They're truely external, not just remote corporate offices. They could be in a corporate/campus network, DSL/Cable, even Dialup. Currently, clients push new data to the server and pull new data from the server on 15-minute polling loop. The server currently does not push data - the client hits the "messagecount" method, to see if there is new data to pull. If 0, it sleeps for another 15 min and checks again. We're trying to get that down to 7 seconds. If this were an internal app, with one or just a few dozen clients, we'd write a cilent "listener" soap service, and would push data to it. But since they're external, sit behind their own firewalls, and sometimes private networks behind NAT routers, this is not practical. So we're left with polling on a much quicker loop. 10K clients, each checking their messagecount every 10 seconds, is going to be 1000/sec messages that will mostly just waste bandwidth, server, firewall, and authenticator resources. So I'm trying to design something better than what would amount to a self-inflicted DoS attack. I don't think it's practical to have the server send soap messages to the client (push) as this would require too much configuration at the client end. But I think there are alternatives that I don't know about. Such as: 1) Is there a way for the client to make a request for GetMessageCount() via Soap 1.1, and get the response, and then perhaps, "stay on the line" for perhaps 5-10 minutes to get additional responses in case new data arrives? i.e the server says "0", then a minute later in response to some SQL trigger (the server is C# on Sql Server, btw), knows that this client is still "on the line" and sends the updated message count of "5"? 2) Is there some other protocol that we could use to "ping" the client, using information gathered from their last GetMessageCount() request? 3) I don't even know. I guess I'm looking for some magic protocol where the client can send a GetMessageCount() request, which would include info for "oh by the way, in case the answer changes in the next hour, ping me at this address...". Also, I'm assuming that any of these "keep the line open" schemes would seriously impact the server sizing, as it would need to keep many thousands of connections open, simultaneously. That would likely impact the firewalls too, I think. Is there anything out there like that? Or am I pretty much stuck with polling? TIA, Chris

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  • OpenGL ES Polygon with Normals rendering (Note the 'ES!')

    - by MarqueIV
    Ok... imagine I have a relatively simple solid that has six distinct normals but actually has close to 48 faces (8 faces per direction) and there are a LOT of shared vertices between faces. What's the most efficient way to render that in OpenGL? I know I can place the vertices in an array, then use an index array to render them, but I have to keep breaking my rendering steps down to change the normals (i.e. set normal 1... render 8 faces... set normal 2... render 8 faces, etc.) Because of that I have to maintain an array of index arrays... one for each normal! Not good! The other way I can do it is to use separate normal and vertex arrays (or even interleave them) but that means I need to have a one-to-one ratio for normals to vertices and that means the normals would be duplicated 8 times more than they need to be! On something with a spherical or even curved surface, every normal most likely is different, but for this, it really seems like a waste of memory. In a perfect world I'd like to have my vertex and normal arrays have different lengths, then when I go to draw my triangles or quads To specify the index to each array for that vertex. Now the OBJ file format lets you specify exactly that... a vertex array and a normal array of different lengths, then when you specify the face you are rendering, you specify a vertex and a normal index (as well as a UV coord if you are using textures too) which seems like the perfect solution! 48 vertices but only 8 normals, then pairs of indexes defining the shapes' faces. But I'm not sure how to render that in OpenGL ES (again, note the 'ES'.) Currently I have to 'denormalize' (sorry for the SQL pun there) the normals back to a 1-to-1 with the vertex array, then render. Just wastes memory to me. Anyone help? I hope I'm missing something very simple here. Mark

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  • Preg_replace regex, newlines, connection resets

    - by bob_the_destroyer
    I have mixed html, custom code, and regular text I need to examine and change frequently on several, long wiki pages. I'm working with a proprietary wiki-like application and have no control over how the application functions or validates user input. The layout of pages that users add must follow a very specific standard layout and always include very specific text in only certain places - a standard which frequently changes. If users add pages that are so far out of the standard, they will be deleted. The fact that all this is obviously a complete waste of time when alternative platforms to do exactly what's needed here exist is already understood. I've built a PHP based API to automate this post-validation and frequent restandardization process for me. I've been able set up regex patterns to handle all this mixed text, and they all work fine for handling single lines. The problem I have is this: Poorly formed regex against long text with line breaks can lead to unexpected results, such as connection resets. I have no access to server-side logs to troubleshoot. How do I overcome this? This is just one example of what I currently have: {column} and {section} tags I'm searching for below can have any number of attributes, and wrap any text. {section} may or may not exist and may or may not be one or more lines under {column}, but it has to be wrapped inside {column}. {column} itself may or may not exist, and if it doesn't, I don't care. I want to grab the inner section contents and wrap it in an html div tag. I can't recall the exact pattern I'm using offhand at the moment, but it's close enough... $pattern = "/\{column:id=summary([|]?([a-zA-Z0-9-_ ]+[:][a-zA-Z0-9-_ ]+[ ]?))\}(.*)({section([|]([a-zA-Z0-9-_ ]+[:][a-zA-Z0-9-_ ]+[ ]?))\}(.*)\{section\}(.*))?{column\}/s"; $replacement = "{html}<div id='summary'$7</div{html}"; $text = preg_replace($pattern, $replacement, $subject); Handling the {column} and {section} attributes and passing only valid HTML parameters to the new html div or a subtext of it is itself a challenge, but my main focus above right now is getting that (.*) value within {section} above without causing a connection reset. Any pointers?

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  • Should I HttpCombine Google Jquery Hosted File?

    - by chobo2
    Hi I am using something called HttpCombiner: http://code.msdn.microsoft.com/HttpCombiner An HTTP handler that combines multiple CSS, Javascript or URL into one response for faster page load. It can combine, compress and cache response which results in faster page load and better scalability of web application It's a good practice to use many small Javascript and CSS files instead of one large Javascript/CSS file for better code maintainability, but bad in terms of website performance. Although you should write your Javascript code in small files and break large CSS files into small chunks but when browser requests those javascript and css files, it makes one Http request per file. Every Http Request results in a network roundtrip form your browser to the server and the delay in reaching the server and coming back to the browser is called latency. So, if you have four javascripts and three css files loaded by a page, you are wasting time in seven network roundtrips. Within USA, latency is average 70ms. So, you waste 7x70 = 490ms, about half a second of delay. Outside USA, average latency is around 200ms. So, that means 1400ms of waiting. Browser cannot show the page properly until Css and Javascripts are fully loaded. So, the more latency you have, the slower page loads. You can reduce the wait time by using a CDN. Read my previous blog post about using CDN. However, a better solution is to deliver multiple files over one request using an HttpHandler that combines several files and delivers as one output. So, instead of putting many or tag, you just put one and one tag, and point them to the HttpHandler. You tell the handler which files to combine and it delivers those files in one response. This saves browser from making many requests and eliminates the latency. This Http Handler reads the file names defined in a configuration and combines all those files and delivers as one response. It delivers the response as gzip compressed to save bandwidth. Moreover, it generates proper cache header to cache the response in browser cache, so that, browser does not request it again on future visit. Now I am wondering since it can handle adding links should I put in it the jquery file? The reason I am not sure is if it gets combined with my other files I think I might close the advantages of it being hosted on googles servers such as caching(my thinking is if it gets combined it will look different so even if a user has it in it's cache I am not sure if it will use the one for the cahce or not). So should I combine it or only the finals that I am using locally?

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  • SSIS Lookup component tuning tips

    - by jamiet
    Yesterday evening I attended a London meeting of the UK SQL Server User Group at Microsoft’s offices in London Victoria. As usual it was both a fun and informative evening and in particular there seemed to be a few questions arising about tuning the SSIS Lookup component; I rattled off some comments and figured it would be prudent to drop some of them into a dedicated blog post, hence the one you are reading right now. Scene setting A popular pattern in SSIS is to use a Lookup component to determine whether a record in the pipeline already exists in the intended destination table or not and I cover this pattern in my 2006 blog post Checking if a row exists and if it does, has it changed? (note to self: must rewrite that blog post for SSIS2008). Fundamentally the SSIS lookup component (when using FullCache option) sucks some data out of a database and holds it in memory so that it can be compared to data in the pipeline. One of the big benefits of using SSIS dataflows is that they process data one buffer at a time; that means that not all of the data from your source exists in the dataflow at the same time and is why a SSIS dataflow can process data volumes that far exceed the available memory. However, that only applies to data in the pipeline; for reasons that are hopefully obvious ALL of the data in the lookup set must exist in the memory cache for the duration of the dataflow’s execution which means that any memory used by the lookup cache will not be available to be used as a pipeline buffer. Moreover, there’s an obvious correlation between the amount of data in the lookup cache and the time it takes to charge that cache; the more data you have then the longer it will take to charge and the longer you have to wait until the dataflow actually starts to do anything. For these reasons your goal is simple: ensure that the lookup cache contains as little data as possible. General tips Here is a simple tick list you can follow in order to tune your lookups: Use a SQL statement to charge your cache, don’t just pick a table from the dropdown list made available to you. (Read why in SELECT *... or select from a dropdown in an OLE DB Source component?) Only pick the columns that you need, ignore everything else Make the database columns that your cache is populated from as narrow as possible. If a column is defined as VARCHAR(20) then SSIS will allocate 20 bytes for every value in that column – that is a big waste if the actual values are significantly less than 20 characters in length. Do you need DT_WSTR typed columns or will DT_STR suffice? DT_WSTR uses twice the amount of space to hold values that can be stored using a DT_STR so if you can use DT_STR, consider doing so. Same principle goes for the numerical datatypes DT_I2/DT_I4/DT_I8. Only populate the cache with data that you KNOW you will need. In other words, think about your WHERE clause! Thinking outside the box It is tempting to build a large monolithic dataflow that does many things, one of which is a Lookup. Often though you can make better use of your available resources by, well, mixing things up a little and here are a few ideas to get your creative juices flowing: There is no rule that says everything has to happen in a single dataflow. If you have some particularly resource intensive lookups then consider putting that lookup into a dataflow all of its own and using raw files to pass the pipeline data in and out of that dataflow. Know your data. If you think, for example, that the majority of your incoming rows will match with only a small subset of your lookup data then consider chaining multiple lookup components together; the first would use a FullCache containing that data subset and the remaining data that doesn’t find a match could be passed to a second lookup that perhaps uses a NoCache lookup thus negating the need to pull all of that least-used lookup data into memory. Do you need to process all of your incoming data all at once? If you can process different partitions of your data separately then you can partition your lookup cache as well. For example, if you are using a lookup to convert a location into a [LocationId] then why not process your data one region at a time? This will mean your lookup cache only has to contain data for the location that you are currently processing and with the ability of the Lookup in SSIS2008 and beyond to charge the cache using a dynamically built SQL statement you’ll be able to achieve it using the same dataflow and simply loop over it using a ForEach loop. Taking the previous data partitioning idea further … a dataflow can contain more than one data path so why not split your data using a conditional split component and, again, charge your lookup caches with only the data that they need for that partition. Lookups have two uses: to (1) find a matching row from the lookup set and (2) put attributes from that matching row into the pipeline. Ask yourself, do you need to do these two things at the same time? After all once you have the key column(s) from your lookup set then you can use that key to get the rest of attributes further downstream, perhaps even in another dataflow. Are you using the same lookup data set multiple times? If so, consider the file caching option in SSIS 2008 and beyond. Above all, experiment and be creative with different combinations. You may be surprised at what works. Final  thoughts If you want to know more about how the Lookup component differs in SSIS2008 from SSIS2005 then I have a dedicated blog post about that at Lookup component gets a makeover. I am on a mini-crusade at the moment to get a BULK MERGE feature into the database engine, the thinking being that if the database engine can quickly merge massive amounts of data in a similar manner to how it can insert massive amounts using BULK INSERT then that’s a lot of work that wouldn’t have to be done in the SSIS pipeline. If you think that is a good idea then go and vote for BULK MERGE on Connect. If you have any other tips to share then please stick them in the comments. Hope this helps! @Jamiet Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Dealing with HTTP w00tw00t attacks

    - by Saif Bechan
    I have a server with apache and I recently installed mod_security2 because I get attacked a lot by this: My apache version is apache v2.2.3 and I use mod_security2.c This were the entries from the error log: [Wed Mar 24 02:35:41 2010] [error] [client 88.191.109.38] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind:) [Wed Mar 24 02:47:31 2010] [error] [client 202.75.211.90] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind:) [Wed Mar 24 02:47:49 2010] [error] [client 95.228.153.177] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind:) [Wed Mar 24 02:48:03 2010] [error] [client 88.191.109.38] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind:) Here are the errors from the access_log: 202.75.211.90 - - [29/Mar/2010:10:43:15 +0200] "GET /w00tw00t.at.ISC.SANS.DFind:) HTTP/1.1" 400 392 "-" "-" 211.155.228.169 - - [29/Mar/2010:11:40:41 +0200] "GET /w00tw00t.at.ISC.SANS.DFind:) HTTP/1.1" 400 392 "-" "-" 211.155.228.169 - - [29/Mar/2010:12:37:19 +0200] "GET /w00tw00t.at.ISC.SANS.DFind:) HTTP/1.1" 400 392 "-" "-" I tried configuring mod_security2 like this: SecFilterSelective REQUEST_URI "w00tw00t\.at\.ISC\.SANS\.DFind" SecFilterSelective REQUEST_URI "\w00tw00t\.at\.ISC\.SANS" SecFilterSelective REQUEST_URI "w00tw00t\.at\.ISC\.SANS" SecFilterSelective REQUEST_URI "w00tw00t\.at\.ISC\.SANS\.DFind:" SecFilterSelective REQUEST_URI "w00tw00t\.at\.ISC\.SANS\.DFind:\)" The thing in mod_security2 is that SecFilterSelective can not be used, it gives me errors. Instead I use a rule like this: SecRule REQUEST_URI "w00tw00t\.at\.ISC\.SANS\.DFind" SecRule REQUEST_URI "\w00tw00t\.at\.ISC\.SANS" SecRule REQUEST_URI "w00tw00t\.at\.ISC\.SANS" SecRule REQUEST_URI "w00tw00t\.at\.ISC\.SANS\.DFind:" SecRule REQUEST_URI "w00tw00t\.at\.ISC\.SANS\.DFind:\)" Even this does not work. I don't know what to do anymore. Anyone have any advice? Update 1 I see that nobody can solve this problem using mod_security. So far using ip-tables seems like the best option to do this but I think the file will become extremely large because the ip changes serveral times a day. I came up with 2 other solutions, can someone comment on them on being good or not. The first solution that comes to my mind is excluding these attacks from my apache error logs. This will make is easier for me to spot other urgent errors as they occur and don't have to spit trough a long log. The second option is better i think, and that is blocking hosts that are not sent in the correct way. In this example the w00tw00t attack is send without hostname, so i think i can block the hosts that are not in the correct form. Update 2 After going trough the answers I came to the following conclusions. To have custom logging for apache will consume some unnecessary recourses, and if there really is a problem you probably will want to look at the full log without anything missing. It is better to just ignore the hits and concentrate on a better way of analyzing your error logs. Using filters for your logs a good approach for this. Final thoughts on the subject The attack mentioned above will not reach your machine if you at least have an up to date system so there are basically no worries. It can be hard to filter out all the bogus attacks from the real ones after a while, because both the error logs and access logs get extremely large. Preventing this from happening in any way will cost you resources and they it is a good practice not to waste your resources on unimportant stuff. The solution i use now is Linux logwatch. It sends me summaries of the logs and they are filtered and grouped. This way you can easily separate the important from the unimportant. Thank you all for the help, and I hope this post can be helpful to someone else too.

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  • The Incremental Architect&acute;s Napkin - #1 - It&acute;s about the money, stupid

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/05/24/the-incremental-architectacutes-napkin---1---itacutes-about-the.aspx Software development is an economic endeavor. A customer is only willing to pay for value. What makes a software valuable is required to become a trait of the software. We as software developers thus need to understand and then find a way to implement requirements. Whether or in how far a customer really can know beforehand what´s going to be valuable for him/her in the end is a topic of constant debate. Some aspects of the requirements might be less foggy than others. Sometimes the customer does not know what he/she wants. Sometimes he/she´s certain to want something - but then is not happy when that´s delivered. Nevertheless requirements exist. And developers will only be paid if they deliver value. So we better focus on doing that. Although is might sound trivial I think it´s important to state the corollary: We need to be able to trace anything we do as developers back to some requirement. You decide to use Go as the implementation language? Well, what´s the customer´s requirement this decision is linked to? You decide to use WPF as the GUI technology? What´s the customer´s requirement? You decide in favor of a layered architecture? What´s the customer´s requirement? You decide to put code in three classes instead of just one? What´s the customer´s requirement behind that? You decide to use MongoDB over MySql? What´s the customer´s requirement behind that? etc. I´m not saying any of these decisions are wrong. I´m just saying whatever you decide be clear about the requirement that´s driving your decision. You have to be able to answer the question: Why do you think will X deliver more value to the customer than the alternatives? Customers are not interested in romantic ideals of hard working, good willing, quality focused craftsmen. They don´t care how and why you work - as long as what you deliver fulfills their needs. They want to trust you to recognize this as your top priority - and then deliver. That´s all. Fundamental aspects of requirements If you´re like me you´re probably not used to such scrutinization. You want to be trusted as a professional developer - and decide quite a few things following your gut feeling. Or by relying on “established practices”. That´s ok in general and most of the time - but still… I think we should be more conscious about our decisions. Which would make us more responsible, even more professional. But without further guidance it´s hard to reason about many of the myriad decisions we´ve to make over the course of a software project. What I found helpful in this situation is structuring requirements into fundamental aspects. Instead of one large heap of requirements then there are smaller blobs. With them it´s easier to check if a decisions falls in their scope. Sure, every project has it´s very own requirements. But all of them belong to just three different major categories, I think. Any requirement either pertains to functionality, non-functional aspects or sustainability. For short I call those aspects: Functionality, because such requirements describe which transformations a software should offer. For example: A calculator software should be able to add and multiply real numbers. An auction website should enable you to set up an auction anytime or to find auctions to bid for. Quality, because such requirements describe how functionality is supposed to work, e.g. fast or secure. For example: A calculator should be able to calculate the sinus of a value much faster than you could in your head. An auction website should accept bids from millions of users. Security of Investment, because functionality and quality need not just be delivered in any way. It´s important to the customer to get them quickly - and not only today but over the course of several years. This aspect introduces time into the “requrements equation”. Security of Investments (SoI) sure is a non-functional requirement. But I think it´s important to not subsume it under the Quality (Q) aspect. That´s because SoI has quite special properties. For one, SoI for software means something completely different from what it means for hardware. If you buy hardware (a car, a hair blower) you find that a worthwhile investment, if the hardware does not change it´s functionality or quality over time. A car still running smoothly with hardly any rust spots after 10 years of daily usage would be a very secure investment. So for hardware (or material products, if you like) “unchangeability” (in the face of usage) is desirable. With software you want the contrary. Software that cannot be changed is a waste. SoI for software means “changeability”. You want to be sure that the software you buy/order today can be changed, adapted, improved over an unforseeable number of years so as fit changes in its usage environment. But that´s not the only reason why the SoI aspect is special. On top of changeability[1] (or evolvability) comes immeasurability. Evolvability cannot readily be measured by counting something. Whether the changeability is as high as the customer wants it, cannot be determined by looking at metrics like Lines of Code or Cyclomatic Complexity or Afferent Coupling. They may give a hint… but they are far, far from precise. That´s because of the nature of changeability. It´s different from performance or scalability. Also it´s because a customer cannot tell upfront, “how much” evolvability he/she wants. Whether requirements regarding Functionality (F) and Q have been met, a customer can tell you very quickly and very precisely. A calculation is missing, the calculation takes too long, the calculation time degrades with increased load, the calculation is accessible to the wrong users etc. That´s all very or at least comparatively easy to determine. But changeability… That´s a whole different thing. Nevertheless over time the customer will develop a feedling if changeability is good enough or degrading. He/she just has to check the development of the frequency of “WTF”s from developers ;-) F and Q are “timeless” requirement categories. Customers want us to deliver on them now. Just focusing on the now, though, is rarely beneficial in the long run. So SoI adds a counterweight to the requirements picture. Customers want SoI - whether they know it or not, whether they state if explicitly or not. In closing A customer´s requirements are not monolithic. They are not all made the same. Rather they fall into different categories. We as developers need to recognize these categories when confronted with some requirement - and take them into account. Only then can we make true professional decisions, i.e. conscious and responsible ones. I call this fundamental trait of software “changeability” and not “flexibility” to distinguish to whom it´s a concern. “Flexibility” to me means, software as is can easily be adapted to a change in its environment, e.g. by tweaking some config data or adding a library which gets picked up by a plug-in engine. “Flexibiltiy” thus is a matter of some user. “Changeability”, on the other hand, to me means, software can easily be changed in its structure to adapt it to new requirements. That´s a matter of the software developer. ?

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  • CodePlex Daily Summary for Monday, March 22, 2010

    CodePlex Daily Summary for Monday, March 22, 2010New Projects[Tool] Vczh Non-public DLL Classes Caller: Generate C# code for you to call non-public classes in DLLs very easily.Artefact Animator: Artefact Animator provides an easy to use framework for procedural time-based animations in Silverlight and WPF.cacheroo: Cacheroo is a social networking community that will make it easier for people who love geocaching to get connected.Data Processing Toolkit: An utility app to collected data from different sources (i.e. bugzilla bug reports) in a structured way. We are currently setting up the site. Mo...eXternal SQL Bridge (PHP): The eXternal SQL Bridge (XSB) allows you to bridge two websites together in a secure manner through pre-shared keys. XSB is resilient against repla...'G' - Language to Define Gestures for Touch Based Applications: A cross plat form multi-touch application framework with a language to define gestures. The application is build on Silverlight 4.0 and the languag...IIS Network Diagnostic Tools: Web implementation of "looking glass" like services (ping, traceroute) as HTTP modules for Internet Information Services.Interop Router: This project establishes a communication framework and job dispatcher for a mixed operating system cluster environment.L2 Commander: L2Commander makes it easier for both new and old l2j users to manage your server.You no longer have to waste time on finding the files you need and...MediaHelper: A utility to help clean up empty/unwanted files and folders in your filesystem.mhinze: matt hinze stuffOneMan: Focus on Silverlight and WCF technology.Rss Photo Frame Android Widget: RSS Photo Frame Android Widget permits showing pictures from any RSS feed on your Android device's desktopSingle Web Session: Web Tool Kits Current project provide developer with different tools that help to enhance web site performance, security, and other common functio...Work Item Visualization: Use DGML to visualize and analyze your TFS Work Items. Included is the ability to perform basic risk/impact analysis. It helps answer the question,...New Releases[Tool] Vczh Non-public DLL Classes Caller: Wrapper Coder (beta): Click "<Click Me To Open Assembly File>", WrapperCoder will load the assembly and referenced assembly. Check the non-public classes that you want...APS - Automatic Print Screen: APS 1.0: APS automatizes the tasks of paste the image in Paint and save it after print screen or alt+print screen. Choose directory, name and file extension...BTP Tools: e-Sword generator build 20100321: 1. Modify the indent after subtitle. 2. Add 2 spaces after subtitle.Combres - WebForm & MVC Client-side Resource Combine Library: Combres 2.0: Changes since last version (1.2) Support ignore Combres pipeline in debug mode - see issue #6088 Debug mode generates comment helping identify in...Desafio Office 2010 Brasil: DesafioOutlook: Controlando um robo com o Outlook 2010dylan.NET: dylan.NET v. 9.4: Adding Platform Invocation Services Support, full Managed Pointer Support, Charset,Dllimport,Callconv setting for P/Invoke, MarshalAs for parametersFamily Tree Analyzer: Version 1.3.2.0: Version 1.3.2.0 Add open folder button to IGI Search Form Fixes to Fact Location processing - IGIName renamed to RegionID Fix if Region ID not fou...Fasterflect - A Fast and Simple Reflection API: Fasterflect 2.0: We are pleased to release version 2.0 of Fasterflect, which contains a lot of additions and improvements from the previous version. Please refer t...IIS Network Diagnostic Tools: 1.0: Initial public release.Informant: Informant (Desktop) v0.1: This release allows users to send sms messages to 1-Many Groups or 1-Many contacts. It is a very basic release of the application. No styling has b...InfoService: InfoService v1.5 - MPE1 Package: InfoService Release v1.5.0.65 Please read Plugin installation for installation instructions.InfoService: InfoService v1.5 - RAR Package: InfoService Release v1.5.0.65 Please read Plugin installation for installation instructions.L2 Commander: Source Code Link: Where to find our source.ModularCMS: ModularCMS 1.2: Minor bug fixes.NMTools: NMTools-v40b0-20100321-0: The most noticeable aspect of this release is that NMTools is now an independent project. It will no longer tied to OpenSLIM. Nevertheless, OpenSLI...SharePoint LogViewer: SharePoint LogViewer 1.5.3: Log loading performance enhanced. Search text box now has auto complete feature.Single Web Session: Single Web Session: !Single Web Session! <httpModules> <add name="SingleSession" type="SingleWebSession.Model.WebSessionModule, SingleWebSession"/> </httpModules>Sprite Sheet Packer: 2.1 Release: Made a few crucial fixes from 2.0: - Fixed error with paths having spaces. - Fixed error with UI not unlocking. - Fixed NullReferenceException on ...uManage - AD Self-Service Portal: uManage v1.1 (.NET 4.0 RC): Updated Releasev1.1 Adds the primary ability to setup and configure the application through a setup wizard. The setup wizard will continue to evol...VCC: Latest build, v2.1.30321.0: Automatic drop of latest buildVS ChessMania: VS ChessMania V2 March Beta: Second Beta Release with move correction and making application more safe for user. New features will be added soon.WatchersNET CKEditor™ Provider for DotNetNuke: CKEditor Provider 1.9.00: Whats New Added New Toolbar Plugin (By Kent Safransk) 'MediaEmbed' to Include Embed Media from Youtube, Vimeo, etc. Media Embed Plugin Added New ...WeatherBar: WeatherBar 1.0 [No Installation]: Extract the ZIP archive and run WeatherBar.exe. Current release contains some bugs that will be fixed in the next version. Check the Issue Tracker...Work Item Visualization: Release 1.0: This is the initial release of the Work Item Visualization tool. There are no known issues when it comes to the visualization aspects of the tool b...WPF Application Framework (WAF): WPF Application Framework (WAF) 1.0.0.10: Version: 1.0.0.10 (Milestone 10): This release contains the source code of the WPF Application Framework (WAF) and the sample applications. Requi...WPF AutoComplete TextBox Control: Version 1.2: What's Newadds AutoAppend feature adds a new provider: UrlHistoryDataProvider sample application is updated to reflect the new things Bug Fixe...ZoomBarPlus: V2 (Beta): - Fixed bug: if the active window changed while you were in the middle of a single tap delay, long tap delay, or swipe-repeat, it would continue re...Most Popular ProjectsMetaSharpSavvy DateTimeRawrWBFS ManagerSilverlight ToolkitASP.NET Ajax LibraryMicrosoft SQL Server Product Samples: DatabaseAJAX Control ToolkitLiveUpload to FacebookWindows Presentation Foundation (WPF)Most Active ProjectsLINQ to TwitterRawrOData SDK for PHPjQuery Library for SharePoint Web ServicesDirectQPHPExcelFarseer Physics Enginepatterns & practices – Enterprise LibraryBlogEngine.NETNB_Store - Free DotNetNuke Ecommerce Catalog Module

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  • The last MVVM you'll ever need?

    - by Nuri Halperin
    As my MVC projects mature and grow, the need to have some omnipresent, ambient model properties quickly emerge. The application no longer has only one dynamic pieced of data on the page: A sidebar with a shopping cart, some news flash on the side – pretty common stuff. The rub is that a controller is invoked in context of a single intended request. The rest of the data, even though it could be just as dynamic, is expected to appear on it's own. There are many solutions to this scenario. MVVM prescribes creating elaborate objects which expose your new data as a property on some uber-object with more properties exposing the "side show" ambient data. The reason I don't love this approach is because it forces fairly acute awareness of the view, and soon enough you have many MVVM objects laying around, and views have to start doing null-checks in order to ensure you really supplied all the values before binding to them. Ick. Just as unattractive is the ViewData dictionary. It's not strongly typed, and in both this and the MVVM approach someone has to populate these properties – n'est pas? Where does that live? With MVC2, we get the formerly-futures  feature Html.RenderAction(). The feature allows you plant a line in a view, of the format: <% Html.RenderAction("SessionInterest", "Session"); %> While this syntax looks very clean, I can't help being bothered by it. MVC was touting a very strong separation of concerns, the Model taking on the role of the business logic, the controller handling route and performing minimal view-choosing operations and the views strictly focused on rendering out angled-bracket tags. The RenderAction() syntax has the view calling some controller and invoking it inline with it's runtime rendering. This – to my taste – embeds too much  knowledge of controllers into the view's code – which was allegedly forbidden.  The one way flow "Controller Receive Data –> Controller invoke Model –> Controller select view –> Controller Hand data to view" now gets a "View calls controller and gets it's own data" which is not so one-way anymore. Ick. I toyed with some other solutions a bit, including some base controllers, special view classes etc. My current favorite though is making use of the ExpandoObject and dynamic features with C# 4.0. If you follow Phil Haack or read a bit from David Heyden you can see the general picture emerging. The game changer is that using the new dynamic syntax, one can sprout properties on an object and make use of them in the view. Well that beats having a bunch of uni-purpose MVVM's any day! Rather than statically exposed properties, we'll just use the capability of adding members at runtime. Armed with new ideas and syntax, I went to work: First, I created a factory method to enrich the focuse object: public static class ModelExtension { public static dynamic Decorate(this Controller controller, object mainValue) { dynamic result = new ExpandoObject(); result.Value = mainValue; result.SessionInterest = CodeCampBL.SessoinInterest(); result.TagUsage = CodeCampBL.TagUsage(); return result; } } This gives me a nice fluent way to have the controller add the rest of the ambient "side show" items (SessionInterest, TagUsage in this demo) and expose them all as the Model: public ActionResult Index() { var data = SyndicationBL.Refresh(TWEET_SOURCE_URL); dynamic result = this.Decorate(data); return View(result); } So now what remains is that my view knows to expect a dynamic object (rather than statically typed) so that the ASP.NET page compiler won't barf: <%@ Page Language="C#" Title="Ambient Demo" MasterPageFile="~/Views/Shared/Ambient.Master" Inherits="System.Web.Mvc.ViewPage<dynamic>" %> Notice the generic ViewPage<dynamic>. It doesn't work otherwise. In the page itself, Model.Value property contains the main data returned from the controller. The nice thing about this, is that the master page (Ambient.Master) also inherits from the generic ViewMasterPage<dynamic>. So rather than the page worrying about all this ambient stuff, the side bars and panels for ambient data all reside in a master page, and can be rendered using the RenderPartial() syntax: <% Html.RenderPartial("TagCloud", Model.SessionInterest as Dictionary<string, int>); %> Note here that a cast is necessary. This is because although dynamic is magic, it can't figure out what type this property is, and wants you to give it a type so its binder can figure out the right property to bind to at runtime. I use as, you can cast if you like. So there we go – no violation of MVC, no explosion of MVVM models and voila – right? Well, I could not let this go without a tweak or two more. The first thing to improve, is that some views may not need all the properties. In that case, it would be a waste of resources to populate every property. The solution to this is simple: rather than exposing properties, I change d the factory method to expose lambdas - Func<T> really. So only if and when a view accesses a member of the dynamic object does it load the data. public static class ModelExtension { // take two.. lazy loading! public static dynamic LazyDecorate(this Controller c, object mainValue) { dynamic result = new ExpandoObject(); result.Value = mainValue; result.SessionInterest = new Func<Dictionary<string, int>>(() => CodeCampBL.SessoinInterest()); result.TagUsage = new Func<Dictionary<string, int>>(() => CodeCampBL.TagUsage()); return result; } } Now that lazy loading is in place, there's really no reason not to hook up all and any possible ambient property. Go nuts! Add them all in – they won't get invoked unless used. This now requires changing the signature of usage on the ambient properties methods –adding some parenthesis to the master view: <% Html.RenderPartial("TagCloud", Model.SessionInterest() as Dictionary<string, int>); %> And, of course, the controller needs to call LazyDecorate() rather than the old Decorate(). The final touch is to introduce a convenience method to the my Controller class , so that the tedium of calling Decorate() everywhere goes away. This is done quite simply by adding a bunch of methods, matching View(object), View(string,object) signatures of the Controller class: public ActionResult Index() { var data = SyndicationBL.Refresh(TWEET_SOURCE_URL); return AmbientView(data); } //these methods can reside in a base controller for the solution: public ViewResult AmbientView(dynamic data) { dynamic result = ModelExtension.LazyDecorate(this, data); return View(result); } public ViewResult AmbientView(string viewName, dynamic data) { dynamic result = ModelExtension.LazyDecorate(this, data); return View(viewName, result); } The call to AmbientView now replaces any call the View() that requires the ambient data. DRY sattisfied, lazy loading and no need to replace core pieces of the MVC pipeline. I call this a good MVC day. Enjoy!

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  • User Experience Highlights in PeopleSoft and PeopleTools: Direct from Jeff Robbins

    - by mvaughan
    By Kathy Miedema, Oracle Applications User Experience  This is the fifth in a series of blog posts on the user experience (UX) highlights in various Oracle product families. The last posted interview was with Nadia Bendjedou, Senior Director, Product Strategy on upcoming Oracle E-Business Suite user experience highlights. You’ll see themes around productivity and efficiency, and get an early look at the latest mobile offerings coming through these product lines. Today’s post is on the user experience in PeopleSoft and PeopleTools. To learn more about what’s ahead, attend PeopleSoft or PeopleTools OpenWorld presentations.This interview is with Jeff Robbins, Senior Director, PeopleSoft Development. Jeff Robbins Q: How would you describe the vision you have for the user experience of PeopleSoft?A: Intuitive – Specifically, customers use PeopleSoft to help their employees do their day-to-day work, and the UI (user interface) has been helpful and assistive in that effort. If it’s not obvious what they need to do a task, then the UI isn’t working. So the application needs to make it simple for users to find information they need, complete a task, do all the things they are responsible for, and it really helps when the UI just makes sense. Productive – PeopleSoft is a tool used to support people to do their work, and a lot of users are measured by how much work they’re able to get done per hour, per day, etc. The UI needs to help them be as productive as possible, and can’t make them waste time or energy. The UI needs to reflect the type of work necessary for a task -- if it's data entry, the UI needs to assist the user to get information into the system. For analysts, the UI needs help users assess or analyze information in a particular way. Innovative – The concept of the UI being innovative is something we’ve been working on for years. It’s not just that we want to be seen as innovative, the fact is that companies are asking their employees to do more than they’ve ever asked before. More often companies want to roll out processes as employee or manager self-service, where an employee is responsible to review and maintain their own data. So we’ve had to reinvent, and ask,  “How can we modify the ways an employee interacts with our applications so that they can be more productive and efficient – even with tasks that are entirely unfamiliar?”  Our focus on innovation has forced us to design new ways for users to interact with the entire application.Q: How are the UX features you have delivered so far resonating with customers?  A: Resonating very well. We’re hearing tremendous responses from users, managers, decision-makers -- who are very happy with the improved user experience. Many of the individual features resonate well. Some have really hit home, others are better than they used to be but show us that there’s still room for improvement.A couple innovations really stand out; features that have a significant effect on how users interact with PeopleSoft.First, the deployment of PeopleSoft in a way that’s more like a consumer website with the PeopleSoft Home page and Dashboards.  This new approach is very web-centric, where users feel they’re coming to a website rather than logging into an enterprise application.  There’s lots of information from all around the organization collected in a way that feels very familiar to users. In order to do your job, you can come to this web site rather than having to learn how to log into an application and figure out a complicated menu. Companies can host these really rich web sites for employees that are home pages for accessing critical tasks and information. The UI elements of incorporating search into the whole navigation process is another hit. Rather than having to log in and choose a task from a menu, users come to the web site and begin a task by simply searching for data: themselves, another employee, a customer record, whatever.  The search results include the data along with a set of actions the user might take, completely eliminating the need to hunt through a complicated system menu. Search-centric navigation is really sitting well with customers who are trying to deploy an intuitive set of systems. Q: Are any UX highlights more popular than you expected them to be?  A: We introduced a feature called Pivot Grid in the last release, which is a combination of an interactive grid, like an Excel Pivot Table, along with a dynamic visual chart that automatically graphs the data. I wasn’t certain at first how extensively this would be used. It looked like an innovative tool, but it wasn’t clear how it would be incorporated in business process applications. The fact is that everyone who sees Pivot Grids is thrilled with that kind of interactivity.  It reflects the amount of analytical thinking customers are asking employees to do. Employees can’t just enter data any more. They must interact with it, analyze it, and make decisions. Pivot Grids fit into this way of working. Q: What can you tell us about PeopleSoft’s mobile offerings?A: A lot of customers are finding that mobile is the chief priority in their organization.  They tell us they want their employees to be able to access company information from their mobile devices.  Of course, not everyone has the same requirements, so we’re working to make sure we can help our customers accomplish what they’re trying to do.  We’ve already delivered a number of mobile features.  For instance, PeopleSoft home pages, dashboards and workcenters all work well on an iPad, straight out of the box.  We’ve delivered a number of key functions and tasks for mobile workers – those who are responsible for using a mobile device to manage inventory, for example.  Customers tell us they also need a holistic strategy, one that allows their employees to access nearly every task from a mobile device.  While we don’t expect users to do extensive data entry from their smartphone, it makes sense that they have access to company information and systems while away from their desk.  That’s where our strategy is going now.  We plan to unveil a number of new mobile offerings at OpenWorld.  Some will be available then, some shortly after. Q: What else are you working on now that you think is going to be exciting to customers at Oracle OpenWorld?A: Our next release -- the big thing is PeopleSoft 9.2, and we’ll be talking about the huge amount of work that’s gone into the next versions. A new toolset, 8.53, will be coming, and there’s a lot to talk about there, and the next generation of PeopleSoft 9.2.  We have a ton of new stuff coming.Q: What do you want PeopleSoft customers to know? A: We have been focusing on the user experience in PeopleSoft as a very high priority for the last 4 years, and it’s had interesting effects. One thing is that the application is better, more usable.  We’ve made visible improvements. Another aspect is that in customers’ minds, the PeopleSoft brand is being reinvigorated. Customers invested in PeopleSoft years ago, and then they weren’t sure where PeopleSoft was going.  This investment in the UI and overall user experience keeps PeopleSoft current, innovative and fresh.  Customers  are able to take advantage of a lot of new features, even on the older applications, simply by upgrading their PeopleTools. The interest in that ability has been tremendous. Knowing they have a lot of these features available -- right now, that’s pretty huge. There’s been a tremendous amount of positive response, just on the fact that we’re focusing on the user experience. Editor’s note: For more on PeopleSoft and PeopleTools user experience highlights, visit the Usable Apps web site.To find out more about these enhancements at Openworld, be sure to check out these sessions: GEN8928     General Session: PeopleSoft Update and Product RoadmapCON9183     PeopleSoft PeopleTools Technology Roadmap CON8932     New Functional PeopleSoft PeopleTools Capabilities for the Line-of-Business UserCON9196     PeopleSoft PeopleTools Roadmap: Mobile ApplicationsCON9186     Case Study: Delivering a Groundbreaking User Interface with PeopleSoft PeopleTools

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  • When OneTug Just Isn&rsquo;t Enough&hellip;

    - by onefloridacoder
    I stole that from the back of a T-shirt I saw at the Orlando Code Camp 2010.  This was my first code camp and my first time volunteering for an event like this as well.  It was an awesome day.  I cannot begin to count the “aaahh”, “I did-not-know I could do that”, in the crowds and for myself.  I think it was a great day of learning for everyone at all levels.  All of the presenters were different and provided great insights into the topics they were presenting.  Here’s a list of the ones that I attended. KodeFuGuru, “Pirates vs. Ninjas” He touched on many good topics to relax some of the ways we think when we are writing out code, and still looks good, readable, etc.  As he pointed out in all of his examples, we might not always realize everything that’s going on under the covers.  He exposed a bug in his own code, and verbalized the mental gymnastics he went through when he knew there was something wrong with one of his IEnumerable implementations.  For me, it was great to hear that someone else labors over these gut reactions to code quickly snapped together, to the point that we rush to the refactor stage to fix what’s bothering us – and learn.  He has some content on extension methods that was very interesting.  My “that is so cool” moment was when he swapped out AddEntity method on an entity class and used a With extension method instead.  Some of the LINQ scales fell off my eyes at that moment, and I realized my own code could be a lot more powerful (and readable) if incorporate a few of these examples at the appropriate times.  And he cautioned as well… “don’t go crazy with this stuff”, there’s a place and time for everything.  One of his examples demo’d toward the end of the talk is on his sight where he’s chaining methods together, cool stuff. Quotes I liked: “Extension Methods - Extension methods to put features back on the model type, without impacting the type.” “Favor Declarative Code” – Check out the ? and ?? operators if you’re not already using them. “Favor Fluent Code” “Avoid Pirate Ninja Zombies!  If you see one run!” I’m definitely going to be looking at “Extract Projection” when I get into VS2010. BDD 101 – Sean Chambers http://github.com/schambers This guy had a whole host of gremlins against him, final score Sean 5, Gremlins 1.  He ran the code samples from his github repo  in the code github code viewer since the PC they school gave him to use didn’t have VS installed. He did a great job of converting the grammar between BDD and TDD, and how this style of development can be used in integration tests as well as the different types of gated builds on a CI box – he didn’t go into a discussion around CI, but we could infer that it could work. Like when we use WSSF, it does cause a class explosion to happen however the amount of code per class it limit to just covering the concern at hand – no more, no less.  As in “When I as a <Role>, expect {something} to happen, because {}”  This keeps us (the developer) from gold plating our solutions and creating less waste.  He basically keeps the code that prove out the requirement to two lines of code.  Nice. He uses SpecUnit to merge this grammar into his .NET projects and gave an overview on how this ties into writing his own BDD tests.  Some folks were familiar with Given / When / Then as story acceptance criteria and here’s how he mapped it: “Given <Context>  When <Something Happens> Then <I expect...>”  There are a few base classes and overrides in the SpecUnit framework that help with setting up the context for each test which looked very handy. Successfully Running Your Own Coding Business The speaker ran through a list of items that sounded like common sense stuff LLC, banking, separating expenses, etc.  Then moved into role playing with business owners and an ISV.  That was pretty good stuff, it pays to be a good listener all of the time even if your client is sitting on the other side of the phone tearing you head off for you – but that’s all it is, and get used to it its par for the course.  Oh, yeah always answer the phone was one simple thing that you can do to move  your business forward.  But like Cory Foy tweeted this week, “If you owe me a lot of money, don’t have a message that says your away for five weeks skiing in Colorado.”  Lots of food for thought that’s on my list of “todo’s and to-don’ts”. Speaker Idol Next, I had the pleasure of helping Russ Fustino tape this part of Code Camp as my primary volunteer opportunity that day.  You remember Russ, “know the code” from the awesome Russ’ Tool Shed series.  He did a great job orchestrating and capturing the Speaker Idol finals.   So I didn’t actually miss any sessions, but was able to see three back to back in one setting.  The idol finalists gave a 10 minute talk and very deep subjects, but different styles of talks.  No one walked away empty handed for jobs very well done.  Russ has details on his site.  The pictures and  video captured is supposed to be published on Channel 9 at a later date.  It was also a valuable experience to see what makes technical speakers effective in their talks.  I picked up quite a few speaking tips from what I heard from the judges and contestants. Design For Developers – Diane Leeper If you are a great developer, you’re probably a lousy designer.  Diane didn’t come to poke holes in what we think we can do with UI layout and design, but she provided some tools we can use to figure out metaphors for visualizing data.  If you need help with that check out Silverlight Pivot – that’s what she was getting at.  I was first introduced to her at one of John Papa’s talks last year at a Lakeland User Group meeting and she’s very passionate about design.  She was able to discuss different elements of Pivot, while to a developer is just looked cool. I believe she was providing the deck from her talk to folks after her talk, so send her an email if you’re interested.   She says she can talk about design for hours and hours – we all left that session believing her.   Rinse and Repeat Orlando Code Camp 2010 was awesome, and would totally do it again.  There were lots of folks from my shop there, and some that have left my shop to go elsewhere.  So it was a reunion of sorts and a great celebration for the simple fact that its great to be a developer and there’s a community that supports and recognizes it as well.  The sponsors were generous and the organizers were very tired, namely Esteban Garcia and Will Strohl who were responsible for making a lot of this magic happen.  And if you don’t believe me, check out the chatter on Twitter.

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  • DialogFX: A New Approach to JavaFX Dialogs

    - by HecklerMark
    How would you like a quick and easy drop-in dialog box capability for JavaFX? That's what I was thinking when a weekend presented itself. And never being one to waste a good weekend...  :-) After doing some "roll-your-own" basic dialog building for a JavaFX app, I recently stumbled across Anton Smirnov's work on GitHub. It was a good start, but it wasn't exactly what I was after, and ideas just kept popping up of things I'd do differently. I wanted something a bit more streamlined, a bit easier to just "drop in and use". And so DialogFX was born. DialogFX wasn't intended to be overly fancy, overly clever - just useful and robust. Here were my goals: Easy to use. A dialog "system" should be so simple to use a new developer can drop it in quickly with nearly no learning curve. A seasoned developer shouldn't even have to think, just tap in a few lines and go. Why should dialogs slow "actual development"?  :-) Defaults. If you don't specify something (dialog type, buttons, etc.), a good dialog system should still work. It may not be pretty, but it shouldn't throw gears. Sharable. It's all open source. Even the icons are in the commons, so they can be reused at will. Let's take a look at some screen captures and the code used to produce them.   DialogFX INFO dialog Screen captures Windows Mac  Sample code         DialogFX dialog = new DialogFX();        dialog.setTitleText("Info Dialog Box Example");        dialog.setMessage("This is an example of an INFO dialog box, created using DialogFX.");        dialog.showDialog(); DialogFX ERROR dialog Screen captures Windows Mac  Sample code         DialogFX dialog = new DialogFX(Type.ERROR);        dialog.setTitleText("Error Dialog Box Example");        dialog.setMessage("This is an example of an ERROR dialog box, created using DialogFX.");        dialog.showDialog(); DialogFX ACCEPT dialog Screen captures Windows Mac  Sample code         DialogFX dialog = new DialogFX(Type.ACCEPT);        dialog.setTitleText("Accept Dialog Box Example");        dialog.setMessage("This is an example of an ACCEPT dialog box, created using DialogFX.");        dialog.showDialog(); DialogFX Question dialog (Yes/No) Screen captures Windows Mac  Sample code         DialogFX dialog = new DialogFX(Type.QUESTION);        dialog.setTitleText("Question Dialog Box Example");        dialog.setMessage("This is an example of an QUESTION dialog box, created using DialogFX. Would you like to continue?");        dialog.showDialog(); DialogFX Question dialog (custom buttons) Screen captures Windows Mac  Sample code         List<String> buttonLabels = new ArrayList<>(2);        buttonLabels.add("Affirmative");        buttonLabels.add("Negative");         DialogFX dialog = new DialogFX(Type.QUESTION);        dialog.setTitleText("Question Dialog Box Example");        dialog.setMessage("This is an example of an QUESTION dialog box, created using DialogFX. This also demonstrates the automatic wrapping of text in DialogFX. Would you like to continue?");        dialog.addButtons(buttonLabels, 0, 1);        dialog.showDialog(); A couple of things to note You may have noticed in that last example the addButtons(buttonLabels, 0, 1) call. You can pass custom button labels in and designate the index of the default button (responding to the ENTER key) and the cancel button (for ESCAPE). Optional parameters, of course, but nice when you may want them. Also, the showDialog() method actually returns the index of the button pressed. Rather than create EventHandlers in the dialog that really have little to do with the dialog itself, you can respond to the user's choice within the calling object. Or not. Again, it's your choice.  :-) And finally, I've Javadoc'ed the code in the main places. Hopefully, this will make it easy to get up and running quickly and with a minimum of fuss. How Do I Get (Git?) It? To try out DialogFX, just point your browser here to the DialogFX GitHub repository and download away! Please take a look, try it out, and let me know what you think. All feedback welcome! All the best, Mark 

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  • Lessons from rewriting POP Forums for MVC, open source-like

    - by Jeff
    It has been a ton of work, interrupted over the last two years by unemployment, moving, a baby, failing to sell houses and other life events, but it's really exciting to see POP Forums v9 coming together. I'm not even sure when I decided to really commit to it as an open source project, but working on the same team as the CodePlex folks probably had something to do with it. Moving along the roadmap I set for myself, the app is now running on a quasi-production site... we launched MouseZoom last weekend. (That's a post-beta 1 build of the forum. There's also some nifty Silverlight DeepZoom goodness on that site.)I have to make a point to illustrate just how important starting over was for me. I started this forum thing for my sites in old ASP more than ten years ago. What a mess that stuff was, including SQL injection vulnerabilities and all kinds of crap. It went to ASP.NET in 2002, but even then, it felt a little too much like script. More than a year later, in 2003, I did an honest to goodness rewrite. If you've been in this business of writing code for any amount of time, you know how much you hate what you wrote a month ago, so just imagine that with seven years in between. The subsequent versions still carried a fair amount of crap, and that's why I had to start over, to make a clean break. Mind you, much of that crap is still running on some of my production sites in a stable manner, but it's a pain in the ass to maintain.So with that clean break, there is much that I have learned. These are a few of those lessons, in no particular order...Avoid shiny object syndromeOver the years, I've embraced new things without bothering to ask myself why. I remember spending the better part of a year trying to adapt this app to use the membership and profile API's in ASP.NET, just because they were there. They didn't solve any known problem. Early on in this version, I dabbled in exotic ORM's, even though I already had the fundamental SQL that I knew worked. I bloated up the client side code with all kinds of jQuery UI and plugins just because, and it got in the way. All the new shiny can be distracting, and I've come to realize that I've allowed it to be a distraction most of my professional life.Just query what you needI've spent a lot of time over-thinking how to query data. In the SQL world, this means exotic joins, special caches, the read-update-commit loop of ORM's, etc. There are times when you have to remind yourself that you aren't Facebook, you'll never be Facebook, and that databases are in fact intended to serve data. In a lot of projects, back in the day, I used to have these big, rich data objects and pass them all over the place, through various application tiers, when in reality, all I needed was some ID from the entity. I try to be mindful of how many queries hit the database on a given request, but I don't obsess over it. I just get what I need.Don't spend too much time worrying about your unit testsIf you've looked at any of the tests for POP Forums, you might offer an audible WTF. That's OK. There's a whole lot of mocking going on. In some cases, it points out where you're doing too much, and that's good for improving your design. In other cases it shows where your design sucks. But the biggest trap of unit testing is that you worry it should be prettier. That's a waste of time. When you write a test, in many cases before the production code, the important part is that you're testing the right thing. If you have to mock up a bunch of stuff to test the outcome, so be it, but it's not wasted time. You're still doing up the typical arrange-action-assert deal, and you'll be able to read that later if you need to.Get back to your HTTP rootsASP.NET Webforms did a reasonably decent job at abstracting us away from the stateless nature of the Web. A lot of people criticize it, but I think it all worked pretty well. These days, with MVC, jQuery, REST services, and what not, we've gone back to thinking about the wire. The nuts and bolts passing between our Web browser and server matters. This doesn't make things harder, in my opinion, it makes them easier. There is something incredibly freeing about how we approach development of Web apps now. HTTP is a really simple protocol, and the stuff we push through it, in particular HTML and JSON, are pretty simple too. The debugging points are really easy to trap and trace.Premature optimization is prematureI'll go back to the data thing for a moment. I've been known to look at a particular action or use case and stress about the number of calls that are made to the database. I'm not suggesting that it's a bad thing to keep these in mind, but if you worry about it outside of the context of the actual impact, you're wasting time. For example, I query the database for last read times in a forum separately of the user and the list of forums. The impact on performance barely exists. If I put it under load, exceeding the kind of load I expect, it still barely has an impact. Then consider it only counts for logged in users. The context of this "inefficient" action is that it doesn't matter. Did I mention I won't be Facebook?Solve your own problems firstThis is another trap I've fallen into. I've often thought about what other people might need for some feature or aspect of the app. In other words, I was willing to make design decisions based on non-existent data. How stupid is that? When I decided to truly open source this thing, building for myself first was a stated design goal. This app has to server the audiences of CoasterBuzz, MouseZoom and other sites first. In this development scenario, you don't have access to mountains of usability studies or user focus groups. You have to start with what you know.I'm sure there are other points I could make too. It has been a lot of fun to work on, and I look forward to evolving the UI as time goes on. That's where I hope to see more magic in the future.

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  • Premature-Optimization and Performance Anxiety

    - by James Michael Hare
    While writing my post analyzing the new .NET 4 ConcurrentDictionary class (here), I fell into one of the classic blunders that I myself always love to warn about.  After analyzing the differences of time between a Dictionary with locking versus the new ConcurrentDictionary class, I noted that the ConcurrentDictionary was faster with read-heavy multi-threaded operations.  Then, I made the classic blunder of thinking that because the original Dictionary with locking was faster for those write-heavy uses, it was the best choice for those types of tasks.  In short, I fell into the premature-optimization anti-pattern. Basically, the premature-optimization anti-pattern is when a developer is coding very early for a perceived (whether rightly-or-wrongly) performance gain and sacrificing good design and maintainability in the process.  At best, the performance gains are usually negligible and at worst, can either negatively impact performance, or can degrade maintainability so much that time to market suffers or the code becomes very fragile due to the complexity. Keep in mind the distinction above.  I'm not talking about valid performance decisions.  There are decisions one should make when designing and writing an application that are valid performance decisions.  Examples of this are knowing the best data structures for a given situation (Dictionary versus List, for example) and choosing performance algorithms (linear search vs. binary search).  But these in my mind are macro optimizations.  The error is not in deciding to use a better data structure or algorithm, the anti-pattern as stated above is when you attempt to over-optimize early on in such a way that it sacrifices maintainability. In my case, I was actually considering trading the safety and maintainability gains of the ConcurrentDictionary (no locking required) for a slight performance gain by using the Dictionary with locking.  This would have been a mistake as I would be trading maintainability (ConcurrentDictionary requires no locking which helps readability) and safety (ConcurrentDictionary is safe for iteration even while being modified and you don't risk the developer locking incorrectly) -- and I fell for it even when I knew to watch out for it.  I think in my case, and it may be true for others as well, a large part of it was due to the time I was trained as a developer.  I began college in in the 90s when C and C++ was king and hardware speed and memory were still relatively priceless commodities and not to be squandered.  In those days, using a long instead of a short could waste precious resources, and as such, we were taught to try to minimize space and favor performance.  This is why in many cases such early code-bases were very hard to maintain.  I don't know how many times I heard back then to avoid too many function calls because of the overhead -- and in fact just last year I heard a new hire in the company where I work declare that she didn't want to refactor a long method because of function call overhead.  Now back then, that may have been a valid concern, but with today's modern hardware even if you're calling a trivial method in an extremely tight loop (which chances are the JIT compiler would optimize anyway) the results of removing method calls to speed up performance are negligible for the great majority of applications.  Now, obviously, there are those coding applications where speed is absolutely king (for example drivers, computer games, operating systems) where such sacrifices may be made.  But I would strongly advice against such optimization because of it's cost.  Many folks that are performing an optimization think it's always a win-win.  That they're simply adding speed to the application, what could possibly be wrong with that?  What they don't realize is the cost of their choice.  For every piece of straight-forward code that you obfuscate with performance enhancements, you risk the introduction of bugs in the long term technical debt of the application.  It will become so fragile over time that maintenance will become a nightmare.  I've seen such applications in places I have worked.  There are times I've seen applications where the designer was so obsessed with performance that they even designed their own memory management system for their application to try to squeeze out every ounce of performance.  Unfortunately, the application stability often suffers as a result and it is very difficult for anyone other than the original designer to maintain. I've even seen this recently where I heard a C++ developer bemoaning that in VS2010 the iterators are about twice as slow as they used to be because Microsoft added range checking (probably as part of the 0x standard implementation).  To me this was almost a joke.  Twice as slow sounds bad, but it almost never as bad as you think -- especially if you're gaining safety.  The only time twice is really that much slower is when once was too slow to begin with.  Think about it.  2 minutes is slow as a response time because 1 minute is slow.  But if an iterator takes 1 microsecond to move one position and a new, safer iterator takes 2 microseconds, this is trivial!  The only way you'd ever really notice this would be in iterating a collection just for the sake of iterating (i.e. no other operations).  To my mind, the added safety makes the extra time worth it. Always favor safety and maintainability when you can.  I know it can be a hard habit to break, especially if you started out your career early or in a language such as C where they are very performance conscious.  But in reality, these type of micro-optimizations only end up hurting you in the long run. Remember the two laws of optimization.  I'm not sure where I first heard these, but they are so true: For beginners: Do not optimize. For experts: Do not optimize yet. This is so true.  If you're a beginner, resist the urge to optimize at all costs.  And if you are an expert, delay that decision.  As long as you have chosen the right data structures and algorithms for your task, your performance will probably be more than sufficient.  Chances are it will be network, database, or disk hits that will be your slow-down, not your code.  As they say, 98% of your code's bottleneck is in 2% of your code so premature-optimization may add maintenance and safety debt that won't have any measurable impact.  Instead, code for maintainability and safety, and then, and only then, when you find a true bottleneck, then you should go back and optimize further.

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  • Postfix sasl login failing no mechanism found

    - by Nat45928
    following the link here: http://flurdy.com/docs/postfix/ with posfix, courier, MySql, and sasl gave me a web server that has imap functionality working fine but when i go to log into the server to send a message using the same user id and password for connecting the the imap server it rejects my login to the smtp server. If i do not specify a login for the outgoing mail server then it will send the message just fine. the error in postfix's log is: Jul 6 17:26:10 Sj-Linux postfix/smtpd[19139]: connect from unknown[10.0.0.50] Jul 6 17:26:10 Sj-Linux postfix/smtpd[19139]: warning: SASL authentication failure: unable to canonify user and get auxprops Jul 6 17:26:10 Sj-Linux postfix/smtpd[19139]: warning: unknown[10.0.0.50]: SASL DIGEST-MD5 authentication failed: no mechanism available Jul 6 17:26:10 Sj-Linux postfix/smtpd[19139]: warning: unknown[10.0.0.50]: SASL LOGIN authentication failed: no mechanism available Ive checked all usernames and passwords for mysql. what could be going wrong? edit: here is some other information: installed libraires for postfix, courier and sasl: aptitude install postfix postfix-mysql aptitude install libsasl2-modules libsasl2-modules-sql libgsasl7 libauthen-sasl-cyrus-perl sasl2-bin libpam-mysql aptitude install courier-base courier-authdaemon courier-authlib-mysql courier-imap courier-imap-ssl courier-ssl and here is my /etc/postfix/main.cf myorigin = domain.com smtpd_banner = $myhostname ESMTP $mail_name biff = no # appending .domain is the MUA's job. append_dot_mydomain = no # Uncomment the next line to generate "delayed mail" warnings #delay_warning_time = 4h readme_directory = no # TLS parameters smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key smtpd_use_tls=yes smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache # See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for # information on enabling SSL in the smtp client. #myhostname = my hostname alias_maps = hash:/etc/aliases alias_database = hash:/etc/aliases myorigin = /etc/mailname local_recipient_maps = mydestination = relayhost = mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 mailbox_size_limit = 0 recipient_delimiter = + inet_interfaces = all mynetworks_style = host # how long if undelivered before sending warning update to sender delay_warning_time = 4h # will it be a permanent error or temporary unknown_local_recipient_reject_code = 450 # how long to keep message on queue before return as failed. # some have 3 days, I have 16 days as I am backup server for some people # whom go on holiday with their server switched off. maximal_queue_lifetime = 7d # max and min time in seconds between retries if connection failed minimal_backoff_time = 1000s maximal_backoff_time = 8000s # how long to wait when servers connect before receiving rest of data smtp_helo_timeout = 60s # how many address can be used in one message. # effective stopper to mass spammers, accidental copy in whole address list # but may restrict intentional mail shots. # but may restrict intentional mail shots. smtpd_recipient_limit = 16 # how many error before back off. smtpd_soft_error_limit = 3 # how many max errors before blocking it. smtpd_hard_error_limit = 12 # Requirements for the HELO statement smtpd_helo_restrictions = permit_mynetworks, permit # Requirements for the sender details smtpd_sender_restrictions = permit_sasl_authenticated, permit_mynetworks, warn_if_reject reject_non_fqdn_sender, reject_unknown_sender_domain, reject_unauth_pipelining, permit # Requirements for the connecting server smtpd_client_restrictions = reject_rbl_client sbl.spamhaus.org, reject_rbl_client blackholes.easynet.nl, reject_rbl_client dnsbl.njabl.org # Requirement for the recipient address smtpd_recipient_restrictions = reject_unauth_pipelining, permit_mynetworks, permit_sasl_authenticated, reject_non_fqdn_recipient, reject_unknown_recipient_domain, reject_unauth_destination, permit smtpd_data_restrictions = reject_unauth_pipelining # require proper helo at connections smtpd_helo_required = yes # waste spammers time before rejecting them smtpd_delay_reject = yes disable_vrfy_command = yes # not sure of the difference of the next two # but they are needed for local aliasing alias_maps = hash:/etc/postfix/aliases alias_database = hash:/etc/postfix/aliases # this specifies where the virtual mailbox folders will be located virtual_mailbox_base = /var/spool/mail/virtual # this is for the mailbox location for each user virtual_mailbox_maps = mysql:/etc/postfix/mysql_mailbox.cf # and this is for aliases virtual_alias_maps = mysql:/etc/postfix/mysql_alias.cf # and this is for domain lookups virtual_mailbox_domains = mysql:/etc/postfix/mysql_domains.cf # this is how to connect to the domains (all virtual, but the option is there) # not used yet # transport_maps = mysql:/etc/postfix/mysql_transport.cf virtual_uid_maps = static:5000 virtual_gid_maps = static:5000 # SASL smtpd_sasl_auth_enable = yes # If your potential clients use Outlook Express or other older clients # this needs to be set to yes broken_sasl_auth_clients = yes smtpd_sasl_security_options = noanonymous smtpd_sasl_local_domain =

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