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  • SharePoint: what does "System.Runtime.InteropServices.COMException (0x81071003)" mean?

    - by kpinhack
    Hallo, i've got some code that imports documents into a SharePoint (WSS 3.0 SP1) document-library. That code works most of the time without any problems, but sometimes the document is not imported into the document-library and i get this nasty exception instead. Microsoft.SharePoint.SPException: Unable to update the information in the Microsoft Office document myFileName. ---> System.Runtime.InteropServices.COMException (0x81071003): Unable to update the information in the Microsoft Office document myFileName. bei Microsoft.SharePoint.Library.SPRequestInternalClass.AddOrUpdateItem(String bstrUrl, String bstrListName, Boolean bAdd, Boolean bSystemUpdate, Boolean bPreserveItemVersion, Boolean bUpdateNoVersion, Int32& plID, String& pbstrGuid, Guid pbstrNewDocId, Boolean bHasNewDocId, String bstrVersion, Object& pvarAttachmentNames, Object& pvarAttachmentContents, Object& pvarProperties, Boolean bCheckOut, Boolean bCheckin, Boolean bMigration, Boolean bPublish) bei Microsoft.SharePoint.Library.SPRequest.AddOrUpdateItem(String bstrUrl, String bstrListName, Boolean bAdd, Boolean bSystemUpdate, Boolean bPreserveItemVersion, Boolean bUpdateNoVersion, Int32& plID, String& pbstrGuid, Guid pbstrNewDocId, Boolean bHasNewDocId, String bstrVersion, Object& pvarAttachmentNames, Object& pvarAttachmentContents, Object& pvarProperties, Boolean bCheckOut, Boolean bCheckin, Boolean bMigration, Boolean bPublish) What does this exception mean? And why does it occur only sometimes? Thanks!

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  • Do you known a reputable backup software that can capture ONLY file system structure + attributes, WITHOUT file content

    - by bogdan
    Is there, on Windows, a reputable backup software out there capable of capturing ONLY a file system's directory and file structure, along with each item's attributes, WITHOUT capturing the actual file content (all files should be zero-length in the backup). I thoroughly searched the web for a solution and wasn't able to find one. Scenario when this would be very useful: I have a large drive with a huge amount of files. If the drive dies, I don't care so much about the content in these files (I can always download this content again from the Internet at any time) but I do care HUGELY about the names of the files that were on it, possibly also about their MD5 hashes and other classic file attributes (especially created-date / modified-date). The functionality I need is present to an extent in "media"/file cataloging software (i.e. whereisit) and, to a lesser extent, in a Total Commander set of extensions (DiskDir, DiskDirExtended). The huge drawback with cataloging software is that it's not designed to store previous versions of each item (AFAIK) and, most importantly, it has very weak content backup capabilities. I managed to think of a hack but I hope there's some backup software out there that already has this capability and I just failed to find it, thus this question. The hack: RoboCopy could be used with /CREATE (CREATE directory tree and zero-length files only) or /COPY (what to COPY for files) without the D=Data flag, to clone a directory structure into one where all files are zero-length but have the desired attributes. Then I would backup the cloned directory structure with a reputable backup software. I would really love to avoid a hack like this one, if possible. Thanks, Bogdan

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  • Troubleshooting: Monitor never turns on, system fans running, DVD-ROM does not open.

    - by Wesley
    Hi all, Here are my specs beforehand: ECS P4VXASD2+ (V5.0) motherboard FSB 533MHz Intel Pentium 4 2.40A GHz Prescott Socket 478 2x 256MB PC2100 DDR RAM, 2x 256MB PC133 SDRAM CoolMax 350W PSU DVD-ROM - will edit with brand & model 128MB ATi Radeon 9800 Pro AGP No hard drive So, I just put those parts together today and I tried to power it up, with the monitor connected to the Radeon 9800 in the AGP slot (mobo does not have VGA port). After turning it on, the CPU fan, graphics fan and system fan go on. However, the monitor remains in standby mode, despite being plugged in. Also, after pushing the button on the DVD-ROM drive, it does not open. I've used the DVD-ROM drive before with absolutely no issues. The graphics card was slightly buggy when I put it on another machine, which was left outside in winter weather for 3 months. (Still that computer's integrated graphics worked fine.) CMOS battery was replaced and jumpers are all set correctly. Now, I'm wondering whether the motherboard, CPU, PSU or GPU is the problem. What can I do to test which part is the problem? Just to clarify, I don't have a hard drive, so I usually boot Ubuntu from the disc drive. Anyways, thanks in advance!

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  • trying to figure out how to bridge two virtual networks together and in turn bridge that to the internet for a virtual inline IDS/IPS system

    - by Tony robinson
    I'm trying to figure out how to bridge two vmware (server or workstation, workstation) or virtualbox networks together with a linux IDS/IPS system transparently inline between both the virtual networks. How do I accomplish this? I understand how to bridge to virtual networks together, but how to I make the linux virtual machine sit between them and force traffic to go across the transparent bridge? I would like to have something along the lines of: vmnet a various vms host-only network ---- inline linux box vmnet a boxes forced to go through here to get to the internet --- vmnet b network with internet access configured as either NAT or bridged -- internet I know that basically the linux box needs two virtual nics, one on vmnet a and vmnet b, but other than that, I don't know how to force all the traffic to go across the "transparent" bridging linux box on its way to the internet. Do vmnet a and b have to be the same ip network with the same default route? does vmnet a not have a default route and vmnet b have a default route? I've read in vmware forums that on the linux host you need to change permissions on the vmnet files for promiscuous mode? is this true? how do you configure this scenario on a windows box?

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  • Knowledge and user generated content management system to track files, research, proposals, etc.?

    - by Eshwar
    I'll try keep it short. Here's the scenario: We have employees all over the world performing similar work i.e. research, generating powerpoint slides, word documents, graphics, etc. Many times a lot of this previous work can be reused for another future project. The current arrangement is email and phone calls which as you would agree is quick if you know where to look but otherwise archaic and very very inefficient. So I am looking for software that will allow me to do the following: Tag files e.g. an investor presentation on cellphone usage in kenya would be tagged investor, cellphone, kenya Manage references e.g. if we read something on the internet, should be able to paste that link in some fashion and tag it as above. Preferably cloud based so that it can be accessed by anybody and additionally would be nice (though NOT must) to have access levels (director, manager, everyone) A nice interface that non technically savvy folks can warm up to ;) A desktop app would be handy so that people don't always have to click upload or something A tree based system is inefficient in this case because content is usually linked across branches and also people might not quite agree on one format of a tree. Tagging works around this very nicely. What I have considered so far: Evernote (for its more professional look) Springpad (for its versatility with content) Mendeley (this is a research manager and in some ways ideal, but i fear its limited to PDFs) The goal is that when somebody wants to look for a document, they don't have to ask a colleague, they can just search with keywords and all relevant information shows up. Thanks!

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  • How to determine the root cause of a system lockup on Ubuntu 8.04 LTS?

    - by jdt141
    I'm currently working a project that involves setting up a PC/104 stack and running Ubuntu 8.04 LTS. We need to use the PC/104 stack because its an embedded application - and we're required to use a DeviceNet peripheral card to communicate to other devices. (DeviceNet is just a protocol on top of CAN.) Anyway, the following hardware is on the stack: Kontron MOPSPM104 with a 1GHz Intel Celeron processor ConnectTech FlashDrive/104 4GB Industrial Temp (-40 to +85 C) Woodhead (Molex) PC104DVNIO DeviceNet card A run of the mill 104 power supply The Kontron Board offers two serial ports, one VGA out, and two USB ports. The DeviceNet card is an ISA card. Because of this (per the User's Guide for the Kontron Board), I have manually set the IRQs in the BIOS to be appropriately configured, and turned off ACPI in both the BIOS and passed the appropriate flag in GRUB. I've installed Ubuntu 8.04 desktop, 32 bit. The problem that I'm having is that, from time to time, the entire 104 stack locks up. This only seems to happen in two cases, both of which we're running GNOME. We have a custom application that uses the DeviceNet card, and the system will lock up, or (more frequently) when we're running Firefox and either surfing for some information or trying to test it - typically by streaming video from a IP-camera. The reason I ask this questions is I cannot determine the root cause of this lockup. The IRQs appear to correctly configured in the BIOS and as the Kernel sees them, and nothing is logged to dmesg. If you all could help me determine the root cause of this lockup, I would greatly appreciate it. Thanks.

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  • What are the replacement options for an IDE hard disk for a DOS based system?

    - by dummzeuch
    I have got a few "embedded" systems running MSDOS 6.2 which boot from and store data to IDE hard disks. Since these drives are nearing their end of life, the question arises how we can replace them. The requirements are: DOS must be able to install and boot from these drives. They must be able to sustain heavy (mostly) write access. If possible, they should be able to survive moderate vibrations (not too bad since the current hard disks have survived several years of that) I considered the following options so far: other ide hard drives: Unfortunately modern IDE drives are too large so DOS cannot boot from them even if I create small partitions. Older IDE drives are just that: old, so they are probably not the most reliable ones any more. SSDs: There are a few SSDs with IDE interface available. I have not yet tried them. Does anybody have any experience with them? They look like the ideal replacement provided that DOS can boot from them and that writing speed does not deteriorate too much (the old hard disks are no race cars either). Compact Flash: There are adapters for using CF with IDE controllers and they work fine. DOS can boot from them and they have no problems at all with vibrations. What I am not sure about is their durability. DOS uses FAT so some very few sectors are written every time the medium is being written to. IDE to SATA converters: I have no idea whether they are any good. Has anybody tried them? It might be an option to use one of these to connect an SATA SSD to the system. Are there any alternatives that I have missed? (We are working on replacing these systems, but it will still take a few years.)

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  • how to diagnose a hard system seizure? Dell+Ubuntu

    - by rob
    I've got Ubuntu 9.10 on a Dell Vostro 420 desktop, a little over a year old, which I use for plain vanilla work stuff (email, web, terminal, text editor). Every now and then, at totally random times, it completely freezes on me. Hard. Mouse and keyboard stop working, cursor stops blinking, clock stops moving. All I can do is hold down the power button on the front of the box to shut it off. Sometimes it happens after several months of continuous uptime; sometimes it happens a few minutes after a reboot, while all I've done is open a terminal to look at log files, or maybe firefox to do a google search. Each time, there is nothing at all in /var/log/messages at the time of the crash. This makes it seem like a hardware problem, and indeed a few months ago I opened the box and wiggled everything and the problem went away for a while. But now it's back. I went in and checked everything, took out each RAM card and reseated. No luck. I ran all the system diagnostics (the long version) and everything passed with flying colors. Something is messed up in this box, but without any useful logs or failed tests, how in the world am I going to find it? And of course, Dell's not gonna help me cause I went and replaced Windows with Ubuntu. What steps would you take next to track down this problem?

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  • What are the replacement options for an IDE hd for a DOS based system?

    - by dummzeuch
    I have got a few "embedded" systems running MSDOS 6.2 which boot from and store data to IDE hard disks. Since these drives are nearing their end of life, the question arises how we can replace them. The requirements are: DOS must be able to install and boot from these drives. They must be able to sustain heavy (mostly) write access. If possible, they should be able to survive moderate vibrations (not too bad since the current hds have survived several years of that) I considered the following options so far: other ide hard drives: Unfortunately modern IDE drives are too large so DOS cannot boot from them even if I create small partitions. Older IDE drives are just that: old, so they are probably not the most reliable ones any more. SSDs: There are a few SSDs with IDE interface available. I have not yet tried them. Does anybody have any experience with them? They look like the ideal replacement provided that DOS can boot from them and that writing speed does not deteriorate too much (the old hds are no race cars either). Compact Flash: There are adapters for using CF with IDE controllers and they work fine. DOS can boot from them and they have no problems at all with vibrations. What I am not sure about is their durability. DOS uses FAT so some very few sectors are written every time the medium is being written to. IDE to SATA converters: I have no idea whether they are any good. Has anybody tried them? It might be an option to use one of these to connect an SATA SSD to the system. Are there any alternatives that I have missed? (We are working on replacing these systems, but it will still take a few years.)

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  • Is there any method of backing up Google Drive files in some sort of versioning system?

    - by VictorKilo
    Backstory My company is utilizing Google Drive for our shared files. Each user has their own Drive account. In addition, we have a corporate Drive account which holds documents which are shared to each user. Each folder is shared to different users depending on their permissions and positions in the company. Many users are able to add files, and updated folders within this shared Drive account. This is fine. What is not fine, is when someone deletes something that they shouldn't. I have little to no way of knowing when I file is deleted wrongfully. Furthermore, anything that gets deleted goes into the trash bin of the file's creator, so I can't just restore it from the trash. Question Is there any method of backing up Google Drive files in some sort of versioning system that would allow me to revert files back to defined points in time? What i have Tried I currently have this corporate drive account synced up to my personal computer through the Google Drive application. Each night, I run a backup on the file using Windows "Backup and Restore." This allows me to at least get back files that are lost, but I a cleaner method than this. It's very possible that I may not have the very latest version of a document on my computer when the utility runs.

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  • System randomly freezes yet mouse still moves, SSD out of reallocatable sectors, should I replace it?

    - by user784446
    This problem has lasted for the past 48 hours. The first time it happened, a program I was running stopped responding, so I tried to end it from task manager. The processes at first were listed fine until hovered upon. Eventually, despite the mouse still being able to move, after a few persisting clicks the mouse finally stopped moving. The screen went blank shortly thereafter. The second time it occurred, items on the screen stopped responding - hovering over the taskbar or such wouldn't elicit a response. Sound would still play however. Eventually, the mouse became unresponsive and the system restarted itself. I suspect that it may be a problem of my SSD drive. After looking through some Google search results, I downloaded HDTunePro to determine if there's a problem with the drive. Results returned a problem of reallocated sector count. An error scan also revealed 48 bad sectors. Also, an attempt to backup the contents of the most important areas of the drive returned a few explorer "Error: cannot read source from disk" errors. Should I ditch the drive and use another drive or is there anything that can be done to repair the drive? SSD: OCZ Petrol 64gb CPU: AMD Athlon II X4 640 RAM: Generic 3GB DDR2 Motherboard: Gigabyte MA74GM-S2H OS: Windows 7 Ultimate x64 Thanks!

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  • How best to handle end user notification in the event of system failure incl. email?

    - by BrianLy
    I've been asked to research ways of handling end user notifications when systems such as email are experiencing problems. Perhaps an example will make this a little clearer. We have a number of sites in different countries. Recently email was impacted at one of the sites, but it could have been a complete network outage. Information was provided by phone to local IT managers at the site but onward communication was slower than some would have liked. It seems like almost everyone at the site has a personal mobile phone which could receive text messages, and perhaps access a remote website with postings on the situation. However managing and supporting a system to text people on these relatively infrequent occasions would be very costly to do internally. What are other people doing to handle situations like this? Some things I've thought of include: Database of phone numbers to text. Seems costly and not very easy to maintain for an already stretched IT group. Is there an external service that would let you do this policies? Send voicemail message to all phones on site. Maintain an external website. This would not work in all situations (network failure), and there is a limit on the amount of info that can be posted externally. A site outage could be sensitive information in some situations. How could the site be password protected? Maybe OpenId/Facebook connect would work. Use a site like Yammer.com which is publicly accessible but only by people with a company email address. Anyone using this for IT outage notifications? To me it looks like there is no clear answer, and that there are solutions for some subsets of users. To be comprehensive a number of solutions would need to be combined. Any additional thoughts or recommendations? What worked or didn't work for your organization?

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  • puppet execution of a python script where os.system(...) command is not working

    - by philippe
    I am trying to manage Unix users with puppet. Puppet provides enough tools to create accounts and provide authorized_keys files for instance, but no to set up user password, and it tell to the user. What I have done is a python script which generate a random password and send it to the user by email. The problem is, it is not possible to launch passwd Unix command with python, I have then written a bash script with the command: echo -ne "$password\n$password\n" | passwd $user passwd -e $user Launched manually, the script works fine and the created user has its password sent by email. But when puppet launches it, only the python script gets executed, as if the os.system('/bin/bash my_bash_script') is ignored. No error is displayed. And the user gets its password, but the passwd commands are not launched. Is there any limitation with puppet preventing to perform what I described? Or, how can I otherwise change the user account, its expiration, and send password by email? I can provide more information, but right now, I don't know which are accurate. Many thanks!

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  • Why doesn't the value in /proc/meminfo seem to map exactly to the system RAM?

    - by Eric Asberry
    The values in /proc/meminfo for MemTotal don't make sense. As a human, eyeballing it, it seems to roughly correspond to the installed RAM, but for using it to display the installed RAM from an automated utility it appears to be inexact, and inconsistent. For a system with 1G of RAM, I would expect the MemTotal line to have a value of 1048576 - 1024*1024. But instead, I'm seeing 1029392. On another 4G box, I'm seeing 3870172, which is not a multiple of 1024, and it's not even close to 1029392*4. On an 8G box, I get 8128204, which again seems to have no correlation to the other values, nor is it a multiple of 1024. I'm trying to use this information to report the RAM on a status web page. My work-around is to just "round" it to the nearest 1G multiple, but I'd like to understand why these values seem inconsistent and don't match my expectations. Can somebody fill me in on what I'm missing here? EDIT: To expand on the accepted answer below.... The reference can be found here. Also of interest to me from that page, which explains the inconsistency, is this bit: meminfo: Provides information about distribution and utilization of memory. This varies by architecture and compile options. ...

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  • My system is always disk-bound (the disk light is always on). Why is this?

    - by Scoobie
    I have been given a laptop by the good folks at my company on which to do my work (Java development). I usually use eclipse as my primary development platform. The laptop is a Dell D830 and runs Windows 7 - 32 bit. Although the processor supports a 64 bit instruction-set, licensing limits me to running the 32 bit OS. The HDD is a WD1600BEVT (Western Digital). I have noticed that my disk is always very slow. Windows start up is usually pretty quick, however as soon as I log on, my disk light stays on and usually, the laptop takes about 4 minutes (after logging in -- immediately upon getting the prompt to press Ctrl + Alt + Del to log in) before it's usable. Questions: Is this expected behavior? What can I do to examine the disk and determine the cause of the problem? What can I do to improve my disk's performance? Any optimizations you may be able to suggest? Other Questions: Some have suggested running Process Monitor (from sysinternals), but how would i get the log since start up? Instead of trying to fix this myself, should I simply push this onto the system administrator? Thanks all.

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  • Can I recover a non-system disk deleted during 2008 R2 setup?

    - by serialhobbyist
    I've done a truly stupid thing and 'deleted' the data disk on a Server 2008 R2 box. Can I recover it? If so, how? I was rebuilding the box because a motherboard change had broken things. I've built loads of boxes and was going through the standard stuff without much concentration. I got to the disk screen which normally displays the two paritions on the drive: the recovery one and the system one. As normal, I deleted the two things I saw. It was only when two lots of unallocated space didn't merge into one that the full horror of what I'd done hit me. Yes, I've got backups... of the stuff I have space to back up. The real irony is that, earlier in the day, I'd ordered to 1 TB disks to deal with the problem. So, anyway, I'd really like to get this partition back because it'll save me a lot of time. How can I do it?

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  • How do I fix a permissions problem with MS Distributed File System?

    - by charlesrandall
    I have a computer that is new, Windows 7, that is supposed to have access to particular network resources on a Distributed File System. However, despite all permissions being set correctly, I have consistent trouble accessing them. For instance, I'm supposed to be able to reach \company.org\main\subdir. All the permissions have been granted, only when I try to access it by name, it tells me I don't have permission to access \main. This is where the fun starts. If I ping company.org, get the IP, replace company.org by the IP, I can then access \IP\main\subdir without any problems at all. However we have a ton of scripts and build tools that access the network resource by name. My sysadmin has found that using MS's dfsutil.exe, we can fix it temporary using this sequence of commands: C:\dfsutil.exe /pktinfo C:\dfsutil.exe /PktFlush C:\dfsutil.exe /SpcFlush C:\dfsutil.exe /PurgeMupCache C:\dfsutil.exe /pktinfo After that, everything is great... until I reboot, or until some unspecified time later where suddenly I don't have access to \main\ anymore. Hoping to find a more permanent solution than waiting for it to break and running a batch file.

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  • Start a Mapping or Process Flow from OWB Browser

    - by Dong Ruirong
    Basically, we start a Mapping or Process Flow from Oracle Warehouse Builder (OWB) Design Client. But actually we can also start a Mapping or Process Flow from OWB Browser. This paper will introduce the Start Report first and then introduce how to start/rerun a Mapping or Process Flow from OWB Browser. Start Report Start Report is used to start an execution of a Mapping or Process Flow. So there are two kinds of Start Report: Mapping Start Report (See Figure 1) and Process Flow Start Report (See Figure 2). Start Report shows the Mapping or Process Flow identification properties, including latest deployment and latest execution, lists all execution parameters for the Mapping or Process Flow, which were specified by the latest deployment, and assigns parameter default values from the latest deployment specification. You can do a couple of things from Start Report: Sort execution parameters on name, category. Table 1 lists all parameters of a Mapping. Table 2 lists all parameters of a Process Flow. Change values of any input parameter where permitted. For some parameters, selection lists are provided. For example, Mapping’s parameter Audit Level has a selection list. Reset all parameter settings to their default values. Apply basic validation to parameter values before starting an execution. Start the Mapping or Process Flow, which means it is executed immediately. Navigate to Deployment Report for latest deployment details of the Mapping or Process Flow. Navigate to Execution Job Report for latest execution of current Mapping or Process Flow Link to on-link help Warehouse Report Page, Deployment Report, Execution Report, Execution Schedule Report and Execution Summary Report. Figure 1 Mapping Start Report Table 1 Execution Parameters and default values for a Mapping Category Name Mode Input Value System Audit Level In Error Details System Bulk Size In 1000 System Commit Frequency In 1000 System EXECUTE_RESUME_TASK In FALSE System FORCE_RESUME_OPTION In FALSE System Max No of Errors In 50 System NUMBER_OF_TIMES_TO_RETRY In 2 System Operating Mode In Set Based Fail Over to Row Based System PARALLEL_LEVEL In 0 System Procedure Name In main System Purge Group In WB Figure 2 Process Flow Start Report Table 2 Execution Parameters and default values for a Process Flow Category Name Mode Input Value System EVAL_LOCATION In   System Item Key In-Out   System Item Type In PFPKG_1 Start a Mapping or Process Flow To navigate to Start Report, it’s better to login OWB Browser with Control Center option; if not, after logging in OWB Browser, go to Control Center first. Then you can follow the ways introduced in this section to navigate to Start Report. One more thing you need to pay attention to is that you are not allowed to deploy any Mappings and Process Flows from OWB Browser as it’s not supported. So it’s necessary to deploy the Mappings and Process Flows first before starting them from OWB Browser. If you have deployed a Mapping or Process Flow but have not started it, please navigate from Object Summary Report or Deployment Schedule Report to Start Report. 1. Navigating from Object Summary Report to Start Report Open the Object Summary Report to see all deployed Mappings and Process Flows. Click the Mapping Name or Process Flow Name link to see its Deployment Report. Select the Start link in the Available Reports tab for the given Mapping or Process Flow to display a Start Report for the Mapping or Process Flow. The execution parameters have the default deployment-time settings. Change any of the input parameter values as required. Click Start Execution button to execute the Mapping or Process Flow. 2. Navigating from Deployment Schedule Report to Start Report Open the Deployment Schedule Report to see deployment details of Mapping and Process Flow. Expand the project trees to find the deployed Mappings and Process Flows. Click the Mapping Name or Process Flow Name link to see its Deployment Report. Select the Start link in the Available Reports tab for the given Mapping or Process Flow to display a Start Report for the Mapping or Process Flow. The execution parameters have the default deployment-time settings. Change any of the input parameter values as required. Click Start Execution button to execute the Mapping or Process Flow. Re-run a Mapping or Process Flow If you have executed a Mapping or Process Flow, you can navigate from Object Summary Report, Deployment Schedule Report, Execution Summary Report or Execution Schedule Report to Start Report. 1. Navigating from the Execution Summary Report to Start Report Open the Execution Summary Report to see all execution jobs including Mapping jobs and Process Flow jobs. Click on the Mapping Name or Process Flow Name to see its Execution Report. Select the Start link in the Available Reports tab for the given Mapping or Process Flow to display a Start Report for the Mapping or Process Flow. The execution parameters have the default deployment-time settings. Change any of the input parameter values as required. Click Start Execution button to execute the Mapping or Process Flow. 2. Navigating from the Execution Schedule Report to Start Report Open the Execution Schedule Report to see list of all executions of Mapping and Process Flow. Click on the Mapping Name or Process Flow Name to see its Execution Report. Select the Start link in the Available Reports tab for the given Mapping or Process Flow to display a Start Report for the Mapping or Process Flow. The execution parameters have the default deployment-time settings. Change any of the input parameter values as required. Click Start Execution button to execute the Mapping or Process Flow. If the execution of a Mapping or Process Flow is successful, you will see this message from the Start Report: Start Execution request successful. (See Figure 3) Figure 3 Execution Result You can also confirm the execution of the Mapping or Process Flow by referring to Execution Report of the current Mapping or Process Flow by clicking the link in the Available Reports tab for the given Mapping or Process Flow. One new record of execution job details is added to Execution Report of the Mapping or Process Flow which shows the details of the execution such as Start Time, Elapsed Time, Status, the number of records selected, inserted, updated, deleted etc.

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  • The Proper Use of the VM Role in Windows Azure

    - by BuckWoody
    At the Professional Developer’s Conference (PDC) in 2010 we announced an addition to the Computational Roles in Windows Azure, called the VM Role. This new feature allows a great deal of control over the applications you write, but some have confused it with our full infrastructure offering in Windows Hyper-V. There is a proper architecture pattern for both of them. Virtualization Virtualization is the process of taking all of the hardware of a physical computer and replicating it in software alone. This means that a single computer can “host” or run several “virtual” computers. These virtual computers can run anywhere - including at a vendor’s location. Some companies refer to this as Cloud Computing since the hardware is operated and maintained elsewhere. IaaS The more detailed definition of this type of computing is called Infrastructure as a Service (Iaas) since it removes the need for you to maintain hardware at your organization. The operating system, drivers, and all the other software required to run an application are still under your control and your responsibility to license, patch, and scale. Microsoft has an offering in this space called Hyper-V, that runs on the Windows operating system. Combined with a hardware hosting vendor and the System Center software to create and deploy Virtual Machines (a process referred to as provisioning), you can create a Cloud environment with full control over all aspects of the machine, including multiple operating systems if you like. Hosting machines and provisioning them at your own buildings is sometimes called a Private Cloud, and hosting them somewhere else is often called a Public Cloud. State-ful and Stateless Programming This paradigm does not create a new, scalable way of computing. It simply moves the hardware away. The reason is that when you limit the Cloud efforts to a Virtual Machine, you are in effect limiting the computing resources to what that single system can provide. This is because much of the software developed in this environment maintains “state” - and that requires a little explanation. “State-ful programming” means that all parts of the computing environment stay connected to each other throughout a compute cycle. The system expects the memory, CPU, storage and network to remain in the same state from the beginning of the process to the end. You can think of this as a telephone conversation - you expect that the other person picks up the phone, listens to you, and talks back all in a single unit of time. In “Stateless” computing the system is designed to allow the different parts of the code to run independently of each other. You can think of this like an e-mail exchange. You compose an e-mail from your system (it has the state when you’re doing that) and then you walk away for a bit to make some coffee. A few minutes later you click the “send” button (the network has the state) and you go to a meeting. The server receives the message and stores it on a mail program’s database (the mail server has the state now) and continues working on other mail. Finally, the other party logs on to their mail client and reads the mail (the other user has the state) and responds to it and so on. These events might be separated by milliseconds or even days, but the system continues to operate. The entire process doesn’t maintain the state, each component does. This is the exact concept behind coding for Windows Azure. The stateless programming model allows amazing rates of scale, since the message (think of the e-mail) can be broken apart by multiple programs and worked on in parallel (like when the e-mail goes to hundreds of users), and only the order of re-assembling the work is important to consider. For the exact same reason, if the system makes copies of those running programs as Windows Azure does, you have built-in redundancy and recovery. It’s just built into the design. The Difference Between Infrastructure Designs and Platform Designs When you simply take a physical server running software and virtualize it either privately or publicly, you haven’t done anything to allow the code to scale or have recovery. That all has to be handled by adding more code and more Virtual Machines that have a slight lag in maintaining the running state of the system. Add more machines and you get more lag, so the scale is limited. This is the primary limitation with IaaS. It’s also not as easy to deploy these VM’s, and more importantly, you’re often charged on a longer basis to remove them. your agility in IaaS is more limited. Windows Azure is a Platform - meaning that you get objects you can code against. The code you write runs on multiple nodes with multiple copies, and it all works because of the magic of Stateless programming. you don’t worry, or even care, about what is running underneath. It could be Windows (and it is in fact a type of Windows Server), Linux, or anything else - but that' isn’t what you want to manage, monitor, maintain or license. You don’t want to deploy an operating system - you want to deploy an application. You want your code to run, and you don’t care how it does that. Another benefit to PaaS is that you can ask for hundreds or thousands of new nodes of computing power - there’s no provisioning, it just happens. And you can stop using them quicker - and the base code for your application does not have to change to make this happen. Windows Azure Roles and Their Use If you need your code to have a user interface, in Visual Studio you add a Web Role to your project, and if the code needs to do work that doesn’t involve a user interface you can add a Worker Role. They are just containers that act a certain way. I’ll provide more detail on those later. Note: That’s a general description, so it’s not entirely accurate, but it’s accurate enough for this discussion. So now we’re back to that VM Role. Because of the name, some have mistakenly thought that you can take a Virtual Machine running, say Linux, and deploy it to Windows Azure using this Role. But you can’t. That’s not what it is designed for at all. If you do need that kind of deployment, you should look into Hyper-V and System Center to create the Private or Public Infrastructure as a Service. What the VM Role is actually designed to do is to allow you to have a great deal of control over the system where your code will run. Let’s take an example. You’ve heard about Windows Azure, and Platform programming. You’re convinced it’s the right way to code. But you have a lot of things you’ve written in another way at your company. Re-writing all of your code to take advantage of Windows Azure will take a long time. Or perhaps you have a certain version of Apache Web Server that you need for your code to work. In both cases, you think you can (or already have) code the the software to be “Stateless”, you just need more control over the place where the code runs. That’s the place where a VM Role makes sense. Recap Virtualizing servers alone has limitations of scale, availability and recovery. Microsoft’s offering in this area is Hyper-V and System Center, not the VM Role. The VM Role is still used for running Stateless code, just like the Web and Worker Roles, with the exception that it allows you more control over the environment of where that code runs.

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  • class hierarchy design for small java project

    - by user523956
    I have written a java code which does following:- Main goal is to fetch emails from (inbox, spam) folders and store them in database. It fetches emails from gmail,gmx,web.de,yahoo and Hotmail. Following attributes are stored in mysql database. Slno, messagedigest, messageid, foldername, dateandtime, receiver, sender, subject, cc, size and emlfile. For gmail,gmy and web.de, I have used javamail API, because email form it can be fetched with IMAP. For yahoo and hotmail, I have used html parser and httpclient to fetch emails form spam folder and for inbox folder, I have used pop3 javamail API. I want to have proper class hierarchy which makes my code efficient and easily reusable. As of now I have designed class hierarchy as below: I am sure it can still be improved. So I would like to have different opinions on it. I have following classes and methods as of now. MainController:- Here I pass emailid, password and foldername from which emails have to be fetched. Abstract Class :-EmailProtocol Abstract Methods of it (All methods except executeParser contains method definition):- connectImap() // used by gmx,gmail and web.de email ids connectPop3() // used by hotmail and yahoo to fetch emails of inbox folder createMessageDigest // used by every email provider(gmx, gmail,web.de,yahoo,hotmail) establishDBConnection // used by every email emailAlreadyExists // used by every email which checks whether email already exists in db or not, if not then store it. storeemailproperties // used by every email to store emails properties to mysql database executeParser // nothing written in it. Overwridden and used by just hotmail and yahoo to fetch emails form spam folder. Imap extends EmailProtocol (nothing in it. But I have to have it to access methods of EmailProtocol. This is used to fetch emails from gmail,gmx and web.de) I know this is really a bad way but don't know how to do it other way. Hotmsil extends EmailProtocol Methods:- executeParser() :- This is used by just hotmail email id. fetchjunkemails() :- This is also very specific for only hotmail email id. Yahoo extends EmailProtocol Methods:- executeParser() storeEmailtotemptable() MoveEmailtoInbox() getFoldername() nullorEquals() All above methods are specific for yahoo email id. public DateTimeFormat(class) format() //this formats datetime of gmax,gmail and web.de emails. formatYahoodate //this formats datetime of yahoo email. formatHotmaildate // this formats datetime of hotmail email. public StringFormat ConvertStreamToString() // Accessed by every class except DateTimeFormat class. formatFromTo() // Accessed by every class except DateTimeFormat class. public Class CheckDatabaseExistance public static void checkForDatabaseTablesAvailability() (This method checks at the beginnning whether database and required tables exist in mysql or not. if not it creates them) Please see code of my MainController class so that You can have an idea about how I use different classes. public class MainController { public static void main(String[] args) throws Exception { ArrayList<String> web_de_folders = new ArrayList<String>(); web_de_folders.add("INBOX"); web_de_folders.add("Unbekannt"); web_de_folders.add("Spam"); web_de_folders.add("OUTBOX"); web_de_folders.add("SENT"); web_de_folders.add("DRAFTS"); web_de_folders.add("TRASH"); web_de_folders.add("Trash"); ArrayList<String> gmx_folders = new ArrayList<String>(); gmx_folders.add("INBOX"); gmx_folders.add("Archiv"); gmx_folders.add("Entwürfe"); gmx_folders.add("Gelöscht"); gmx_folders.add("Gesendet"); gmx_folders.add("Spamverdacht"); gmx_folders.add("Trash"); ArrayList<String> gmail_folders = new ArrayList<String>(); gmail_folders.add("Inbox"); gmail_folders.add("[Google Mail]/Spam"); gmail_folders.add("[Google Mail]/Trash"); gmail_folders.add("[Google Mail]/Sent Mail"); ArrayList<String> pop3_folders = new ArrayList<String>(); pop3_folders.add("INBOX"); CheckDatabaseExistance.checkForDatabaseTablesAvailability(); EmailProtocol imap = new Imap(); System.out.println("CHECKING FOR NEW EMAILS IN WEB.DE...(IMAP)"); System.out.println("*********************************************************************************"); imap.connectImap("[email protected]", "pwd", web_de_folders); System.out.println("\nCHECKING FOR NEW EMAILS IN GMX.DE...(IMAP)"); System.out.println("*********************************************************************************"); imap.connectImap("[email protected]", "pwd", gmx_folders); System.out.println("\nCHECKING FOR NEW EMAILS IN GMAIL...(IMAP)"); System.out.println("*********************************************************************************"); imap.connectImap("[email protected]", "pwd", gmail_folders); EmailProtocol yahoo = new Yahoo(); Yahoo y=new Yahoo(); System.out.println("\nEXECUTING YAHOO PARSER"); System.out.println("*********************************************************************************"); y.executeParser("http://de.mc1321.mail.yahoo.com/mc/welcome?ymv=0","[email protected]","pwd"); System.out.println("\nCHECKING FOR NEW EMAILS IN INBOX OF YAHOO (POP3)"); System.out.println("*********************************************************************************"); yahoo.connectPop3("[email protected]","pwd",pop3_folders); System.out.println("\nCHECKING FOR NEW EMAILS IN INBOX OF HOTMAIL (POP3)"); System.out.println("*********************************************************************************"); yahoo.connectPop3("[email protected]","pwd",pop3_folders); EmailProtocol hotmail = new Hotmail(); Hotmail h=new Hotmail(); System.out.println("\nEXECUTING HOTMAIL PARSER"); System.out.println("*********************************************************************************"); h.executeParser("https://login.live.com/ppsecure/post.srf","[email protected]","pwd"); } } I have kept DatetimeFormat and StringFormat class public so that I can access its public methods by just (DatetimeFormat.formatYahoodate for e.g. from different methods). This is the first time I have developed something in java. It serves its purpose but of course code is still not so efficient I think. I need your suggestions on this project.

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  • PostSharp, Obfuscation, and IL

    - by Simon Cooper
    Aspect-oriented programming (AOP) is a relatively new programming paradigm. Originating at Xerox PARC in 1994, the paradigm was first made available for general-purpose development as an extension to Java in 2001. From there, it has quickly been adapted for use in all the common languages used today. In the .NET world, one of the primary AOP toolkits is PostSharp. Attributes and AOP Normally, attributes in .NET are entirely a metadata construct. Apart from a few special attributes in the .NET framework, they have no effect whatsoever on how a class or method executes within the CLR. Only by using reflection at runtime can you access any attributes declared on a type or type member. PostSharp changes this. By declaring a custom attribute that derives from PostSharp.Aspects.Aspect, applying it to types and type members, and running the resulting assembly through the PostSharp postprocessor, you can essentially declare 'clever' attributes that change the behaviour of whatever the aspect has been applied to at runtime. A simple example of this is logging. By declaring a TraceAttribute that derives from OnMethodBoundaryAspect, you can automatically log when a method has been executed: public class TraceAttribute : PostSharp.Aspects.OnMethodBoundaryAspect { public override void OnEntry(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Entering {0}.{1}.", method.DeclaringType.FullName, method.Name)); } public override void OnExit(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Leaving {0}.{1}.", method.DeclaringType.FullName, method.Name)); } } [Trace] public void MethodToLog() { ... } Now, whenever MethodToLog is executed, the aspect will automatically log entry and exit, without having to add the logging code to MethodToLog itself. PostSharp Performance Now this does introduce a performance overhead - as you can see, the aspect allows access to the MethodBase of the method the aspect has been applied to. If you were limited to C#, you would be forced to retrieve each MethodBase instance using Type.GetMethod(), matching on the method name and signature. This is slow. Fortunately, PostSharp is not limited to C#. It can use any instruction available in IL. And in IL, you can do some very neat things. Ldtoken C# allows you to get the Type object corresponding to a specific type name using the typeof operator: Type t = typeof(Random); The C# compiler compiles this operator to the following IL: ldtoken [mscorlib]System.Random call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle( valuetype [mscorlib]System.RuntimeTypeHandle) The ldtoken instruction obtains a special handle to a type called a RuntimeTypeHandle, and from that, the Type object can be obtained using GetTypeFromHandle. These are both relatively fast operations - no string lookup is required, only direct assembly and CLR constructs are used. However, a little-known feature is that ldtoken is not just limited to types; it can also get information on methods and fields, encapsulated in a RuntimeMethodHandle or RuntimeFieldHandle: // get a MethodBase for String.EndsWith(string) ldtoken method instance bool [mscorlib]System.String::EndsWith(string) call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle( valuetype [mscorlib]System.RuntimeMethodHandle) // get a FieldInfo for the String.Empty field ldtoken field string [mscorlib]System.String::Empty call class [mscorlib]System.Reflection.FieldInfo [mscorlib]System.Reflection.FieldInfo::GetFieldFromHandle( valuetype [mscorlib]System.RuntimeFieldHandle) These usages of ldtoken aren't usable from C# or VB, and aren't likely to be added anytime soon (Eric Lippert's done a blog post on the possibility of adding infoof, methodof or fieldof operators to C#). However, PostSharp deals directly with IL, and so can use ldtoken to get MethodBase objects quickly and cheaply, without having to resort to string lookups. The kicker However, there are problems. Because ldtoken for methods or fields isn't accessible from C# or VB, it hasn't been as well-tested as ldtoken for types. This has resulted in various obscure bugs in most versions of the CLR when dealing with ldtoken and methods, and specifically, generic methods and methods of generic types. This means that PostSharp was behaving incorrectly, or just plain crashing, when aspects were applied to methods that were generic in some way. So, PostSharp has to work around this. Without using the metadata tokens directly, the only way to get the MethodBase of generic methods is to use reflection: Type.GetMethod(), passing in the method name as a string along with information on the signature. Now, this works fine. It's slower than using ldtoken directly, but it works, and this only has to be done for generic methods. Unfortunately, this poses problems when the assembly is obfuscated. PostSharp and Obfuscation When using ldtoken, obfuscators don't affect how PostSharp operates. Because the ldtoken instruction directly references the type, method or field within the assembly, it is unaffected if the name of the object is changed by an obfuscator. However, the indirect loading used for generic methods was breaking, because that uses the name of the method when the assembly is put through the PostSharp postprocessor to lookup the MethodBase at runtime. If the name then changes, PostSharp can't find it anymore, and the assembly breaks. So, PostSharp needs to know about any changes an obfuscator does to an assembly. The way PostSharp does this is by adding another layer of indirection. When PostSharp obfuscation support is enabled, it includes an extra 'name table' resource in the assembly, consisting of a series of method & type names. When PostSharp needs to lookup a method using reflection, instead of encoding the method name directly, it looks up the method name at a fixed offset inside that name table: MethodBase genericMethod = typeof(ContainingClass).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: get_Prop1 21: set_Prop1 22: DoFoo 23: GetWibble When the assembly is later processed by an obfuscator, the obfuscator can replace all the method and type names within the name table with their new name. That way, the reflection lookups performed by PostSharp will now use the new names, and everything will work as expected: MethodBase genericMethod = typeof(#kGy).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: #kkA 21: #zAb 22: #EF5a 23: #2tg As you can see, this requires direct support by an obfuscator in order to perform these rewrites. Dotfuscator supports it, and now, starting with SmartAssembly 6.6.4, SmartAssembly does too. So, a relatively simple solution to a tricky problem, with some CLR bugs thrown in for good measure. You don't see those every day!

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  • PostSharp, Obfuscation, and IL

    - by Simon Cooper
    Aspect-oriented programming (AOP) is a relatively new programming paradigm. Originating at Xerox PARC in 1994, the paradigm was first made available for general-purpose development as an extension to Java in 2001. From there, it has quickly been adapted for use in all the common languages used today. In the .NET world, one of the primary AOP toolkits is PostSharp. Attributes and AOP Normally, attributes in .NET are entirely a metadata construct. Apart from a few special attributes in the .NET framework, they have no effect whatsoever on how a class or method executes within the CLR. Only by using reflection at runtime can you access any attributes declared on a type or type member. PostSharp changes this. By declaring a custom attribute that derives from PostSharp.Aspects.Aspect, applying it to types and type members, and running the resulting assembly through the PostSharp postprocessor, you can essentially declare 'clever' attributes that change the behaviour of whatever the aspect has been applied to at runtime. A simple example of this is logging. By declaring a TraceAttribute that derives from OnMethodBoundaryAspect, you can automatically log when a method has been executed: public class TraceAttribute : PostSharp.Aspects.OnMethodBoundaryAspect { public override void OnEntry(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Entering {0}.{1}.", method.DeclaringType.FullName, method.Name)); } public override void OnExit(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Leaving {0}.{1}.", method.DeclaringType.FullName, method.Name)); } } [Trace] public void MethodToLog() { ... } Now, whenever MethodToLog is executed, the aspect will automatically log entry and exit, without having to add the logging code to MethodToLog itself. PostSharp Performance Now this does introduce a performance overhead - as you can see, the aspect allows access to the MethodBase of the method the aspect has been applied to. If you were limited to C#, you would be forced to retrieve each MethodBase instance using Type.GetMethod(), matching on the method name and signature. This is slow. Fortunately, PostSharp is not limited to C#. It can use any instruction available in IL. And in IL, you can do some very neat things. Ldtoken C# allows you to get the Type object corresponding to a specific type name using the typeof operator: Type t = typeof(Random); The C# compiler compiles this operator to the following IL: ldtoken [mscorlib]System.Random call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle( valuetype [mscorlib]System.RuntimeTypeHandle) The ldtoken instruction obtains a special handle to a type called a RuntimeTypeHandle, and from that, the Type object can be obtained using GetTypeFromHandle. These are both relatively fast operations - no string lookup is required, only direct assembly and CLR constructs are used. However, a little-known feature is that ldtoken is not just limited to types; it can also get information on methods and fields, encapsulated in a RuntimeMethodHandle or RuntimeFieldHandle: // get a MethodBase for String.EndsWith(string) ldtoken method instance bool [mscorlib]System.String::EndsWith(string) call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle( valuetype [mscorlib]System.RuntimeMethodHandle) // get a FieldInfo for the String.Empty field ldtoken field string [mscorlib]System.String::Empty call class [mscorlib]System.Reflection.FieldInfo [mscorlib]System.Reflection.FieldInfo::GetFieldFromHandle( valuetype [mscorlib]System.RuntimeFieldHandle) These usages of ldtoken aren't usable from C# or VB, and aren't likely to be added anytime soon (Eric Lippert's done a blog post on the possibility of adding infoof, methodof or fieldof operators to C#). However, PostSharp deals directly with IL, and so can use ldtoken to get MethodBase objects quickly and cheaply, without having to resort to string lookups. The kicker However, there are problems. Because ldtoken for methods or fields isn't accessible from C# or VB, it hasn't been as well-tested as ldtoken for types. This has resulted in various obscure bugs in most versions of the CLR when dealing with ldtoken and methods, and specifically, generic methods and methods of generic types. This means that PostSharp was behaving incorrectly, or just plain crashing, when aspects were applied to methods that were generic in some way. So, PostSharp has to work around this. Without using the metadata tokens directly, the only way to get the MethodBase of generic methods is to use reflection: Type.GetMethod(), passing in the method name as a string along with information on the signature. Now, this works fine. It's slower than using ldtoken directly, but it works, and this only has to be done for generic methods. Unfortunately, this poses problems when the assembly is obfuscated. PostSharp and Obfuscation When using ldtoken, obfuscators don't affect how PostSharp operates. Because the ldtoken instruction directly references the type, method or field within the assembly, it is unaffected if the name of the object is changed by an obfuscator. However, the indirect loading used for generic methods was breaking, because that uses the name of the method when the assembly is put through the PostSharp postprocessor to lookup the MethodBase at runtime. If the name then changes, PostSharp can't find it anymore, and the assembly breaks. So, PostSharp needs to know about any changes an obfuscator does to an assembly. The way PostSharp does this is by adding another layer of indirection. When PostSharp obfuscation support is enabled, it includes an extra 'name table' resource in the assembly, consisting of a series of method & type names. When PostSharp needs to lookup a method using reflection, instead of encoding the method name directly, it looks up the method name at a fixed offset inside that name table: MethodBase genericMethod = typeof(ContainingClass).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: get_Prop1 21: set_Prop1 22: DoFoo 23: GetWibble When the assembly is later processed by an obfuscator, the obfuscator can replace all the method and type names within the name table with their new name. That way, the reflection lookups performed by PostSharp will now use the new names, and everything will work as expected: MethodBase genericMethod = typeof(#kGy).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: #kkA 21: #zAb 22: #EF5a 23: #2tg As you can see, this requires direct support by an obfuscator in order to perform these rewrites. Dotfuscator supports it, and now, starting with SmartAssembly 6.6.4, SmartAssembly does too. So, a relatively simple solution to a tricky problem, with some CLR bugs thrown in for good measure. You don't see those every day!

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  • Exception Handling And Other Contentious Political Topics

    - by Justin Jones
    So about three years ago, around the time of my last blog post, I promised a friend I would write this post. Keeping promises is a good thing, and this is my first step towards easing back into regular blogging. I fully expect him to return from Pennsylvania to buy me a beer over this. However, it’s been an… ahem… eventful three years or so, and blogging, unfortunately, got pushed to the back burner on my priority list, along with a few other career minded activities. Now that the personal drama of the past three years is more or less resolved, it’s time to put a few things back on the front burner. What I consider to be proper exception handling practices is relatively well known these days. There are plenty of blog posts out there already on this topic which more or less echo my opinions on this topic. I’ll try to include a few links at the bottom of the post. Several years ago I had an argument with a co-worker who posited that exceptions should be caught at every level and logged. This might seem like sanity on the surface, but the resulting error log looked something like this: Error: System.SomeException Followed by small stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace.   These were all the same exception. The problem with this approach is that the error log, if you run any kind of analytics on in, becomes skewed depending on how far up the stack trace your exception was thrown. To mitigate this problem, we came up with the concept of the “PreLoggedException”. Basically, we would log the exception at the very top level and subsequently throw the exception back up the stack encapsulated in this pre-logged type, which our logging system knew to ignore. Now the error log looked like this: Error: System.SomeException Followed by small stack trace. Much cleaner, right? Well, there’s still a problem. When your exception happens in production and you go about trying to figure out what happened, you’ve lost more or less all context for where and how this exception was thrown, because all you really know is what method it was thrown in, but really nothing about who was calling the method or why. What gives you this clue is the entire stack trace, which we’re losing here. I believe that was further mitigated by having the logging system pull a system stack trace and add it to the log entry, but what you’re actually getting is the stack for how you got to the logging code. You’re still losing context about the actual error. Not to mention you’re executing a whole slew of catch blocks which are sloooooooowwwww……… In other words, we started with a bad idea and kept band-aiding it until it didn’t suck quite so bad. When I argued for not catching exceptions at every level but rather catching them following a certain set of rules, my co-worker warned me “do yourself a favor, never express that view in any future interviews.” I suppose this is my ultimate dismissal of that advice, but I’m not too worried. My approach for exception handling follows three basic rules: Only catch an exception if 1. You can do something about it. 2. You can add useful information to it. 3. You’re at an application boundary. Here’s what that means: 1. Only catch an exception if you can do something about it. We’ll start with a trivial example of a login system that uses a file. Please, never actually do this in production code, it’s just concocted example. So if our code goes to open a file and the file isn’t there, we get a FileNotFound exception. If the calling code doesn’t know what to do with this, it should bubble up. However, if we know how to create the file from scratch we can create the file and continue on our merry way. When you run into situations like this though, What should really run through your head is “How can I avoid handling an exception at all?” In this case, it’s a trivial matter to simply check for the existence of the file before trying to open it. If we detect that the file isn’t there, we can accomplish the same thing without having to handle in in a catch block. 2. Only catch an exception if you can do something about it. Continuing with the poorly thought out file based login system we contrived in part 1, if the code calls a Login(…) method and the FileNotFound exception is thrown higher up the stack, the code that calls Login must account for a FileNotFound exception. This is kind of counterintuitive because the calling code should not need to know the internals of the Login method, and the data file is an implementation detail. What makes more sense, assuming that we didn’t implement any of the good advice from step 1, is for Login to catch the FileNotFound exception and wrap it in a new exception. For argument’s sake we’ll say LoginSystemFailureException. (Sorry, couldn’t think of anything better at the moment.) This gives us two stack traces, preserving the original stack trace in the inner exception, and also is much more informative to the calling code. 3. Only catch an exception if you’re at an application boundary. At some point we have to catch all the exceptions, even the ones we don’t know what to do with. WinForms, ASP.Net, and most other UI technologies have some kind of built in mechanism for catching unhandled exceptions without fatally terminating the application. It’s still a good idea to somehow gracefully exit the application in this case if possible though, because you can no longer be sure what state your application is in, but nothing annoys a user more than an application just exploding. These unhandled exceptions need to be logged, and this is a good place to catch them. Ideally you never want this option to be exercised, but code as though it will be. When you log these exceptions, give them a “Fatal” status (e.g. Log4Net) and make sure these bugs get handled in your next release. That’s it in a nutshell. If you do it right each exception will only get logged once and with the largest stack trace possible which will make those 2am emergency severity 1 debugging sessions much shorter and less frustrating. Here’s a few people who also have interesting things to say on this topic:  http://blogs.msdn.com/b/ericlippert/archive/2008/09/10/vexing-exceptions.aspx http://www.codeproject.com/Articles/9538/Exception-Handling-Best-Practices-in-NET I know there’s more but I can’t find them at the moment.

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  • PostSharp, Obfuscation, and IL

    - by simonc
    Aspect-oriented programming (AOP) is a relatively new programming paradigm. Originating at Xerox PARC in 1994, the paradigm was first made available for general-purpose development as an extension to Java in 2001. From there, it has quickly been adapted for use in all the common languages used today. In the .NET world, one of the primary AOP toolkits is PostSharp. Attributes and AOP Normally, attributes in .NET are entirely a metadata construct. Apart from a few special attributes in the .NET framework, they have no effect whatsoever on how a class or method executes within the CLR. Only by using reflection at runtime can you access any attributes declared on a type or type member. PostSharp changes this. By declaring a custom attribute that derives from PostSharp.Aspects.Aspect, applying it to types and type members, and running the resulting assembly through the PostSharp postprocessor, you can essentially declare 'clever' attributes that change the behaviour of whatever the aspect has been applied to at runtime. A simple example of this is logging. By declaring a TraceAttribute that derives from OnMethodBoundaryAspect, you can automatically log when a method has been executed: public class TraceAttribute : PostSharp.Aspects.OnMethodBoundaryAspect { public override void OnEntry(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Entering {0}.{1}.", method.DeclaringType.FullName, method.Name)); } public override void OnExit(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Leaving {0}.{1}.", method.DeclaringType.FullName, method.Name)); } } [Trace] public void MethodToLog() { ... } Now, whenever MethodToLog is executed, the aspect will automatically log entry and exit, without having to add the logging code to MethodToLog itself. PostSharp Performance Now this does introduce a performance overhead - as you can see, the aspect allows access to the MethodBase of the method the aspect has been applied to. If you were limited to C#, you would be forced to retrieve each MethodBase instance using Type.GetMethod(), matching on the method name and signature. This is slow. Fortunately, PostSharp is not limited to C#. It can use any instruction available in IL. And in IL, you can do some very neat things. Ldtoken C# allows you to get the Type object corresponding to a specific type name using the typeof operator: Type t = typeof(Random); The C# compiler compiles this operator to the following IL: ldtoken [mscorlib]System.Random call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle( valuetype [mscorlib]System.RuntimeTypeHandle) The ldtoken instruction obtains a special handle to a type called a RuntimeTypeHandle, and from that, the Type object can be obtained using GetTypeFromHandle. These are both relatively fast operations - no string lookup is required, only direct assembly and CLR constructs are used. However, a little-known feature is that ldtoken is not just limited to types; it can also get information on methods and fields, encapsulated in a RuntimeMethodHandle or RuntimeFieldHandle: // get a MethodBase for String.EndsWith(string) ldtoken method instance bool [mscorlib]System.String::EndsWith(string) call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle( valuetype [mscorlib]System.RuntimeMethodHandle) // get a FieldInfo for the String.Empty field ldtoken field string [mscorlib]System.String::Empty call class [mscorlib]System.Reflection.FieldInfo [mscorlib]System.Reflection.FieldInfo::GetFieldFromHandle( valuetype [mscorlib]System.RuntimeFieldHandle) These usages of ldtoken aren't usable from C# or VB, and aren't likely to be added anytime soon (Eric Lippert's done a blog post on the possibility of adding infoof, methodof or fieldof operators to C#). However, PostSharp deals directly with IL, and so can use ldtoken to get MethodBase objects quickly and cheaply, without having to resort to string lookups. The kicker However, there are problems. Because ldtoken for methods or fields isn't accessible from C# or VB, it hasn't been as well-tested as ldtoken for types. This has resulted in various obscure bugs in most versions of the CLR when dealing with ldtoken and methods, and specifically, generic methods and methods of generic types. This means that PostSharp was behaving incorrectly, or just plain crashing, when aspects were applied to methods that were generic in some way. So, PostSharp has to work around this. Without using the metadata tokens directly, the only way to get the MethodBase of generic methods is to use reflection: Type.GetMethod(), passing in the method name as a string along with information on the signature. Now, this works fine. It's slower than using ldtoken directly, but it works, and this only has to be done for generic methods. Unfortunately, this poses problems when the assembly is obfuscated. PostSharp and Obfuscation When using ldtoken, obfuscators don't affect how PostSharp operates. Because the ldtoken instruction directly references the type, method or field within the assembly, it is unaffected if the name of the object is changed by an obfuscator. However, the indirect loading used for generic methods was breaking, because that uses the name of the method when the assembly is put through the PostSharp postprocessor to lookup the MethodBase at runtime. If the name then changes, PostSharp can't find it anymore, and the assembly breaks. So, PostSharp needs to know about any changes an obfuscator does to an assembly. The way PostSharp does this is by adding another layer of indirection. When PostSharp obfuscation support is enabled, it includes an extra 'name table' resource in the assembly, consisting of a series of method & type names. When PostSharp needs to lookup a method using reflection, instead of encoding the method name directly, it looks up the method name at a fixed offset inside that name table: MethodBase genericMethod = typeof(ContainingClass).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: get_Prop1 21: set_Prop1 22: DoFoo 23: GetWibble When the assembly is later processed by an obfuscator, the obfuscator can replace all the method and type names within the name table with their new name. That way, the reflection lookups performed by PostSharp will now use the new names, and everything will work as expected: MethodBase genericMethod = typeof(#kGy).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: #kkA 21: #zAb 22: #EF5a 23: #2tg As you can see, this requires direct support by an obfuscator in order to perform these rewrites. Dotfuscator supports it, and now, starting with SmartAssembly 6.6.4, SmartAssembly does too. So, a relatively simple solution to a tricky problem, with some CLR bugs thrown in for good measure. You don't see those every day! Cross posted from Simple Talk.

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  • The "CreateRiaClientFilesTask" task failed unexpectedly.

    - by Mohammadreza
    Hi guys. I've VS 2010 and recently installed WCF RIA Services V1.0. For testing I have created a new Silverligh Business project but now every now and then when I rebuild the solution I receive the following error: Does anybody know why I get this? Thanks Error 1 The "CreateRiaClientFilesTask" task failed unexpectedly. System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.ServiceModel.DomainServices.Tools, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified. File name: 'Microsoft.ServiceModel.DomainServices.Tools, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMarkHandle stackMark, Boolean loadTypeFromPartialName, ObjectHandleOnStack type) at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, Boolean loadTypeFromPartialName) at System.RuntimeType.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark) at System.Type.GetType(String typeName, Boolean throwOnError) at System.Web.Hosting.HostingEnvironment.CreateWellKnownObjectInstance(String assemblyQualifiedName, Boolean failIfExists) at System.Web.Hosting.HostingEnvironment.CreateWellKnownObjectInstance(String assemblyQualifiedName, Boolean failIfExists) at System.Web.Hosting.ApplicationManager.CreateObjectInternal(String appId, Type type, IApplicationHost appHost, Boolean failIfExists, HostingEnvironmentParameters hostingParameters) at System.Web.Hosting.ApplicationManager.CreateObjectInternal(String appId, Type type, IApplicationHost appHost, Boolean failIfExists) at System.Web.Compilation.ClientBuildManager.CreateObject(Type type, Boolean failIfExists) at Microsoft.ServiceModel.DomainServices.Tools.CreateRiaClientFilesTask.CreateSharedTypeService(ClientBuildManager clientBuildManager, IEnumerable`1 serverAssemblies, ILogger logger) at Microsoft.ServiceModel.DomainServices.Tools.CreateRiaClientFilesTask.GenerateClientProxies() at Microsoft.ServiceModel.DomainServices.Tools.CreateRiaClientFilesTask.ExecuteInternal() at Microsoft.ServiceModel.DomainServices.Tools.RiaClientFilesTask.Execute() at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute() at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask, Boolean& taskResult) WRN: Assembly binding logging is turned OFF. To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There is some performance penalty associated with assembly bind failure logging. To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog]. BusinessApplication2

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