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  • Feeding PDF through IInternetSession to WebBrowser control - Error

    - by Codesleuth
    As related to my previous question, I have developed a temporary asynchronous pluggable protocol with the specific aim to be able to serve PDF documents directly to a WebBrowser control via a database. I need to do this because my limitations include not being able to access the disk other than IsolatedStorage; and a MemoryStream would be far better for serving up PDF documents that average around 31kb. Unfortunately the code doesn't work, and I'm getting an error from the WebBrowser control (i.e. IE): Unable to download . Unable to open this Internet site. The requested site is either unavailable or cannot be found. Please try again later. The line in my code where this occurs is within the following: pOIProtSink.ReportData(BSCF.BSCF_LASTDATANOTIFICATION, (uint)_stream.Length, (uint)_stream.Length); However, if you download the project and run it, you will be able to see the stream is successfully read and passed to the browser, so it seems like there's a problem somewhere to do with the end of reading the data: public uint Read(IntPtr pv, uint cb, out uint pcbRead) { var bytesToRead = Math.Min(cb, _streamBuffer.Length); pcbRead = (uint)_stream.Read(_streamBuffer, 0, (int)bytesToRead); Marshal.Copy(_streamBuffer, 0, pv, (int)pcbRead); return (pcbRead == 0 || pcbRead < cb) ? HRESULT.S_FALSE : HRESULT.S_OK; } Here is the entire sample project: InternetSessionSample.zip (VS2010) I will leave this up for as long as I can to help other people in the future If anyone has any ideas why I might be getting this message and can shed some light on the problem, I would be grateful for the assistance. EDIT: A friend suggested inserting a line that calls the IInternetProtocolSink.ReportProgress with BINDSTATUS_CACHEFILENAMEAVAILABLE pointing at the original file. This prevents it from failing now and shows the PDF in the Adobe Reader control, but means it defeats the purpose of this by having Adobe Reader simply load from the cache file (which I can't provide). See below: pOIProtSink.ReportProgress(BINDSTATUS.BINDSTATUS_CACHEFILENAMEAVAILABLE, @"D:\Visual Studio Solutions\Projects\InternetSessionSample\bin\Debug\sample.pdf"); pOIProtSink.ReportData(BSCF.BSCF_LASTDATANOTIFICATION, (uint)_stream.Length, (uint)_stream.Length); This is progress though, I guess.

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  • How can I await the first completed async task of a list in .Net?

    - by Eyal
    My input is a long list of files located on an Amazon S3 server. I'd like to download the metadata of the files, compute the hashes of the local files, and compare the metadata hash with the local files' hash. Currently, I use a loop to start all the metadata downloads asynchronously, then as each completes, compute MD5 on the local file if needed and compare. Here's the code (just the relevant lines): Dim s3client As New AmazonS3Client(KeyId.Text, keySecret.Text) Dim responseTasks As New List(Of System.Tuple(Of ListViewItem, Task(Of GetObjectMetadataResponse))) For Each lvi As ListViewItem In lvStatus.Items Dim gomr As New Amazon.S3.Model.GetObjectMetadataRequest gomr.BucketName = S3FileDialog.GetBucketName(lvi.SubItems(2).Text) gomr.Key = S3FileDialog.GetPrefix(lvi.SubItems(2).Text) responseTasks.Add(New System.Tuple(Of ListViewItem, Task(Of GetObjectMetadataResponse))(lvi, s3client.GetObjectMetadataAsync(gomr))) Next For Each t As System.Tuple(Of ListViewItem, Task(Of GetObjectMetadataResponse)) In responseTasks Dim response As GetObjectMetadataResponse = Await t.Item2 If response.ETag.Trim(""""c) = MD5CalcFile(lvi.SubItems(1).Text) Then lvi.SubItems(3).Text = "Match" UpdateLvi(lvi) End If Next I've got two problems: I'm awaiting the reponses in the order that I made them. I'd rather process them in the order that they complete so that I get them faster. The MD5 calculation is long and synchronous. I tried making it async but the process locked up. I think that the MD5 task was added to the end of .Net's task list and it didn't get to run until all the downloads completed. Ideally, I process the response as they arrive, not in order, and the MD5 is asynchronous but gets a chance to run. Edit: Incorporating WhenAll, it looks like this now: Dim s3client As New Amazon.S3.AmazonS3Client(KeyId.Text, keySecret.Text) Dim responseTasks As New Dictionary(Of Task(Of GetObjectMetadataResponse), ListViewItem) For Each lvi As ListViewItem In lvStatus.Items Dim gomr As New Amazon.S3.Model.GetObjectMetadataRequest gomr.BucketName = S3FileDialog.GetBucketName(lvi.SubItems(2).Text) gomr.Key = S3FileDialog.GetPrefix(lvi.SubItems(2).Text) responseTasks.Add(s3client.GetObjectMetadataAsync(gomr), lvi) Next Dim startTime As DateTimeOffset = DateTimeOffset.Now Do While responseTasks.Count > 0 Dim currentTask As Task(Of GetObjectMetadataResponse) = Await Task.WhenAny(responseTasks.Keys) Dim response As GetObjectMetadataResponse = Await currentTask If response.ETag.Trim(""""c) = MD5CalcFile(lvi.SubItems(1).Text) Then lvi.SubItems(3).Text = "Match" UpdateLvi(lvi) End If Loop MsgBox((DateTimeOffset.Now - startTime).ToString) The UI locks up momentarily whenever MDSCalcFile is done. The whole loop takes about 45s and the first file's MD5 result happens within 1s of starting. If I change the line to: If response.ETag.Trim(""""c) = Await Task.Run(Function () MD5CalcFile(lvi.SubItems(1).Text)) Then The UI doesn't lock up when MD5CalcFile is done. The whole loop takes about 75s, up from 45s, and the first file's MD5 result happens after 40s of waiting.

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  • JSON and WebOS simple example?

    - by user558361
    I have been following this tutorial http://tinyurl.com/327p325 which has been GREAT up until this point where I can't get his code to work. I get the list working with static items but I can't get it to work with the json items. I've tried to simplify it with what I really want it to do to try and debug what is wrong (also if someone could please tell me how to view the Mojo log that would be awesome) In the tutorial he has to use the yahoo service to convert the site into json data, while the site I want to interact with already has json data generated so this is what I have PageAssistant.prototype.setup = function() { this.myListModel = { items : [] }; this.myListAttr = { itemTemplate: "page/itemTemplate", renderLimit: 20, }; this.controller.setupWidget("MyList",this.myListAttr,this.myListModel); this.controller.setupWidget("search_divSpinner", { spinnerSize : "large" }, { spinning: true } ); }; PageAssistant.prototype.activate = function(event) { this.getData(); }; PageAssistant.prototype.getData = function () { // the spinner doesn't show up at all $("search_divScrim").show(); var url = "http://www.website.com/.json"; var request = new Ajax.Request(url, { method: 'get', asynchronous: true, evalJSON: "false", onSuccess: this.parseResult.bind(this), on0: function (ajaxResponse) { // connection failed, typically because the server is overloaded or has gone down since the page loaded Mojo.Log.error("Connection failed"); }, onFailure: function(response) { // Request failed (404, that sort of thing) Mojo.Log.error("Request failed"); }, onException: function(request, ex) { // An exception was thrown Mojo.Log.error("Exception"); }, }); } PageAssistant.prototype.parseResult = function (transport){ var newData = []; var theStuff=transport.responseText; try { var json = theStuff.evalJSON(); } catch(e) { Mojo.Log.error(e); } // this is where I believe I am wrong for (j=0;j < json.data.count;j++) { var thread=json.data.children[j]; newData[j] = { title: thread.data.author }; } this.myListModel["items"] = newData; this.controller.modelChanged(this.myListModel , this); $("search_divScrim").hide(); } So where I commented that I believe I am wrong I am just trying to get the title out of this json data { kind: Listing data: { children: [ { kind: food data: { author: Foodmaster hidden: false title: You should eat this } }, // then it repeats with the kind: and data Anyone see where I went wrong? I would like to know how to view the log as I have log events but can't figure out where to look to see if any of them are being thrown.

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  • Strange behaviour with mediaplayer and seekTo

    - by Mathias Lin
    I'm implementing a custom video player because I need custom video controls. I have an app with only one activity, which on startup shall start playing a video right away. Now, the problem I have is: I don't want the video to start from the beginning, but from a later position. Therefore I do a seekTo(16867). Since seekTo is asynchronous, I place the start call of the mediaplayer (player.start()) in the onSeekComplete of the onSeekCompleteListener. The strange behaviour I experience though is that I can see/hear the video playing from the beginning for a few millisecs before it actually plays from/jumps to the position I seeked to. But - on the other hand - the Log output I call before the player.start returns the correct position 16867, where I seeked to. Below is the relevant code section, the complete class is at http://pastebin.com/jqAAFsuX (I'm on Nexus One / 2.2 StageFright) private void playVideo(String url) { try { btnVideoPause.setEnabled(false); if (player==null) { player=new MediaPlayer(); player.setScreenOnWhilePlaying(true); } else { player.stop(); player.reset(); } url = "/sdcard/myapp/main/videos/main.mp4"; // <--- just for test purposes hardcoded here now player.setDataSource(url); player.setDisplay(holder); player.setAudioStreamType(AudioManager.STREAM_MUSIC); player.setOnCompletionListener(this); player.setOnPreparedListener(this); player.setOnSeekCompleteListener(new MediaPlayer.OnSeekCompleteListener() { public void onSeekComplete(MediaPlayer mediaPlayer) { Log.d("APP", "current pos... "+ player.getCurrentPosition() ); player.start(); // <------------------ start video on seek completed player.setOnSeekCompleteListener(null); } }); player.prepareAsync(); } catch (Throwable t) { Log.e(TAG, "Exception in btnVideoPause prep", t); } } public void onPrepared(MediaPlayer mediaplayer) { width=player.getVideoWidth(); height=player.getVideoHeight(); if (width!=0 && height!=0) { holder.setFixedSize(width, height); progressBar.setProgress(0); progressBar.setMax(player.getDuration()); player.seekTo(16867); // <------------------ seeking to position } btnVideoPause.setEnabled(true); }

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  • Multi-Threading Question Concerning WPF

    - by Andrew
    Hello, I'm a newbie to threading, and I don't really know how to code a particular task. I would like to handle a mouse click event on a window that will kick off a while loop in a seperate thread. This thread, which is distinct from the UI thread, should call a function in the while loop which updates a label on the window being serviced by the UI thread. The while loop should stop running when the left mouse button is no longer being pressed. All the loop does is increment a counter, and then repeatedly call the function which displays the updated value in the window. The code for the window and all of the threading is given below (I keep getting some error about STA threading, but don't know where to put the attribute). Also, I'm hoping to use this solution, if it ever works, in another project that makes asynchronous calls elsewhere to a service via wcf, so I was hoping not to make any application-wide special configurations, since I'm really new to multi-threading and am quite worried about breaking other code in a larger program... Here's what I have: <Window x:Class="WpfApplication2.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:WpfApplication2" Name="MyMainWindow" Title="MainWindow" Width="200" Height="150" PreviewMouseLeftButtonDown="MyMainWindow_PreviewMouseLeftButtonDown"> <Label Height="28" Name="CounterLbl" /> </Window> And here's the code-behind: using System.Windows; using System.Windows.Input; using System.Threading; namespace WpfApplication2 { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { private int counter = 0; public MainWindow() { InitializeComponent(); } private delegate void EmptyDelegate(); private void MyMainWindow_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e) { Thread counterThread = new Thread(new ThreadStart(MyThread)); counterThread.Start(); } private void MyThread() { while (Mouse.LeftButton == MouseButtonState.Pressed) { counter++; Dispatcher.Invoke(new EmptyDelegate(UpdateLabelContents), null); } } private void UpdateLabelContents() { CounterLbl.Content = counter.ToString(); } } } Anyways, multi-threading is really new to me, and I don't have any experience implementing it, so any thoughts or suggestions are welcome! Thanks, Andrew

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  • Persistent (purely functional) Red-Black trees on disk performance

    - by Waneck
    I'm studying the best data structures to implement a simple open-source object temporal database, and currently I'm very fond of using Persistent Red-Black trees to do it. My main reasons for using persistent data structures is first of all to minimize the use of locks, so the database can be as parallel as possible. Also it will be easier to implement ACID transactions and even being able to abstract the database to work in parallel on a cluster of some kind. The great thing of this approach is that it makes possible implementing temporal databases almost for free. And this is something quite nice to have, specially for web and for data analysis (e.g. trends). All of this is very cool, but I'm a little suspicious about the overall performance of using a persistent data structure on disk. Even though there are some very fast disks available today, and all writes can be done asynchronously, so a response is always immediate, I don't want to build all application under a false premise, only to realize it isn't really a good way to do it. Here's my line of thought: - Since all writes are done asynchronously, and using a persistent data structure will enable not to invalidate the previous - and currently valid - structure, the write time isn't really a bottleneck. - There are some literature on structures like this that are exactly for disk usage. But it seems to me that these techniques will add more read overhead to achieve faster writes. But I think that exactly the opposite is preferable. Also many of these techniques really do end up with a multi-versioned trees, but they aren't strictly immutable, which is something very crucial to justify the persistent overhead. - I know there still will have to be some kind of locking when appending values to the database, and I also know there should be a good garbage collecting logic if not all versions are to be maintained (otherwise the file size will surely rise dramatically). Also a delta compression system could be thought about. - Of all search trees structures, I really think Red-Blacks are the most close to what I need, since they offer the least number of rotations. But there are some possible pitfalls along the way: - Asynchronous writes -could- affect applications that need the data in real time. But I don't think that is the case with web applications, most of the time. Also when real-time data is needed, another solutions could be devised, like a check-in/check-out system of specific data that will need to be worked on a more real-time manner. - Also they could lead to some commit conflicts, though I fail to think of a good example of when it could happen. Also commit conflicts can occur in normal RDBMS, if two threads are working with the same data, right? - The overhead of having an immutable interface like this will grow exponentially and everything is doomed to fail soon, so this all is a bad idea. Any thoughts? Thanks! edit: There seems to be a misunderstanding of what a persistent data structure is: http://en.wikipedia.org/wiki/Persistent_data_structure

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  • On Click alert if $.get returns a value, if not, submit the form

    - by bradenkeith
    If the submit button is clicked, prevent the default action and see if the field 'account_name' is already in use. If the $.get() returns a result, alert the user of the results. If it doesn't, submit form with id="add_account_form". My problem is that my else{} statement is not submitting the form. I get no response when submit is clicked & there is no value returned. Also I would like to change my code where it goes $("#add_account_form").submit(..) instead of .click() however, would that cause a problem when trying to submit the form later in the script? <script type="text/javascript"> $(document).ready( function () { $("#submit").click( function () { var account_name = $("input[name=account_name]").val(); $.get( "'.url::site("ajax/check_account_name").'", {account_name: account_name}, function(data){ if(data.length > 0){ confirm( "The account name you entered looks like the following:\n" +data+ "Press cancel if this account already exists or ok to create it." ); }else{ $("#add_account_form").submit(); } }); return false; }); }); </script> <p> <input type="submit" id="submit" class="submit small" name="submit" value="Submit" /> </p> </form> Thanks for your help. EDIT So anyone who runs into my problems, it's that $.get() is asynchronous, so it will always return false, or true depending on what submitForm is defined as. $.ajax() however, allows async to be set as false, which allows the function to finish before moving on. See what I mean: $(document).ready( function () { $("#add_account_form").submit( function () { var submitForm = true; var account_name = $("input[name=account_name]").val(); $.ajax({ type: "GET", async: false, url: "'.url::site("ajax/check_account_name").'", data: ({account_name: account_name}), success: function(data){ if(data.length > 0){ if(!confirm( "The account name you entered looks like the following:\n" +data+ "Press cancel if this account already exists or ok to create it." )){ submitForm = false; } } } }); if (submitForm == false ) { return false; } }); }); Thanks for your help @Dan

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  • AJAX XML reply node value iteration

    - by XpiritO
    Hi there, guys. I would really appreciate to get your help on this, as I can't seem to detect and solve the problem I'm having with an AJAX functionality on a site that I'm currently developing. I have a webform that makes an asynchronous call to a handler (.ashx) that delivers a XML response that is later processed by a Javascript client-side function that places it's contents into the user-interface. I'm attaching an example of the response generated by my handler, and what I would like to know is how can I get all the <body> element innerHTML (with the text and child nodes) contents to append it to a <span> element on the user-interface. Can anyone help me out with this? XML Response returned by the handler (checked via Firebug): <message> <content> <messageId>2</messageId> <from>Barack Obama</from> <fromMail>[email protected]</fromMail> <subject>Yes, we can... get World Peace</subject> <body>Hello, dear citizen. I'm sending you this message to invite you to join us! <a href="http://www.whitehouse.gov">Test link</a> Thank you for your time.</body> </content> </message> Client-side Javascript function to affect the user-interface innerHTML property with the data returned via AJAX: function GetMessageContentsCallback(args, resp) { //XML Parser try { //Internet Explorer xmlDoc = new ActiveXObject("Microsoft.XMLDOM"); xmlDoc.async = "false"; xmlDoc.loadXML(resp); } catch (e) { parser = new DOMParser(); xmlDoc = parser.parseFromString(resp, "text/xml"); } var msgReply = xmlDoc.getElementsByTagName('message')[0]; var ajaxRespondeBodyInnerHTML = msgReply.getElementsByTagName(body)[0].firstChild.nodeValue; //this currently only delivers inner text content, without the <a href... bit and subsequent text document.getElementById("bodySpan").innerHTML = ajaxRespondeBodyInnerHTML; }

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  • which way is correct to retrive data from oracle??

    - by rima
    before answer me plz thinking about the futures of these kind of program and answer me plz. I wanna get some data from oracle server like: 1-get all the function,package,procedure and etc for showing them or drop them & etc... 2-compile my *.sql files,get the result if they have problem & etc... becuz I was beginner in oracle first of all I for solve the second problem I try to connect to sqlPlus by RUN sqlplus and trace the output(I mean,I change the output stream of shell and trace what happend and handle the assigned message to customer. NOW THIS PART SUCCEED. just a little bit I have problem with get all result because the output is asynchronous.any way... [in this case I log in to oracle Server by send argument to the sqlplus by make a process in c#] after that I try to get all function,package or procedure name,but I have problem in speed!so I try to use oracle.DataAccess.dll to connect the database. now I m so confusing about: which way is correct way to build a program that work like Oracle Developer! I do not have any experience for like these program how work. If Your answer is I must use the second way follow this part plz: I search a little bit the Golden,PLedit (Benthic software),I have little bit problem how I must create the connection string?because I thinking about how I can find the host name or port number that oracle work on them?? am I need read the TNSNames.Ora file? IF your answer is I must use the first way follow this part plz: do u have any Idea for how I parse the output?because for example the result of a table is so confusing...[i can handle & program it but I really need someone experience,because the important things to me learn how such software work so nice and with quick response?] All of the has different style in output... If you are not sure Can u help me which book can help me in this way i become expert? becuz for example all the C# write just about how u can connect to DB and the DB books write how u can use this DB program,I looking for a book that give me some Idea how develop an interface for do transaction between these two.not simple send and receive data,for example how write a compiler for them. the language of book is not different for me i know C#,java,VB,sql,Oracle Thanks.

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  • multithreading with database

    - by Darsin
    I am looking out for a strategy to utilize multithreading (probably asynchronous delegates) to do a synchronous operation. I am new to multithreading so i will outline my scenario first. This synchronous operation right now is done for one set of data (portfolio) based on the the parameters provided. The (psudeo-code) implementation is given below: public DataSet DoTests(int fundId, DateTime portfolioDate) { // Get test results for the portfolio // Call the database adapter method, which in turn is a stored procedure, // which in turns runs a series of "rule" stored procs and fills a local temp table and returns it back. DataSet resultsDataSet = GetTestResults(fundId, portfolioDate); try { // Do some local processing on the results DoSomeProcessing(resultsDataSet); // Save the results in Test, TestResults and TestAllocations tables in a transaction. // Sets a global transaction which is provided to all the adapter methods called below // It is defined in the Base class StartTransaction("TestTransaction"); // Save Test and get a testId int testId = UpdateTest(resultsDataSet); // Adapter method, uses the same transaction // Update testId in the other tables in the dataset UpdateTestId(resultsDataSet, testId); // Update TestResults UpdateTestResults(resultsDataSet); // Adapter method, uses the same transaction // Update TestAllocations UpdateTestAllocations(resultsDataSet); // Adapter method, uses the same transaction // It is defined in the base class CommitTransaction("TestTransaction"); } catch { RollbackTransaction("TestTransaction"); } return resultsDataSet; } Now the requirement is to do it for multiple set of data. One way would be to call the above DoTests() method in a loop and get the data. I would prefer doing it in parallel. But there are certain catches: StartTransaction() method creates a connection (and transaction) every time it is called. All the underlying database tables, procedures are the same for each call of DoTests(). (obviously). Thus my question are: Will using multithreading anyway improve performance? What are the chances of deadlock especially when new TestId's are being created and the Tests, TestResults and TestAllocations are being saved? How can these deadlocked be handled? Is there any other more efficient way of doing the above operation apart from looping over the DoTests() method repeatedly?

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  • Network throughput issue (ARP-related)

    - by Joel Coel
    The small college where I work is having some very strange network issues. I'm looking for any advice or ideas here. We were fine over the summer, but the trouble began few days after students returned to campus in force for the fall term. Symptoms The main symptom is that internet access will work, but it's very slow... often to the point of timeouts. As an example, a typical result from Speedtest.net will return .4Mbps download, but allow 3 to 8 Mbps upload speed. Lesser symptoms may include severely limited performance transferring data to and from our file server, or even in some cases the inability to log in to the computer (cannot reach the domain controller). The issue crosses multiple vlans, and has effected devices on nearly every vlan we operate. The issue does not impact all machines on the network. An unaffected machine will typically see at least 11Mbps download from speedtest.net, and perhaps much more depending on larger campus traffic patterns at the time. There is one variation on the larger issue. We have one vlan where users were unable to log into nearly all of the machines at all. IT staff would log in using a local administrator account (or in some cases cached credentials), and from there a release/renew or pinging the gateway would allow the machine to work... for a while. Complicating this issue is that this vlan covers our computer labs, which use software called Deep Freeze to completely reset the hard drives after a reboot. It could just the same issue manifesting differently because of stale data on machines that have not permanently altered low-level info for weeks. We were able to solve this, however, by creating a new vlan and moving the labs over to the new vlan wholesale. Instigations Eventually we noticed that the effected machines all had recent dhcp leases. We can predict when a machine will become "slow" by watching when a dhcp lease comes up for renewal. We played with setting the lease time very short for a test vlan, but all that did was remove our ability to predict when the machine would become slow. Machines with static IPs have pretty much always worked normally. Manually releasing/renewing an address will never cause a machine to become slow. In fact, in some cases this process has fixed a machine in that state. Most of the time, though, it doesn't help. We also noticed that mobile machines like laptops are likely to become slow when they cross to new vlans. Wireless on campus is divided up into "zones", where each zone maps to a small set of buildings. Moving to a new building can place you in a zone, thereby causing you to get a new address. A machine resuming from sleep mode is also very likely to be slow. Mitigations Sometimes, but not always, clearing the arp cache on an effected machine will allow it to work normally again. As already mentioned, releasing/renewing a local machine's IP address can fix that machine, but it's not guaranteed. Pinging the default gateway can also sometimes help with a slow machine. What seems to help most to mitigate the issue is clearing the arp cache on our core layer-3 switch. This switch is used for our dhcp system as the default gateway on all vlans, and it handles inter-vlan routing. The model is a 3Com 4900SX. To try to mitigate the issue, we have the cache timeout set on the switch all the way down to the lowest possible time, but it hasn't helped. I also put together a script that runs every few minutes to automatically connect to the switch and reset the cache. Unfortunately, this does not always work, and can even cause some machines to end up in the slow state for a short time (though these seem to correct themselves after a few minutes). We currently have a scheduled job that runs every 10 minutes to force the core switch to clear it's ARP cache, but this is far from perfect or desirable. Reproduction We now have a test machine that we can force into the slow state at will. It is connected to a switch with ports set up for each of our vlans. We make the machine slow by connecting to different vlans, and after a new connection or two it will be slow. It's also worth noting in this section that this has happened before at the start of prior terms, but in the past the problem has gone away on it's own after a few days. It solved itself before we had a chance to do much diagnostic work... hence why we've allowed it to drag so long into the term this time 'round; the expectation was this would be a short-lived situation. Other Factors It's worth mentioning that we have had about half a dozen switches just outright fail over the last year. These are mainly 2003/2004-era 3Coms (mostly 4200's) that were all put in at about the same time. They should still be covered under warranty, buy HP has made getting service somewhat difficult. Mostly in power supplies that have failed, but in a couple cases we have used a power supply from a switch with a failed mainboard to bring a switch with a failed power supply back to life. We do have UPS devices on all but three of four switches now, but that was not the case when I started two and a half years ago. Severe budget constraints (we were on the Dept. of Ed's financially challenged institutions list a couple years back) have forced me to look to the likes of Netgear and TrendNet for replacements, but so far these low-end models seem to be holding their own. It's also worth mentioning that the big change on our network this summer was migrating from a single cross-campus wireless SSID to the zoned approach mentioned earlier. I don't think this is the source of the issue, as like I've said: we've seen this before. However, it's possible this is exacerbating the issue, and may be much of the reason it's been so hard to isolate. Diagnosis At first it seemed clear to us, given the timing and persistent nature of the problem, that the source of the issue was an infected (or malicious) student machine doing ARP cache poisoning. However, repeated attempts to isolate the source have failed. Those attempts include numerous wireshark packet traces, and even taking entire buildings offline for brief periods. We have not been able even to find a smoking gun bad ARP entry. My current best guess is an overloaded or failing core switch, but I'm not sure on how to test for this, and the cost of replacing it blindly is steep. Again, any ideas appreciated.

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  • help me to choose the best soulotion for my purpose to build my software.

    - by rima
    before answer me plz thinking about the futures of these kind of program and answer me plz. I wanna get some data from oracle server like: 1-get all the function,package,procedure and etc for showing them or drop them & etc... 2-compile my *.sql files,get the result if they have problem & etc... becuz I was beginner in oracle first of all I for solve the second problem I try to connect to sqlPlus by RUN sqlplus and trace the output(I mean,I change the output stream of shell and trace what happend and handle the assigned message to customer. NOW THIS PART SUCCEED. just a little bit I have problem with get all result because the output is asynchronous.any way... [in this case I log in to oracle Server by send argument to the sqlplus by make a process in c#] after that I try to get all function,package or procedure name,but I have problem in speed!so I try to use oracle.DataAccess.dll to connect the database. now I m so confusing about: which way is correct way to build a program that work like Oracle Developer! I do not have any experience for like these program how work. If Your answer is I must use the second way follow this part plz: I search a little bit the Golden,PLedit (Benthic software),I have little bit problem how I must create the connection string?because I thinking about how I can find the host name or port number that oracle work on them?? am I need read the TNSNames.Ora file? IF your answer is I must use the first way follow this part plz: do u have any Idea for how I parse the output?because for example the result of a table is so confusing...[i can handle & program it but I really need someone experience,because the important things to me learn how such software work so nice and with quick response?] All of the has different style in output... If you are not sure Can u help me which book can help me in this way i become expert? becuz for example all the C# write just about how u can connect to DB and the DB books write how u can use this DB program,I looking for a book that give me some Idea how develop an interface for do transaction between these two.not simple send and receive data,for example how write a compiler for them. the language of book is not different for me i know C#,java,VB,sql,Oracle Thanks.

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  • What IPC method should I use between Firefox extension and C# code running on the same machine?

    - by Rory
    I have a question about how to structure communication between a (new) Firefox extension and existing C# code. The firefox extension will use configuration data and will produce other data, so needs to get the config data from somewhere and save it's output somewhere. The data is produced/consumed by existing C# code, so I need to decide how the extension should interact with the C# code. Some pertinent factors: It's only running on windows, in a relatively controlled corporate environment. I have a windows service running on the machine, built in C#. Storing the data in a local datastore (like sqlite) would be useful for other reasons. The volume of data is low, e.g. 10kb of uncompressed xml every few minutes, and isn't very 'chatty'. The data exchange can be asynchronous for the most part if not completely. As with all projects, I have limited resources so want an option that's relatively easy. It doesn't have to be ultra-high performance, but shouldn't add significant overhead. I'm planning on building the extension in javascript (although could be convinced otherwise if really necessary) Some options I'm considering: use an XPCOM to .NET/COM bridge use a sqlite db: the extension would read from and save to it. The c# code would run in the service, populating the db and then processing data created by the service. use TCP sockets to communicate between the extension and the service. Let the service manage a local data store. My problem with (1) is I think this will be tricky and not so easy. But I could be completely wrong? The main problem I see with (2) is the locking of sqlite: only a single process can write data at a time so there'd be some blocking. However, it would be nice generally to have a local datastore so this is an attractive option if the performance impact isn't too great. I don't know whether (3) would be particularly easy or hard ... or what approach to take on the protocol: something custom or http. Any comments on these ideas or other suggestions? UPDATE: I was planning on building the extension in javascript rather than c++

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  • Approaches for Content-based Item Recommendations

    - by PartlyCloudy
    Hello, I'm currently developing an application where I want to group similar items. Items (like videos) can be created by users and also their attributes can be altered or extended later (like new tags). Instead of relying on users' preferences as most collaborative filtering mechanisms do, I want to compare item similarity based on the items' attributes (like similar length, similar colors, similar set of tags, etc.). The computation is necessary for two main purposes: Suggesting x similar items for a given item and for clustering into groups of similar items. My application so far is follows an asynchronous design and I want to decouple this clustering component as far as possible. The creation of new items or the addition of new attributes for an existing item will be advertised by publishing events the component can then consume. Computations can be provided best-effort and "snapshotted", which means that I'm okay with the best result possible at a given point in time, although result quality will eventually increase. So I am now searching for appropriate algorithms to compute both similar items and clusters. At important constraint is scalability. Initially the application has to handle a few thousand items, but later million items might be possible as well. Of course, computations will then be executed on additional nodes, but the algorithm itself should scale. It would also be nice if the algorithm supports some kind of incremental mode on partial changes of the data. My initial thought of comparing each item with each other and storing the numerical similarity sounds a little bit crude. Also, it requires n*(n-1)/2 entries for storing all similarities and any change or new item will eventually cause n similarity computations. Thanks in advance! UPDATE tl;dr To clarify what I want, here is my targeted scenario: User generate entries (think of documents) User edit entry meta data (think of tags) And here is what my system should provide: List of similar entries to a given item as recommendation Clusters of similar entries Both calculations should be based on: The meta data/attributes of entries (i.e. usage of similar tags) Thus, the distance of two entries using appropriate metrics NOT based on user votings, preferences or actions (unlike collaborative filtering). Although users may create entries and change attributes, the computation should only take into account the items and their attributes, and not the users associated with (just like a system where only items and no users exist). Ideally, the algorithm should support: permanent changes of attributes of an entry incrementally compute similar entries/clusters on changes scale something better than a simple distance table, if possible (because of the O(n²) space complexity)

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  • iPhone - NSURLConnection does not receive data

    - by Jukurrpa
    Hi, I have a pretty weird problem with NSURLRequest. I'm using them to make an asynchronous image loading in an UITableView. The first time the tableView displays, all connections from NSURLRequests open correctly but receive absolutely no data, regardless of how long I wait. But as soon as I scroll down in the tableView, the newly created requests for the new cells work perfectly! The only way for the images on top of the tableView to load is to make them disappear by scrolling down and then up again, in order to create new requests. Here is what I do in "cellForRowAtIndexPath": UITableViewCell* cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"]; if (cell == nil) { cell = [[UITableViewCell alloc] initWIthFrame:CGRectMake(0, 0, 300, 60)]; AsyncUIImageView imageView = [[AsynUIImageView alloc] initWithFrame:CGRectMake(0, 0, 60, 60)]; imageView.tag = IMG_VIEW // an enum for tags [cell addSubView:imageView]; [imageView release]; } AsyncUIImageView imageView = (AsyncUIImageView*)[cell viewWithTag:IMG_VIEW]; // I do a few cache checks here, but if the image aint cached I do this: [imageView loadImageFromURL:@"http://someurl.com/somepix.jpg"]; // all urls are different, just an example The AsyncUIImageView inherits from UIImageView and contains an NSURLConnection which opens upon calling the loadImageFromURL method: (void) loadImageFromURL:(NSString*)filename { if (self.connection != nil) [self.connection release]; if (self.data != nil) [self.data release]; NSURLRequest* request = [NSURLRequest requestWithURL:[[NSURL alloc] initWithString:fileName] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10.0]; self.connection = [[NSURLConnection alloc] initWithRequest:request delegate:self]; if (self.connection == nil) return; self.data = [[NSMutableData data] retain]; } I've created the delegate methods "connection: didReceiveData", which appends received data to self.data and "connectionDidFinishLoading" which sets the image and closes the connection once the transfer is complete. These work, but are never called for the first requests I create. I suspect this bug to come from the main thread not giving the first requests the control so they can execute themselves, as the same behavior happens if I keep my finger on the screen after a scroll: connections open themselves, but no data is received until I stop touching the screen. What am I doing wrong?

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  • Force deletion of slot in boost::signals2

    - by villintehaspam
    Hi! I have found that boost::signals2 uses sort of a lazy deletion of connected slots, which makes it difficult to use connections as something that manages lifetimes of objects. I am looking for a way to force slots to be deleted directly when disconnected. Any ideas on how to work around the problem by designing my code differently are also appreciated! This is my scenario: I have a Command class responsible for doing something that takes time asynchronously, looking something like this (simplified): class ActualWorker { public: boost::signals2<void ()> OnWorkComplete; }; class Command : boost::enable_shared_from_this<Command> { public: ... void Execute() { m_WorkerConnection = m_MyWorker.OnWorkDone.connect(boost::bind(&Command::Handle_OnWorkComplete, shared_from_this()); // launch asynchronous work here and return } boost::signals2<void ()> OnComplete; private: void Handle_OnWorkComplete() { // get a shared_ptr to ourselves to make sure that we live through // this function but don't keep ourselves alive if an exception occurs. shared_ptr<Command> me = shared_from_this(); // Disconnect from the signal, ideally deleting the slot object m_WorkerConnection.disconnect(); OnComplete(); // the shared_ptr now goes out of scope, ideally deleting this } ActualWorker m_MyWorker; boost::signals2::connection m_WorkerConnection; }; The class is invoked about like this: ... boost::shared_ptr<Command> cmd(new Command); cmd->OnComplete.connect( foo ); cmd->Execute(); // now go do something else, forget all about the cmd variable etcetera. the Command class keeps itself alive by getting a shared_ptr to itself which is bound to the ActualWorker signal using boost::bind. When the worker completes, the handler in Command is invoked. Now, since I would like the Command object to be destroyed, I disconnect from the signal as can be seen in the code above. The problem is that the actual slot object is not deleted when disconnected, it is only marked as invalid and then deleted at a later time. This in turn appears to depend on the signal to fire again, which it doesn't do in my case, leading to the slot never expiring. The boost::bind object thus never goes out of scope, holding a shared_ptr to my object that will never get deleted. I can work around this by binding using the this pointer instead of a shared_ptr and then keeping my object alive using a member shared_ptr which I then release in the handler function, but it kind of makes the design feel a bit overcomplicated. Is there a way to force signals2 to delete the slot when disconnecting? Or is there something else I could do to simplify the design? Any comments are appreciated!

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  • Adding a clustered index to a SQL table: what dangers exist for a live production system?

    - by MoSlo
    Right, keep in mind i need to describe this by abstracting all possible confidential info: I've been put in charge of a 10-year old transactional system of which the majority business logic is implemented at database level (triggers, stored procedures etc). Win2000 server, MSSQL 2000 Enterprise. No immediate plans for replacing/updating the system are being considered :( The core process is a program that executes transactions - specifically, it executes a stored procedure with various parameters, lets call it sp_ProcessTrans. The program executes the stored procedure at asynchronous intervals. By itself, things work fine. But there are 30 instances of this program on remotely located workstations, all of them asynchronously executing sp_ProcessTrans and then retrieving data from the SQL server (execution is pretty regular - ranging 0 to 60 times a minute, depending on what items the program instance is responsible for) . Performance of the system has dropped considerably with 10 yrs of data growth: the reason is the deadlocks and specifically deadlock wait times. The deadlock is on the Employee table. I have discovered: In sp_ProcessTrans' execution, it selects from an Employee table 7 times (dont ask) The select is done on a field that is NOT the primary key No index exists on this field. Thus a table scan is performed. 7 times. per transaction So the reason for deadlocks is clear. I created a non-unique ordered clustered index on the field (field looks good, almost unique, NUM(7), very rarely changes). Immediate improvement in the test environment. The problem is that i cannot simulate the deadlocks in a test environment (I'd need 30 workstations; i'd need to simulate 'realistic' activity on those stations, so visualization is out). I need to know if i must schedule downtime. Creating an index shouldn't be a risky operation for MSSQL, but is there any danger (data corruption in transactions/select statements/extra wait time etc) to create this field index on the production database while the transactions are still taking place? (although i can select a time when transactions are fairly quiet through the 30 stations) Are there any hidden dangers i'm not seeing (not looking forward to needing to restore the DB if something goes wrong, restoring would take a lot of time with 10yrs of data).

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  • What is the best way to connect to an Oracle database to build my own IDE? [closed]

    - by rima
    before answer me plz thinking about the futures of these kind of program and answer me plz. I wanna get some data from oracle server like: 1-get all the function,package,procedure and etc for showing them or drop them & etc... 2-compile my *.sql files,get the result if they have problem & etc... becuz I was beginner in oracle first of all I for solve the second problem I try to connect to sqlPlus by RUN sqlplus and trace the output(I mean,I change the output stream of shell and trace what happend and handle the assigned message to customer. NOW THIS PART SUCCEED. just a little bit I have problem with get all result because the output is asynchronous.any way... [in this case I log in to oracle Server by send argument to the sqlplus by make a process in c#] after that I try to get all function,package or procedure name,but I have problem in speed!so I try to use oracle.DataAccess.dll to connect the database. now I m so confusing about: which way is correct way to build a program that work like Oracle Developer! I do not have any experience for like these program how work. If Your answer is I must use the second way follow this part plz: I search a little bit the Golden,PLedit (Benthic software),I have little bit problem how I must create the connection string?because I thinking about how I can find the host name or port number that oracle work on them?? am I need read the TNSNames.Ora file? IF your answer is I must use the first way follow this part plz: do u have any Idea for how I parse the output?because for example the result of a table is so confusing...[i can handle & program it but I really need someone experience,because the important things to me learn how such software work so nice and with quick response?] All of the has different style in output... If you are not sure Can u help me which book can help me in this way i become expert? becuz for example all the C# write just about how u can connect to DB and the DB books write how u can use this DB program,I looking for a book that give me some Idea how develop an interface for do transaction between these two.not simple send and receive data,for example how write a compiler for them. the language of book is not different for me i know C#,java,VB,sql,Oracle Thanks.

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  • fieldWithErrors not wrapping every error field

    - by Teef L
    Notice the following result when I submit blank :title and :description fields The validations are in the controller: class Question < ActiveRecord::Base validates_presence_of :title validates_presence_of :description And, the form is generated with those names: -form_for(@question) do |f| = f.error_messages = f.label :title = f.text_field :title, :size => 50, :onchange => remote_function(:url => {:action => :display_tag_suggestions}, :with => 'Form.Element.serialize(this)') #suggestions = f.label :description = f.text_area :description ... But, for some reason, only :title gets wrapped in the error div tags: <form action="/questions" class="new_question" id="new_question" method="post"> <div style="margin:0;padding:0"><input name="authenticity_token" type="hidden" value="6HQaiu1D0gBQcKw2pLeZP6Jvn0FSClPD5Sk9HwegzPg=" /></div> <div class="errorExplanation" id="errorExplanation"> <h2>2 errors prohibited this question from being saved</h2> <p>There were problems with the following fields:</p> <ul> <li>Title can't be blank</li> <li>Description can't be blank</li> </ul> </div> <label for="question_title">Title</label> <div class="fieldWithErrors"><input id="question_title" name="question[title]" onchange="new Ajax.Request('/questions/display_tag_suggestions', {asynchronous:true, evalScripts:true, parameters:Form.Element.serialize(this) + '&amp;authenticity_token=' + encodeURIComponent('6HQaiu1D0gBQcKw2pLeZP6Jvn0FSClPD5Sk9HwegzPg=')})" size="50" type="text" value="" /></div> <label for="question_description">Description</label> <textarea cols="40" id="question_description" name="question[description]" rows="20"></textarea> ... I don't think that behavior is expected. The problem most people have is that it's wrapping things with divs, which won't display properly. My problem is that fields aren't being wrapped with divs to begin with! I haven't made any (conscious) changes to how errors are handled, so I'm not sure why it's not working properly.

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  • IntentService android download and return file to Activity

    - by Andrew G
    I have a fairly tricky situation that I'm trying to determine the best design for. The basics are this: I'm designing a messaging system with a similar interface to email. When a user clicks a message that has an attachment, an activity is spawned that shows the text of that message along with a paper clip signaling that there is an additional attachment. At this point, I begin preloading the attachment so that when the user clicks on it - it loads more quickly. currently, when the user clicks the attachment, it prompts with a loading dialog until the download is complete at which point it loads a separate attachment viewer activity, passing in the bmp byte array. I don't ever want to save attachments to persistent storage. The difficulty I have is in supporting rotation as well as home button presses etc. The download is currently done with a thread and handler setup. Instead of this, I'd like the flow to be the following: User loads message as before, preloading begins of attachment as before (invisible to user). When the user clicks on the attachment link, the attachment viewer activity is spawned right away. If the download was done, the image is displayed. If not, a dialog is shown in THIS activity until it is done and can be displayed. Note that ideally the download never restarts or else I've wasted cycles on the preload. Obviously I need some persistent background process that is able to keep downloading and is able to call back to arbitrarily bonded Activities. It seems like the IntentService almost fits my needs as it does its work in a background thread and has the Service (non UI) lifecycle. However, will it work for my other needs? I notice that common implementations for what I want to do get a Messenger from the caller Activity so that a Message object can be sent back to a Handler in the caller's thread. This is all well and good but what happens in my case when the caller Activity is Stopped or Destroyed and the currently active Activity (the attachment viewer) is showing? Is there some way to dynamically bind a new Activity to a running IntentService so that I can send a Message back to the new Activity? The other question is on the Message object. Can I send arbitrarily large data back in this package? For instance, rather than send back that "The file was downloaded", I need to send back the byte array of the downloaded file itself since I never want to write it to disk (and yes this needs to be the case). Any advice on achieving the behavior I want is greatly appreciated. I've not been working with Android for that long and I often get confused with how to best handle asynchronous processes over the course of the Activity lifecycle especially when it comes to orientation changes and home button presses...

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  • Session memory – who’s this guy named Max and what’s he doing with my memory?

    - by extended_events
    SQL Server MVP Jonathan Kehayias (blog) emailed me a question last week when he noticed that the total memory used by the buffers for an event session was larger than the value he specified for the MAX_MEMORY option in the CREATE EVENT SESSION DDL. The answer here seems like an excellent subject for me to kick-off my new “401 – Internals” tag that identifies posts where I pull back the curtains a bit and let you peek into what’s going on inside the extended events engine. In a previous post (Option Trading: Getting the most out of the event session options) I explained that we use a set of buffers to store the event data before  we write the event data to asynchronous targets. The MAX_MEMORY along with the MEMORY_PARTITION_MODE defines how big each buffer will be. Theoretically, that means that I can predict the size of each buffer using the following formula: max memory / # of buffers = buffer size If it was that simple I wouldn’t be writing this post. I’ll take “boundary” for 64K Alex For a number of reasons that are beyond the scope of this blog, we create event buffers in 64K chunks. The result of this is that the buffer size indicated by the formula above is rounded up to the next 64K boundary and that is the size used to create the buffers. If you think visually, this means that the graph of your max_memory option compared to the actual buffer size that results will look like a set of stairs rather than a smooth line. You can see this behavior by looking at the output of dm_xe_sessions, specifically the fields related to the buffer sizes, over a range of different memory inputs: Note: This test was run on a 2 core machine using per_cpu partitioning which results in 5 buffers. (Seem my previous post referenced above for the math behind buffer count.) input_memory_kb total_regular_buffers regular_buffer_size total_buffer_size 637 5 130867 654335 638 5 130867 654335 639 5 130867 654335 640 5 196403 982015 641 5 196403 982015 642 5 196403 982015 This is just a segment of the results that shows one of the “jumps” between the buffer boundary at 639 KB and 640 KB. You can verify the size boundary by doing the math on the regular_buffer_size field, which is returned in bytes: 196403 – 130867 = 65536 bytes 65536 / 1024 = 64 KB The relationship between the input for max_memory and when the regular_buffer_size is going to jump from one 64K boundary to the next is going to change based on the number of buffers being created. The number of buffers is dependent on the partition mode you choose. If you choose any partition mode other than NONE, the number of buffers will depend on your hardware configuration. (Again, see the earlier post referenced above.) With the default partition mode of none, you always get three buffers, regardless of machine configuration, so I generated a “range table” for max_memory settings between 1 KB and 4096 KB as an example. start_memory_range_kb end_memory_range_kb total_regular_buffers regular_buffer_size total_buffer_size 1 191 NULL NULL NULL 192 383 3 130867 392601 384 575 3 196403 589209 576 767 3 261939 785817 768 959 3 327475 982425 960 1151 3 393011 1179033 1152 1343 3 458547 1375641 1344 1535 3 524083 1572249 1536 1727 3 589619 1768857 1728 1919 3 655155 1965465 1920 2111 3 720691 2162073 2112 2303 3 786227 2358681 2304 2495 3 851763 2555289 2496 2687 3 917299 2751897 2688 2879 3 982835 2948505 2880 3071 3 1048371 3145113 3072 3263 3 1113907 3341721 3264 3455 3 1179443 3538329 3456 3647 3 1244979 3734937 3648 3839 3 1310515 3931545 3840 4031 3 1376051 4128153 4032 4096 3 1441587 4324761 As you can see, there are 21 “steps” within this range and max_memory values below 192 KB fall below the 64K per buffer limit so they generate an error when you attempt to specify them. Max approximates True as memory approaches 64K The upshot of this is that the max_memory option does not imply a contract for the maximum memory that will be used for the session buffers (Those of you who read Take it to the Max (and beyond) know that max_memory is really only referring to the event session buffer memory.) but is more of an estimate of total buffer size to the nearest higher multiple of 64K times the number of buffers you have. The maximum delta between your initial max_memory setting and the true total buffer size occurs right after you break through a 64K boundary, for example if you set max_memory = 576 KB (see the green line in the table), your actual buffer size will be closer to 767 KB in a non-partitioned event session. You get “stepped up” for every 191 KB block of initial max_memory which isn’t likely to cause a problem for most machines. Things get more interesting when you consider a partitioned event session on a computer that has a large number of logical CPUs or NUMA nodes. Since each buffer gets “stepped up” when you break a boundary, the delta can get much larger because it’s multiplied by the number of buffers. For example, a machine with 64 logical CPUs will have 160 buffers using per_cpu partitioning or if you have 8 NUMA nodes configured on that machine you would have 24 buffers when using per_node. If you’ve just broken through a 64K boundary and get “stepped up” to the next buffer size you’ll end up with total buffer size approximately 10240 KB and 1536 KB respectively (64K * # of buffers) larger than max_memory value you might think you’re getting. Using per_cpu partitioning on large machine has the most impact because of the large number of buffers created. If the amount of memory being used by your system within these ranges is important to you then this is something worth paying attention to and considering when you configure your event sessions. The DMV dm_xe_sessions is the tool to use to identify the exact buffer size for your sessions. In addition to the regular buffers (read: event session buffers) you’ll also see the details for large buffers if you have configured MAX_EVENT_SIZE. The “buffer steps” for any given hardware configuration should be static within each partition mode so if you want to have a handy reference available when you configure your event sessions you can use the following code to generate a range table similar to the one above that is applicable for your specific machine and chosen partition mode. DECLARE @buf_size_output table (input_memory_kb bigint, total_regular_buffers bigint, regular_buffer_size bigint, total_buffer_size bigint) DECLARE @buf_size int, @part_mode varchar(8) SET @buf_size = 1 -- Set to the begining of your max_memory range (KB) SET @part_mode = 'per_cpu' -- Set to the partition mode for the table you want to generate WHILE @buf_size <= 4096 -- Set to the end of your max_memory range (KB) BEGIN     BEGIN TRY         IF EXISTS (SELECT * from sys.server_event_sessions WHERE name = 'buffer_size_test')             DROP EVENT SESSION buffer_size_test ON SERVER         DECLARE @session nvarchar(max)         SET @session = 'create event session buffer_size_test on server                         add event sql_statement_completed                         add target ring_buffer                         with (max_memory = ' + CAST(@buf_size as nvarchar(4)) + ' KB, memory_partition_mode = ' + @part_mode + ')'         EXEC sp_executesql @session         SET @session = 'alter event session buffer_size_test on server                         state = start'         EXEC sp_executesql @session         INSERT @buf_size_output (input_memory_kb, total_regular_buffers, regular_buffer_size, total_buffer_size)             SELECT @buf_size, total_regular_buffers, regular_buffer_size, total_buffer_size FROM sys.dm_xe_sessions WHERE name = 'buffer_size_test'     END TRY     BEGIN CATCH         INSERT @buf_size_output (input_memory_kb)             SELECT @buf_size     END CATCH     SET @buf_size = @buf_size + 1 END DROP EVENT SESSION buffer_size_test ON SERVER SELECT MIN(input_memory_kb) start_memory_range_kb, MAX(input_memory_kb) end_memory_range_kb, total_regular_buffers, regular_buffer_size, total_buffer_size from @buf_size_output group by total_regular_buffers, regular_buffer_size, total_buffer_size Thanks to Jonathan for an interesting question and a chance to explore some of the details of Extended Event internals. - Mike

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  • Why do we get a sudden spike in response times?

    - by Christian Hagelid
    We have an API that is implemented using ServiceStack which is hosted in IIS. While performing load testing of the API we discovered that the response times are good but that they deteriorate rapidly as soon as we hit about 3,500 concurrent users per server. We have two servers and when hitting them with 7,000 users the average response times sit below 500ms for all endpoints. The boxes are behind a load balancer so we get 3,500 concurrents per server. However as soon as we increase the number of total concurrent users we see a significant increase in response times. Increasing the concurrent users to 5,000 per server gives us an average response time per endpoint of around 7 seconds. The memory and CPU on the servers are quite low, both while the response times are good and when after they deteriorate. At peak with 10,000 concurrent users the CPU averages just below 50% and the RAM sits around 3-4 GB out of 16. This leaves us thinking that we are hitting some kind of limit somewhere. The below screenshot shows some key counters in perfmon during a load test with a total of 10,000 concurrent users. The highlighted counter is requests/second. To the right of the screenshot you can see the requests per second graph becoming really erratic. This is the main indicator for slow response times. As soon as we see this pattern we notice slow response times in the load test. How do we go about troubleshooting this performance issue? We are trying to identify if this is a coding issue or a configuration issue. Are there any settings in web.config or IIS that could explain this behaviour? The application pool is running .NET v4.0 and the IIS version is 7.5. The only change we have made from the default settings is to update the application pool Queue Length value from 1,000 to 5,000. We have also added the following config settings to the Aspnet.config file: <system.web> <applicationPool maxConcurrentRequestsPerCPU="5000" maxConcurrentThreadsPerCPU="0" requestQueueLimit="5000" /> </system.web> More details: The purpose of the API is to combine data from various external sources and return as JSON. It is currently using an InMemory cache implementation to cache individual external calls at the data layer. The first request to a resource will fetch all data required and any subsequent requests for the same resource will get results from the cache. We have a 'cache runner' that is implemented as a background process that updates the information in the cache at certain set intervals. We have added locking around the code that fetches data from the external resources. We have also implemented the services to fetch the data from the external sources in an asynchronous fashion so that the endpoint should only be as slow as the slowest external call (unless we have data in the cache of course). This is done using the System.Threading.Tasks.Task class. Could we be hitting a limitation in terms of number of threads available to the process?

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  • The APEX of Business Value...or...the Business Value of APEX? Oracle Cloud Takes Oracle APEX to New Heights!

    - by Gene Eun
    The attraction of Oracle Application Express (APEX) has increased tremendously with the recent launch of the Oracle Cloud. APEX already supported departmental development and deployment of business applications with minimal involvement from the IT department. Positioned as the ideal replacement for MS Access, APEX probably has managed better to capture the eye of developers and was used for enterprise application development at least as much as for the kind of tactical applications that Oracle strategically positioned it for. With APEX as PaaS from the Oracle Cloud, a leap is made to a much higher level of business value. Now the IT department is not even needed to make infrastructure available with a database running  on it. All the business needs is a credit card. And the business application that is developed, managed and used from the cloud through a standard browser can now just as easily be accessed by users from around the world as by users from the business department itself. As a bonus – the development of the APEX application is also done in the cloud – with no special demands on the location or the enterprise access privileges of the developers. To sum it up: APEX from Oracle Cloud Database Service get the development environment up and running in minutes no involvement from the internal IT department required (not for infrastructure, platform, or development) superior availability and scalability is offered by Oracle users from anywhere in the world can be invited to access the application developers from anywhere in the world can participate in creating and maintaining the application In addition: because the Oracle Cloud platform is the same as the on-premise platform, you can still decide to move the APEX application between the cloud and the local environment – and back again. The REST-ful services that are available through APEX allow programmatic interaction with the database under the APEX application. That means that this database can be synchronized with on premise databases or data stores in (other) clouds. Through the Oracle Cloud Messaging Service, the APEX application can easily enter into asynchronous conversations with other APEX applications, Fusion Middleware applications (ADF, SOA, BPM) and any other type of REST-enabled application. In my opinion, now, for the first time perhaps, APEX offers the attraction to the business that has been suggested before: because of the cloud, all the business needs is  a credit card (a budget of $175 per month), an internet-connection and a browser. Not like before, with a PC hidden under a desk or a database running somewhere in the data center. No matter how unattended: equipment is needed, power is consumed, the database needs to be kept running and if Oracle Database XE does not suffice, software licenses are required as well. And this set up always has a security challenge associated with it. The cloud fee for the Oracle Cloud Database Service includes infrastructure, power, licenses, availability, platform upgrades, a collection of reusable application components and the development and runtime environments containing the APEX platform. Of course this not only means that business departments can move quickly without having to convince their IT colleagues to move along – it also means that small organizations that do not even have IT colleagues can do the same. Getting tailored applications or applications up and running to get in touch with users and customers all over the world is now within easy reach for small outfits – without any investment. My misunderstanding For a long time, I was under the impression that the essence of APEX was that the business could create applications themselves – meaning that business ‘people’ would actually go into APEX to create the application. To me APEX was too much of a developers’ tool to see that happen – apart from the odd business analyst who missed his or her calling as an IT developer. Having looked at various other cloud based development offerings – including Force.com, Mendix, WaveMaker, WorkXpress, OrangeScape, Caspio and Cordys- I have come to realize my mistake. All these platforms are positioned for 'the business' but require a fair amount of coding and technical expertise. However, they make the business happy nevertheless, because they allow the  business to completely circumvent the IT department. That is the essence. Not having to go through the red tape, not having to wait for IT staff who (justifiably) need weeks or months to provide an environment, not having to deal with administrators (again, justifiably) refusing to take on that 'strange environment'. Being able to think of an initiative and turn into action right away. The business does not have to build the application - it can easily hire some external developers or even that nerdy boy next door. They can get started, get an application up and running and invite users in – especially external users such as customers. They will worry later about upgrades and life cycle management and integration. To get applications up and running quickly and start turning ideas into action and results rightaway. That is the key selling point for all these cloud offerings, including APEX from the Cloud. And it is a compelling story. For APEX probably even more so than for the others. While I consider APEX a somewhat proprietary framework compared with ‘regular’ Java/JEE web development (or even .NET and PHP  development), it is still far more open than most cloud environments. APEX is SQL and PL/SQL based – nothing special about those languages – and can run just as easily on site as in the cloud. It has been around since 2004 (that is not including several predecessors that fed straight into APEX) so it can be considered pretty mature. Oracle as a company seems pretty stable – so investments in its technology are bound to last for some time to come. By the way: neither APEX nor the other Cloud DevaaS offerings are targeted at creating applications with enormous life times. They fit into a trend of agile development and rapid life cycle management, with fairly light weight user interfaces that quickly adapt to taste, technology trends and functional requirements and that are easily replaced. APEX and ADF – a match made in heaven?! (or at least in the sky) Note that using APEX only for cloud based database with REST-ful Services is also a perfectly viable scenario: any UI – mobile or browser based – capable of consuming REST-ful services can be created against such a business tier. Creating an ADF Mobile application for example that runs aginst REST-ful services is a best practice for mobile development. Such REST-ful services can be consumed from any service provider – including the Cloud based APEX powered REST-ful services running against the Oracle Cloud Database Service! The ADF Mobile architecture overview can easily be morphed to fit the APEX services in – allowing for a cloud based mobile app: Want to learn more about Oracle Database Cloud Service or Oracle Cloud, just visit cloud.oracle.com  or oracle.com/cloud. Repost of a blog entry by Rick Greenwald, Director of Product Management, Oracle Database Cloud Service.

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  • Silverlight for Everyone!!

    - by subodhnpushpak
    Someone asked me to compare Silverlight / HTML development. I realized that the question can be answered in many ways: Below is the high level comparison between a HTML /JavaScript client and Silverlight client and why silverlight was chosen over HTML / JavaScript client (based on type of users and major functionalities provided): 1. For end users Browser compatibility Silverlight is a plug-in and requires installation first. However, it does provides consistent look and feel across all browsers. For HTML / DHTML, there is a need to tweak JavaScript for each of the browser supported. In fact, tags like <span> and <div> works differently on different browser / version. So, HTML works on most of the systems but also requires lot of efforts coding-wise to adhere to all standards/ browsers / versions. Out of browser support No support in HTML. Third party tools like  Google gears offers some functionalities but there are lots of issues around platform and accessibility. Out of box support for out-of-browser support. provides features like drag and drop onto application surface. Cut and copy paste in HTML HTML is displayed in browser; which, in turn provides facilities for cut copy and paste. Silverlight (specially 4) provides rich features for cut-copy-paste along with full control over what can be cut copy pasted by end users and .advanced features like visual tree printing. Rich user experience HTML can provide some rich experience by use of some JavaScript libraries like JQuery. However, extensive use of JavaScript combined with various versions of browsers and the supported JavaScript makes the solution cumbersome. Silverlight is meant for RIA experience. User data storage on client end In HTML only small amount of data can be stored that too in cookies. In Silverlight large data may be stored, that too in secure way. This increases the response time. Post back In HTML / JavaScript the post back can be stopped by use of AJAX. Extensive use of AJAX can be a bottleneck as browser stack is used for the calls. Both look and feel and data travel over network.                           In Silverlight everything run the client side. Calls are made to server ONLY for data; which also reduces network traffic in long run. 2. For Developers Coding effort HTML / JavaScript can take considerable amount to code if features (requirements) are rich. For AJAX like interfaces; knowledge of third party kits like DOJO / Yahoo UI / JQuery is required which has steep learning curve. ASP .Net coding world revolves mostly along <table> tags for alignments whereas most popular tools provide <div> tags; which requires lots of tweaking. AJAX calls can be a bottlenecks for performance, if the calls are many. In Silverlight; coding is in C#, which is managed code. XAML is also very intuitive and Blend can be used to provide look and feel. Event handling is much clean than in JavaScript. Provides for many clean patterns like MVVM and composable application. Each call to server is asynchronous in silverlight. AJAX is in built into silverlight. Threading can be done at the client side itself to provide for better responsiveness; etc. Debugging Debugging in HTML / JavaScript is difficult. As JavaScript is interpreted; there is NO compile time error handling. Debugging in Silverlight is very helpful. As it is compiled; it provides rich features for both compile time and run time error handling. Multi -targeting browsers HTML / JavaScript have different rendering behaviours in different browsers / and their versions. JavaScript have to be written to sublime the differences in browser behaviours. Silverlight works exactly the same in all browsers and works on almost all popular browser. Multi-targeting desktop No support in HTML / JavaScript Silverlight is very close to WPF. Bot the platform may be easily targeted while maintaining the same source code. Rich toolkit HTML /JavaScript have limited toolkit as controls Silverlight provides a rich set of controls including graphs, audio, video, layout, etc. 3. For Architects Design Patterns Silverlight provides for patterns like MVVM (MVC) and rich (fat)  client architecture. This segregates the "separation of concern" very clearly. Client (silverlight) does what it is expected to do and server does what it is expected of. In HTML / JavaScript world most of the processing is done on the server side. Extensibility Silverlight provides great deal of extensibility as custom controls may be made. Extensibility is NOT restricted by browser but by the plug-in silverlight runs in. HTML / JavaScript works in a certain way and extensibility is generally done on the server side rather than client end. Client side is restricted by the limitations of the browser. Performance Silverlight provides localized storage which may be used for cached data storage. this reduces the response time. As processing can be done on client side itself; there is no need for server round trips. this decreases the round about time. Look and feel of the application is downloaded ONLY initially, afterwards ONLY data is fetched form the server. Security Silverlight is compiled code downloaded as .XAP; As compared to HTML / JavaScript, it provides more secure sandboxed approach. Cross - scripting is inherently prohibited in silverlight by default. If proper guidelines are followed silverlight provides much robust security mechanism as against HTML / JavaScript world. For example; knowing server Address in obfuscated JavaScript is easier than a compressed compiled obfuscated silverlight .XAP file. Some of these like (offline and Canvas support) will be available in HTML5. However, the timelines are not encouraging at all. According to Ian Hickson, editor of the HTML5 specification, the specification to reach the W3C Candidate Recommendation stage during 2012, and W3C Recommendation in the year 2022 or later. see http://en.wikipedia.org/wiki/HTML5 for details. The above is MY opinion. I will love to hear yours; do let me know via comments. Technorati Tags: Silverlight

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  • Taking the training wheels off: Accelerating the Business with Oracle IAM by Brian Mozinski (Accenture)

    - by Greg Jensen
    Today, technical requirements for IAM are evolving rapidly, and the bar is continuously raised for high performance IAM solutions as organizations look to roll out high volume use cases on the back of legacy systems.  Existing solutions were often designed and architected to support offline transactions and manual processes, and the business owners today demand globally scalable infrastructure to support the growth their business cases are expected to deliver. To help IAM practitioners address these challenges and make their organizations and themselves more successful, this series we will outline the: • Taking the training wheels off: Accelerating the Business with Oracle IAM The explosive growth in expectations for IAM infrastructure, and the business cases they support to gain investment in new security programs. • "Necessity is the mother of invention": Technical solutions developed in the field Well proven tricks of the trade, used by IAM guru’s to maximize your solution while addressing the requirements of global organizations. • The Art & Science of Performance Tuning of Oracle IAM 11gR2 Real world examples of performance tuning with Oracle IAM • No Where to go but up: Extending the benefits of accelerated IAM Anything is possible, compelling new solutions organizations are unlocking with accelerated Oracle IAM Let’s get started … by talking about the changing dynamics driving these discussions. Big Companies are getting bigger everyday, and increasingly organizations operate across state lines, multiple times zones, and in many countries or continents at the same time.  No longer is midnight to 6am a safe time to take down the system for upgrades, to run recon’s and import or update user accounts and attributes.  Further IT organizations are operating as shared services with SLA’s similar to telephone carrier levels expected by their “clients”.  Workers are moved in and out of roles on a weekly, daily, or even hourly rate and IAM is expected to support those rapid changes.  End users registering for services during business hours in Singapore are expected their access to be green-lighted in custom apps hosted in Portugal within the hour.  Many of the expectations of asynchronous systems and batched updates are not adequate and the number and types of users is growing. When organizations acted more like independent teams at functional or geographic levels it was manageable to have processes that relied on a handful of people who knew how to make things work …. Knew how to get you access to the key systems to get your job done.  Today everyone is expected to do more with less, the finance administrator previously supporting their local Atlanta sales office might now be asked to help close the books for the Johannesburg team, and access certification process once completed monthly by Joan on the 3rd floor is now done by a shared pool of resources in Sao Paulo.   Fragmented processes that rely on institutional knowledge to get access to systems and get work done quickly break down in these scenarios.  Highly robust processes that have automated workflows for connected or disconnected systems give organizations the dynamic flexibility to share work across these lines and cut costs or increase productivity. As the IT industry computing paradigms continue to change with the passing of time, and as mature or proven approaches become clear, it is normal for organizations to adjust accordingly. Businesses must manage identity in an increasingly hybrid world in which legacy on-premises IAM infrastructures are extended or replaced to support more and more interconnected and interdependent services to a wider range of users. The old legacy IAM implementation models we had relied on to manage identities no longer apply. End users expect to self-request access to services from their tablet, get supervisor approval over mobile devices and email, and launch the application even if is hosted on the cloud, or run by a partner, vendor, or service provider. While user expectations are higher, they are also simpler … logging into custom desktop apps to request approvals, or going through email or paper based processes for certification is unacceptable.  Users expect security to operate within the paradigm of the application … i.e. feel like the application they are using. Citizen and customer facing applications have evolved from every where, with custom applications, 3rd party tools, and merging in from acquired entities or 3rd party OEM’s resold to expand your portfolio of services.  These all have their own user stores, authentication models, user lifecycles, session management, etc.  Often the designers/developers are no longer accessible and the documentation is limited.  Bringing together underlying directories to scale for growth, and improve user experience is critical for revenue … but also for operations. Job functions are more dynamic.... take the Olympics for example.  Endless organizations from corporations broadcasting, endorsing, or marketing through the event … to non-profit athletic foundations and public/government entities for athletes and public safety, all operate simultaneously on the world stage.  Each organization needs to spin up short-term teams, often dealing with proprietary information from hot ads to racing strategies or security plans.  IAM is expected to enable team’s to spin up, enable new applications, protect privacy, and secure critical infrastructure.  Then it needs to be disabled just as quickly as users go back to their previous responsibilities. On a more technical level … Optimized system directory; tuning guidelines and parameters are needed by businesses today. Business’s need to be making the right choices (virtual directories) and considerations via choosing the correct architectural patterns (virtual, direct, replicated, and tuning), challenge is that business need to assess and chose the correct architectural patters (centralized, virtualized, and distributed) Today's Business organizations have very complex heterogeneous enterprises that contain diverse and multifaceted information. With today's ever changing global landscape, the strategic end goal in challenging times for business is business agility. The business of identity management requires enterprise's to be more agile and more responsive than ever before. The continued proliferation of networking devices (PC, tablet, PDA's, notebooks, etc.) has caused the number of devices and users to be granted access to these devices to grow exponentially. Business needs to deploy an IAM system that can account for the demands for authentication and authorizations to these devices. Increased innovation is forcing business and organizations to centralize their identity management services. Access management needs to handle traditional web based access as well as handle new innovations around mobile, as well as address insufficient governance processes which can lead to rouge identity accounts, which can then become a source of vulnerabilities within a business’s identity platform. Risk based decisions are providing challenges to business, for an adaptive risk model to make proper access decisions via standard Web single sign on for internal and external customers,. Organizations have to move beyond simple login and passwords to address trusted relationship questions such as: Is this a trusted customer, client, or citizen? Is this a trusted employee, vendor, or partner? Is this a trusted device? Without a solid technological foundation, organizational performance, collaboration, constituent services, or any other organizational processes will languish. A Single server location presents not only network concerns for distributed user base, but identity challenges. The network risks are centered on latency of the long trip that the traffic has to take. Other risks are a performance around availability and if the single identity server is lost, all access is lost. As you can see, there are many reasons why performance tuning IAM will have a substantial impact on the success of your organization.  In our next installment in the series we roll up our sleeves and get into detailed tuning techniques used everyday by thought leaders in the field implementing Oracle Identity & Access Management Solutions.

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