Introducing PI SDK Buffering

Transcription

1 Introducing PI SDK Buffering PI SDK marks the introduction of PI SDK buffering, which buffers PI point data from PI products and custom applications created with PI SDK. This document contains the following sections: About PI SDK Buffering... 1 Install and Configure PI SDK Buffering... 6 Troubleshooting Note: References to specific punch list items in this document refer to issues discovered during final testing for the Community Technology Preview (CTP). These issues are not included in the release notes provided with this version. About PI SDK Buffering Using the PI Buffer Subsystem (pibufss), you can now buffer both PI SDK and PI API data simultaneously. PI SDK buffering is not available through the API Buffer Server. The table below summarizes the differences between PI SDK buffering and PI API only buffering. PI SDK and PI API buffering (pibufss only): PI API only buffering (pibufss or bufserv): Data buffered PI point data PI point data Applications buffered Functions buffered PI client applications PI SDK applications PI interfaces PI API applications All PI API write functions The following PI SDK functions PIData.UpdateValue PIData.UpdateValues With any of the following modes: dminsertduplicates, dmerrorduplicates dmerrorduplicatessilent PI interfaces PI API applications All PI API write functions Data not buffered Annotations to existing events Annotations to new or existing events Introducing PI SDK Buffering 1

2 Users of this software are bound by the CTP Specific Licensing Terms found in the End User License Agreement provided on the OSIsoft vcampus site ( Note: This document provides preliminary information about PI SDK buffering and is subject to change. If you require information that is not included in this document, or if you would like to submit questions or comments, please contact us at Features Support for PI collectives. PI SDK buffering supports fanning to members of a High Availability (HA) PI collective. Fanning means that the data written to one member of a collective is also written to the other members. For information on how this affects existing PI SDK applications that use PI to PI or other tools to write data to members of a collective, see Effect on Existing Applications on page 4. PI SDK calls that support buffering. The following existing SDK calls support buffering when used with certain modes, assuming that the pibufss service is started and is buffering to the server that the call is attempting to update. Under those conditions, values from these calls will automatically be buffered: PIData.UpdateValue PIData.UpdateValues Supported modes for the above calls are dminsertduplicates, dmerrorduplicates, and dmerrorduplicatessilent. Security. The PI Buffer Subsystem supports the use of Windows authentication (through PI Mappings) as well as PI Trusts. OSIsoft recommends using Windows authentication when setting up buffering to improve security. New buffering configuration utility. The PI SDK Utility (formerly About PI-SDK) includes a new PI Buffer Subsystem Configuration window for configuring PI SDK buffering. The PI Buffer Subsystem Configuration window also indicates which type of pibufss buffering is currently enabled. The following is a summary of available buffering options and configuration utilities. For details of data buffered by PI SDK and PI API buffering and PI API only buffering, see About PI SDK Buffering on page 1. To buffer: Using this buffering method: Use this utility: PI API data only bufserv PI ICU * pibufss PI ICU * PI SDK Utility Both PI SDK and PI API data pibufss PI SDK Utility * PI Interface Configuration Utility (ICU) is available as a standalone install or with PI System Management Tools (SMT). 2

3 Limitations Testing buffering and fanning. For this CTP release only, we recommend that you configure the test environment to buffer to a collective, and ensure that one of the collective member servers is running and available during testing. This avoids known connectivity issues in this version. (Punch list item 23133OSI8) PI SDK buffering and the API Buffer Server (bufserv). Bufserv and the PI Buffer Subsystem cannot run concurrently on a single node. PI SDK calls related to buffering. The PI SDK calls that support buffering can be used only with modes that insert data, not modes that edit or delete data. (See Features on page 2 for a list of supported calls and modes. Calls and modes that are not buffered are listed on page 5.) In addition, the following calls that edit existing events do not support buffering in PI SDK 1.4.0: IPIData2.ReplaceValue IPIData2.RemoveSpecifiedValues IPIData2.RemoveValues Connectivity following pibufss restart. For this CTP release only, if pibufss is restarted, PI SDK applications must reconnect to the PI Server, which can be done by either restarting the application or doing a disconnect and reconnect in the application. This includes PI client applications provided by OSIsoft, which should be manually restarted after restarting pibufss. If pibufss is restarted, the following message is returned by PI SDK: Failed to send data to buffer. [-11441] The buffering key is invalid Single server. PI Buffer Subsystem buffers only to a single server or collective. Security. The PI Buffer Subsystem sends data to PI Server using its process identity, as it has in previous versions that supported only API buffering. API buffering usually buffers data from one type of interface per interface node, meaning one process identity is associated with one type of data. However, a single client node using PI SDK buffering may handle multiple client applications and possibly multiple users concurrently (including, for example, web services and application servers). The various applications and users on a client node will all send data to PI Server using the same identity. The logon identity of the pibufss process requires write access to the PIHOME\DAT folder (typically, C:\Program Files\PIPC\DAT). Data that is not buffered. The following data is not included in PI SDK buffering: Annotations (except annotations that are created when the corresponding event is created) Batch data Data edits and deletes Configuration changes (for example, changes to the PI Point database or PI Module Database) Introducing PI SDK Buffering 3

4 Identifying servers in PICLIENT.INI. For this CTP release only, servers specified in PICLIENT.INI (which is updated by both PI ICU and PI SDK Utility) must match existing entries in the PI SDK Known Servers Table (KST). For example, an error message is displayed if the KST contains the server name and PICLIENT.INI contains its IP address. For more information, see Messages in PI SDK Utility on page 14. The PI Buffer Subsystem Configuration window identifies collective members by each server s node name even if PICLIENT.INI uses each server s fully qualified domain name (FQDN). If an interface batch file uses /host=fqdn, interface buffering may not function correctly. Effect on Existing Applications Security. You will need to set up security (a PI Trust or Windows authentication and associated permissions) that will allow the logon identity of the PI Buffer Subsystem service to access PI Server. See Configure PI SDK Buffering on page 7 for more information. PI collectives configured for buffering. When PI SDK buffering is enabled for a collective, PI SDK can be connected to any member, write data, and the data will be fanned and buffered. If any member is disabled in the configuration, the PISDK can still write to any member and pibufss will write to only the configured members. (A member is disabled when it is excluded from the Buffered Servers List, and the AUTOCONFIG parameter is set to 0 in piclient.ini indicating that data will not be replicated to all collective members.) When PI SDK buffering is enabled for a collective, PI SDK cannot write to members of a different, unbuffered collective unless MemberOpen is used. Without PI SDK buffering, behavior will be unchanged from previous versions. In other words, PI SDK can be connected to any collective member, but by default it can write data only to the primary. If PI SDK is connected to a secondary member where AllowSDKWriteValues is set to true, then PI SDK will write to that connected member. PI to PI and buffering PI collectives. If your PI SDK application writes only to the primary server in a collective, and PI to PI is used to write data to the other servers in the collective, PI SDK buffering and PI to PI will both attempt to write the same data to the PI Server. This may cause errors, duplicate events, or both. We recommend modifying these applications to rely on PI SDK buffering instead of PI to PI. PI SDK applications that open each collective member separately using MemberOpen will continue to work without changes. Data will not be fanned to any members not explicitly opened by the application. However, we recommend modifying these applications to rely on fanning functionality in PI SDK buffering. 4

5 Behavior if buffering issues occur PI SDK buffering may reject a buffering request for any of the following reasons: Reason Problems during initial registration of PI SDK buffering Data calls from PI SDK that do not support PI SDK buffering Details The pibufss service is stopped The specified server is not the targeted buffered server The targeted PI Server software is a version prior to The installed version of pibufss is older than the version installed with PI SDK The following edit calls: IPIData2.ReplaceValue IPIData2.RemoveSpecifiedValues IPIData2.RemoveValues UpdateValue calls that use the following editing modes: dmreplaceduplicates dmreplaceonlyduplicates dmreplaceonlyduplicatessilent By default, attempts to buffer data written by the above calls will result in an error. If PI Buffer Subsystem is unable to accept buffered data for any of the reasons above, PI SDK will do the following: If the problem occurs when attempting to buffer to: A single server that is not part of a collective A collective member that is accessed by an SDK application using ServerOpen and is not configured to use PI SDK buffering A collective member that is accessed by an SDK application using MemberOpen PI SDK will: Send the data to PI Server, but will not buffer any data Return an error. This is a change from existing behavior that will result in errors when using some existing PI SDK applications with PI SDK buffering. For details, see PI collectives configured for buffering earlier in this section. Send the data only to that collective member Introducing PI SDK Buffering 5

6 Install and Configure PI SDK Buffering The PI Buffer Subsystem (pibufss.exe) was previously installed with PI ICU. Starting with PI SDK 1.4.0, it will also be installed with PI SDK. Note: Before you begin, make sure your system meets the requirements described below. Check System Requirements The following system requirements apply to PI SDK buffering only. For PI SDK system requirements, refer to the PI SDK CTP Release Notes. Supported Operating Systems Windows Server 2008, Windows Server 2003 Service Pack 1, Windows 7, Windows Vista, Windows XP Service Pack 2 or higher Supported PI Server versions , , and (PI Server 2010) Disk space requirements It is important to allow sufficient disk space for the queue files pibufss creates to store buffered data. The space required depends on the buffering time and data volume expected for a particular node. For detailed information about estimating disk space requirements for buffering, see the PI Buffer Subsystem User Guide. Download the Files You can download the installation files from the vcampus Download Center ( Install PI SDK Besides checking system requirements and downloading the files, no special preparation is required. PI SDK setup is designed to check for PI-related Windows Services that are running and prompt you to stop them if needed. To install PI SDK 1.4.0: 1. Double-click PISDK_2010-CTP.exe. 2. Follow the instructions on the setup screens. Most do not require you to modify or enter data. Those with settings that may affect the behavior of the installation are described in the steps that follow. 3. On the WinZip Self-Extractor PISDK_2010-CTP.EXE screen, accept the default settings unless: a. You want to extract the temporary installation files to a different location. To do this, click Browse and select the location you prefer. 6

7 Note: The default path is defined by the Windows TEMP environment variable. To view it, open a command window and type SET TEMP. b. You want to extract the files now and run setup later. To do this, clear the check box labeled When done unzipping open:.\pisdk_2010_ctp\setup.exe. Make note of the path you are extracting to so you can find the setup file later. 4. If the Stop PI Network Manager screen appears, click the Stop pinetmgr button to stop pinetmgr, then click Next to continue the installation process. Note: You can also stop pinetmgr using Windows Services. However, you will still need to click Stop pinetmgr to make the Next button available. 5. When the PI-Buffer Server Configuration screen appears, select the Enable PI-Buffer Server operation check box if you intend to use either API or SDK buffering. 6. If the Files in use screen appears, OSIsoft recommends that you stop the listed applications, then click Retry. The other options are as follows: Exit, which exits setup without completing the installation. Ignore, which skips the listed files until the rest of the setup process is finished, then prompts you to reboot. The skipped files are installed after rebooting. (Some newer operating systems may not require, or prompt for, a reboot.) 7. If the PI Buffer Subsystem screen appears, OSIsoft recommends the default option (Automatically close applications and attempt to restart them after setup is complete). The other option is as follows: Do not close applications. (A Reboot will be required.), which skips the listed files until the rest of the setup process is finished, then prompts you to reboot. The skipped files are installed after rebooting. (Some newer operating systems may not require, or prompt for, a reboot.) When setup is finished, an Installation Complete screen appears. The Status column for each listed component should show Installed. Configure PI SDK Buffering Note: By default, PI SDK buffering is turned off, and installing PI SDK will not affect your existing buffering configuration. To use SDK buffering, you will need to do the following: 1. Set up security that allows the buffering service to connect to the PI Server, preferably using Windows authentication. 2. Set up permissions required for buffering. 3. Set up a service identity for buffering (or by default, use the LocalSystem account) 4. (for PI Server 2010 only) Enable delegation on the PI Server. 5. Enable PI SDK buffering. The rest of this section contains recommendations for setting up PI SDK buffering security, as well as instructions (or references to instructions in existing documentation). Introducing PI SDK Buffering 7

8 Recommendations for Connecting to PI Server To buffer data, you need to ensure that the PI Buffer Subsystem (pibufss.exe) can connect to the PI Server(s) it will buffer to. To verify that you can connect to and read data from a server: 1. In the left pane of PI SDK Utility, click Current Values. 2. In the toolbar, click Connections. The PI Connection Manager window appears. 3. Connect to the server, then close PI Connection Manager. 4. In the PI SDK Utility window, specify an appropriate tag in the Tag= box. 5. Click the Search button. If the client node can read data from this server, data appears. To verify that you can write data to the server from a client node, configure and enable PI SDK buffering using the steps in the rest of this section. Note: When buffering to a collective, buffering should be turned off for any collective member that the buffered client node cannot connect to. The following connection options are available for the PI Buffer Subsystem: [Recommended] Connect to the PI Server via Windows Security with a PI identity. Details of this setup depend on the account used to run the PI Buffer Subsystem Windows Service. By default, the pibufss service runs using the LocalSystem account on the client machine. If you use this configuration, map the PI identity to the client machine (see instructions later in this section). If you run the pibufss service as a domain user, map the PI identity to the domain user. Connect to the PI Server via a PI trust set up with a PI identity. If you use this option, set up the PI identity with a PI trust for pibufss.exe on the client machine. For additional information and instructions, see Configuring PI Server Security. To Map a PI Identity to the Client Machine 1. Run PI System Management Tools. 2. Under Collectives and Servers, select the server. 3. Under System Management Tools, select Security > Identities, Users, & Groups. 4. Select the PI Identities tab. 5. If you have not yet created a PI Identity for the buffering service, create it now. 6. Double-click the identity to open its Properties dialog box. 7. Click the Mappings & Trusts tab. The top portion shows all existing mappings for this PI identity. The bottom portion shows all existing PI trusts for this PI identity. 8

9 8. Click Add under the mappings to open the Add New Mapping dialog box. (There is also an Add button under the trusts; be sure to click the right button.) Note: The Add button is disabled if the selected PI identity is disabled or not usable in a mapping. 9. Click the ellipsis button next to the Windows Account box. The Select User, Computer, or Group dialog box appears. 10. Click the Object Types button. The Object Types dialog box appears. 11. In the Object Types list, make sure Computers is selected, then click OK. 12. In the Select User, Computer, or Group dialog box, enter the computer name (for example, \\my_client_node) and click OK. 13. Click OK to create the new mapping. Permissions Required for Buffering The buffering service requires the following permissions: Read access to the PIReplication database. By default, all users have this access. If needed, you can set it using Database Security in PI System Management Tools. Write access to the points it will buffer to. You can set this using Point Builder or PI Tag Configurator in PI System Management Tools. For additional information and instructions, see Configuring PI Server Security. Recommended Service Identity for Buffering By default, the PI Buffer Subsystem runs as a Windows Service using the Local System account. This is the recommended service configuration for this version. Alternatively, you can set up the service to run using a domain user account, but this requires the following additional configuration: The PI identity associated with buffering must be mapped to the domain user configured to run the pibufss service On each buffered node: The pibufss service must be configured to run using the domain user The domain user must have write access to \PIPC\DAT folder If the domain user s password changes, the pibufss service must be updated with the new password For additional information and instructions related to PI identities and mappings, see Configuring PI Server Security. Introducing PI SDK Buffering 9

10 (PI Server 2010 only) Enable Delegation on the PI Server By default delegation is disabled on PI Server 2010 (version ). To allow PI SDK buffering, you need to enable it. To enable delegation on the PI Server: 1. Run piconfig on the server and type the following name, value ENABLEDELEGATION, 1 2. If the PI SDK application connects to the server via a PI trust or explicit login (not Windows authentication), type this command as well: PINetMgr_RequireSSPIForDelegation, 0 3. After adding the settings, restart the PI Server. Enable PI SDK Buffering To enable PI SDK buffering: 1. Start the PI SDK Utility. 2. Click File > PI Buffer Subsystem Configuration. The PI Buffer Subsystem Configuration window appears. 3. In the Buffering Setting list, select Buffer PI-SDK and PI-API Data. 4. In the Buffered Server/Collective list, select the server or collective that will receive the buffered data. 5. (Optional) If you are buffering to a collective, by default you will buffer to all collective members. To prevent buffering to one or more members, clear the Enabled check box next to the member(s). 6. Click Save. If prompted to restart the pibufss service, click Yes to restart it. More about Buffering Configuration Utilities The PI Buffer Subsystem can now be configured using either PI ICU or the PI SDK Utility. However, each configuration utility provides different capabilities. As a general rule: Use PI ICU to set up buffering for interfaces and other PI API applications Use the PI SDK Utility to set up buffering for clients and other PI SDK applications Key buffering features available in each utility are summarized below. Buffering feature Enable PI SDK and PI API buffering with PI Buffer Subsystem* PI SDK Utility X PI ICU Enable PI API only buffering with PI Buffer Subsystem** X X 10

11 Buffering feature PI SDK Utility PI ICU Disable buffering with PI Buffer Subsystem X X Enable / disable buffering with API Buffer Server X Configure logon account and start/stop pibufss service X X Configure additional buffering settings such as TCP/IP port, buffer file size, retry rate, event queue file size, and so on*** X * By default, PI SDK buffering is not enabled until you enable it using the PI SDK Utility. PI SDK buffering can be enabled or disabled in either of two ways: using the PI SDK Utility, or programmatically using the IPISDKOptions interface (GetEnvironmentOptions, GetAvailableEnvironmentOptions, and SetEnvironmentOptions methods) described in PI SDK Help. PI ICU does not modify PI SDK buffering status. ** Once you have enabled PI SDK and PI API buffering using the PI SDK Utility, PI ICU can be used only to modify certain buffering settings and to enable or disable buffering. You cannot use PI ICU to change back to PI API only buffering. To make this change, use the PI SDK Utility to disable PI SDK and PI API buffering, then use PI ICU to enable buffering for PI API data only. *** If you want to use any of these additional settings for PI SDK buffering on a given node, you can use PI ICU to set them. Troubleshooting During troubleshooting, you may want to run PI Buffer Subsystem interactively, because doing so provides immediate access to additional messages that may be helpful. These messages are not immediately available when you run the PI Buffer Subsystem as a service, because they are written to the Windows Event Log first and copied to the PI message log shortly thereafter. This delay may make it more difficult to diagnose an issue, because all messages related to the issue will not appear in the PI message log at the same time. The pigetmsg f command does not display the additional messages, so running PI Buffer Subsystem interactively is the best way to display all messages as they are returned. This section provides information about messages returned by commands, written to the PI Message Log, or in the PI SDK Utility or PI SMT and how to resolve or work around the corresponding issue. Introducing PI SDK Buffering 11

12 Messages Returned by Commands or Written to the PI Message Log The following table shows examples of messages that may appear in the PI message log and steps you can take to resolve or work around the corresponding issue. Note: References to PIHOME in pathnames refer to the installation folder. The default value for PIHOME is C:\Program Files\PIPC. Symptom The pibufss -trace command does not return any results C 12-Sep-10 08:26:37 pibufss (1) >> Subsystem not entering run state (6). Fatal error in PI subsystem pibufss: Failed to create API buffer manager, status: [ ] Error creating shared memory buffers or disk buffer file C 12-Sep-10 08:23:13 pibufss (1) >> Subsystem not entering run state (6). Fatal error in PI subsystem pibufss: PICLIENT.INI configuration error, status: [-11417] Buffering is turned off, process exiting Description and steps to resolve Description: (Punch list item 23141OSI8) When pibufss has never sent data to a point, it is unable to sign up trace for the point, but the trace command does not get any indication that signup failed. It appears to be working but does not report any events when events are sent to the point in the future. Steps to resolve (Workaround): 1. Have pibufss send data to each of the points you want to trace 2. Run the pibufss -trace command 3. To check which points pibufss sent data to, run the pibufss -sp command and look for the points listed under Cached points and Unresolved points. Description: One or more of the following is running, which prevents pibufss from starting: An interface PI API Buffer Server (bufserv) The bufutil command Steps to resolve: Shut down all of the above processes, then try starting pibufss again. Description: In PICLIENT.INI, BUFFERING=1 is not set in the [APIBUFFER] section. To use PI SDK buffering, BUFFERING=1 must appear in both the [APIBUFFER] and [PIBUFSS] sections of PICLIENT.INI. Steps to resolve: Use the PI SDK Utility to enable PI SDK buffering. 12

13 Symptom C 12-Sep-10 08:51:31 pibufss (6043) >> Fatal error in PI subsystem pibufss: Installation, status: [-11422] Buffer Subsystem is not configured to run on PI Server nodes W 12-Sep-10 08:51:31 pibufss (18000) >> WARNING! Terminating compress thread, session: server_name I 12-Sep-10 08:51:32 pibufss (4) >> GetConsoleCtrlHandler shutdown priority of 0x280 for service pibufss C 24-Sep-10 21:29: pibufss (6043) >> Fatal error in PI subsystem pibufss: Error starting API shared buffer, status: [-10007] Bad or Null Pointer Description and steps to resolve Description: In the [PIBUFSS] section of PICLIENT.INI, RUNSONSERVER=0. To use buffering on a PI Server, it should be set to 1, not 0. Steps to resolve: In PICLIENT.INI, set RUNSONSERVER=1. Description: pibufss is shutting down. Steps to resolve: If this shutdown is unexpected, check the PI message log to troubleshoot the problem. Description: This is an informational message displayed during pibufss startup and shutdown. Steps to resolve: Not applicable. Description: (Punch list item 23096OSI8) This happens when pibufss has no cached server or collective information. For example, this may occur with a new pibufss installation, a change to the target server or collective, or if pibufmem.dat is deleted. This error occurs when pibufss cannot connect to a collective member listed in the buffered servers list by its host name. Steps to resolve (Workaround): 1. Verify that the server(s) are available. 2. Verify that security settings allow pibufss to connect to and read from the server(s). 3. If the server creating the issue cannot (or should not) be made available to pibufss, remove it from the buffered servers list. Introducing PI SDK Buffering 13

14 Symptom C 23-Aug-10 13:49:58 pibufss (6043) >> Fatal error in PI subsystem pibufss: Failed to initialize buffer sessions, status: [-11419] Buffering is supported for only one PI Server or Collective Description and steps to resolve Description: This message can appear under the following conditions: 1. All servers in the buffered servers list (the [BUFFEREDSERVERLIST] section of PICLIENT.INI) do not belong to the same collective. This is expected behavior. 2. (Punch list item 22938OSI8) PIbufss has no cached server or collective information and cannot connect to, or does not have permission to read configuration from, all servers in the buffered servers list. In this case, pibufss should report that it is "Unable to retrieve server configuration". 3. (Punch list item 22938OSI8) Pibufss cannot connect to a server in the buffered servers list, and the server uses a fully qualified domain name (FQDN). In this case, pibufss should start and queue data for this server. Steps to resolve: 1. Ensure that all servers in the [BUFFEREDSERVERLIST] section of PICLIENT.INI belong to the same collective. 2 and 3. (Workaround): In this version, for successful buffering, at least one server in a collective must be available. Messages in PI SDK Utility The following table shows examples of buffering-related messages that may appear in the PI SDK Utility and steps you can take to resolve the corresponding issue: Symptom Description and steps to resolve Description: In this CTP release only, this message appears when you start PI SDK Utility. Steps to resolve (Workaround): Click Continue to use PI SDK Utility. 14

15 Symptom Description and steps to resolve Description: In the PI Buffer Subsystem Configuration dialog box, if you attempt to select a collective, enable one or more of its servers, and then select Disabled on the Buffering Setting list, you may see this message. Steps to resolve: 1. In the PIHOME\PISDK folder, right-click PISDKUtility.exe, then click Properties. 2. On the Compatibility tab, select the Run as administrator check box. 3. Click OK to save the change. When you run the PI SDK Utility with the Run as administrator setting selected, the message does not appear. Description: This message appears when a server specified in PICLIENT.INI does not match an existing entry in the PI SDK Known Servers Table (KST). For example, it may appear if the KST contains the server name and PICLIENT.INI contains its IP address. Steps to resolve: 1. Click OK to close the message. 2. In the PI Buffer Subsystem Configuration window, open the Buffered Server/Collective list and do one of the following: If the server is listed, select it and click Save. If the server is not listed, add it to the KST. In PI SDK Utility click File > Connections to display PI Connection Manager, then click Server > Add Server and provide the required data. For more information about PICLIENT.INI, see the PI Buffer Subsystem User Guide. Introducing PI SDK Buffering 15

16 Messages in PI SMT The following table shows examples of messages that may appear in PI SMT after installing PI SDK and steps you can take to resolve the corresponding issue: Symptom Description and steps to resolve Description: Certain files installed with PI SDK are a different version than those used by PI SMT versions 3.2 and 3.3. Steps to resolve: Install the files located in the PIHOME\PISDK\Interops1300 folder. There are two ways to do this: A. Use the following command syntax to install each file (this requires Visual Studio): gacutil /i filename or B. Drag the files to the following folder: \Windows\assembly 16