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  • Windows Server 2008 (x64): Wont boot past bios page

    - by WebSolProv
    Happy New Year, Since a month or so ago I inherited responsibility for small network administration for my sins. The domain controller (yes there is only one, and yes I know it is best practice to have two even in a small domain setup) went down overnight and I have been trying all day to get it back up and running. Unfortunately this machine also administers our entire ActiveDirectory setup: 1) It goes thru the BIOS without any errors, nothing whatsoever 2) It gets into the “select safe mode, safe mode with networking, normal” etc and if you select either of the safe mode options it loads a few files then reboots. If you select normal it just runs for a bit (doesn’t get to the windows splash screen) and then reboots again. 3) If you select windows repair, it asks for an image to repair too: however it would appear that none was taken that can be used (!!) or one is not being shown. 4) I have tried repairing the boot sector and the boot configuration using Bootrec.exe, both which it says were completed successfully but still it doesn’t work. 5) I have tried swapping the drives into another server to rule out hardware and that didn’t work either so clearly it’s the OS. 6) I have tried running chkdsk which ran fine, and also memory check which was also fine. We do have another machine on the network that was installed as a DC so when we decommission the current infrastructure but when I try and "promote" this to the lead DC then I get “you cannot modify domain or trust information because a PDC emulator cannot be contacted" so I am unable to replicare the ActiveDirectory details. If anyone can think of any direction I should follow it would be greatly appreciated, Thanks, Alex

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  • Horrorble performance using ListViews with nested objects in WPF

    - by Christian
    Hi community, like mentioned in the title I get a horrible performance if I use ListViews with nested objects. My scenario is: Each row of a ListView presents an object of the class Transaction with following attributes: private int mTransactionID; private IBTTransactionSender mSender; private IBTTransactionReceiver mReceiver; private BTSubstrate mSubstrate; private double mAmount; private string mDeliveryNote; private string mNote; private DateTime mTransactionDate; private DateTime mCreationTimestamp; private BTEmployee mEmployee; private bool mImported; private bool mDescendedFromRecurringTransaction; Each attribute can be accessed by its corresponding property. An ObservableCollection<Transaction> is bound to the ItemsSource of a ListView. The ListView itself looks like the following: </ListView.GroupStyle> <ListView.View> <GridView> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.ToSave" Width="80"> <GridViewColumnHeader Name="GVCHLoadedToSave" Style="{StaticResource ListViewHeaderStyle}">Speichern</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <CheckBox Name="CBListViewItem" IsChecked="{Binding Path=Transaction.ToSave, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"></CheckBox> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.TransactionDate" Width="80"> <GridViewColumnHeader Name="GVCHLoadedDate" Style="{StaticResource ListViewHeaderStyle}">Datum</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding ElementName=DPDate, Path=Text}" Style="{StaticResource GridBlockStyle}"/> <toolkit:DatePicker Name="DPDate" Width="{Binding ElementName=GVCHDate, Path=ActualWidth}" SelectedDateFormat="Short" Style="{StaticResource GridEditStyle}" SelectedDate="{Binding Path=Transaction.TransactionDate, Mode=TwoWay}" SelectedDateChanged="DPDate_SelectedDateChanged"/> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.Sender.Description" Width="120"> <GridViewColumnHeader Name="GVCHLoadedSender" Style="{StaticResource ListViewHeaderStyle}">Von</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.Sender.Description}" Style="{StaticResource GridBlockStyle}"/> <ComboBox Name="CBSender" Width="{Binding ElementName=GVCHSender, Path=ActualWidth}" SelectedItem="{Binding Path=Transaction.Sender}" DisplayMemberPath="Description" Text="{Binding Path=Sender.Description, Mode=OneWay}" ItemsSource="{Binding ElementName=Transaction, Path=SenderList}" Style="{StaticResource GridEditStyle}"> </ComboBox> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.Receiver.Description" Width="120"> <GridViewColumnHeader Name="GVCHLoadedReceiver" Style="{StaticResource ListViewHeaderStyle}">Nach</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.Receiver.Description}" Style="{StaticResource GridBlockStyle}"/> <ComboBox Name="CBReceiver" Width="{Binding ElementName=GVCHReceiver, Path=ActualWidth}" SelectedItem="{Binding Path=Transaction.Receiver}" DisplayMemberPath="Description" Text="{Binding Path=Receiver.Description, Mode=OneWay}" ItemsSource="{Binding ElementName=Transaction, Path=ReceiverList}" Style="{StaticResource GridEditStyle}"> </ComboBox> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.Substrate.Description" Width="140"> <GridViewColumnHeader Name="GVCHLoadedSubstrate" Style="{StaticResource ListViewHeaderStyle}">Substrat</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.Substrate.Description}" Style="{StaticResource GridBlockStyle}"/> <ComboBox Name="CBSubstrate" Width="{Binding ElementName=GVCHSubstrate, Path=ActualWidth}" SelectedItem="{Binding Path=Transaction.Substrate}" DisplayMemberPath="Description" Text="{Binding Path=Substrate.Description, Mode=OneWay}" ItemsSource="{Binding ElementName=Transaction, Path=SubstrateList}" Style="{StaticResource GridEditStyle}"> </ComboBox> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.Amount" Width="80"> <GridViewColumnHeader Name="GVCHLoadedAmount" Style="{StaticResource ListViewHeaderStyle}">Menge [kg]</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.Amount}" Style="{StaticResource GridBlockStyle}"/> <TextBox Name="TBAmount" Text="{Binding Path=Transaction.Amount, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="{Binding ElementName=GVCHAmount, Path=ActualWidth}" Style="{StaticResource GridTextBoxStyle}" /> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.DeliveryNote" Width="100"> <GridViewColumnHeader Name="GVCHLoadedDeliveryNote" Style="{StaticResource ListViewHeaderStyle}">Lieferschein Nr.</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.DeliveryNote}" Style="{StaticResource GridBlockStyle}"/> <TextBox Name="TBDeliveryNote" Text="{Binding Path=Transaction.DeliveryNote, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="{Binding ElementName=GVCHDeliveryNote, Path=ActualWidth}" Style="{StaticResource GridEditStyle}" /> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.Note" Width="190"> <GridViewColumnHeader Name="GVCHLoadedNote" Style="{StaticResource ListViewHeaderStyle}">Bemerkung</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.Note}" Style="{StaticResource GridBlockStyle}"/> <TextBox Name="TBNote" Text="{Binding Path=Transaction.Note, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="{Binding ElementName=GVCHNote, Path=ActualWidth}" Style="{StaticResource GridEditStyle}" /> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.Employee.LastName" Width="100"> <GridViewColumnHeader Name="GVCHLoadedEmployee" Style="{StaticResource ListViewHeaderStyle}">Mitarbeiter</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.Employee.LastName}" Style="{StaticResource GridBlockStyle}"/> <ComboBox Name="CBEmployee" Width="{Binding ElementName=GVCHEmployee, Path=ActualWidth}" SelectedItem="{Binding Path=Transaction.Employee}" DisplayMemberPath="LastName" Text="{Binding Path=Employee.LastName, Mode=OneWay}" ItemsSource="{Binding ElementName=Transaction, Path=EmployeeList}" Style="{StaticResource GridEditStyle}"> </ComboBox> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> </GridView> </ListView.View> </ListView> As you can see in the screenshot the user got the possibility to change the values of the transaction attributes with comboboxes. Ok now to my problem. If I click on the "Laden" button the application will load about 150 entries in the ObservableCollection<Transaction>. Before I fill the collection I set the ItemsSource of the ListView to null and after filling I bind the collection to the ItemsSource once again. The loading itself takes a few milliseconds, but the rendering of the filled collection takes a long time (150 entries = about 20 sec). I tested to delete all Comboboxes out of the xaml and i got a better performance, because I don't have to fill the ComboBoxes for each row. But I need to have these comboboxes for modifing the attributes of the Transaction. Does anybody know how to improve the performance? THX

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  • Website displays in chrome perfectly, but not in mozilla or IE

    - by Atharul Khan
    here are the code snippets for the html and css. It works finds in Google chrome, but when I try to display it in mozilla or IE, it shows something completely different. I cannot attach images as I do not have the required reputation. I really appreciate the help. Thank you! HTML <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <meta http-equiv="Content-type" content="text/html; charset=utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1" /> <link rel="stylesheet" type="text/css" href="style.css"> <link rel="shortcut icon" href="ak.png"> <title>Home</title> </head> <body> <div class="Nav"> <nav> <ul class="navigation fade-in2"> <li><a href="#home">Home</a></li> <li><a href="#about">About</a></li> <li><a href="#portfolio">Portfolio</a></li> <li><a href="#shop">Shop</a></li> <li><a href="#blog">Blog</a></li> <li><a href="#contact">Contact</a></li> </ul> </nav> </div> <div class="logo"><a href="#home"><img class="ak fade-in2" src="ak.png"></a></div> <div class="background"><img class="beauty" src="beauty.jpg"></div> <div class="header"> <h1 class="headerName fade-in">DESIGN | DEVELOP | BRAND</h1> <h4 class="service fade-in3"><a href="#portfolio">VIEW PORTFOLIO</a></h4> <h4 class="service fade-in3"><a href="#services">VIEW SERVICES</a></h4> </div> <!--<div class="mainbody"><p>safsdaf</p></div>--> </body> </html> CSS @-webkit-keyframes fadeIn { from { opacity:0; } to { opacity:1; } } @-moz-keyframes fadeIn { from { opacity:0; } to { opacity:1; } } @keyframes fadeIn { from { opacity:0; } to { opacity:1; } } * { padding: 0; margin: 0; } li { display: inline; font-size: 15px; font-family: verdana; } nav { width: 100%; text-align: right; background-color: #222222; padding: 0; margin: 0px; line-height: 47px; position: fixed; z-index: 100; } .ak{ width: 90px; height: 55px; z-index: 101; position: fixed; background: transparent; color: transparent; background-color: transparent; } .Nav a{ text-decoration: none; padding: 15px; } .Nav a:link{ color: #A7A7A7; } .Nav a:visited{ color: #A7A7A7; } .Nav a:hover{ color: #DBDBDB; transition: all 0.3s ease-out 0s; transition-property: all; transition-duration: 0.3s; transition-timing-function: ease-out; transition-delay: 0s; } .header { background-color: rgba(0,0,0, 0.25); width: 100%; height: 626px; text-align: center; position: fixed; z-index: 10; } .background { position: fixed; z-index: 8; } .beauty { width: 100%; height: 626px; } .headerName { font-size: 2.5em; text-align: center; color: #D3D3D3; padding: 180px; padding-bottom: 50px; margin: 0px; letter-spacing: 4px; font-weight: 100; font-family: 'Lato', sans-serif; } .fade-in { opacity:0; /* make things invisible upon start */ -webkit-animation:fadeIn ease-in 1; /* call our keyframe named fadeIn, use animation ease-in and repeat it only 1 time */ -moz-animation:fadeIn ease-in 1; animation:fadeIn ease-in 1; -webkit-animation-fill-mode:forwards; /* this makes sure that after animation is done we remain at the last keyframe value (opacity: 1)*/ -moz-animation-fill-mode:forwards; animation-fill-mode:forwards; -webkit-animation-duration:1s; -moz-animation-duration:1s; animation-duration:1s; -webkit-animation-delay: 0.3s; -moz-animation-delay:0.3s; animation-delay: 0.3s; } .fade-in2 { opacity:0; /* make things invisible upon start */ -webkit-animation:fadeIn ease-in 1; /* call our keyframe named fadeIn, use animation ease-in and repeat it only 1 time */ -moz-animation:fadeIn ease-in 1; animation:fadeIn ease-in 1; -webkit-animation-fill-mode:forwards; /* this makes sure that after animation is done we remain at the last keyframe value (opacity: 1)*/ -moz-animation-fill-mode:forwards; animation-fill-mode:forwards; -webkit-animation-duration:1s; -moz-animation-duration:1s; animation-duration:1s; -webkit-animation-delay: 0.6s; -moz-animation-delay:0.6s; animation-delay: 0.6s; } .fade-in3 { opacity:0; /* make things invisible upon start */ -webkit-animation:fadeIn ease-in 1; /* call our keyframe named fadeIn, use animation ease-in and repeat it only 1 time */ -moz-animation:fadeIn ease-in 1; animation:fadeIn ease-in 1; -webkit-animation-fill-mode:forwards; /* this makes sure that after animation is done we remain at the last keyframe value (opacity: 1)*/ -moz-animation-fill-mode:forwards; animation-fill-mode:forwards; -webkit-animation-duration:1s; -moz-animation-duration:1s; animation-duration:1s; -webkit-animation-delay: 0.9s; -moz-animation-delay:0.9s; animation-delay: 0.9s; } .service{ font-size: 14px; width: 190px; text-align: center; font-family: 'Lato', sans-serif; color: #D3D3D3; border: 2px #A7A7A7 solid; border-color: rgba(255, 255, 255, 0.5); display: inline-block; border-radius: 5px; background-color: transparent; letter-spacing: 2px; } .service a{ text-decoration: none; display: block; padding: 15px 20px; } .service a:link{ color: #D3D3D3; } .service a:visited{ color: #D3D3D3; } .service a:hover{ background-color: rgba(255, 255, 255, 0.15); transition: background-color .15s ease-in; -webkit-transition: background-color .15s ease-in; -moz-transition: background-color .15s ease-in; -o-transition: background-color .15s ease-in; } UPDATE 1: I updated both browsers and it seems the css3 animations work perfectly fine on both browsers. What seems to be the problem is the positioning of the pages UPDATE 2: Here are the links to the different browser screen shots Chrome: https://www.dropbox.com/s/jlpa4vu51kdnews/Chrome.JPG InternetExplorer: https://www.dropbox.com/s/zbchs3su9ahxr0n/IE.JPG Mozilla Firefox: dropbox(.)com/s/fyalnhsha9ktadz/Mozilla.JPG (I can't post the third link because I don't have enough reputation)

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  • SQL SERVER – PAGEIOLATCH_DT, PAGEIOLATCH_EX, PAGEIOLATCH_KP, PAGEIOLATCH_SH, PAGEIOLATCH_UP – Wait Type – Day 9 of 28

    - by pinaldave
    It is very easy to say that you replace your hardware as that is not up to the mark. In reality, it is very difficult to implement. It is really hard to convince an infrastructure team to change any hardware because they are not performing at their best. I had a nightmare related to this issue in a deal with an infrastructure team as I suggested that they replace their faulty hardware. This is because they were initially not accepting the fact that it is the fault of their hardware. But it is really easy to say “Trust me, I am correct”, while it is equally important that you put some logical reasoning along with this statement. PAGEIOLATCH_XX is such a kind of those wait stats that we would directly like to blame on the underlying subsystem. Of course, most of the time, it is correct – the underlying subsystem is usually the problem. From Book On-Line: PAGEIOLATCH_DT Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Destroy mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_EX Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Exclusive mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_KP Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Keep mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_SH Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Shared mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_UP Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Update mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_XX Explanation: Simply put, this particular wait type occurs when any of the tasks is waiting for data from the disk to move to the buffer cache. ReducingPAGEIOLATCH_XX wait: Just like any other wait type, this is again a very challenging and interesting subject to resolve. Here are a few things you can experiment on: Improve your IO subsystem speed (read the first paragraph of this article, if you have not read it, I repeat that it is easy to say a step like this than to actually implement or do it). This type of wait stats can also happen due to memory pressure or any other memory issues. Putting aside the issue of a faulty IO subsystem, this wait type warrants proper analysis of the memory counters. If due to any reasons, the memory is not optimal and unable to receive the IO data. This situation can create this kind of wait type. Proper placing of files is very important. We should check file system for the proper placement of files – LDF and MDF on separate drive, TempDB on separate drive, hot spot tables on separate filegroup (and on separate disk), etc. Check the File Statistics and see if there is higher IO Read and IO Write Stall SQL SERVER – Get File Statistics Using fn_virtualfilestats. It is very possible that there are no proper indexes on the system and there are lots of table scans and heap scans. Creating proper index can reduce the IO bandwidth considerably. If SQL Server can use appropriate cover index instead of clustered index, it can significantly reduce lots of CPU, Memory and IO (considering cover index has much lesser columns than cluster table and all other it depends conditions). You can refer to the two articles’ links below previously written by me that talk about how to optimize indexes. Create Missing Indexes Drop Unused Indexes Updating statistics can help the Query Optimizer to render optimal plan, which can only be either directly or indirectly. I have seen that updating statistics with full scan (again, if your database is huge and you cannot do this – never mind!) can provide optimal information to SQL Server optimizer leading to efficient plan. Checking Memory Related Perfmon Counters SQLServer: Memory Manager\Memory Grants Pending (Consistent higher value than 0-2) SQLServer: Memory Manager\Memory Grants Outstanding (Consistent higher value, Benchmark) SQLServer: Buffer Manager\Buffer Hit Cache Ratio (Higher is better, greater than 90% for usually smooth running system) SQLServer: Buffer Manager\Page Life Expectancy (Consistent lower value than 300 seconds) Memory: Available Mbytes (Information only) Memory: Page Faults/sec (Benchmark only) Memory: Pages/sec (Benchmark only) Checking Disk Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All of the discussions of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – PAGELATCH_DT, PAGELATCH_EX, PAGELATCH_KP, PAGELATCH_SH, PAGELATCH_UP – Wait Type – Day 12 of 28

    - by pinaldave
    This is another common wait type. However, I still frequently see people getting confused with PAGEIOLATCH_X and PAGELATCH_X wait types. Actually, there is a big difference between the two. PAGEIOLATCH is related to IO issues, while PAGELATCH is not related to IO issues but is oftentimes linked to a buffer issue. Before we delve deeper in this interesting topic, first let us understand what Latch is. Latches are internal SQL Server locks which can be described as very lightweight and short-term synchronization objects. Latches are not primarily to protect pages being read from disk into memory. It’s a synchronization object for any in-memory access to any portion of a log or data file.[Updated based on comment of Paul Randal] The difference between locks and latches is that locks seal all the involved resources throughout the duration of the transactions (and other processes will have no access to the object), whereas latches locks the resources during the time when the data is changed. This way, a latch is able to maintain the integrity of the data between storage engine and data cache. A latch is a short-living lock that is put on resources on buffer cache and in the physical disk when data is moved in either directions. As soon as the data is moved, the latch is released. Now, let us understand the wait stat type  related to latches. From Book On-Line: PAGELATCH_DT Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Destroy mode. PAGELATCH_EX Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Exclusive mode. PAGELATCH_KP Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Keep mode. PAGELATCH_SH Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Shared mode. PAGELATCH_UP Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Update mode. PAGELATCH_X Explanation: When there is a contention of access of the in-memory pages, this wait type shows up. It is quite possible that some of the pages in the memory are of very high demand. For the SQL Server to access them and put a latch on the pages, it will have to wait. This wait type is usually created at the same time. Additionally, it is commonly visible when the TempDB has higher contention as well. If there are indexes that are heavily used, contention can be created as well, leading to this wait type. Reducing PAGELATCH_X wait: The following counters are useful to understand the status of the PAGELATCH: Average Latch Wait Time (ms): The wait time for latch requests that have to wait. Latch Waits/sec: This is the number of latch requests that could not be granted immediately. Total Latch Wait Time (ms): This is the total latch wait time for latch requests in the last second. If there is TempDB contention, I suggest that you read the blog post of Robert Davis right away. He has written an excellent blog post regarding how to find out TempDB contention. The same blog post explains the terms in the allocation of GAM, SGAM and PFS. If there was a TempDB contention, Paul Randal explains the optimal settings for the TempDB in his misconceptions series. Trace Flag 1118 can be useful but use it very carefully. I totally understand that this blog post is not as clear as my other blog posts. I suggest if this wait stats is on one of your higher wait type. Do leave a comment or send me an email and I will get back to you with my solution for your situation. May the looking at all other wait stats and types together become effective as this wait type can help suggest proper bottleneck in your system. Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussions of Wait Stats in this blog are generic and vary from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com)   Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • How to UEFI install Ubuntu 12.10?

    - by Geezanansa
    Running a newer FM1 motherboard which is using an AMD 3870k APU with a new 1TB HDD. Following the advice in the motherboard manual and https://help.ubuntu.com/community/UEFI have now got to grub option screen for UEFI install. see http://imgur.com/VW5vz The dvd.iso being used is Ubuntu 12.10 desktop amd64 from ubuntu .com. The hdd has had a gpt partition table made for, by using gparted when in a live desktop session when booted in bios mode. (*edit/update: Although the old cd updates on running it is an old kernel and it did make a gpt but that version of gparted uses fdisk whereas gdisk is required to make gpt. Think am going to have to spend more time here http://www.dedoimedo.com/computers/gparted.html lol Using the gparted from 12.10 live session to make partitions; following the guidance regarding this at https://help.ubuntu.com/community/UEFI#Creating_an_EFI_partition, but can only boot to grub option screen http://imgur.com/VW5vz when 12.10 options to "try ubuntu" or "install ubuntu" are selected they give errors as described below*) but after making the gpt decided to leave it unformatted/unallocated space with the intention of using installer to set up partitions. update-originally but gparted now sees hdd as http://imgur.com/hFIvm as described above. *Booting live dvd in EFI mode gives "Secure Boot not installed" just before grub kernel option list with the option to "install ubuntu" but get "can not read cd/0" and "the kernel must be loaded first" errors; when that option is selected. Any pointers on how to get installer going for UEFI install would be good. Thanks in advance. update: Hopefully these screenshots can help better highlight where i am going wrong or if there is something else going on http://imgur.com/g30RB, http://imgur.com/VW5vz, http://imgur.com/31E0q, http://imgur.com/bnuaG, http://imgur.com/y4KGu, http://imgur.com/3u2QE, http://imgur.com/n9lN3, http://imgur.com/FEKvz, http://imgur.com/hFIvm, update: Thank you fernando garcia for pointing me in the right direction to start the process of elimantion. What i have done since asking question is a little home work starting here http://askubuntu.com/faq#bounty and here http://askubuntu.com/questions/how-to-ask. Looking at other similar questions was good fun and found this 12.10 UEFI Secure Boot install the most relative in helping getting ubuntu to uefi install on my system. In response to wolverine's question this article was referred to http://web.dodds.net/~vorlon/wiki/blog/SecureBoot_in_Ubuntu_12.10/ This article in the first sentence gives a link to http://www.ubuntu.com/download which is where i downloaded the 12.10 desktop amd64 .iso(and others) but have been unable to do a efi install of ubuntu on this system and as this is a new system have ended up just going with bios installer running which at least puts my mind at ease that i have not bricked my new mobo.(had to do a clrcmos and flash to latest bios version) So it possibly could be the bios settings or the bios version being used that is problem. To try and eliminate bios version i can not get to post screen in order to id bios version being used. Pressing tab to show post instead of logo and trying to pausebreak to catch post is proving difficult. If logo screen in bios is disabled just get black screen no post shown and pressing tab does not show post. Appreciate using appropriate bios settings and latest 12.10 release should simply get uefi installer running when selected from the grub list (nice graphic details in Identifying if computer boots the cd in efi mode section at https://help.ubuntu.com/community/UEFI#Identifying_if_the_computer_boots_the_CD_in_EFI_mode) And to confirm the hdd is booting in efi mode https://help.ubuntu.com/community/UEFI#Identifying_if_the_computer_boots_the_HDD_in_EFI_mode running the command [ -d /sys/firmware/efi ] && echo "EFI boot on HDD" || echo "Legacy boot on HDD" gave Legacy boot on HDD This is as expected because i allowed the bios installer (which was 12.04 desktop amd64 after trying 12.10 desktop amd64 in efi mode) to run to get a working installation. Which is not what was intended or wished for but wanted to get a working os to bench test new mobo i.e. prove it is working. There are other options as in installing other bootmanagers/loaders but do not wish to do so as shim should get grub2 going that is after secure boot has been signed.(Now got rough idea what should happen just it aint happening. Is it possible ahci drivers are required?) Will post boot info script url of the updated config/setup. The original question asked seems irrelevant to what is being said in this update but as the problem is not resolved will keep on trying efi installing! i.e the problem is same as when question asked just trying to update. Have tried to edit and update the best i can!

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  • Can not print after upgrading from 12.x to 14.04

    - by user318889
    After upgrading from V12.04 to V14.04 I am not able to print. I am using an HP LaserJet 400 M451dn. The printer troubleshooter told me that there is no solution to the problem. This is the output of the advanced diagnositc output. (Due to limited space I cut the output!) Can anybody tell me what is going wrong. I am using the printer via USB ? Page 1 (Scheduler not running?): {'cups_connection_failure': False} Page 2 (Is local server publishing?): {'local_server_exporting_printers': False} Page 3 (Choose printer): {'cups_dest': , 'cups_instance': None, 'cups_queue': u'HP-LaserJet-400-color-M451dn', 'cups_queue_listed': True} Page 4 (Check printer sanity): {'cups_device_uri_scheme': u'hp', 'cups_printer_dict': {'device-uri': u'hp:/usb/HP_LaserJet_400_color_M451dn?serial=CNFF308670', 'printer-info': u'Hewlett-Packard HP LaserJet 400 color M451dn', 'printer-is-shared': True, 'printer-location': u'Pinatubo', 'printer-make-and-model': u'HP LJ 300-400 color M351-M451 Postscript (recommended)', 'printer-state': 4, 'printer-state-message': u'', 'printer-state-reasons': [u'none'], 'printer-type': 8556636, 'printer-uri-supported': u'ipp://localhost:631/printers/HP-LaserJet-400-color-M451dn'}, 'cups_printer_remote': False, 'hplip_output': (['', '\x1b[01mHP Linux Imaging and Printing System (ver. 3.14.6)\x1b[0m', '\x1b[01mDevice Information Utility ver. 5.2\x1b[0m', '', 'Copyright (c) 2001-13 Hewlett-Packard Development Company, LP', 'This software comes with ABSOLUTELY NO WARRANTY.', 'This is free software, and you are welcome to distribute it', 'under certain conditions. See COPYING file for more details.', '', '', '\x1b[01mhp:/usb/HP_LaserJet_400_color_M451dn?serial=CNFF308670\x1b[0m', '', '\x1b[01mDevice Parameters (dynamic data):\x1b[0m', '\x1b[01m Parameter Value(s) \x1b[0m', ' ---------------------------- ----------------------------------------------------------', ' back-end hp ', " cups-printers ['HP-LaserJet-400-color-M451dn'] ", ' cups-uri hp:/usb/HP_LaserJet_400_color_M451dn?serial=CNFF308670 ', ' dev-file ', ' device-state -1 ', ' device-uri hp:/usb/HP_LaserJet_400_color_M451dn?serial=CNFF308670 ', ' deviceid ', ' error-state 101 ', ' host ', ' is-hp True ', ' panel 0 ', ' panel-line1 ', ' panel-line2 ', ' port 1 ', ' serial CNFF308670 ', ' status-code 5002 ', ' status-desc ', '\x1b[01m', 'Model Parameters (static data):\x1b[0m', '\x1b[01m Parameter Value(s) \x1b[0m', ' ---------------------------- ----------------------------------------------------------', ' align-type 0 ', ' clean-type 0 ', ' color-cal-type 0 ', ' copy-type 0 ', ' embedded-server-type 0 ', ' fax-type 0 ', ' fw-download False ', ' icon hp_color_laserjet_cp2025.png ', ' io-mfp-mode 1 ', ' io-mode 1 ', ' io-support 6 ', ' job-storage 0 ', ' linefeed-cal-type 0 ', ' model HP_LaserJet_400_color_M451dn ', ' model-ui HP LaserJet 400 Color m451dn ', ' model1 HP LaserJet 400 Color M451dn ', ' monitor-type 0 ', ' panel-check-type 0 ', ' pcard-type 0 ', ' plugin 0 ', ' plugin-reason 0 ', ' power-settings 0 ', ' ppd-name lj_300_400_color_m351_m451 ', ' pq-diag-type 0 ', ' r-type 0 ', ' r0-agent1-kind 4 ', ' r0-agent1-sku CE410A/CE410X ', ' r0-agent1-type 1 ', ' r0-agent2-kind 4 ', ' r0-agent2-sku CE411A ', ' r0-agent2-type 4 ', ' r0-agent3-kind 4 ', ' r0-agent3-sku CE413A ', ' r0-agent3-type 5 ', ' r0-agent4-kind 4 ', ' r0-agent4-sku CE412A ', ' r0-agent4-type 6 ', ' scan-src 0 ', ' scan-type 0 ', ' status-battery-check 0 ', ' status-dynamic-counters 0 ', ' status-type 3 ', ' support-released True ', ' support-subtype 2202411 ', ' support-type 2 ', ' support-ver 3.12.2 ', " tech-class ['Postscript'] ", " tech-subclass ['Normal'] ", ' tech-type 4 ', ' usb-pid 3882 ', ' usb-vid 1008 ', ' wifi-config 0 ', '\x1b[01m', 'Status History (most recent first):\x1b[0m', '\x1b[01m Date/Time Code Status Description User Job ID \x1b[0m', ' -------------------- ----- ---------------------------------------- -------- --------', ' 08/21/14 00:07:25 5012 Device communication error richard 0 ', ' 08/20/14 13:42:44 500 Started a print job richard 4214 ', '', '', 'Done.', ''], ['\x1b[35;01mwarning: No display found.\x1b[0m', '\x1b[31;01merror: hp-info -u/--gui requires Qt4 GUI support. Entering interactive mode.\x1b[0m', '\x1b[31;01merror: Unable to communicate with device (code=12): hp:/usb/HP_LaserJet_400_color_M451dn?serial=CNFF308670\x1b[0m', '\x1b[31;01merror: Error opening device (Device not found).\x1b[0m', ''], 0), 'is_cups_class': False, 'local_cups_queue_attributes': {'charset-configured': u'utf-8', 'charset-supported': [u'us-ascii', u'utf-8'], 'color-supported': True, 'compression-supported': [u'none', u'gzip'], 'copies-default': 1, 'copies-supported': (1, 9999), 'cups-version': u'1.7.2', 'device-uri': u'hp:/usb/HP_LaserJet_400_color_M451dn?serial=CNFF308670', 'document-format-default': u'application/octet-stream', 'document-format-supported': [u'application/octet-stream', u'application/pdf', u'application/postscript', u'application/vnd.adobe-reader-postscript', u'application/vnd.cups-command', u'application/vnd.cups-pdf', u'application/vnd.cups-pdf-banner', u'application/vnd.cups-postscript', u'application/vnd.cups-raw', u'application/vnd.samsung-ps', u'application/x-cshell', u'application/x-csource', u'application/x-perl', u'application/x-shell', u'image/gif', u'image/jpeg', u'image/png', u'image/tiff', u'image/urf', u'image/x-bitmap', u'image/x-photocd', u'image/x-portable-anymap', u'image/x-portable-bitmap', u'image/x-portable-graymap', u'image/x-portable-pixmap', u'image/x-sgi-rgb', u'image/x-sun-raster', u'image/x-xbitmap', u'image/x-xpixmap', u'image/x-xwindowdump', u'text/css', u'text/html', u'text/plain'], 'finishings-default': 3, 'finishings-supported': [3], 'generated-natural-language-supported': [u'en-us'], 'ipp-versions-supported': [u'1.0', u'1.1', u'2.0', u'2.1'], 'ippget-event-life': 15, 'job-creation-attributes-supported': [u'copies', u'finishings', u'ipp-attribute-fidelity', u'job-hold-until', u'job-name', u'job-priority', u'job-sheets', u'media', u'media-col', u'multiple-document-handling', u'number-up', u'output-bin', u'orientation-requested', u'page-ranges', u'print-color-mode', u'print-quality', u'printer-resolution', u'sides'], 'job-hold-until-default': u'no-hold', 'job-hold-until-supported': [u'no-hold', u'indefinite', u'day-time', u'evening', u'night', u'second-shift', u'third-shift', u'weekend'], 'job-ids-supported': True, 'job-k-limit': 0, 'job-k-octets-supported': (0, 470914416), 'job-page-limit': 0, 'job-priority-default': 50, 'job-priority-supported': [100], 'job-quota-period': 0, 'job-settable-attributes-supported': [u'copies', u'finishings', u'job-hold-until', u'job-name', u'job-priority', u'media', u'media-col', u'multiple-document-handling', u'number-up', u'output-bin', u'orientation-requested', u'page-ranges', u'print-color-mode', u'print-quality', u'printer-resolution', u'sides'], 'job-sheets-default': (u'none', u'none'), 'job-sheets-supported': [u'none', u'classified', u'confidential', u'form', u'secret', u'standard', u'topsecret', u'unclassified'], 'jpeg-k-octets-supported': (0, 470914416), 'jpeg-x-dimension-supported': (0, 65535), 'jpeg-y-dimension-supported': (1, 65535), 'marker-change-time': 0, 'media-bottom-margin-supported': [423], 'media-col-default': u'(unknown IPP value tag 0x34)', 'media-col-supported': [u'media-bottom-margin', u'media-left-margin', u'media-right-margin', u'media-size', u'media-source', u'media-top-margin', u'media-type'], 'media-default': u'iso_a4_210x297mm', 'media-left-margin-supported': [423], 'media-right-margin-supported': [423],

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  • Steganography : Encoded audio and video file not being played, getting corrupted. What is the issue

    - by Shantanu Gupta
    I have made a steganography program to encrypt/Decrypt some text under image audio and video. I used image as bmp(54 byte header) file, audio as wav(44 byte header) file and video as avi(56 byte header) file formats. When I tries to encrypt text under all these file then it gets encrypted successfully and are also getting decrypted correctly. But it is creating a problem with audio and video i.e these files are not being played after encrypted result. What can be the problem. I am working on Turbo C++ compiler. I know it is super outdated compiler but I have to do it in this only. Here is my code to encrypt. int Binary_encode(char *txtSourceFileName, char *binarySourceFileName, char *binaryTargetFileName,const short headerSize) { long BinarySourceSize=0,TextSourceSize=0; char *Buffer; long BlockSize=10240, i=0; ifstream ReadTxt, ReadBinary; //reads ReadTxt.open(txtSourceFileName,ios::binary|ios::in);//file name, mode of open, here input mode i.e. read only if(!ReadTxt) { cprintf("\nFile can not be opened."); return 0; } ReadBinary.open(binarySourceFileName,ios::binary|ios::in);//file name, mode of open, here input mode i.e. read only if(!ReadBinary) { ReadTxt.close();//closing opened file cprintf("\nFile can not be opened."); return 0; } ReadBinary.seekg(0,ios::end);//setting pointer to a file at the end of file. ReadTxt.seekg(0,ios::end); BinarySourceSize=(long )ReadBinary.tellg(); //returns the position of pointer TextSourceSize=(long )ReadTxt.tellg(); //returns the position of pointer ReadBinary.seekg(0,ios::beg); //sets the pointer to the begining of file ReadTxt.seekg(0,ios::beg); //sets the pointer to the begining of file if(BinarySourceSize<TextSourceSize*50) //Minimum size of an image should be 50 times the size of file to be encrypted { cout<<"\n\n"; cprintf("Binary File size should be bigger than text file size."); ReadBinary.close(); ReadTxt.close(); return 0; } cout<<"\n"; cprintf("\n\nSize of Source Image/Audio File is : "); cout<<(float)BinarySourceSize/1024; cprintf("KB"); cout<<"\n"; cprintf("Size of Text File is "); cout<<TextSourceSize; cprintf(" Bytes"); cout<<"\n"; getch(); //write header to file without changing else file will not open //bmp image's header size is 53 bytes Buffer=new char[headerSize]; ofstream WriteBinary; // writes to file WriteBinary.open(binaryTargetFileName,ios::binary|ios::out|ios::trunc);//file will be created or truncated if already exists ReadBinary.read(Buffer,headerSize);//reads no of bytes and stores them into mem, size contains no of bytes in a file WriteBinary.write(Buffer,headerSize);//writes header to 2nd image delete[] Buffer;//deallocate memory /* Buffer = new char[sizeof(long)]; Buffer = (char *)(&TextSourceSize); cout<<Buffer; */ WriteBinary.write((char *)(&TextSourceSize),sizeof(long)); //writes no of byte to be written in image immediate after header ends //to decrypt file if(!(Buffer=new char[TextSourceSize])) { cprintf("Enough Memory could not be assigned."); return 0; } ReadTxt.read(Buffer,TextSourceSize);//read all data from text file ReadTxt.close();//file no more needed WriteBinary.write(Buffer,TextSourceSize);//writes all text file data into image delete[] Buffer;//deallocate memory //replace Tsize+1 below with Tsize and run the program to see the change //this is due to the reason that 50-54 byte no are of colors which we will be changing ReadBinary.seekg(TextSourceSize+1,ios::cur);//move pointer to the location-current loc i.e. 53+content of text file //write remaining image content to image file while(i<BinarySourceSize-headerSize-TextSourceSize+1) { i=i+BlockSize; Buffer=new char[BlockSize]; ReadBinary.read(Buffer,BlockSize);//reads no of bytes and stores them into mem, size contains no of bytes in a file WriteBinary.write(Buffer,BlockSize); delete[] Buffer; //clear memory, else program can fail giving correct output } ReadBinary.close(); WriteBinary.close(); //Encoding Completed return 0; } Code to decrypt int Binary_decode(char *binarySourceFileName, char *txtTargetFileName, const short headerSize) { long TextDestinationSize=0; char *Buffer; long BlockSize=10240; ifstream ReadBinary; ofstream WriteText; ReadBinary.open(binarySourceFileName,ios::binary|ios::in);//file will be appended if(!ReadBinary) { cprintf("File can not be opened"); return 0; } ReadBinary.seekg(headerSize,ios::beg); Buffer=new char[4]; ReadBinary.read(Buffer,4); TextDestinationSize=*((long *)Buffer); delete[] Buffer; cout<<"\n\n"; cprintf("Size of the File that will be created is : "); cout<<TextDestinationSize; cprintf(" Bytes"); cout<<"\n\n"; sleep(1); WriteText.open(txtTargetFileName,ios::binary|ios::out|ios::trunc);//file will be created if not exists else truncate its data while(TextDestinationSize>0) { if(TextDestinationSize<BlockSize) BlockSize=TextDestinationSize; Buffer= new char[BlockSize]; ReadBinary.read(Buffer,BlockSize); WriteText.write(Buffer,BlockSize); delete[] Buffer; TextDestinationSize=TextDestinationSize-BlockSize; } ReadBinary.close(); WriteText.close(); return 0; } int text_encode(char *SourcefileName, char *DestinationfileName) { ifstream fr; //reads ofstream fw; // writes to file char c; int random; clrscr(); fr.open(SourcefileName,ios::binary);//file name, mode of open, here input mode i.e. read only if(!fr) { cprintf("File can not be opened."); getch(); return 0; } fw.open(DestinationfileName,ios::binary|ios::out|ios::trunc);//file will be created or truncated if already exists while(fr) { int i; while(fr!=0) { fr.get(c); //reads a character from file and increments its pointer char ch; ch=c; ch=ch+1; fw<<ch; //appends character in c to a file } } fr.close(); fw.close(); return 0; } int text_decode(char *SourcefileName, char *DestinationName) { ifstream fr; //reads ofstream fw; // wrrites to file char c; int random; clrscr(); fr.open(SourcefileName,ios::binary);//file name, mode of open, here input mode i.e. read only if(!fr) { cprintf("File can not be opened."); return 0; } fw.open(DestinationName,ios::binary|ios::out|ios::trunc);//file will be created or truncated if already exists while(fr) { int i; while(fr!=0) { fr.get(c); //reads a character from file and increments its pointer char ch; ch=c; ch=ch-1; fw<<ch; //appends character in c to a file } } fr.close(); fw.close(); return 0; }

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  • Is SPLFileObject atomic?

    - by Jakub Lédl
    I'm wondering whether methods of PHPs SPLFileObject are atomic (e.g. thread-safe) or not? If they aren't, I'll implement my own class, which will use flock(), but is this enough? Is the flock function really thread-safe? What if the collision occurs after I fopen() the file, but before I flock() it?

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  • Django: How do I prepend

    - by voidnothings
    Hello, I'm exploring Django and got this particular problem. How do I prepend <span class="label">Note:</span> inside {{article.content_html|safe}}? The content of {{article.content_html|safe}} are paragraph blocks, and I just wanna add <span class="label">Note:</span> in the very first paragraph. Thanks!

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  • Are there any platforms where using structure copy on an fd_set (for select() or pselect()) causes p

    - by Jonathan Leffler
    The select() and pselect() system calls modify their arguments (the 'struct fd_set *' arguments), so the input value tells the system which file descriptors to check and the return values tell the programmer which file descriptors are currently usable. If you are going to call them repeatedly for the same set of file descriptors, you need to ensure that you have a fresh copy of the descriptors for each call. The obvious way to do that is to use a structure copy: struct fd_set ref_set_rd; struct fd_set ref_set_wr; struct fd_set ref_set_er; ... ...code to set the reference fd_set_xx values... ... while (!done) { struct fd_set act_set_rd = ref_set_rd; struct fd_set act_set_wr = ref_set_wr; struct fd_set act_set_er = ref_set_er; int bits_set = select(max_fd, &act_set_rd, &act_set_wr, &act_set_er, &timeout); if (bits_set > 0) { ...process the output values of act_set_xx... } } My question: Are there any platforms where it is not safe to do a structure copy of the struct fd_set values as shown? I'm concerned lest there be hidden memory allocation or anything unexpected like that. (There are macros/functions FD_SET(), FD_CLR(), FD_ZERO() and FD_ISSET() to mask the internals from the application.) I can see that MacOS X (Darwin) is safe; other BSD-based systems are likely to be safe, therefore. You can help by documenting other systems that you know are safe in your answers. (I do have minor concerns about how well the struct fd_set would work with more than 8192 open file descriptors - the default maximum number of open files is only 256, but the maximum number is 'unlimited'. Also, since the structures are 1 KB, the copying code is not dreadfully efficient, but then running through a list of file descriptors to recreate the input mask on each cycle is not necessarily efficient either. Maybe you can't do select() when you have that many file descriptors open, though that is when you are most likely to need the functionality.) There's a related SO question - asking about 'poll() vs select()' which addresses a different set of issues from this question.

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  • Building a life-critical System using Agile

    - by Ben Breen
    Looking at the general trend of comments in my question about Building an Aircraft using Agile, the biggest problem other than cost appears to be safety. Do people feel that it is not possible to build a safe system (or prove it is safe) using agile? Doesn’t all the iterative testing mitigate this? Is it likely that a piece of software developed using agile will never be as reliable as counterparts such as waterfall?

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  • What is the fastest XML parser in PHP?

    - by Jakub Lédl
    Hi, for a certain project, I need some way to parse XML and get data from it. So I wonder, which one of built-in parsers is the fastest? Also, it would be nice of the parser could accept a XML string as input - I have my own implementation of thread-safe working with files and I don't want some nasty non-thread-safe libraries to make my efforts useless.

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  • When exactly would a DLL use a different heap than the executable?

    - by Milo
    I know that if your DLL static links against a different version of the runtime then it creates its own heap. It will also if it is instructed to make a heap. Under these circumstances, it is unsafe for the DLL to delete what the exe allocated. In what cases does this NOT apply (as in, it is safe for the DLL to delete what the exe allocated)? Is it safe if both the exe and the DLL static link against the same runtime library? Thanks

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  • Sharing the same file between different projects

    - by selsine
    Hi Everyone, For version control we currently use Visual Source Safe and are thinking of migrating to another version control system (SVN, Mercurial, Git). Currently we use Visual Source Safe's "Shared" file feature quite heavily. This allows us to share code between design and runtimes of a single product, and between multiple products as well. For example: **Product One** - Design Login.cpp Login.h Helper.cpp Helper.h - Runtime Login.cpp Login.h Helper.cpp Helper.h **Product Two** - Design Login.cpp Login.h - Launcher Login.cpp Login.h - Runtime Login.cpp Login.h In this example Login.cpp and Login.h contain common code that all of our projects need, Helper.cpp and Helper.h is only used in Product One. In Visual Source Safe they are shared between the specific projects, which means that whenever the files are updated in one project they are updated in any project they are shared with. This is a simple example but hopefully it explains why we use the shared feature: to reduce the amount of duplicated code and ensure that when a bug is fixed all projects automatically have access to the new fixed code. After researching alternatives to Visual Source Safe it seems that most version control systems do not have the idea of shared files, instead they seem to use the idea of sub repositories. (http://mercurial.selenic.com/wiki/subrepos http://svnbook.red-bean.com/en/1.0/ch07s03.html) My question (after all of that) is about what the best practices for achieving this are using other version control systems? Should we restructure our projects so that two copies of the files do not exist and an include directory is used instead? e.g. Product One Design Login.cpp Login.h Runtime Login.cpp Login.h Common Helper.cpp Helper.h This still leaves what to do with Login.cpp and Logon.h Should the shared files be moved to their own repository and then compiled into a lib or dll? This would make bug fixing more time consuming as the lib projects would have to be edited and then rebuilt. Should we use externals or sub repositories? Should we combine our projects (i.e. runtime, design, and launcher) into one large project? Any help would be appreciated. We have the feeling that our project design has evolved based on the tools that we used and now that we are thinking of switching tools it's difficult for us to see how we can best modify our practices. Or maybe we are the only people are there doing this...? Also, we use Visual Studio for all of our stuff. Thanks.

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  • Thread safety with heap-allocated memory

    - by incrediman
    I was reading this: http://en.wikipedia.org/wiki/Thread_safety Is the following function thread-safe? void foo(int y){ int * x = new int[50]; /*...do some stuff with the allocated memory...*/ delete x; } In the article it says that to be thread-safe you can only use variables from the stack. Really? Why? Wouldn't subsequent calls of the above function allocate memory elsewhere?

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  • final fields and thread-safety

    - by pcjuzer
    Should it be all fields, including super-fields, of a purposively immutable java class 'final' in order to be thread-safe or is it enough to have no modifier methods? Suppose I have a POJO with non-final fields where all fields are type of some immutable class. This POJO has getters-setters, and a constructor wich sets some initial value. If I extend this POJO with knocking out modifier methods, thus making it immutable, will extension class be thread-safe?

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  • safely reading directory contents

    - by Jack
    Is it safe to read directory entries via readdir() or scandir() while files are being created/deleted in this directory? Should I prefer one over the other? When I say "safe" I mean entries returned by these functions are valid and can be operated without crushing the program. Thanks.

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  • Service Discovery in WCF 4.0 &ndash; Part 1

    - by Shaun
    When designing a service oriented architecture (SOA) system, there will be a lot of services with many service contracts, endpoints and behaviors. Besides the client calling the service, in a large distributed system a service may invoke other services. In this case, one service might need to know the endpoints it invokes. This might not be a problem in a small system. But when you have more than 10 services this might be a problem. For example in my current product, there are around 10 services, such as the user authentication service, UI integration service, location service, license service, device monitor service, event monitor service, schedule job service, accounting service, player management service, etc..   Benefit of Discovery Service Since almost all my services need to invoke at least one other service. This would be a difficult task to make sure all services endpoints are configured correctly in every service. And furthermore, it would be a nightmare when a service changed its endpoint at runtime. Hence, we need a discovery service to remove the dependency (configuration dependency). A discovery service plays as a service dictionary which stores the relationship between the contracts and the endpoints for every service. By using the discovery service, when service X wants to invoke service Y, it just need to ask the discovery service where is service Y, then the discovery service will return all proper endpoints of service Y, then service X can use the endpoint to send the request to service Y. And when some services changed their endpoint address, all need to do is to update its records in the discovery service then all others will know its new endpoint. In WCF 4.0 Discovery it supports both managed proxy discovery mode and ad-hoc discovery mode. In ad-hoc mode there is no standalone discovery service. When a client wanted to invoke a service, it will broadcast an message (normally in UDP protocol) to the entire network with the service match criteria. All services which enabled the discovery behavior will receive this message and only those matched services will send their endpoint back to the client. The managed proxy discovery service works as I described above. In this post I will only cover the managed proxy mode, where there’s a discovery service. For more information about the ad-hoc mode please refer to the MSDN.   Service Announcement and Probe The main functionality of discovery service should be return the proper endpoint addresses back to the service who is looking for. In most cases the consume service (as a client) will send the contract which it wanted to request to the discovery service. And then the discovery service will find the endpoint and respond. Sometimes the contract and endpoint are not enough. It also contains versioning, extensions attributes. This post I will only cover the case includes contract and endpoint. When a client (or sometimes a service who need to invoke another service) need to connect to a target service, it will firstly request the discovery service through the “Probe” method with the criteria. Basically the criteria contains the contract type name of the target service. Then the discovery service will search its endpoint repository by the criteria. The repository might be a database, a distributed cache or a flat XML file. If it matches, the discovery service will grab the endpoint information (it’s called discovery endpoint metadata in WCF) and send back. And this is called “Probe”. Finally the client received the discovery endpoint metadata and will use the endpoint to connect to the target service. Besides the probe, discovery service should take the responsible to know there is a new service available when it goes online, as well as stopped when it goes offline. This feature is named “Announcement”. When a service started and stopped, it will announce to the discovery service. So the basic functionality of a discovery service should includes: 1, An endpoint which receive the service online message, and add the service endpoint information in the discovery repository. 2, An endpoint which receive the service offline message, and remove the service endpoint information from the discovery repository. 3, An endpoint which receive the client probe message, and return the matches service endpoints, and return the discovery endpoint metadata. WCF 4.0 discovery service just covers all these features in it's infrastructure classes.   Discovery Service in WCF 4.0 WCF 4.0 introduced a new assembly named System.ServiceModel.Discovery which has all necessary classes and interfaces to build a WS-Discovery compliant discovery service. It supports ad-hoc and managed proxy modes. For the case mentioned in this post, what we need to build is a standalone discovery service, which is the managed proxy discovery service mode. To build a managed discovery service in WCF 4.0 just create a new class inherits from the abstract class System.ServiceModel.Discovery.DiscoveryProxy. This class implemented and abstracted the procedures of service announcement and probe. And it exposes 8 abstract methods where we can implement our own endpoint register, unregister and find logic. These 8 methods are asynchronized, which means all invokes to the discovery service are asynchronously, for better service capability and performance. 1, OnBeginOnlineAnnouncement, OnEndOnlineAnnouncement: Invoked when a service sent the online announcement message. We need to add the endpoint information to the repository in this method. 2, OnBeginOfflineAnnouncement, OnEndOfflineAnnouncement: Invoked when a service sent the offline announcement message. We need to remove the endpoint information from the repository in this method. 3, OnBeginFind, OnEndFind: Invoked when a client sent the probe message that want to find the service endpoint information. We need to look for the proper endpoints by matching the client’s criteria through the repository in this method. 4, OnBeginResolve, OnEndResolve: Invoked then a client sent the resolve message. Different from the find method, when using resolve method the discovery service will return the exactly one service endpoint metadata to the client. In our example we will NOT implement this method.   Let’s create our own discovery service, inherit the base System.ServiceModel.Discovery.DiscoveryProxy. We also need to specify the service behavior in this class. Since the build-in discovery service host class only support the singleton mode, we must set its instance context mode to single. 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Text; 5: using System.ServiceModel.Discovery; 6: using System.ServiceModel; 7:  8: namespace Phare.Service 9: { 10: [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple)] 11: public class ManagedProxyDiscoveryService : DiscoveryProxy 12: { 13: protected override IAsyncResult OnBeginFind(FindRequestContext findRequestContext, AsyncCallback callback, object state) 14: { 15: throw new NotImplementedException(); 16: } 17:  18: protected override IAsyncResult OnBeginOfflineAnnouncement(DiscoveryMessageSequence messageSequence, EndpointDiscoveryMetadata endpointDiscoveryMetadata, AsyncCallback callback, object state) 19: { 20: throw new NotImplementedException(); 21: } 22:  23: protected override IAsyncResult OnBeginOnlineAnnouncement(DiscoveryMessageSequence messageSequence, EndpointDiscoveryMetadata endpointDiscoveryMetadata, AsyncCallback callback, object state) 24: { 25: throw new NotImplementedException(); 26: } 27:  28: protected override IAsyncResult OnBeginResolve(ResolveCriteria resolveCriteria, AsyncCallback callback, object state) 29: { 30: throw new NotImplementedException(); 31: } 32:  33: protected override void OnEndFind(IAsyncResult result) 34: { 35: throw new NotImplementedException(); 36: } 37:  38: protected override void OnEndOfflineAnnouncement(IAsyncResult result) 39: { 40: throw new NotImplementedException(); 41: } 42:  43: protected override void OnEndOnlineAnnouncement(IAsyncResult result) 44: { 45: throw new NotImplementedException(); 46: } 47:  48: protected override EndpointDiscoveryMetadata OnEndResolve(IAsyncResult result) 49: { 50: throw new NotImplementedException(); 51: } 52: } 53: } Then let’s implement the online, offline and find methods one by one. WCF discovery service gives us full flexibility to implement the endpoint add, remove and find logic. For the demo purpose we will use an internal dictionary to store the services’ endpoint metadata. In the next post we will see how to serialize and store these information in database. Define a concurrent dictionary inside the service class since our it will be used in the multiple threads scenario. 1: [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple)] 2: public class ManagedProxyDiscoveryService : DiscoveryProxy 3: { 4: private ConcurrentDictionary<EndpointAddress, EndpointDiscoveryMetadata> _services; 5:  6: public ManagedProxyDiscoveryService() 7: { 8: _services = new ConcurrentDictionary<EndpointAddress, EndpointDiscoveryMetadata>(); 9: } 10: } Then we can simply implement the logic of service online and offline. 1: protected override IAsyncResult OnBeginOnlineAnnouncement(DiscoveryMessageSequence messageSequence, EndpointDiscoveryMetadata endpointDiscoveryMetadata, AsyncCallback callback, object state) 2: { 3: _services.AddOrUpdate(endpointDiscoveryMetadata.Address, endpointDiscoveryMetadata, (key, value) => endpointDiscoveryMetadata); 4: return new OnOnlineAnnouncementAsyncResult(callback, state); 5: } 6:  7: protected override void OnEndOnlineAnnouncement(IAsyncResult result) 8: { 9: OnOnlineAnnouncementAsyncResult.End(result); 10: } 11:  12: protected override IAsyncResult OnBeginOfflineAnnouncement(DiscoveryMessageSequence messageSequence, EndpointDiscoveryMetadata endpointDiscoveryMetadata, AsyncCallback callback, object state) 13: { 14: EndpointDiscoveryMetadata endpoint = null; 15: _services.TryRemove(endpointDiscoveryMetadata.Address, out endpoint); 16: return new OnOfflineAnnouncementAsyncResult(callback, state); 17: } 18:  19: protected override void OnEndOfflineAnnouncement(IAsyncResult result) 20: { 21: OnOfflineAnnouncementAsyncResult.End(result); 22: } Regards the find method, the parameter FindRequestContext.Criteria has a method named IsMatch, which can be use for us to evaluate which service metadata is satisfied with the criteria. So the implementation of find method would be like this. 1: protected override IAsyncResult OnBeginFind(FindRequestContext findRequestContext, AsyncCallback callback, object state) 2: { 3: _services.Where(s => findRequestContext.Criteria.IsMatch(s.Value)) 4: .Select(s => s.Value) 5: .All(meta => 6: { 7: findRequestContext.AddMatchingEndpoint(meta); 8: return true; 9: }); 10: return new OnFindAsyncResult(callback, state); 11: } 12:  13: protected override void OnEndFind(IAsyncResult result) 14: { 15: OnFindAsyncResult.End(result); 16: } As you can see, we checked all endpoints metadata in repository by invoking the IsMatch method. Then add all proper endpoints metadata into the parameter. Finally since all these methods are asynchronized we need some AsyncResult classes as well. Below are the base class and the inherited classes used in previous methods. 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Text; 5: using System.Threading; 6:  7: namespace Phare.Service 8: { 9: abstract internal class AsyncResult : IAsyncResult 10: { 11: AsyncCallback callback; 12: bool completedSynchronously; 13: bool endCalled; 14: Exception exception; 15: bool isCompleted; 16: ManualResetEvent manualResetEvent; 17: object state; 18: object thisLock; 19:  20: protected AsyncResult(AsyncCallback callback, object state) 21: { 22: this.callback = callback; 23: this.state = state; 24: this.thisLock = new object(); 25: } 26:  27: public object AsyncState 28: { 29: get 30: { 31: return state; 32: } 33: } 34:  35: public WaitHandle AsyncWaitHandle 36: { 37: get 38: { 39: if (manualResetEvent != null) 40: { 41: return manualResetEvent; 42: } 43: lock (ThisLock) 44: { 45: if (manualResetEvent == null) 46: { 47: manualResetEvent = new ManualResetEvent(isCompleted); 48: } 49: } 50: return manualResetEvent; 51: } 52: } 53:  54: public bool CompletedSynchronously 55: { 56: get 57: { 58: return completedSynchronously; 59: } 60: } 61:  62: public bool IsCompleted 63: { 64: get 65: { 66: return isCompleted; 67: } 68: } 69:  70: object ThisLock 71: { 72: get 73: { 74: return this.thisLock; 75: } 76: } 77:  78: protected static TAsyncResult End<TAsyncResult>(IAsyncResult result) 79: where TAsyncResult : AsyncResult 80: { 81: if (result == null) 82: { 83: throw new ArgumentNullException("result"); 84: } 85:  86: TAsyncResult asyncResult = result as TAsyncResult; 87:  88: if (asyncResult == null) 89: { 90: throw new ArgumentException("Invalid async result.", "result"); 91: } 92:  93: if (asyncResult.endCalled) 94: { 95: throw new InvalidOperationException("Async object already ended."); 96: } 97:  98: asyncResult.endCalled = true; 99:  100: if (!asyncResult.isCompleted) 101: { 102: asyncResult.AsyncWaitHandle.WaitOne(); 103: } 104:  105: if (asyncResult.manualResetEvent != null) 106: { 107: asyncResult.manualResetEvent.Close(); 108: } 109:  110: if (asyncResult.exception != null) 111: { 112: throw asyncResult.exception; 113: } 114:  115: return asyncResult; 116: } 117:  118: protected void Complete(bool completedSynchronously) 119: { 120: if (isCompleted) 121: { 122: throw new InvalidOperationException("This async result is already completed."); 123: } 124:  125: this.completedSynchronously = completedSynchronously; 126:  127: if (completedSynchronously) 128: { 129: this.isCompleted = true; 130: } 131: else 132: { 133: lock (ThisLock) 134: { 135: this.isCompleted = true; 136: if (this.manualResetEvent != null) 137: { 138: this.manualResetEvent.Set(); 139: } 140: } 141: } 142:  143: if (callback != null) 144: { 145: callback(this); 146: } 147: } 148:  149: protected void Complete(bool completedSynchronously, Exception exception) 150: { 151: this.exception = exception; 152: Complete(completedSynchronously); 153: } 154: } 155: } 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Text; 5: using System.ServiceModel.Discovery; 6: using Phare.Service; 7:  8: namespace Phare.Service 9: { 10: internal sealed class OnOnlineAnnouncementAsyncResult : AsyncResult 11: { 12: public OnOnlineAnnouncementAsyncResult(AsyncCallback callback, object state) 13: : base(callback, state) 14: { 15: this.Complete(true); 16: } 17:  18: public static void End(IAsyncResult result) 19: { 20: AsyncResult.End<OnOnlineAnnouncementAsyncResult>(result); 21: } 22:  23: } 24:  25: sealed class OnOfflineAnnouncementAsyncResult : AsyncResult 26: { 27: public OnOfflineAnnouncementAsyncResult(AsyncCallback callback, object state) 28: : base(callback, state) 29: { 30: this.Complete(true); 31: } 32:  33: public static void End(IAsyncResult result) 34: { 35: AsyncResult.End<OnOfflineAnnouncementAsyncResult>(result); 36: } 37: } 38:  39: sealed class OnFindAsyncResult : AsyncResult 40: { 41: public OnFindAsyncResult(AsyncCallback callback, object state) 42: : base(callback, state) 43: { 44: this.Complete(true); 45: } 46:  47: public static void End(IAsyncResult result) 48: { 49: AsyncResult.End<OnFindAsyncResult>(result); 50: } 51: } 52:  53: sealed class OnResolveAsyncResult : AsyncResult 54: { 55: EndpointDiscoveryMetadata matchingEndpoint; 56:  57: public OnResolveAsyncResult(EndpointDiscoveryMetadata matchingEndpoint, AsyncCallback callback, object state) 58: : base(callback, state) 59: { 60: this.matchingEndpoint = matchingEndpoint; 61: this.Complete(true); 62: } 63:  64: public static EndpointDiscoveryMetadata End(IAsyncResult result) 65: { 66: OnResolveAsyncResult thisPtr = AsyncResult.End<OnResolveAsyncResult>(result); 67: return thisPtr.matchingEndpoint; 68: } 69: } 70: } Now we have finished the discovery service. The next step is to host it. The discovery service is a standard WCF service. So we can use ServiceHost on a console application, windows service, or in IIS as usual. The following code is how to host the discovery service we had just created in a console application. 1: static void Main(string[] args) 2: { 3: using (var host = new ServiceHost(new ManagedProxyDiscoveryService())) 4: { 5: host.Opened += (sender, e) => 6: { 7: host.Description.Endpoints.All((ep) => 8: { 9: Console.WriteLine(ep.ListenUri); 10: return true; 11: }); 12: }; 13:  14: try 15: { 16: // retrieve the announcement, probe endpoint and binding from configuration 17: var announcementEndpointAddress = new EndpointAddress(ConfigurationManager.AppSettings["announcementEndpointAddress"]); 18: var probeEndpointAddress = new EndpointAddress(ConfigurationManager.AppSettings["probeEndpointAddress"]); 19: var binding = Activator.CreateInstance(Type.GetType(ConfigurationManager.AppSettings["bindingType"], true, true)) as Binding; 20: var announcementEndpoint = new AnnouncementEndpoint(binding, announcementEndpointAddress); 21: var probeEndpoint = new DiscoveryEndpoint(binding, probeEndpointAddress); 22: probeEndpoint.IsSystemEndpoint = false; 23: // append the service endpoint for announcement and probe 24: host.AddServiceEndpoint(announcementEndpoint); 25: host.AddServiceEndpoint(probeEndpoint); 26:  27: host.Open(); 28:  29: Console.WriteLine("Press any key to exit."); 30: Console.ReadKey(); 31: } 32: catch (Exception ex) 33: { 34: Console.WriteLine(ex.ToString()); 35: } 36: } 37:  38: Console.WriteLine("Done."); 39: Console.ReadKey(); 40: } What we need to notice is that, the discovery service needs two endpoints for announcement and probe. In this example I just retrieve them from the configuration file. I also specified the binding of these two endpoints in configuration file as well. 1: <?xml version="1.0"?> 2: <configuration> 3: <startup> 4: <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/> 5: </startup> 6: <appSettings> 7: <add key="announcementEndpointAddress" value="net.tcp://localhost:10010/announcement"/> 8: <add key="probeEndpointAddress" value="net.tcp://localhost:10011/probe"/> 9: <add key="bindingType" value="System.ServiceModel.NetTcpBinding, System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> 10: </appSettings> 11: </configuration> And this is the console screen when I ran my discovery service. As you can see there are two endpoints listening for announcement message and probe message.   Discoverable Service and Client Next, let’s create a WCF service that is discoverable, which means it can be found by the discovery service. To do so, we need to let the service send the online announcement message to the discovery service, as well as offline message before it shutdown. Just create a simple service which can make the incoming string to upper. The service contract and implementation would be like this. 1: [ServiceContract] 2: public interface IStringService 3: { 4: [OperationContract] 5: string ToUpper(string content); 6: } 1: public class StringService : IStringService 2: { 3: public string ToUpper(string content) 4: { 5: return content.ToUpper(); 6: } 7: } Then host this service in the console application. In order to make the discovery service easy to be tested the service address will be changed each time it’s started. 1: static void Main(string[] args) 2: { 3: var baseAddress = new Uri(string.Format("net.tcp://localhost:11001/stringservice/{0}/", Guid.NewGuid().ToString())); 4:  5: using (var host = new ServiceHost(typeof(StringService), baseAddress)) 6: { 7: host.Opened += (sender, e) => 8: { 9: Console.WriteLine("Service opened at {0}", host.Description.Endpoints.First().ListenUri); 10: }; 11:  12: host.AddServiceEndpoint(typeof(IStringService), new NetTcpBinding(), string.Empty); 13:  14: host.Open(); 15:  16: Console.WriteLine("Press any key to exit."); 17: Console.ReadKey(); 18: } 19: } Currently this service is NOT discoverable. We need to add a special service behavior so that it could send the online and offline message to the discovery service announcement endpoint when the host is opened and closed. WCF 4.0 introduced a service behavior named ServiceDiscoveryBehavior. When we specified the announcement endpoint address and appended it to the service behaviors this service will be discoverable. 1: var announcementAddress = new EndpointAddress(ConfigurationManager.AppSettings["announcementEndpointAddress"]); 2: var announcementBinding = Activator.CreateInstance(Type.GetType(ConfigurationManager.AppSettings["bindingType"], true, true)) as Binding; 3: var announcementEndpoint = new AnnouncementEndpoint(announcementBinding, announcementAddress); 4: var discoveryBehavior = new ServiceDiscoveryBehavior(); 5: discoveryBehavior.AnnouncementEndpoints.Add(announcementEndpoint); 6: host.Description.Behaviors.Add(discoveryBehavior); The ServiceDiscoveryBehavior utilizes the service extension and channel dispatcher to implement the online and offline announcement logic. In short, it injected the channel open and close procedure and send the online and offline message to the announcement endpoint.   On client side, when we have the discovery service, a client can invoke a service without knowing its endpoint. WCF discovery assembly provides a class named DiscoveryClient, which can be used to find the proper service endpoint by passing the criteria. In the code below I initialized the DiscoveryClient, specified the discovery service probe endpoint address. Then I created the find criteria by specifying the service contract I wanted to use and invoke the Find method. This will send the probe message to the discovery service and it will find the endpoints back to me. The discovery service will return all endpoints that matches the find criteria, which means in the result of the find method there might be more than one endpoints. In this example I just returned the first matched one back. In the next post I will show how to extend our discovery service to make it work like a service load balancer. 1: static EndpointAddress FindServiceEndpoint() 2: { 3: var probeEndpointAddress = new EndpointAddress(ConfigurationManager.AppSettings["probeEndpointAddress"]); 4: var probeBinding = Activator.CreateInstance(Type.GetType(ConfigurationManager.AppSettings["bindingType"], true, true)) as Binding; 5: var discoveryEndpoint = new DiscoveryEndpoint(probeBinding, probeEndpointAddress); 6:  7: EndpointAddress address = null; 8: FindResponse result = null; 9: using (var discoveryClient = new DiscoveryClient(discoveryEndpoint)) 10: { 11: result = discoveryClient.Find(new FindCriteria(typeof(IStringService))); 12: } 13:  14: if (result != null && result.Endpoints.Any()) 15: { 16: var endpointMetadata = result.Endpoints.First(); 17: address = endpointMetadata.Address; 18: } 19: return address; 20: } Once we probed the discovery service we will receive the endpoint. So in the client code we can created the channel factory from the endpoint and binding, and invoke to the service. When creating the client side channel factory we need to make sure that the client side binding should be the same as the service side. WCF discovery service can be used to find the endpoint for a service contract, but the binding is NOT included. This is because the binding was not in the WS-Discovery specification. In the next post I will demonstrate how to add the binding information into the discovery service. At that moment the client don’t need to create the binding by itself. Instead it will use the binding received from the discovery service. 1: static void Main(string[] args) 2: { 3: Console.WriteLine("Say something..."); 4: var content = Console.ReadLine(); 5: while (!string.IsNullOrWhiteSpace(content)) 6: { 7: Console.WriteLine("Finding the service endpoint..."); 8: var address = FindServiceEndpoint(); 9: if (address == null) 10: { 11: Console.WriteLine("There is no endpoint matches the criteria."); 12: } 13: else 14: { 15: Console.WriteLine("Found the endpoint {0}", address.Uri); 16:  17: var factory = new ChannelFactory<IStringService>(new NetTcpBinding(), address); 18: factory.Opened += (sender, e) => 19: { 20: Console.WriteLine("Connecting to {0}.", factory.Endpoint.ListenUri); 21: }; 22: var proxy = factory.CreateChannel(); 23: using (proxy as IDisposable) 24: { 25: Console.WriteLine("ToUpper: {0} => {1}", content, proxy.ToUpper(content)); 26: } 27: } 28:  29: Console.WriteLine("Say something..."); 30: content = Console.ReadLine(); 31: } 32: } Similarly, the discovery service probe endpoint and binding were defined in the configuration file. 1: <?xml version="1.0"?> 2: <configuration> 3: <startup> 4: <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/> 5: </startup> 6: <appSettings> 7: <add key="announcementEndpointAddress" value="net.tcp://localhost:10010/announcement"/> 8: <add key="probeEndpointAddress" value="net.tcp://localhost:10011/probe"/> 9: <add key="bindingType" value="System.ServiceModel.NetTcpBinding, System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> 10: </appSettings> 11: </configuration> OK, now let’s have a test. Firstly start the discovery service, and then start our discoverable service. When it started it will announced to the discovery service and registered its endpoint into the repository, which is the local dictionary. And then start the client and type something. As you can see the client asked the discovery service for the endpoint and then establish the connection to the discoverable service. And more interesting, do NOT close the client console but terminate the discoverable service but press the enter key. This will make the service send the offline message to the discovery service. Then start the discoverable service again. Since we made it use a different address each time it started, currently it should be hosted on another address. If we enter something in the client we could see that it asked the discovery service and retrieve the new endpoint, and connect the the service.   Summary In this post I discussed the benefit of using the discovery service and the procedures of service announcement and probe. I also demonstrated how to leverage the WCF Discovery feature in WCF 4.0 to build a simple managed discovery service. For test purpose, in this example I used the in memory dictionary as the discovery endpoint metadata repository. And when finding I also just return the first matched endpoint back. I also hard coded the bindings between the discoverable service and the client. In next post I will show you how to solve the problem mentioned above, as well as some additional feature for production usage. You can download the code here.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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