Develop Reference

Best practice for peristantly storing a string on a C# IIS WCF web service

I have a text string I want to persist in a WCF web service. What is the best practice for storing it between sessions and between reboots/restarts of IIS?
Storing it in a text file on the operating system? Or is there a built in persistence object?
This string is a piece of text I need to return from the web service and occasionally update via a call being made to the web service. (The web service has a Read Only database back end, so I don't have the option to save this string to a database--without adding a separate database call and I'd rather avoid that extra point of failure.)

You mean a connection string? web.config
Or a password, or key? web.config
Something that's displayed to the user? resource table
P.s. I ended up using the web.config solution. For those interested in doing what I did here's the hoops I jumped through:
1) Set up a directory under the web application's root and opened that up to write permission to the IISUser. (Used a sub directory to avoid compromising security in the main application directory) Then added the following to the top of my source code:
System.Configuration.Configuration _webConfig =
WebConfigurationManager.OpenWebConfiguration("~\\directory_where_IISUser_has_write_permisions\\");
2) Namespaces needed:
using System.Web.Configuration;
using System.Configuration;
3) Code to create a new setting. The try/catch handles when the setting doesn't exist. Yes, it's a total hack. If someone knows how to check for the existence of the setting please let me know in a comment!
try
{
_webConfig.AppSettings.Settings["SettingName"].Value = textMessage;
} catch {
_webConfig.AppSettings.Settings.Add("SettingName", textMessage);
}
_webConfig.Save(ConfigurationSaveMode.Modified);
4) Code to read:
TextMessage = _webConfig.AppSettings.Settings["SettingName"].Value;
EDIT:
You can do something like:
bool bKeyExists = false;
foreach (SettingsProperty settingsProperty in appSettings.Properties)
{
if (settingsProperty.Name == _strKey)
{
bKeyExists = true;
break;
}
}
Or, with LINQ:
bool bKeyExists = appSettings.Properties.Cast<SettingsProperty>().Where(x => x.Name == _strKey).FirstOrDefault() != null;

How to change DCOM config identity programmatically

Is there any way to get the information about Launching identity of DCOM application programmatically. See the picture attached to understand what i mean.
I tried to use WMI
ManagementObjectSearcher s = new ManagementObjectSearcher(new ManagementScope(#"\\.\root\cimv2"), new ObjectQuery(
"select * from Win32_DCOMApplicationSetting where AppID='{048EB43E-2059-422F-95E0-557DA96038AF}'"))
ManagementObjectCollection dcomSett = s.Get();
var value = dcomSett.Cast<ManagementObject>().ToArray()
[0].Properties["RunAsUser"].Value;
but "RunAsUser" property was empty.
Also tried Interop.COMAdmin
COMAdmin.COMAdminCatalogClass catalog = (COMAdmin.COMAdminCatalogClass)new COMAdmin.COMAdminCatalog();
(COMAdmin.COMAdminCatalogCollection)catalog.GetCollection("Applications")
in this way i managed to get applications which are listed under the "COM+ Applications" node in the "Component Services" snap-in of MMC:
I'm new in COM, DCOM, COM+ stuff and sure that i missed something important.
After a while i found out why i used to get NULL in the first approach (ManagementObject).
You will receive:
NULL if identity is currently set to The launching user
"Interactive User" in case of "The interactive user"
some string with username in case of third option (see the first picture)
But still i need a way to change identity for items like Microsoft PowerPoint Slide under DCOM Config node in MMC.

In the DCOM config, if you are using a specific user for the identity and you want to update the password via code, you need to update it in the Local Security Authority (LSA). This is possible with Windows API calls. MS has some sample code for a utility called dcomperm that does it, and you can see how they implemented in C++. You could make the same calls in C#. See the SetRunAsPassword method here. They are using the method LsaOpenPolicy to get a handle to the policy and calling LsaStorePrivateData to update the password. Then they are adding "login as a batch job" access to the account (but that shouldn't be necessary if you are only changing the password).
This sample code on pinvoke.net looks like it is making the requisite calls, except for the optional part about granting the login as a batch job permission. Note the "key" in the LSA is in the format SCM:{GUID-of-DCOM-object} Example: SCM:{00000000-0000-0000-0000-000000000000}
Oh, and I should mention as an aside that if you wanted to change the RunAs user itself (i.e. the username), you'd need to also update that in the windows registry directly (AFAIK that's the only way to do it). DCOM entries are stored under HKLM\SOFTWARE\Classes\AppID. You can do that with WMI or just use the Registry classes in .NET.

This is very simple , you can get APPId from
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AppID\{048EB43E-2059-422F-95E0-557DA96038AF}
using
(RegistryKey dcomPPTIdentity = Registry.LocalMachine.OpenSubKey("Software\\Classes\\AppID\\{048EB43E-2059-422F-95E0-557DA96038AF}"))
{
if (dcomPPTIdentity != null)
{
Registry.SetValue(dcomPPTIdentity.ToString(), "RunAs", "userName");
}
}

I am using COMAdmin DLL successfully. Try something like this:
COMAdminCatalog catalog = new COMAdminCatalog();
COMAdminCatalogCollection applications = catalog.GetCollection("Applications");
applications.Populate();
for (int i = 0; i < applications.Count; i++)
{
COMAdminCatalogObject application = COMAppCollectionInUse.Item[i];
if (application.Name == "Your COM+ application name")
{
application.Value["Identity"] = "nt authority\\localservice"; // for example
}
}

This works for me on my development server. Keep in mind, it is run against the server directly on the server
using COMAdmin;
using System;
namespace ComComponents
{
class Program
{
static void Main(string[] args)
{
COMAdminCatalog catalog = new COMAdminCatalog();
COMAdminCatalogCollection applications = catalog.GetCollection("Applications");
applications.Populate();
for (int i = 0; i < applications.Count; i++)
{
COMAdminCatalogObject application = applications.Item[i];
Console.WriteLine(application.Name);
Console.WriteLine(application.Value["Identity"]);
}
Console.WriteLine("Press any key to continue...");
Console.ReadKey();
}
}
}

How to detect RDC from C#.net [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
How do you retrieve a list of logged-in/connected users in .NET?
I have hosted WCF service in IIS on a machine. Now i want to write a method in the service by which I could detect whether the hosted machine is currently being used by any Remote Desktop Connection or not.
Is there any other better way to find out this, and what are the exact code APIs by which RDC connection is detected.
I am using C#.net, framework 3.5

There are two options for you. You can use the P/Invoke Calls to the WSTAPI library however it is easy to mess stuff up and get resource leaks.
Your other option is to use the WTSAPI wrapper library Cassia. I have used that before and it is easy to use and the classes are fairly self documenting.
In Cassia your function would simply be
public bool IsComputerUsedByTS()
{
var tsMgr = new TerminalServicesManager();
var localSvr = tsMgr.GetLocalServer();
var sessions = localSvr.GetSessions();
foreach(var session in sessions)
{
if(session.ConnectionState == ConnectionState.Active ||
session.ConnectionState == ConnectionState.Connected) //Add more states you want to check for as needed
{
return true;
}
}
return false;
}
I did not test the above, and I think "active" is used if you are a console session where "Connected" is for RDP sessions. there are lot more states, look at the enum for all of the options.

RDP servers listen on port 3389 by default (but can be configured differently).
Therefore (even not being 100% reliable) this can be used to check any active RDP connections.
bool inUse = IPGlobalProperties.GetIPGlobalProperties()
.GetActiveTcpConnections()
.Any(tcp => tcp.LocalEndPoint.Port == 3389);
EDIT
I added #t3hn00b's suggestion.
int port = 3389;
using (var key = Microsoft.Win32.Registry.LocalMachine.OpenSubKey(#"SYSTEM\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp", false))
{
if (key != null)
{
object value = key.GetValue("PortNumber");
if (value != null) port = Convert.ToInt32(value);
}
}
namespace: System.Net.NetworkInformation

Use C# to interact with Windows Update

Is there any API for writing a C# program that could interface with Windows update, and use it to selectively install certain updates?
I'm thinking somewhere along the lines of storing a list in a central repository of approved updates. Then the client side applications (which would have to be installed once) would interface with Windows Update to determine what updates are available, then install the ones that are on the approved list. That way the updates are still applied automatically from a client-side perspective, but I can select which updates are being applied.
This is not my role in the company by the way, I was really just wondering if there is an API for windows update and how to use it.

Add a Reference to WUApiLib to your C# project.
using WUApiLib;
protected override void OnLoad(EventArgs e){
base.OnLoad(e);
UpdateSession uSession = new UpdateSession();
IUpdateSearcher uSearcher = uSession.CreateUpdateSearcher();
uSearcher.Online = false;
try {
ISearchResult sResult = uSearcher.Search("IsInstalled=1 And IsHidden=0");
textBox1.Text = "Found " + sResult.Updates.Count + " updates" + Environment.NewLine;
foreach (IUpdate update in sResult.Updates) {
textBox1.AppendText(update.Title + Environment.NewLine);
}
}
catch (Exception ex) {
Console.WriteLine("Something went wrong: " + ex.Message);
}
}
Given you have a form with a TextBox this will give you a list of the currently installed updates. See http://msdn.microsoft.com/en-us/library/aa387102(VS.85).aspx for more documentation.
This will, however, not allow you to find KB hotfixes which are not distributed via Windows Update.

The easiest way to do what you want is using WSUS. It's free and basically lets you setup your own local windows update server where you decide which updates are "approved" for your computers. Neither the WSUS server nor the clients need to be in a domain, though it makes it easier to configure the clients if they are. If you have different sets of machines that need different sets of updates approved, that's also supported.
Not only does this accomplish your stated goal, it saves your overall network bandwidth as well by only downloading the updates once from the WSUS server.

If in your context you're allowed to use Windows Server Update Service (WSUS), it will give you access to the Microsoft.UpdateServices.Administration Namespace.
From there, you should be able to do some nice things :)

P-L right. I tried first the Christoph Grimmer-Die method, and in some case, it was not working. I guess it was due to different version of .net or OS architecture (32 or 64 bits).
Then, to be sure that my program get always the Windows Update waiting list of each of my computer domain, I did the following :
Install a serveur with WSUS (may save some internet bandwith) : http://www.microsoft.com/en-us/download/details.aspx?displaylang=en&id=5216
Add all your workstations & servers to your WSUS server
Get SimpleImpersonation Lib to run this program with different admin right (optional)
Install only the administration console component on your dev workstation and run the following program :
It will print in the console all Windows updates with UpdateInstallationStates.Downloaded
using System;
using Microsoft.UpdateServices.Administration;
using SimpleImpersonation;
namespace MAJSRS_CalendarChecker
{
class WSUS
{
public WSUS()
{
// I use impersonation to use other logon than mine. Remove the following "using" if not needed
using (Impersonation.LogonUser("mydomain.local", "admin_account_wsus", "Password", LogonType.Batch))
{
ComputerTargetScope scope = new ComputerTargetScope();
IUpdateServer server = AdminProxy.GetUpdateServer("wsus_server.mydomain.local", false, 80);
ComputerTargetCollection targets = server.GetComputerTargets(scope);
// Search
targets = server.SearchComputerTargets("any_server_name_or_ip");
// To get only on server FindTarget method
IComputerTarget target = FindTarget(targets, "any_server_name_or_ip");
Console.WriteLine(target.FullDomainName);
IUpdateSummary summary = target.GetUpdateInstallationSummary();
UpdateScope _updateScope = new UpdateScope();
// See in UpdateInstallationStates all other properties criteria
_updateScope.IncludedInstallationStates = UpdateInstallationStates.Downloaded;
UpdateInstallationInfoCollection updatesInfo = target.GetUpdateInstallationInfoPerUpdate(_updateScope);
int updateCount = updatesInfo.Count;
foreach (IUpdateInstallationInfo updateInfo in updatesInfo)
{
Console.WriteLine(updateInfo.GetUpdate().Title);
}
}
}
public IComputerTarget FindTarget(ComputerTargetCollection coll, string computername)
{
foreach (IComputerTarget target in coll)
{
if (target.FullDomainName.Contains(computername.ToLower()))
return target;
}
return null;
}
}
}

What is the Fastest way to read event log on remote machine?

I am working on an application which reads eventlogs(Application) from remote machines. I am making use of EventLog class in .net and then iterating on the Log entries but this is very slow. In some cases, some machines have 40000+ log entries and it takes hours to iterate through the entries.
what is the best way to accomplish this task? Are there any other classes in .net which are faster or in any other technology?

Man, I feel your pain. We had the exact same issue in our app.
Your solution has a branch depending on what server version you're running on and what server version your "target" machine is running on.
If you're both on Vista or Windows Server 2008, you're in luck. You should look at System.Diagnostics.Eventing.Reader.EventLogQuery and System.Diagnostics.Eventing.Reader.EventLogReader. These are new in .net 3.5.
Basically, you can build a query in XML and ship it over to run on the remote computer. Maybe you're just searching for events of a specific type, or maybe just new events from a specific point in time. The search runs on the remote machine, and then you just get back the matching events. The new classes are much faster than the old .net 2.0 way, but again, they are only supported on Vista or Windows Server 2008.
For our app when the target is NOT on Vista/Win2008, we downloaded the raw .evt file from the remote system, and then parsed the file using its binary format. There are several sources of data about the event log format for .evt files (pre-Vista), including link text and an article I recall on codeproject.com that had some c# code.
Vista and Windows Server 2008 machines use a new .evtx format that is a new format, so you can't use the same binary parsing approach across all versions. But the new EventLogQuery and EventLogReader classes are so fast that you won't have to. It's now perfectly speedy to just use the built-in classes.

Event Log Reader is horribly slow... too slow. WTF Microsoft?
Use LogParser 2.2 - Search for C# and LogParser on the Internet (or you can use the log parser commands from the command line). I don't want to duplicate the work already contributed by others.
I pull the log from the remote system by having the log exported as an EVTX file. I then copy the file from the remote system. This process is really quick - even with a network that spans the planet (I had issues with having the log exported to a network resource). Once you have it local, you can do your searches and processing.
There are multiple reasons for having the EVTX - I won't get into the reasons why we do this.
The following is a working example of the code to save a copy of the log as an EVTX:
(Notes: "device" is the network host name or IP. "LogName" is the name of the log desired: "System", "Security", or "Application". outputPathOnRemoteSystem is the path on the remote computer, such as "c:\temp\%hostname%.%LogName%.%YYYYMMDD_HH.MM%.evtx".)
static public bool DumpLog(string device, string LogName, string outputPathOnRemoteSystem, out string errMessage)
{
bool wasExported = false;
string errorMessage = "";
try
{
System.Diagnostics.Eventing.Reader.EventLogSession els = new System.Diagnostics.Eventing.Reader.EventLogSession(device);
els.ExportLogAndMessages(LogName, PathType.LogName, "*", outputPathOnRemoteSystem);
wasExported = true;
}
catch (UnauthorizedAccessException e)
{
errorMessage = "Unauthorized - Access Denied: " + e.Message;
}
catch (EventLogNotFoundException e)
{
errorMessage = "Event Log Not Found: " + e.Message;
}
catch (EventLogException e)
{
errorMessage = "Export Failed: " + e.Message + ", Log: " + LogName + ", Device: " + device;
}
errMessage = errorMessage;
return wasExported;
}

A good Explanation/Example can be found on MSDN.
EventLogSession session = new EventLogSession(Environment.MachineName);
// [System/Level=2] filters out the errors
// Where "Log" is the log you want to get data from.
EventLogQuery query = new EventLogQuery("Log", PathType.LogName, "*[System/Level=2]");
EventLogReader reader = new EventLogReader(query);
for (EventRecord eventInstance = reader.ReadEvent();
null != eventInstance;
eventInstance = reader.ReadEvent())
{
// Output or save your event data here.
}
When waiting 5-20 minutes with the old code this one does it in less than 10 seconds.

Maybe WMI can help you:
WMI with C#

Have you tried using the remoting features in powershell 2.0? They allow you to execute cmdlets (like ones to read event logs) on remote machines and return the results (as objects, of course) to the calling session.

You could place a Program at those machines that save the log to file and sends it to your webapplication i think that would be alot faster as you can do the looping local but im not sure how to do it so i cant ive you any code :(

I recently did such thing via WCF callback interface however my clients interacted with the server through WCF and adding a WCF Callback was easy in my project, full code with examples is available here

Just had the same issue and want to share my solution. It makes a search through application, system and security eventlogs from 260 seconds (using EventLog) about a 100 times faster (using EventLogQuery).
And this in a way where it is possible to check if the event message contains a pattern or any other check without the requirement of FormatDescription().
My trick is to use the same mechanism as PowerShells Get-WinEvent does and then pass it through the result check.
Here is my code to find all events within last 4 days where the event message contains a filter pattern.
string[] eventLogSources = {"Application", "System", "Security"};
var messagePattern = "*Your Message Search Pattern*";
var timeStamp = DateTime.Now.AddDays(-4);
var matchingEvents = new List<EventRecord>();
foreach (var eventLogSource in eventLogSources)
{
var i = 0;
var query = string.Format("*[System[TimeCreated[#SystemTime >= '{0}']]]",
timeStamp.ToUniversalTime().ToString("o"));
var elq = new EventLogQuery(eventLogSource, PathType.LogName, query);
var elr = new EventLogReader(elq);
EventRecord entryEventRecord;
while ((entryEventRecord = elr.ReadEvent()) != null)
{
if ((entryEventRecord.Properties)
.FirstOrDefault(x => (x.Value.ToString()).Contains(messagePattern)) != null)
{
matchingEvents.Add(entryEventRecord);
i++;
}
}
}

Maybe that the remote computers could do a little bit of computing. So this way your server would only deal with relevant information. It would be a kind of cluster using the remote computer to do some light filtering and the server would the the analysis part.