I am having problem creating a script to monitor Rest/API services.

samflex

Hi David and thanks a lot for your response. When you say to pass the URL as command line argument, do you mean when scheduling the app to run? This is all new for me unfortunately and I ask that you guys forgive me for the questions if they appear silly as probably are. //UPDATE: I tried changing the code to the one below so user doesn't have to be prompted to enter URL:

using System;
using System.Net.NetworkInformation;
using System.Text;

namespace showserverstatus
{
class Program
{
static void Main(string[] args)
{
//Console.Write("Enter server url:");
//var url = Console.ReadLine();
//Console.Clear();
//ServerStatusBy(url);
//Console.ReadLine();
}

    public static void ServerStatusBy()
    {
        Ping pingSender = new Ping();

        // Create a buffer of 32 bytes of data to be transmitted.
        string data = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
        byte\[\] buffer = Encoding.ASCII.GetBytes(data);

        // Wait 10 seconds for a reply.
        int timeout = 10000;

        PingOptions options = new PingOptions(64, true);

        // Send the request.
        PingReply reply = pingSender.Send("www.yahoo.com", timeout, buffer, options);


        if (reply.Status == IPStatus.Success)
        {
            Console.WriteLine("IP Address: {0}", reply.Address.ToString());
            Console.WriteLine("RoundTrip time: {0}", reply.RoundtripTime);
            Console.WriteLine("Time to live: {0}", reply.Options.Ttl);
            Console.WriteLine("Don't fragment: {0}", reply.Options.DontFragment);
            Console.WriteLine("Buffer size: {0}", reply.Buffer.Length);
        }
        else
            Console.WriteLine(reply.Status);
    }

}

I got the following: Press any key to continue... When I do, the console closes. No records shows.

samflex

Any help with this please? I know this is not your issue but I am being pressured for completion of this task. Many thanks in advance.

David Mujica

I see a few problems with your code: 1) Looks like your main() does not call your ServerStatusBy() function 2) You are not reading any values from the command line. Here is a VB example:

Sub Main()
Dim args() As String = System.Environment.GetCommandLineArgs()
Dim s As String

    For i As Integer = 0 To args.Length - 1
        Console.WriteLine(String.Format("Arg {0}): {1} ", i, args(i)))
    Next

    s = Console.ReadLine

End Sub

When you run the program from a command prompt like HellowWorld.exe www.google.com jdoe@companyabc.com The output is as follows: Arg 0): C:\_WorkingCopies\HelloWorld\HelloWorld\bin\Debug\HelloWorld.vshost.exe Arg 1): www.google.com Arg 2): jdoe@companyabc.com You can see that you want to grab Arg(1) as the URL and Arg(2) as the email address you want to send the report.

samflex

David, Thank you so much for your help. I converted your VB to C# and this is my code after integrating yours but still doesn't work. I am also getting this: Unnecessary assignment of a value to 's' Just so you know, I am not limited to using only C# for this task. I can use VB if that's available. Thank you again for your help.

using System;
using System.Net.NetworkInformation;
using System.Text;

namespace showserverstatus
{
class Program
{
static void Main()
{
string[] args = System.Environment.GetCommandLineArgs();
string s;

        for (int i = 0; i <= args.Length - 1; i++)
            Console.WriteLine(string.Format("Arg {0}): {1} ", i, args\[i\]));

        s = Console.ReadLine();
    }
    public static void ServerStatusBy()
    {
        Ping pingSender = new Ping();


        // Wait 10 seconds for a reply.
        int timeout = 10000;


        // Send the request.
        PingReply reply = pingSender.Send("www.yahoo.com", timeout);


        if (reply.Status == IPStatus.Success)
        {
            Console.WriteLine("IP Address: {0}", reply.Address.ToString());
            Console.WriteLine("RoundTrip time: {0}", reply.RoundtripTime);
            Console.WriteLine("Time to live: {0}", reply.Options.Ttl);
            Console.WriteLine("Don't fragment: {0}", reply.Options.DontFragment);
            Console.WriteLine("Buffer size: {0}", reply.Buffer.Length);
        }
        else
            Console.WriteLine(reply.Status);
    }

}

}

Richard Deeming

You can get the command-line arguments by changing the declaration of your Main method to Main(string[] args). You don't want to call Console.ReadLine if you're going to schedule your application to run in the background. There won't be a user to press a key and end the application. Instead, return an exit code indicating the status of your application - 0 generally indicates success, and anything else indicates an error. You'll want to pass each command-line argument to your status function, and use that as the site to test - for example:

static int Main(string[] args)
{
int result = 0;
foreach (string site in args)
{
if (!ServerStatusBy(site))
{
result++;
}
}

return result;

}

static bool ServerStatusBy(string site)
{
Ping pingSender = new Ping();
PingReply reply = pingSender.Send(site, 10000);
if (reply.Status != IPStatus.Success)
{
Console.WriteLine("{0}: {1}", site, reply.Status);
return false;
}

...
return true;

}

YourApp.exe site1.local codeproject.com google.com

"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

samflex

WOW, thank you very much sir. You remind me so much of this super guru called Bill Wilkinson of classic ASP and JavaScript way back when I was learning classic ASP. Just when I felt stuck and in trouble, he would come out of nowhere to help me out. God bless you sir. Please forgive me for additional questions. 1, does this ... (the dot dot dot) mean there is more code to go in there? 2, I use this -> YourApp.exe site1.local codeproject.com google.com for scheduling the run times, correct? 3, This -> YourApp.exe site1.local codeproject.com google.com means that I can add the five links all at once correct? Many thanks again. I really appreciate your help. I feel a bit better now. UPDATE: I think I answered question #1. This is how I *THINK* the code should look like now. I added the email component since users will be getting emails with the status of the servers whether up or down. Email subject should indicate Server Up or Down bases on what happens on ServerStatusBy() method

using System;
using System.IO;
using System.Net;
using System.Net.Mail;
using System.Net.NetworkInformation;
using System.Text;
using System.Configuration;

namespace showserverstatus
{
class Program
{
private string statusMessage;
static int Main(string[] args)
{
int result = 0;
foreach (string site in args)
{
if (!ServerStatusBy(site))
{
result++;
}
}

        return result;

    }

    static bool ServerStatusBy(string site)
    {
        Ping pingSender = new Ping();
        PingReply reply = pingSender.Send(site, 10000);
        if (reply.Status != IPStatus.Success)
        {
            Console.WriteLine("{0}: {1}", site, reply.Status);
            string statusMessage = "Shw message that Server is down"; //Dont know if I am doing this correctly.
            SendEmail(); // Send out email when server is down
            return false;

        }
        else
            statusMessage = "Shw message that Server is up"; //Dont know if I am doing this correctly.
        Console.WriteLine("IP Address: {0}", reply.Address.ToString());
         Console.WriteLine("RoundTrip time: {0}", reply.RoundtripTime);
         Console.WriteLine("Time to live: {0}", reply.Options.Ttl);
         Console.WriteLine("Don't fragment: {0}", reply.O

Richard Deeming

1. It looks like you've already answered that one. :) 2. Yes, you'd set the application to be the full path to your .exe file, and the command-line arguments to be the list of domains you want to test. 3. You can pass as many domains to test as you want as command-line arguments.

samflex wrote:

if (reply.Status != IPStatus.Success)
{
Console.WriteLine("{0}: {1}", site, reply.Status);
string statusMessage = "Shw message that Server is down"; //Dont know if I am doing this correctly.
SendEmail(); // Send out email when server is down
return false;

}
else
statusMessage = "Shw message that Server is up"; //Dont know if I am doing this correctly.

A couple of problems there: Within the if block, you've created a local variable called statusMessage, which hides the static field of the same name. The value you store in the local variable won't be visible to the SendEmail function. You don't need the else, since you've got a return within the if block.

samflex wrote:

Console.WriteLine("Email Sent.");
System.Threading.Thread.Sleep(3000);
Environment.Exit(0);

You shouldn't call Environment.Exit within the SendEmail function, since that will terminate your app after the first message is sent. I'd avoid using a field, and pass the message subject and body as parameters to the SendEmail function instead.

public static void SendEmail(string subject, string body)
{
using MailMessage mm = new(ConfigurationManager.AppSettings["FromEmail"], "joe.blow@yahoo.com");
mm.To.Add("joesixpack@gmail.com");
mm.CC.Add("jandoe@gmail.com");
mm.Subject = subject;
mm.Body = body;
mm.IsBodyHtml = false;

SmtpClient smtp = new()
{
    Host = ConfigurationManager.AppSettings\["Host"\],
    Port = int.Parse(ConfigurationManager.AppSettings\["Port"\]),
    EnableSsl = true,
    UseDefaultCredentials = false,
    Credentials = new NetworkCredential(ConfigurationManager.AppSettings\["Username"\], ConfigurationManager.AppSettings\["Password"\]),
};

Console.WriteLine("Sending email...");
smtp.Send(mm);
Console.WriteLine("Email sent.");
System.Threading.Thread.Sleep(3000);

}

samflex

Man, looks like you were born with this I work hard and spend a lot of time learning this but still struggle mightily. Many, many thanks sir. I am so grateful as this solution comes in handy as they are demanding demo by 10am togay. Just need one more clarification, is this right?

YourApp.exe site1.local codeproject.com google.com

Richard Deeming

samflex wrote:

YourApp.exe site1.local codeproject.com google.com

That's correct, if your compiled application is YourApp.exe, and you want to test three domains - site1.local, codeproject.com, and google.com. Obviously you'd need to use your real .exe name there, and pass in the actual domains / servers you wanted to test.

"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

samflex

Oh ok. I was confused by site1 thinking it was meant to be site as per the argument in ServerStatusBy() method. Thank God my demo pushed to 1:30pm so i can test this to see what happens. Thank you so much. I can't say this enough.

samflex

I have run into a little problem here. Console app, at least the one I am building and compiling is not generating an .exe file. For instance, the project name is showserverstatus. When I go into the bin folder, debug, I see showserverstatus.dll but not .exe As a result, I am having problem testing the app. Any ideas sir?

Richard Deeming

Looks like you've created a .NET Core / .NET 5 application. You would need to publish the application to generate an exe file: Build .NET Core console application to output an EXE - Stack Overflow[^] Otherwise, you would need run it using the dotnet command:

dotnet showserverstatus.dll site1 site2 ...

Or you could change the target framework to net472 to generate a .NET Framework exe instead. Double-click on the project file, find the line that looks like:

and change it to:

Target frameworks in SDK-style projects - .NET | Microsoft Docs[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

samflex

Sorry for all the trouble sir. Please hang in there with me a little longer if you can. I chose the path of least resistance by publishing and like you correctly stated, it generated .exe file. I tried testing and ran into an error. Please see how I was testing and the error: C:\inetpub\wwwroot\showserverstatus\bin\publish>showserverstatus.exe google.com IP Address: 2607:f8b0:4000:819::200e RoundTrip time: 44 Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object. at showserverstatus.Program.ServerStatusBy(String site) in C:\inetpub\wwwroot\showserverstatus\Program.cs:line 41 at showserverstatus.Program.Main(String[] args) in C:\inetpub\wwwroot\showserverstatus\Program.cs:line 16 As you can see, it displayed status of two lines before the error. This is line 16:

   foreach (string site in args)

and this is line 41:

   Console.WriteLine("Time to live: {0}", reply.Options.Ttl);

UPDATE: My demo went well for the mere fact that this app actually ran and sent email was considered a success even though the email did not contain anything. Here is why. Due to the error I was getting that I posted above, I removed all of those reply.stuff and then just left only DOWN or WORKING. They wanted them worded as those. Per the changes I made below, the app ran and sent the email but when I received the email, there was no message that site is WORKING or DOWN. Is it because of the changes by replacing Subject with hardcoded values and body with hardcoded values? They also brought up something that I overlooked. They wanted Subject to read: Server Status They wanted the body to read: Please find the status of the DMZ servers below: whatever site name is - working or Down (Whatever the status is). This is latest code. Please, please forgive me sir for all these troubles. Looks like we are almost there. I changed the code below to format them just as described above. The only issue now and it is a big one is that it works with pretty much any URL I tested with except anything that begins with gis. For instance, none of these worked: https://gis.massdot.state.ma.us/arcgis/rest gis.massdot.state.ma.us/arcgis/rest/ gis.massdot.state.ma.us/arcgis/rest

using System;
using System.IO;
using System.Net;
using System.Net.Mail;
using System.Net.NetworkInformation;
using System.Text;
using System.Configuration;
using System.Collections.Ge

Richard Deeming

Looks like the reply.Options isn't set. You will need to test for null, or use a null-conditional operator:

if (reply.Options != null)
{
Console.WriteLine("Time to live: {0}", reply.Options.Ttl);
Console.WriteLine("Don't fragment: {0}", reply.Options.DontFragment);
}
...
SendEmail($"{site} Up", $@"Ping {site}
IP Address: {reply.Address}
RoundTrip time: {reply.RoundtripTime}
Time to live: {reply.Options?.Ttl}
Don't fragment: {reply.Options?.DontFragment}
Buffer size: {reply.Buffer?.Length}");

samflex wrote:

For instance, none of these worked: https://gis.massdot.state.ma.us/arcgis/rest gis.massdot.state.ma.us/arcgis/rest/ gis.massdot.state.ma.us/arcgis/rest

You're pinging a server, not a URL. It looks like gis.massdot.state.ma.us either isn't up, or is blocking pings. If you actually want to test a URL, you'd need to use a different approach. For example:

static async Task<int> Main(string[] args)
{
System.Collections.Concurrent.ConcurrentDictionary<string, string> urlToStatus = new();

IEnumerable<Task<bool>> tasks = args.Select(async url =>
{
    bool result = await ServerStatusByAsync(url);
    urlToStatus.TryAdd(url, result ? "UP" : "DOWN");
});

await Task.WhenAll(tasks);

StringBuilder body = new("Please find the status of the servers below:");
foreach (var kvp in urlToStatus)
{
    body.AppendLine();
    body.AppendFormat("{0}: {1}", kvp.Key, kvp.Value);
}

await SendEmailAsync("Server Status", body.ToString());
await Task.Delay(3000);

}

static async Task<bool> ServerStatusByAsync(string url)
{
HttpClient http = new();
using (HttpResponseMessage response = await http.GetAsync(url))
{
Console.WriteLine("GET {0}: {1}", url, response.StatusCode);

    if (response.IsSuccessStatusCode)
    {
        await SendEmailAsync($"{url} WORKING", $"GET {url} returned {response.StatusCode}");
        return true;
    }
    
    await SendEmailAsync($"{url} DOWN", $"GET {url} returned {response.StatusCode}");
    return false;
}

}

static async Task SendEmailAsync(string subject, string body)
{
using MailMessage mm = new(ConfigurationManager.AppSettings["FromEmail"], "joeblow@yahoo.com");
mm.To.Add("johndoe@gmail.com");
mm.CC

samflex

My goodness, how did you learn all of these? WOW. Just a couple of things sir, One, I got this error: Error CS0161 'Program.Main(string[])': not all code paths return a value I am assuming that all I needed to do was copy your latest code and replace from Main all the way down. Second, runing it is still the same? That is, showserverstatus.exe google.com yahoo.com gis..../rest/, etc? I am truly in awe and so sorry for continuing to ask questions about this.

Richard Deeming

Sorry, missed the return statement:

static async Task Main(string[] args)
{
System.Collections.Concurrent.ConcurrentDictionary urlToStatus = new();

IEnumerable\> tasks = args.Select(async url =>
{
    bool result = await ServerStatusByAsync(url);
    urlToStatus.TryAdd(url, result ? "UP" : "DOWN");
});

bool\[\] results = await Task.WhenAll(tasks);

StringBuilder body = new("Please find the status of the servers below:");
foreach (var kvp in urlToStatus)
{
    body.AppendLine();
    body.AppendFormat("{0}: {1}", kvp.Key, kvp.Value);
}

await SendEmailAsync("Server Status", body.ToString());
await Task.Delay(3000);

// Return the number of servers which were down:
return results.Count(result => !result);

}

Running it is still the same, except you now need to pass a list of URLs to test, rather than a list of server names to ping.

"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

samflex

Oh man! Getting the following error: Unhandled exception. System.InvalidCastException: Unable to cast object of type 'SelectArrayIterator`2[System.String,System.Threading.Tasks.Task]' to type 'System.Collections.Generic.IEnumerable`1[System.Threading.Tasks.Task`1[System.Boolean]]'. It says line 21 which is this line:

IEnumerable> tasks = (IEnumerable>)args.Select(async url =>

This is the second line in Main(). Just for clarity sir, this is your version:

IEnumerable < Task > tasks = args.Select(async url =>

However, when I ran it, I got: CS0266 Cannot implicitly convert type 'System.Collections.Generic.IEnumerable' to 'System.Collections.Generic.IEnumerable>'. An explicit conversion exists (are you missing a cast?) When I selected the suggested explicit cast option, the error went away but then I got the other error during testing. The error occurred when I tried passing one URL as an argument to test like: showserverstatus.exe google.com UPDATE: It's always something!!! I got the error worked out; just took me awhile to figure out what was missing - return... Now, email is not working. Not getting sent. UPDATE: Once again, I panicked and didn't calm down to look for solutions. Now, it is working. It turns out that I added myemail.com.net which obviously will make it hard to receive an email. After correcting it, everything is fine now. My Lord, it is impossible to express my most heartfelt gratitude for your patience, incredible ingenuity and most of all, you don't insult me. Thank you very much sir, THANK YOU!!!