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• Solr date range problem and specific date problem

  - by Hamid

  I index some data include date in solr but when search for specific date, i get some record (not all record) include some record in next day for example: http://localhost:8080/solr/select/?q=pubdate:[2010-03-25T00:00:00Z TO 2010-03-25T23:59:59Z]&start=0&rows=10&indent=on&sort=pubdate desc i have 625000 record in 2010-03-25 but above query result return 325412 that include 14 record from 2010-03-26. Also i try with below query, but not get right result http://localhost:8080/solr/select/?q=pubdate:"2010-03-25T00:00:00Z"&start=0&rows=10&indent=on&sort=pubdate desc How to get right result for specific date ??? Could you please help me? Thanks in advanced Hamid

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• set variables in an MVC application?

  - by Melissa

  I am trying to learn about the Orchard MVC application. I see the following code but cannot understand what it is doing. Can someone explain what this: User.As<UserPart>().Record.UserName = value; means? public class UserEditViewModel { [Required] public string UserName { get { return User.As<UserPart>().Record.UserName; } set { User.As<UserPart>().Record.UserName = value; } } [Required] public string Email { get { return User.As<UserPart>().Record.Email; } set { User.As<UserPart>().Record.Email = value; } } public IContent User { get; set; } }

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• php mysql flex unicode

  - by JonoB

  I have a problem with saving the £ symbol to a mysql database. I am running a flex front end, with a php + mysql backend When I save a record from flex, the string gets sent to the server as "This amount is £10" php views the string as above, and when it gets saved into the DB, it gets saved as "This amount is £10". My understanding is that this is correct based on MySQL or PHP is appending a  whenever the £ is used I now retrieve the above record, and it gets sent to flex as "This amount is £10". Flex correctly displays this in a textarea as "This amount is £10" I change another field in the same record in flex, and re-save the transaction. The string now gets sent to the server as "This amount is £10" The record is now saved into the DB as "The amount is £10". Each time the record is re-saved, this effect snowballs. Thanks for any advice you can give.

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• How to do animation using swing and clojure ?

  - by Humberto Pinheiro

  I'm trying to animate a chess piece in a board. First I created a java.util.Timer object that "scheduleAtFixedRate" a TimerTask implemented as a proxy function. So I kept a record of the piece to move (piece-moving-record) and when it's apropriate (when the user move the piece using the mouse) the TimerTask proxy function should be test if the record is not nil and execute the piece-moving function. The piece-moving function just updates the x and y coordinates of the piece, according to a vector pre-calculated. I put a add-watch on the piece-moving-record so when it changes it should repaint the board (canvas). The paint method tests if this piece-moving-record is not nil to paint it. The problem is that the animation doesn't appear. The piece just jump to the destiny, without the movement between. There is some problem with the animation scheme ou there is a better way to do it?

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• MySQL: Is it possible to return a "mixed" dataset?

  - by Tom

  Hi, I'm wondering if there's some clever way in MySQL to return a "mixed/balanced" dataset according to a specific criterion? To illustrate, let's say that there are potential results in a table that can be of Type 1 or Type 2 (i.e. a column has a value 1 or 2 for each record). Is there a clever query that would be able to directly return results alternating between 1 and 2 in sequence: 1st record is of type 1, 2nd record is of type 2, 3rd record is of type 1, 4th record is of type 2, etc... Apologies if the question is silly, just looking for some options. Of course, I could return any data and do this in PHP, but it does add some code. Thanks.

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• Postgresql sequences

  - by Dylan

  When I delete all records from a Postgresql table and then try to reset the sequence to start a new record with number 1 when it is inserted, i get different results : SELECT setval('tblname_id_seq', (SELECT COALESCE(MAX(id),1) FROM tblname)); This sets the current value of the sequence to 1, but the NEXT record (actually the first because there are no records yet) gets number 2! And I can't set it to 0, because the minimum value in the sequence is 1! When I use : ALTER SEQUENCE tblname_id_seq RESTART WITH 1; the first record that is inserted actually gets number 1 ! But the above code doesn't accept a SELECT as a value instead of 1. I wish to reset the sequence to number 1 when there are no records, and the first record then should start with 1. But when there ARE already records in the table, I want to reset the sequence so that the next record that is inserted will get {highest}+1 Does anyone have a clear solution for this?

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• C Struct : typedef Doubt !

  - by Mahesh

  In the given code snippet, I expected the error symbol Record not found. But it compiled and ran fine on Visual Studio 2010 Compiler. I ran it as a C program from Visual Studio 2010 Command Prompt in the manner - cl Record.c Record Now the doubt is, doesn't typedef check for symbols ? Does it work more like a forward declaration ? #include "stdio.h" #include "conio.h" typedef struct Record R; struct Record { int a; }; int main() { R obj = {10}; getch(); return 0; }

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• regular expression not behaving as expected - Python

  - by philippe

  I have the following function which is supposed to read a .html file and search for <input> tags, and inject a <input type='hidden' > tag into the string to be shown into the page. However, that condition is never met:( e.g the if statement is never executed. ) What's wrong with my regex? def print_choose( params, name ): filename = path + name f = open( filename, 'r' ) records = f.readlines() print "Content-Type: text/html" print page = "" flag = True for record in records: if re.match( '<input*', str(record) ) != None: print record page += record page += "<input type='hidden' name='pagename' value='psychology' />" else: page += record print page Thank you

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• INSERT INTO othertbl SELECT * tbl

  - by Harry

  Current situation: INSERT INTO othertbl SELECT * FROM tbl WHERE id = '1' So i want to copy a record from tbl to othertbl. Both tables have an autoincremented unique index. Now the new record should have a new index, rather then the value of the index of the originating record else copying results in a index not unique error. A solution would be to not use the * but since these tables have quite some columns i really think it's getting ugly. So,.. is there a better way to copy a record which results in a new record in othertbl which has a new autoincremented index without having to write out all columns in the query and using a NULL value for the index. -hope it makes sense....-

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• C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

  - by James Michael Hare

  Once again we consider some of the lesser known classes and keywords of C#.  In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T> and ConcurrentQueue<T>.  Then in the following post we’ll discuss the ConcurrentDictionary<T> and ConcurrentBag<T>.  Finally, we shall close on the third post with a discussion of the BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. A brief history of collections In the beginning was the .NET 1.0 Framework.  And out of this framework emerged the System.Collections namespace, and it was good.  It contained all the basic things a growing programming language needs like the ArrayList and Hashtable collections.  The main problem, of course, with these original collections is that they held items of type object which means you had to be disciplined enough to use them correctly or you could end up with runtime errors if you got an object of a type you weren't expecting. Then came .NET 2.0 and generics and our world changed forever!  With generics the C# language finally got an equivalent of the very powerful C++ templates.  As such, the System.Collections.Generic was born and we got type-safe versions of all are favorite collections.  The List<T> succeeded the ArrayList and the Dictionary<TKey,TValue> succeeded the Hashtable and so on.  The new versions of the library were not only safer because they checked types at compile-time, in many cases they were more performant as well.  So much so that it's Microsoft's recommendation that the System.Collections original collections only be used for backwards compatibility. So we as developers came to know and love the generic collections and took them into our hearts and embraced them.  The problem is, thread safety in both the original collections and the generic collections can be problematic, for very different reasons. Now, if you are only doing single-threaded development you may not care – after all, no locking is required.  Even if you do have multiple threads, if a collection is “load-once, read-many” you don’t need to do anything to protect that container from multi-threaded access, as illustrated below: 1: public static class OrderTypeTranslator 2: { 3: // because this dictionary is loaded once before it is ever accessed, we don't need to synchronize 4: // multi-threaded read access 5: private static readonly Dictionary<string, char> _translator = new Dictionary<string, char> 6: { 7: {"New", 'N'}, 8: {"Update", 'U'}, 9: {"Cancel", 'X'} 10: }; 11:  12: // the only public interface into the dictionary is for reading, so inherently thread-safe 13: public static char? Translate(string orderType) 14: { 15: char charValue; 16: if (_translator.TryGetValue(orderType, out charValue)) 17: { 18: return charValue; 19: } 20:  21: return null; 22: } 23: } Unfortunately, most of our computer science problems cannot get by with just single-threaded applications or with multi-threading in a load-once manner.  Looking at  today's trends, it's clear to see that computers are not so much getting faster because of faster processor speeds -- we've nearly reached the limits we can push through with today's technologies -- but more because we're adding more cores to the boxes.  With this new hardware paradigm, it is even more important to use multi-threaded applications to take full advantage of parallel processing to achieve higher application speeds. So let's look at how to use collections in a thread-safe manner. Using historical collections in a concurrent fashion The early .NET collections (System.Collections) had a Synchronized() static method that could be used to wrap the early collections to make them completely thread-safe.  This paradigm was dropped in the generic collections (System.Collections.Generic) because having a synchronized wrapper resulted in atomic locks for all operations, which could prove overkill in many multithreading situations.  Thus the paradigm shifted to having the user of the collection specify their own locking, usually with an external object: 1: public class OrderAggregator 2: { 3: private static readonly Dictionary<string, List<Order>> _orders = new Dictionary<string, List<Order>>(); 4: private static readonly _orderLock = new object(); 5:  6: public void Add(string accountNumber, Order newOrder) 7: { 8: List<Order> ordersForAccount; 9:  10: // a complex operation like this should all be protected 11: lock (_orderLock) 12: { 13: if (!_orders.TryGetValue(accountNumber, out ordersForAccount)) 14: { 15: _orders.Add(accountNumber, ordersForAccount = new List<Order>()); 16: } 17:  18: ordersForAccount.Add(newOrder); 19: } 20: } 21: } Notice how we’re performing several operations on the dictionary under one lock.  With the Synchronized() static methods of the early collections, you wouldn’t be able to specify this level of locking (a more macro-level).  So in the generic collections, it was decided that if a user needed synchronization, they could implement their own locking scheme instead so that they could provide synchronization as needed. The need for better concurrent access to collections Here’s the problem: it’s relatively easy to write a collection that locks itself down completely for access, but anything more complex than that can be difficult and error-prone to write, and much less to make it perform efficiently!  For example, what if you have a Dictionary that has frequent reads but in-frequent updates?  Do you want to lock down the entire Dictionary for every access?  This would be overkill and would prevent concurrent reads.  In such cases you could use something like a ReaderWriterLockSlim which allows for multiple readers in a lock, and then once a writer grabs the lock it blocks all further readers until the writer is done (in a nutshell).  This is all very complex stuff to consider. Fortunately, this is where the Concurrent Collections come in.  The Parallel Computing Platform team at Microsoft went through great pains to determine how to make a set of concurrent collections that would have the best performance characteristics for general case multi-threaded use. Now, as in all things involving threading, you should always make sure you evaluate all your container options based on the particular usage scenario and the degree of parallelism you wish to acheive. This article should not be taken to understand that these collections are always supperior to the generic collections. Each fills a particular need for a particular situation. Understanding what each container is optimized for is key to the success of your application whether it be single-threaded or multi-threaded. General points to consider with the concurrent collections The MSDN points out that the concurrent collections all support the ICollection interface. However, since the collections are already synchronized, the IsSynchronized property always returns false, and SyncRoot always returns null.  Thus you should not attempt to use these properties for synchronization purposes. Note that since the concurrent collections also may have different operations than the traditional data structures you may be used to.  Now you may ask why they did this, but it was done out of necessity to keep operations safe and atomic.  For example, in order to do a Pop() on a stack you have to know the stack is non-empty, but between the time you check the stack’s IsEmpty property and then do the Pop() another thread may have come in and made the stack empty!  This is why some of the traditional operations have been changed to make them safe for concurrent use. In addition, some properties and methods in the concurrent collections achieve concurrency by creating a snapshot of the collection, which means that some operations that were traditionally O(1) may now be O(n) in the concurrent models.  I’ll try to point these out as we talk about each collection so you can be aware of any potential performance impacts.  Finally, all the concurrent containers are safe for enumeration even while being modified, but some of the containers support this in different ways (snapshot vs. dirty iteration).  Once again I’ll highlight how thread-safe enumeration works for each collection. ConcurrentStack<T>: The thread-safe LIFO container The ConcurrentStack<T> is the thread-safe counterpart to the System.Collections.Generic.Stack<T>, which as you may remember is your standard last-in-first-out container.  If you think of algorithms that favor stack usage (for example, depth-first searches of graphs and trees) then you can see how using a thread-safe stack would be of benefit. The ConcurrentStack<T> achieves thread-safe access by using System.Threading.Interlocked operations.  This means that the multi-threaded access to the stack requires no traditional locking and is very, very fast! For the most part, the ConcurrentStack<T> behaves like it’s Stack<T> counterpart with a few differences: Pop() was removed in favor of TryPop() Returns true if an item existed and was popped and false if empty. PushRange() and TryPopRange() were added Allows you to push multiple items and pop multiple items atomically. Count takes a snapshot of the stack and then counts the items. This means it is a O(n) operation, if you just want to check for an empty stack, call IsEmpty instead which is O(1). ToArray() and GetEnumerator() both also take snapshots. This means that iteration over a stack will give you a static view at the time of the call and will not reflect updates. Pushing on a ConcurrentStack<T> works just like you’d expect except for the aforementioned PushRange() method that was added to allow you to push a range of items concurrently. 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: // but you can also push multiple items in one atomic operation (no interleaves) 7: stack.PushRange(new [] { "Second", "Third", "Fourth" }); For looking at the top item of the stack (without removing it) the Peek() method has been removed in favor of a TryPeek().  This is because in order to do a peek the stack must be non-empty, but between the time you check for empty and the time you execute the peek the stack contents may have changed.  Thus the TryPeek() was created to be an atomic check for empty, and then peek if not empty: 1: // to look at top item of stack without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (stack.TryPeek(out item)) 5: { 6: Console.WriteLine("Top item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Stack was empty."); 11: } Finally, to remove items from the stack, we have the TryPop() for single, and TryPopRange() for multiple items.  Just like the TryPeek(), these operations replace Pop() since we need to ensure atomically that the stack is non-empty before we pop from it: 1: // to remove items, use TryPop or TryPopRange to get multiple items atomically (no interleaves) 2: if (stack.TryPop(out item)) 3: { 4: Console.WriteLine("Popped " + item); 5: } 6:  7: // TryPopRange will only pop up to the number of spaces in the array, the actual number popped is returned. 8: var poppedItems = new string[2]; 9: int numPopped = stack.TryPopRange(poppedItems); 10:  11: foreach (var theItem in poppedItems.Take(numPopped)) 12: { 13: Console.WriteLine("Popped " + theItem); 14: } Finally, note that as stated before, GetEnumerator() and ToArray() gets a snapshot of the data at the time of the call.  That means if you are enumerating the stack you will get a snapshot of the stack at the time of the call.  This is illustrated below: 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: var results = stack.GetEnumerator(); 7:  8: // but you can also push multiple items in one atomic operation (no interleaves) 9: stack.PushRange(new [] { "Second", "Third", "Fourth" }); 10:  11: while(results.MoveNext()) 12: { 13: Console.WriteLine("Stack only has: " + results.Current); 14: } The only item that will be printed out in the above code is "First" because the snapshot was taken before the other items were added. This may sound like an issue, but it’s really for safety and is more correct.  You don’t want to enumerate a stack and have half a view of the stack before an update and half a view of the stack after an update, after all.  In addition, note that this is still thread-safe, whereas iterating through a non-concurrent collection while updating it in the old collections would cause an exception. ConcurrentQueue<T>: The thread-safe FIFO container The ConcurrentQueue<T> is the thread-safe counterpart of the System.Collections.Generic.Queue<T> class.  The concurrent queue uses an underlying list of small arrays and lock-free System.Threading.Interlocked operations on the head and tail arrays.  Once again, this allows us to do thread-safe operations without the need for heavy locks! The ConcurrentQueue<T> (like the ConcurrentStack<T>) has some departures from the non-concurrent counterpart.  Most notably: Dequeue() was removed in favor of TryDequeue(). Returns true if an item existed and was dequeued and false if empty. Count does not take a snapshot It subtracts the head and tail index to get the count.  This results overall in a O(1) complexity which is quite good.  It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. ToArray() and GetEnumerator() both take snapshots. This means that iteration over a queue will give you a static view at the time of the call and will not reflect updates. The Enqueue() method on the ConcurrentQueue<T> works much the same as the generic Queue<T>: 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: queue.Enqueue("Second"); 6: queue.Enqueue("Third"); For front item access, the TryPeek() method must be used to attempt to see the first item if the queue.  There is no Peek() method since, as you’ll remember, we can only peek on a non-empty queue, so we must have an atomic TryPeek() that checks for empty and then returns the first item if the queue is non-empty. 1: // to look at first item in queue without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (queue.TryPeek(out item)) 5: { 6: Console.WriteLine("First item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Queue was empty."); 11: } Then, to remove items you use TryDequeue().  Once again this is for the same reason we have TryPeek() and not Peek(): 1: // to remove items, use TryDequeue. If queue is empty returns false. 2: if (queue.TryDequeue(out item)) 3: { 4: Console.WriteLine("Dequeued first item " + item); 5: } Just like the concurrent stack, the ConcurrentQueue<T> takes a snapshot when you call ToArray() or GetEnumerator() which means that subsequent updates to the queue will not be seen when you iterate over the results.  Thus once again the code below will only show the first item, since the other items were added after the snapshot. 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5:  6: var iterator = queue.GetEnumerator(); 7:  8: queue.Enqueue("Second"); 9: queue.Enqueue("Third"); 10:  11: // only shows First 12: while (iterator.MoveNext()) 13: { 14: Console.WriteLine("Dequeued item " + iterator.Current); 15: } Using collections concurrently You’ll notice in the examples above I stuck to using single-threaded examples so as to make them deterministic and the results obvious.  Of course, if we used these collections in a truly multi-threaded way the results would be less deterministic, but would still be thread-safe and with no locking on your part required! For example, say you have an order processor that takes an IEnumerable<Order> and handles each other in a multi-threaded fashion, then groups the responses together in a concurrent collection for aggregation.  This can be done easily with the TPL’s Parallel.ForEach(): 1: public static IEnumerable<OrderResult> ProcessOrders(IEnumerable<Order> orderList) 2: { 3: var proxy = new OrderProxy(); 4: var results = new ConcurrentQueue<OrderResult>(); 5:  6: // notice that we can process all these in parallel and put the results 7: // into our concurrent collection without needing any external locking! 8: Parallel.ForEach(orderList, 9: order => 10: { 11: var result = proxy.PlaceOrder(order); 12:  13: results.Enqueue(result); 14: }); 15:  16: return results; 17: } Summary Obviously, if you do not need multi-threaded safety, you don’t need to use these collections, but when you do need multi-threaded collections these are just the ticket! The plethora of features (I always think of the movie The Three Amigos when I say plethora) built into these containers and the amazing way they acheive thread-safe access in an efficient manner is wonderful to behold. Stay tuned next week where we’ll continue our discussion with the ConcurrentBag<T> and the ConcurrentDictionary<TKey,TValue>. For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here.   Tweet Technorati Tags: C#,.NET,Concurrent Collections,Collections,Multi-Threading,Little Wonders,BlackRabbitCoder,James Michael Hare

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• wcf http 504: Working on a mystery

  - by James Fleming

  Ok,  So you're here because you've been trying to solve the mystery of why you're getting a 504 error. If you've made it to this lonely corner of the Internet, then the advice you're getting from other bloggers isn't the answer you are after. It wasn't the answer I needed either, so once I did solve my problem, I thought I'd share the answer with you. For starters, if by some miracle, you landed here first you may not already know that the 504 error is NOT coming from IIS or Casini, that response code is coming from Fiddler. HTTP/1.1 504 Fiddler - Receive Failure Content-Type: text/html Connection: close Timestamp: 09:43:05.193 ReadResponse() failed: The server did not return a response for this request.       The take away here is Fiddler won't help you with the diagnosis and any further digging in that direction is a red herring. Assuming you've dug around a bit, you may have arrived at posts which suggest you may be getting the error because you're trying to hump too much data over the wire, and have an urgent need to employ an anti-pattern: due to a special case: http://delphimike.blogspot.com/2010/01/error-504-in-wcfnet-35.html Or perhaps you're experiencing wonky behavior using WCF-CustomIsolated Adapter on Windows Server 2008 64bit environment, in which case the rather fly MVP Dwight Goins' advice is what you need. http://dgoins.wordpress.com/2009/12/18/64bit-wcf-custom-isolated-%E2%80%93-rest-%E2%80%93-%E2%80%9C504%E2%80%9D-response/ For me, none of that was helpful. I could perform a get on a single record  http://localhost:8783/Criterion/Skip(0)/Take(1) but I couldn't get more than one record in my collection as in:  http://localhost:8783/Criterion/Skip(0)/Take(2) I didn't have a big payload, or a large number of objects (as you can see by the size of one record below) - - A-1B f5abd850-ec52-401a-8bac-bcea22c74138 .biological/legal mother This item refers to the supervisor’s evaluation of the caseworker’s ability to involve the biological/legal mother in the permanency planning process. 75d8ecb7-91df-475f-aa17-26367aeb8b21 false true Admin account 2010-01-06T17:58:24.88 1.20 764a2333-f445-4793-b54d-1c3084116daa So while I was able to retrieve one record without a hitch (thus the record above) I wasn't able to return multiple records. I confirmed I could get each record individually, (Skip(1)/Take(1))so it stood to reason the problem wasn't with the data at all, so I suspected a serialization error. The first step to resolving this was to enable WCF Tracing. Instructions on how to set it up are here: http://msdn.microsoft.com/en-us/library/ms733025.aspx. The tracing log led me to the solution. The use of type 'Application.Survey.Model.Criterion' as a get-only collection is not supported with NetDataContractSerializer.  Consider marking the type with the CollectionDataContractAttribute attribute or the SerializableAttribute attribute or adding a setter to the property. So I was wrong (but close!). The problem was a deserializing issue in trying to recreate my read only collection. http://msdn.microsoft.com/en-us/library/aa347850.aspx#Y1455 So looking at my underlying model, I saw I did have a read only collection. Adding a setter was all it took.         public virtual ICollection<string> GoverningResponses         {             get             {                 if (!string.IsNullOrEmpty(GoverningResponse))                 {                     return GoverningResponse.Split(';');                 }                 else                     return null;             }                  } Hope this helps. If it does, post a comment.

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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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• Seperating Javascript and Html, when dynamically adding html via javascript

  - by optician

  I am currently building a very dynamic table for a list application, which will basically perform basic CRUD functions via AJAX. What I would like to do is separate the visual design and javascript to the point where I can change the design side without touching the JS side. This would only work where the design stays roughly the same(i would like to use it for rapid protyping) Here is an example. <table> <tr><td>record-123</td><td>I am line 123</td><td>delete row</td></tr> <tr><td>record-124</td><td>I am line 124</td><td>delete row</td></tr> <tr><td>record-125</td><td>I am line 125</td><td>delete row</td></tr> <tr><td>add new record</td></tr> </table> Now, when I add a new record, I would like to insert a new row of html, but I would rather not put this html into the javascript file. What I am considering is creating a row like this on the page, near the table. <tr style='visble:none;' id='template-row'><td>record-id</td><td>content-area</td><td>delete row</td></tr> And when I come to add the new row, I search the page for the tags with the id=template-row , and then grab it, do a string replace on it, and then put it in the right place in the page. As long as the design doesn't shift radically, and I keep the placeholder strings the same, it means designs can be quickly modified without touching the js. Can any give any advice on a methodology like this?

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• Separating Javascript and Html, when dynamically adding html via javascript

  - by optician

  I am currently building a very dynamic table for a list application, which will basically perform basic CRUD functions via AJAX. What I would like to do is separate the visual design and javascript to the point where I can change the design side without touching the JS side. This would only work where the design stays roughly the same(i would like to use it for rapid protyping) Here is an example. <table> <tr><td>record-123</td><td>I am line 123</td><td>delete row</td></tr> <tr><td>record-124</td><td>I am line 124</td><td>delete row</td></tr> <tr><td>record-125</td><td>I am line 125</td><td>delete row</td></tr> <tr><td>add new record</td></tr> </table> Now, when I add a new record, I would like to insert a new row of html, but I would rather not put this html into the javascript file. What I am considering is creating a row like this on the page, near the table. <tr style='visble:none;' id='template-row'><td>record-id</td><td>content-area</td><td>delete row</td></tr> And when I come to add the new row, I search the page for the tags with the id=template-row , and then grab it, do a string replace on it, and then put it in the right place in the page. As long as the design doesn't shift radically, and I keep the placeholder strings the same, it means designs can be quickly modified without touching the js. Can any give any advice on a methodology like this?

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• Problem using AVAudioRecorder.

  - by tek3

  Hi all, I am facing a strange problem with AVAudioRecorder. In my application i need to record audio and play it. I am creating my player as : if(recorder) { if(recorder.recording) [recorder stop]; [recorder release]; recorder = nil; } NSString * filePath = [NSHomeDirectory() stringByAppendingPathComponent: [NSString stringWithFormat:@"Documents/%@.caf",songTitle]]; NSDictionary *recordSettings = [[NSDictionary alloc] initWithObjectsAndKeys: [NSNumber numberWithFloat: 44100.0],AVSampleRateKey, [NSNumber numberWithInt: kAudioFormatAppleIMA4],AVFormatIDKey, [NSNumber numberWithInt: 1], AVNumberOfChannelsKey, [NSNumber numberWithInt: AVAudioQualityMax],AVEncoderAudioQualityKey,nil]; recorder = [[AVAudioRecorder alloc] initWithURL: [NSURL fileURLWithPath:filePath] settings: recordSettings error: nil]; recorder.delegate = self; if ([recorder prepareToRecord] == YES){ [recorder record]; I am releasing and creating player every time i press record button. But the problem is that ,AVAudiorecorder is taking some time before starting to record , and so if i press record button multiple times continuously ,my application freezes for some time. The same code works fine without any problem when headphones are connected to device...there is no delay in recording, and the app doesn't freeze even if i press record button multiple times. Any help in this regard will be highly appreciated. Thanx in advance.

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• Problem merging similar XML files with XSL

  - by LOlliffe

  I have two documents that I need to merge, that happen in a way that I don't seem to be able to find covered in other examples. Namely, that it needs to match not only on a node's attribute at one level, but also on the value of an attribute a node level below that, to get that node's value. I'm trying to take this sample: <?xml version="1.0" encoding="UTF-8" ?> <marc:collection xmlns:marc="http://www.loc.gov/MARC21/slim" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <marc:record> <marc:datafield tag="035" ind1=" " ind2=" "> <marc:subfield code="a">12345</marc:subfield> </marc:datafield> <marc:datafield tag="041" ind1=" " ind2=" "> <marc:subfield code="a">eng</marc:subfield> </marc:datafield> <marc:datafield tag="650" ind1=" " ind2="4"> <marc:subfield code="a">Art</marc:subfield> </marc:datafield> <marc:datafield tag="949" ind1=" " ind2=" "> <marc:subfield code="i">Review of conference proceedings</marc:subfield> </marc:datafield> </marc:record> <marc:record> <marc:datafield tag="035" ind1=" " ind2=" "> <marc:subfield code="a">54321</marc:subfield> </marc:datafield> <marc:datafield tag="041" ind1=" " ind2=" "> <marc:subfield code="a">eng</marc:subfield> </marc:datafield> <marc:datafield tag="650" ind1=" " ind2="4"> <marc:subfield code="a">Byzantine</marc:subfield> </marc:datafield> </marc:record> </marc:collection> And when the value of "datafield" '035', "subfield" 'a' matches e.g. "12345" <marc:collection xmlns:marc="http://www.loc.gov/MARC21/slim" xmlns:fn="http://www.w3.org/2005/xpath-functions" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:fo="http://www.w3.org/1999/XSL/Format"> <marc:record> <marc:datafield ind2=" " ind1=" " tag="035"> <marc:subfield code="a">12345</marc:subfield> </marc:datafield> <marc:datafield ind2="4" ind1=" " tag="650"> <marc:subfield code="a">General works</marc:subfield> <marc:subfield code="x">Historians and critics</marc:subfield> <marc:subfield code="x">Smith, John, 1834-1917</marc:subfield> </marc:datafield> <marc:datafield ind2="4" ind1=" " tag="650"> <marc:subfield code="a">Généralités</marc:subfield> <marc:subfield code="x">Historiens et critiques d'art</marc:subfield> <marc:subfield code="x">Dietrichson, Lorentz, 1834-1917</marc:subfield> </marc:datafield> <marc:datafield ind2=" " ind1=" " tag="654"> <marc:subfield code="a">General works</marc:subfield> </marc:datafield> <marc:datafield ind2=" " ind1=" " tag="654"> <marc:subfield code="a">Généralités</marc:subfield> <marc:subfield code="b">Historiens et critiques d'art</marc:subfield> <marc:subfield code="b">Smith, John, 1834-1917</marc:subfield> </marc:datafield> </marc:record> <marc:record> <marc:datafield ind2=" " ind1=" " tag="035"> <marc:subfield code="a">54321</marc:subfield> </marc:datafield> <marc:datafield ind2="4" ind1=" " tag="650"> <marc:subfield code="a">General works</marc:subfield> <marc:subfield code="x">Historians and critics</marc:subfield> <marc:subfield code="x">Lange, Julius Henrik, 1838-1896</marc:subfield> </marc:datafield> </marc:record> </marc:collection> The result should be: <?xml version="1.0" encoding="UTF-8" ?> <marc:collection xmlns:marc="http://www.loc.gov/MARC21/slim" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <marc:record> <marc:datafield tag="035" ind1=" " ind2=" "> <marc:subfield code="a">12345</marc:subfield> </marc:datafield> <marc:datafield tag="041" ind1=" " ind2=" "> <marc:subfield code="a">eng</marc:subfield> </marc:datafield> <marc:datafield tag="650" ind1=" " ind2="4"> <marc:subfield code="a">Art</marc:subfield> </marc:datafield> <marc:datafield ind2="4" ind1=" " tag="650"> <marc:subfield code="a">General works</marc:subfield> <marc:subfield code="x">Historians and critics</marc:subfield> <marc:subfield code="x">Smith, John, 1834-1917</marc:subfield> </marc:datafield> <marc:datafield ind2="4" ind1=" " tag="650"> <marc:subfield code="a">Généralités</marc:subfield> <marc:subfield code="x">Historiens et critiques d'art</marc:subfield> <marc:subfield code="x">Dietrichson, Lorentz, 1834-1917</marc:subfield> </marc:datafield> <marc:datafield ind2=" " ind1=" " tag="654"> <marc:subfield code="a">General works</marc:subfield> </marc:datafield> <marc:datafield ind2=" " ind1=" " tag="654"> <marc:subfield code="a">Généralités</marc:subfield> <marc:subfield code="b">Historiens et critiques d'art</marc:subfield> <marc:subfield code="b">Smith, John, 1834-1917</marc:subfield> </marc:datafield> <marc:datafield tag="949" ind1=" " ind2=" "> <marc:subfield code="i">Review of conference proceedings</marc:subfield> </marc:datafield> </marc:record> <marc:record> <marc:datafield tag="035" ind1=" " ind2=" "> <marc:subfield code="a">54321</marc:subfield> </marc:datafield> <marc:datafield tag="041" ind1=" " ind2=" "> <marc:subfield code="a">eng</marc:subfield> </marc:datafield> <marc:datafield tag="650" ind1=" " ind2="4"> <marc:subfield code="a">Byzantine</marc:subfield> </marc:datafield> <marc:datafield ind2="4" ind1=" " tag="650"> <marc:subfield code="a">General works</marc:subfield> <marc:subfield code="x">Historians and critics</marc:subfield> <marc:subfield code="x">Lange, Julius Henrik, 1838-1896</marc:subfield> </marc:datafield> </marc:record> </marc:collection> I've tried using examples that I've found that did lookups, but none of them seemed to work. I didn't include any of my XSL, because all of my results were disasterous. I keep looking at it, like it must be simple, but I'm just not getting any decent results. Any help or pointers would be greatly appreciated. Thanks!

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• Gridview empty when SelectedIndexChanged called

  - by xan

  I have a DataGrid which is being bound dynamically to a database query. The user enters some search text into a text field, clicks search, and the code behind creates the appropriate database query using LINQ (searches a table based on the string and returns a limited set of the columns). It then sets the GridView datasource to be the query and calls DataBind(). protected void btnSearch_Click(object sender, EventArgs e) { var query = from record in DB.Table where record.Name.Contains(txtSearch.Text) //Extra string checking etc. removed. select new { record.ID, record.Name, record.Date }; gvResults.DataSource = query; gvResults.DataBind(); } This works fine. When a user selects a row in the grid, the SelectedIndexChanged event handler gets the id from the row in the grid (one of the fields), queries the full record from the DB and then populates a set of editor / details fields with the records full details. protected void gvResults_SelectedIndexChanged(object sender, EventArgs e) { int id = int.Parse(gvResults.SelectedRow.Cells[1].Text); DisplayDetails(id); } This works fine on my local machine where I'm developing the code. On the production server however, the function is called successfully, but the row and column count on gvResults, the GridVeiw is 0 - the table is empty. The GridView's viewstate is enabled and I can't see obvious differences. Have I made some naive assumptions, or am I relying on something that is likely to be configured differently in debug? Locally I am running an empty asp.net web project in VS2008 to make development quicker. The production server is running the sitecore CMS so is configured rather differently. Any thoughts or suggestions would be most welcome. Thanks in advance!

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• searching XML documents using php

  - by dbomb101

  I am trying to make a search function using the combination of DOM, PHP and XML. I got something up and running but the problem is that my search function will only accept exact terms, on top of this am wondering if the method I picked the most efficient $searchTerm = "Lupe"; $doc = new DOMDocument(); foreach (file('musicInformation.xml')as $node) { $xmlString .= trim($node); } $doc->loadXML($xmlString); $records = $doc->documentElement->childNodes; $records = $doc->getElementsByTagName("musicdetails"); foreach( $records as $record ) { $artistnames = $record->getElementsByTagName("artistname"); $artistname = $artistnames->item(0)->nodeValue; $recordnames = $record->getElementsByTagName("recordname"); $recordname = $recordnames->item(0)->nodeValue; $recordtypes = $record->getElementsByTagName("recrodtype"); $recordtype = $recordtypes->item(0)->nodeValue; $formats = $record->getElementsByTagName("format"); $format = $formats->item(0)->nodeValue; $prices = $record->getElementsByTagName("price"); $price = $prices->item(0)->nodeValue; if($searchTerm == $artistname|| $searchTerm == $recordname || $searchTerm == $recordtype ||$searchTerm == $format || $searchTerm == $price) { echo "$artistname - $recordname - $recordtype - $format -$price\n"; }

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• XML/C#: Read content if only if attribute is correct

  - by Zach

  Hi Guys, I have an XML file as follows, and I'm trying to read the content of the Name tag, only if the attribute of the Record tag is what I want. (continued below code) The XML file is: <?xml version="1.0" encoding="utf-8" ?> <Database> <Record Number="1"> <Name>John Doe</Name> <Position>1</Position> <HoursWorked>290</HoursWorked> <LastMonthChecked>0310</LastMonthChecked> </Record> <Record Number="2"> <Name>Jane Doe</Name> <Position>1</Position> <HoursWorked>251</HoursWorked> <LastMonthChecked>0310</LastMonthChecked> </Record> </Database> This is the C# code I have so far: public static string GetName(int EmployeeNumber) { XmlTextReader DataReader = new XmlTextReader("Database.xml"); DataReader.MoveToContent(); while (DataReader.Read()) { if (DataReader.NodeType == XmlNodeType.Element && DataReader.HasAttributes && DataReader.Name == "Record") { DataReader.MoveToAttribute(EmployeeNumber); DataReader.MoveToContent(); if (DataReader.NodeType == XmlNodeType.Element && DataReader.Name == "Name") { return DataReader.ReadContentAsString(); } } } } So for example, if 2 is passed to the function, I want it to return the string "Jane Doe". I'm new to XML parsing, so any help would be appreciated. Thanks.

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• Why does the OnDeserialization not fire for XML Deserialization?

  - by Jonathan

  I have a problem which I have been bashing my head against for the better part of three hours. I am almost certain that I've missed something blindingly obvious... I have a simple XML file: <?xml version="1.0" encoding="utf-8"?> <WeightStore xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Records> <Record actual="150" date="2010-05-01T00:00:00" /> <Record actual="155" date="2010-05-02T00:00:00" /> </Records> </WeightStore> I have a simple class structure: [Serializable] public class Record { [XmlAttribute("actual")] public double weight { get; set; } [XmlAttribute("date")] public DateTime date { get; set; } [XmlIgnore] public double trend { get; set; } } [Serializable] [XmlRoot("WeightStore")] public class SimpleWeightStore { [XmlArrayAttribute("Records")] private List<Record> records = new List<Record>(); public List<Record> Records { get { return records; } } [OnDeserialized()] public void OnDeserialized_Method(StreamingContext context) { // This code never gets called Console.WriteLine("OnDeserialized"); } } I am using these in both calling code and in the class files: using System.Xml.Serialization; using System.Runtime.Serialization; I have some calling code: SimpleWeightStore weight_store_reload = new SimpleWeightStore(); TextReader reader = new StringReader(xml); XmlSerializer deserializer = new XmlSerializer(weight_store.GetType()); weight_store_reload = (SimpleWeightStore)deserializer.Deserialize(reader); The problem is that I am expecting OnDeserialized_Method to get called, and it isn't. I suspect it might have something to do with the fact that it's XML deserialization rather than Runtime deserialization, and perhaps I am using the wrong attribute name, but I can't find out what it might be. Any ideas, folks?

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• Setting up a pc bluetooth server for android

  - by Del

  Alright, I've been reading a lot of topics the past two or three days and nothing seems to have asked this. I am writing a PC side server for my andriod device, this is for exchanging some information and general debugging. Eventually I will be connecting to a SPP device to control a microcontroller. I have managed, using the following (Android to pc) to connect to rfcomm channel 11 and exchange data between my android device and my pc. Method m = device.getClass().getMethod("createRfcommSocket", new Class[] { int.class }); tmp = (BluetoothSocket) m.invoke(device, Integer.valueOf(11)); I have attempted the createRfcommSocketToServiceRecord(UUID) method, with absolutely no luck. For the PC side, I have been using the C Bluez stack for linux. I have the following code which registers the service and opens a server socket: int main(int argc, char **argv) { struct sockaddr_rc loc_addr = { 0 }, rem_addr = { 0 }; char buf[1024] = { 0 }; char str[1024] = { 0 }; int s, client, bytes_read; sdp_session_t *session; socklen_t opt = sizeof(rem_addr); session = register_service(); s = socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM); loc_addr.rc_family = AF_BLUETOOTH; loc_addr.rc_bdaddr = *BDADDR_ANY; loc_addr.rc_channel = (uint8_t) 11; bind(s, (struct sockaddr *)&loc_addr, sizeof(loc_addr)); listen(s, 1); client = accept(s, (struct sockaddr *)&rem_addr, &opt); ba2str( &rem_addr.rc_bdaddr, buf ); fprintf(stderr, "accepted connection from %s\n", buf); memset(buf, 0, sizeof(buf)); bytes_read = read(client, buf, sizeof(buf)); if( bytes_read 0 ) { printf("received [%s]\n", buf); } sprintf(str,"to Android."); printf("sent [%s]\n",str); write(client, str, sizeof(str)); close(client); close(s); sdp_close( session ); return 0; } sdp_session_t *register_service() { uint32_t svc_uuid_int[] = { 0x00000000,0x00000000,0x00000000,0x00000000 }; uint8_t rfcomm_channel = 11; const char *service_name = "Remote Host"; const char *service_dsc = "What the remote should be connecting to."; const char *service_prov = "Your mother"; uuid_t root_uuid, l2cap_uuid, rfcomm_uuid, svc_uuid; sdp_list_t *l2cap_list = 0, *rfcomm_list = 0, *root_list = 0, *proto_list = 0, *access_proto_list = 0; sdp_data_t *channel = 0, *psm = 0; sdp_record_t *record = sdp_record_alloc(); // set the general service ID sdp_uuid128_create( &svc_uuid, &svc_uuid_int ); sdp_set_service_id( record, svc_uuid ); // make the service record publicly browsable sdp_uuid16_create(&root_uuid, PUBLIC_BROWSE_GROUP); root_list = sdp_list_append(0, &root_uuid); sdp_set_browse_groups( record, root_list ); // set l2cap information sdp_uuid16_create(&l2cap_uuid, L2CAP_UUID); l2cap_list = sdp_list_append( 0, &l2cap_uuid ); proto_list = sdp_list_append( 0, l2cap_list ); // set rfcomm information sdp_uuid16_create(&rfcomm_uuid, RFCOMM_UUID); channel = sdp_data_alloc(SDP_UINT8, &rfcomm_channel); rfcomm_list = sdp_list_append( 0, &rfcomm_uuid ); sdp_list_append( rfcomm_list, channel ); sdp_list_append( proto_list, rfcomm_list ); // attach protocol information to service record access_proto_list = sdp_list_append( 0, proto_list ); sdp_set_access_protos( record, access_proto_list ); // set the name, provider, and description sdp_set_info_attr(record, service_name, service_prov, service_dsc); int err = 0; sdp_session_t *session = 0; // connect to the local SDP server, register the service record, and // disconnect session = sdp_connect( BDADDR_ANY, BDADDR_LOCAL, SDP_RETRY_IF_BUSY ); err = sdp_record_register(session, record, 0); // cleanup //sdp_data_free( channel ); sdp_list_free( l2cap_list, 0 ); sdp_list_free( rfcomm_list, 0 ); sdp_list_free( root_list, 0 ); sdp_list_free( access_proto_list, 0 ); return session; } And another piece of code, in addition to 'sdptool browse local' which can verifty that the service record is running on the pc: int main(int argc, char **argv) { uuid_t svc_uuid; uint32_t svc_uuid_int[] = { 0x00000000,0x00000000,0x00000000,0x00000000 }; int err; bdaddr_t target; sdp_list_t *response_list = NULL, *search_list, *attrid_list; sdp_session_t *session = 0; str2ba( "01:23:45:67:89:AB", &target ); // connect to the SDP server running on the remote machine session = sdp_connect( BDADDR_ANY, BDADDR_LOCAL, SDP_RETRY_IF_BUSY ); // specify the UUID of the application we're searching for sdp_uuid128_create( &svc_uuid, &svc_uuid_int ); search_list = sdp_list_append( NULL, &svc_uuid ); // specify that we want a list of all the matching applications' attributes uint32_t range = 0x0000ffff; attrid_list = sdp_list_append( NULL, &range ); // get a list of service records that have UUID 0xabcd err = sdp_service_search_attr_req( session, search_list, \ SDP_ATTR_REQ_RANGE, attrid_list, &response_list); sdp_list_t *r = response_list; // go through each of the service records for (; r; r = r-next ) { sdp_record_t *rec = (sdp_record_t*) r-data; sdp_list_t *proto_list; // get a list of the protocol sequences if( sdp_get_access_protos( rec, &proto_list ) == 0 ) { sdp_list_t *p = proto_list; // go through each protocol sequence for( ; p ; p = p-next ) { sdp_list_t *pds = (sdp_list_t*)p-data; // go through each protocol list of the protocol sequence for( ; pds ; pds = pds-next ) { // check the protocol attributes sdp_data_t *d = (sdp_data_t*)pds-data; int proto = 0; for( ; d; d = d-next ) { switch( d-dtd ) { case SDP_UUID16: case SDP_UUID32: case SDP_UUID128: proto = sdp_uuid_to_proto( &d-val.uuid ); break; case SDP_UINT8: if( proto == RFCOMM_UUID ) { printf("rfcomm channel: %d\n",d-val.int8); } break; } } } sdp_list_free( (sdp_list_t*)p-data, 0 ); } sdp_list_free( proto_list, 0 ); } printf("found service record 0x%x\n", rec-handle); sdp_record_free( rec ); } sdp_close(session); } Output: $ ./search rfcomm channel: 11 found service record 0x10008 sdptool: Service Name: Remote Host Service Description: What the remote should be connecting to. Service Provider: Your mother Service RecHandle: 0x10008 Protocol Descriptor List: "L2CAP" (0x0100) "RFCOMM" (0x0003) Channel: 11 And for logcat I'm getting this: 07-22 15:57:06.087: ERROR/BTLD(215): ****************search UUID = 0000*********** 07-22 15:57:06.087: INFO//system/bin/btld(209): btapp_dm_GetRemoteServiceChannel() 07-22 15:57:06.087: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Wake, 0x8003 #### 07-22 15:57:06.097: INFO/ActivityManager(88): Displayed activity com.example.socktest/.socktest: 79 ms (total 79 ms) 07-22 15:57:06.697: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Sleep, 0x8004 #### 07-22 15:57:07.517: WARN/BTLD(215): ccb timer ticks: 2147483648 07-22 15:57:07.517: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Wake, 0x8003 #### 07-22 15:57:07.547: WARN/BTLD(215): info:x10 07-22 15:57:07.547: INFO/BTL-IFS(215): send_ctrl_msg: [BTL_IFS CTRL] send BTLIF_DTUN_SIGNAL_EVT (CTRL) 10 pbytes (hdl 14) 07-22 15:57:07.547: DEBUG/DTUN_HCID_BZ4(253): dtun_dm_sig_link_up() 07-22 15:57:07.547: INFO/DTUN_HCID_BZ4(253): dtun_dm_sig_link_up: dummy_handle = 342 07-22 15:57:07.547: DEBUG/ADAPTER(253): adapter_get_device(00:02:72:AB:7C:EE) 07-22 15:57:07.547: ERROR/BluetoothEventLoop.cpp(88): pollData[0] is revented, check next one 07-22 15:57:07.547: ERROR/BluetoothEventLoop.cpp(88): event_filter: Received signal org.bluez.Device:PropertyChanged from /org/bluez/253/hci0/dev_00_02_72_AB_7C_EE 07-22 15:57:07.777: WARN/BTLD(215): process_service_search_attr_rsp 07-22 15:57:07.787: INFO/BTL-IFS(215): send_ctrl_msg: [BTL_IFS CTRL] send BTLIF_DTUN_SIGNAL_EVT (CTRL) 13 pbytes (hdl 14) 07-22 15:57:07.787: INFO/DTUN_HCID_BZ4(253): dtun_dm_sig_rmt_service_channel: success=0, service=00000000 07-22 15:57:07.787: ERROR/DTUN_HCID_BZ4(253): discovery unsuccessful! 07-22 15:57:08.497: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Sleep, 0x8004 #### 07-22 15:57:09.507: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Wake, 0x8003 #### 07-22 15:57:09.597: INFO/BTL-IFS(215): send_ctrl_msg: [BTL_IFS CTRL] send BTLIF_DTUN_SIGNAL_EVT (CTRL) 11 pbytes (hdl 14) 07-22 15:57:09.597: DEBUG/DTUN_HCID_BZ4(253): dtun_dm_sig_link_down() 07-22 15:57:09.597: INFO/DTUN_HCID_BZ4(253): dtun_dm_sig_link_down device = 0xf7a0 handle = 342 reason = 22 07-22 15:57:09.597: ERROR/BluetoothEventLoop.cpp(88): pollData[0] is revented, check next one 07-22 15:57:09.597: ERROR/BluetoothEventLoop.cpp(88): event_filter: Received signal org.bluez.Device:PropertyChanged from /org/bluez/253/hci0/dev_00_02_72_AB_7C_EE 07-22 15:57:09.597: DEBUG/BluetoothA2dpService(88): Received intent Intent { act=android.bluetooth.device.action.ACL_DISCONNECTED (has extras) } 07-22 15:57:10.107: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Sleep, 0x8004 #### 07-22 15:57:12.107: DEBUG/BluetoothService(88): Cleaning up failed UUID channel lookup: 00:02:72:AB:7C:EE 00000000-0000-0000-0000-000000000000 07-22 15:57:12.107: ERROR/Socket Test(5234): connect() failed 07-22 15:57:12.107: DEBUG/ASOCKWRP(5234): asocket_abort [31,32,33] 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_shutdown: s 31, how 2 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_shutdown: fd (-1:31), bta -1, rc 0, wflags 0x0 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): __close_prot_rfcomm: fd 31 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): __close_prot_rfcomm: bind not completed on this socket 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): btlif_signal_event: fd (-1:31), bta -1, rc 0, wflags 0x0 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): btlif_signal_event: event BTLIF_BTS_EVT_ABORT matched 07-22 15:57:12.107: DEBUG/BTL_IFC_WRP(5234): wrp_close_s_only: wrp_close_s_only [31] (31:-1) [] 07-22 15:57:12.107: DEBUG/BTL_IFC_WRP(5234): wrp_close_s_only: data socket closed 07-22 15:57:12.107: DEBUG/BTL_IFC_WRP(5234): wsactive_del: delete wsock 31 from active list [ad3e1494] 07-22 15:57:12.107: DEBUG/BTL_IFC_WRP(5234): wrp_close_s_only: wsock fully closed, return to pool 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): btsk_free: success 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_write: wrote 1 bytes out of 1 on fd 33 07-22 15:57:12.107: DEBUG/ASOCKWRP(5234): asocket_destroy 07-22 15:57:12.107: DEBUG/ASOCKWRP(5234): asocket_abort [31,32,33] 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_shutdown: s 31, how 2 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_shutdown: btsk not found, normal close (31) 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_write: wrote 1 bytes out of 1 on fd 33 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_close: s 33 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_close: btsk not found, normal close (33) 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_close: s 32 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_close: btsk not found, normal close (32) 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_close: s 31 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_close: btsk not found, normal close (31) 07-22 15:57:12.157: DEBUG/Sensors(88): close_akm, fd=151 07-22 15:57:12.167: ERROR/CachedBluetoothDevice(477): onUuidChanged: Time since last connect14970690 07-22 15:57:12.237: DEBUG/Socket Test(5234): -On Stop- Sorry for bombarding you guys with what seems like a difficult question and a lot to read, but I've been working on this problem for a while and I've tried a lot of different things to get this working. Let me reiterate, I can get it to work, but not using service discovery protocol. I've tried a several different UUIDs and on two different computers, although I only have my HTC Incredible to test with. I've also heard some rumors that the BT stack wasn't working on the HTC Droid, but that isn't the case, at least, for PC interaction.

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• how to model a follower stream in appengine?

  - by molicule

  I am trying to design tables to buildout a follower relationship. Say I have a stream of 140char records that have user, hashtag and other text. Users follow other users, and can also follow hashtags. I am outlining the way I've designed this below, but there are two limitaions in my design. I was wondering if others had smarter ways to accomplish the same goal. The issues with this are The list of followers is copied in for each record If a new follower is added or one removed, 'all' the records have to be updated. The code class HashtagFollowers(db.Model): """ This table contains the followers for each hashtag """ hashtag = db.StringProperty() followers = db.StringListProperty() class UserFollowers(db.Model): """ This table contains the followers for each user """ username = db.StringProperty() followers = db.StringListProperty() class stream(db.Model): """ This table contains the data stream """ username = db.StringProperty() hashtag = db.StringProperty() text = db.TextProperty() def save(self): """ On each save all the followers for each hashtag and user are added into a another table with this record as the parent """ super(stream, self).save() hfs = HashtagFollowers.all().filter("hashtag =", self.hashtag).fetch(10) for hf in hfs: sh = streamHashtags(parent=self, followers=hf.followers) sh.save() ufs = UserFollowers.all().filter("username =", self.username).fetch(10) for uf in ufs: uh = streamUsers(parent=self, followers=uf.followers) uh.save() class streamHashtags(db.Model): """ The stream record is the parent of this record """ followers = db.StringListProperty() class streamUsers(db.Model): """ The stream record is the parent of this record """ followers = db.StringListProperty() Now, to get the stream of followed hastags indexes = db.GqlQuery("""SELECT __key__ from streamHashtags where followers = 'myusername'""") keys = [k,parent() for k in indexes[offset:numresults]] return db.get(keys) Is there a smarter way to do this?

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• Using $this when not in object context--i am using the latest version of php and mysql

  - by user309381

  This is user.php: include("databse.php");//retrieving successfully first name and lastname from databse file into user.php class user { public $first_name; public $last_name; public static function full_name() { if(isset($this->first_name) && isset($this->last_name)) { return $this->first_name . " " . $this->last_name; } else { return ""; } } } ?> Other php file, index.php: <?php include(databse.php); include(user.php); $record = user::find_by_id(1); $object = new user(); $object->id = $record['id']; $object->username = $record['username']; $object->password = $record['password']; $object->first_name = $record['first_name']; $object->last_name = $record['last_name']; // echo $object->full_name(); echo $object->id;// successfully print the id echo $object->username;//success fully print the username echo->$object->full_name();//**ERROR:Using $this when not in object context** ?>

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• Uncommitted reads in SSIS

  - by OldBoy

  I'm trying to debug some legacy Integration Services code, and really want some confirmation on what I think the problem is: We have a very large data task inside a control flow container. This control flow container is set up with TransactionOption = supported - i.e. it will 'inherit' transactions from parent containers, but none are set up here. Inside the data flow there is a call to a stored proc that writes to a table with pseudo code something like: "If a record doesn't exist that matches these parameters then write it" Now, the issue is that there are three records being passed into this proc all with the same parameters, so logically the first record doesn't find a match and a record is created. The second record (with the same parameters) also doesn't find a match and another record is created. My understanding is that the first 'record' passed to the proc in the dataflow is uncommitted and therefore can't be 'read' by the second call. The upshot being that all three records create a row, when logically only the first should. In this scenario am I right in thinking that it is the uncommitted transaction that stops the second call from seeing the first? Even setting the isolation level on the container doesn't help because it's not being wrapped in a transaction anyway.... Hope that makes sense, and any advice gratefully received. Work-arounds confer god-like status on you.

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• database table design

  - by e.b.white

  I design the tables as below for the system which looks like a package delivering system For example, after user received the package, postman should record in system, and the state(history table) is "delivered",and operator is this postman, the current state(state table) is of course "delivered" history table: +---------------+--------------------------+ | Field | Desc | +---------------+--------------------------+ | id | PRIMARY KEY | +---------------+--------------------------+ | package_id | package_tacking_id | +---------------+--------------------------+ | state | package_state | +---------------+--------------------------+ | operators | operators | +---------------+--------------------------+ | create_time| create_time | +---------------+--------------------------+ state table: +---------------+--------------------------+ | Field | Desc | +---------------+--------------------------+ | id | PRIMARY KEY | +---------------+--------------------------+ | package_id | package_tacking_id | +---------------+--------------------------+ | state | latest_package_state | +---------------+--------------------------+ Above is just the basic information to record, some other information( like invoice, destination,...) should be recored as well. But there are different service types like s1 and s2, for s1 it is not needed to record invoice but s1 need, and maybe s1 need some other information to record (like the tel of end user). After all, at delivering way stations there are additional information to record, and for different service type the information type is different. My question is: 1. For different service type, shall I need to declare different tables(option A) or just one big table which can record all information for all types(option B)? 2. If option A, since the basic information above is MUST, how can prevent from declaring there duplicate fields in different tables?

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