Hi everyone,
sorry for keeping your waiting for my next post so long time. I was busy on Android OS investigation. But now I'm back.
Introduction
Do you know how to check is your server is still running and give your customers something? No. Then you should go to administrator room and ask technical stuff there.
I think after hearing the answer you will be a little disappointed. On market still does not exist simple and easy solution.
Microsoft suggest to use there servers that cost a lot; several vendors suggest to buy there services (InternetSeer for example), others simply waiting customer feedback and re-act on it.
I think this is not right. It's time to change those things. I have to feel my servers on fingers, and re-act faster then any customer catch the problem.
Concept
In our company we have several servers each one specially installed for particular task. For administrator is critical to check stability and availability of those servers. But administrator can not sit 24/7 and watching servers. So we need small automation here.
Several questions from the begging catch my attention:
1) if all servers in domain failed, how I can receive notification about that? What happens if internet channel become broken physically?
2) How I can detect that several services on server stop working properly?
3) Can I provide some "sugar" for solution?!
So I start thinking and designing. Phone call interrupt me for a minute, but also give me a nice idea: GSM Modem can become a backup channel that can notify me about server problems.
WOW! Its was very nice idea and easy to implement. 10 minutes and GSM modem was ordered over internet. My choice is: NOVACOM GNS-30 CRA. It cost a little, it done in industrial standard metal case, easy to mount, easy to program.
Second question was easy to answer. I will use old PING ICMP protocol technology for that. If server respond to PING then it's working. But for checking services required something more interesting and solution as always was so easy - we are checking network ports. In case of services that does not communicate with network should be used some other monitoring things, like: event logs, custom logs, MSMQ messages and etc...
Third question is my favorite. And my answer is: check e-mails on server for administrative group and in case of e-mail with high priority notify about it by SMS.
Implementation
Design of library was a simple task and done by me in several hours.
Two general solution points are:
- support GSM modems pool;
- support attachable and enhanceable protocols;
Abstraction used in implementation give other developers great advantage: easy implementation of own protocols, that can access any known to us location; and easy attaching of other GSM Modems/devices.
I implement SMTP, POP3. IMAP4, HTTP and PING protocols which cover 99% of servers functionality. Also can be create protocols for checking SQL Server connection, Network Port or MSMQ, but I leave that for future.
Sending of SMS is well described in article:
Developers Home
Key elements of the solution:
#1 - GSM Modems pool;
#2 - Special exceptions used by GSM modems providers;
#3 - Background Analyzer (ROOT object of the solution). User should instantiate it for accessing library functionality;
#4 - Access Protocol abstraction. Protocol can have several states, like: Unknown, Ok, Error, Pending, etc.
#5 - Message accessing protocols;
Special rules that now how to process "messages" extracted by "access protocols". RulesHelper static class that keeps all rules together and allows fast rules processing.
Actions is a part of the rule and defines how we should re-act on rule match.
Configuration
Configuration that describing our local domain settings will looks like simple and easy XML:
xml version
="1.0"?>
<configuration
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<servers>
<server
name="microsoft.com">
<protocols>
<protocol
xsi:type="PingProtocol"
host="microsoft.com"
protocol-id="813b11d4-5a10-43c3-8507-b108df589fcc" />
protocols>
<accounts />
server>
<server
name="sbs.artfulbits.com">
<protocols>
<protocol
xsi:type="PingProtocol"
host="sbs.artfulbits.com"
protocol-id="eb4d8bb7-d312-49d9-b90d-c2619ab366b7" />
<protocol
xsi:type="Pop3Protocol"
host="sbs.artfulbits.com"
protocol-id="99b0b839-2845-49f6-b832-1fb974f202c9"
port="110"
SPA="false" SSL="false" />
<protocol
xsi:type="SmtpProtocol"
host="sbs.artfulbits.com"
protocol-id="55b3666e-8d21-445a-b59c-5083949a9ab2"
port="25"
SPA="false" SSL="false" />
protocols>
<accounts>
<client
protocol-ref="99b0b839-2845-49f6-b832-1fb974f202c9">
<login>alexk@artfulbits.comlogin>
<password>PASSWORD_PASSWORDpassword>
client>
accounts>
server>
<server
name="fsrv">
<protocols>
<protocol
xsi:type="PingProtocol"
host="fsrv"
protocol-id="4181a782-777e-4edb-8563-0f29a7832dd0" />
protocols>
<accounts />
server>
servers>
<modems>
<modem
xsi:type="GenericModem">
<port>COM4,9600,8,None,One,None,False,False,-1,-1port>
modem>
modems>
<rules>
<rule
xsi:type="HighPriorityRule">
<Action
xsi:type="SendSmsAction">
<PhoneNumbers>
<phone
number="+380676729814"
/>
PhoneNumbers>
Action>
rule>
rules>
configuration>
Prototyping
For testing the library I create console application, that in few hours can be transformed into windows service. And for people that like nice GUI I design simple forms:
Smoke test
Let's code speak for itself.
///
private static void TestNotifyGsm()
{
// ---> CREATE BACKGROUND ANALYZER <---
s_analyzer.Started += analyzer_Started;
s_analyzer.ProgressChanged += analyzer_ProgressChanged;
s_analyzer.Error += analyzer_Error;
s_analyzer.Canceled += analyzer_Canceled;
s_analyzer.Completed += analyzer_Completed;
s_analyzer.RunWorkerCompleted += analyzer_RunWorkerCompleted;
// ---> REGISTER MODEMS <---
// ---> 1) initialize com port, change it settings
// ---> 2) initialize connect to the modem
SerialPort com1 = new SerialPort( "COM4" );
GenericModem provider = new GenericModem( com1 );
s_analyzer.Context.ModemsPool.RegisterModemProvider( provider );
// ---> REGISTER RULES <---
// ---> 3) Create Rules
s_analyzer.Context.Rules.Add( new HighPriorityRule( "+380676729814" ) );
// ---> SERVERS CONFIGURATION <---
// ---> 4) Create Servers List
ServerComputer serverOutside = new ServerComputer( "microsoft.com" ); // gateway
ServerComputer serverSBS = new ServerComputer( "sbs.artfulbits.com" ); // SBS
ServerComputer serverFSRV = new ServerComputer( "fsrv" ); // FSRV
// 4.1) Register ICMP-Ping protocols
serverOutside.RegisterProtocol( new PingProtocol( serverOutside.Name ) );
serverSBS.RegisterProtocol( new PingProtocol( serverSBS.Name ) );
serverFSRV.RegisterProtocol( new PingProtocol( serverFSRV.Name ) );
// 4.2) Register e-mail protocols
EmailProtocol protoPop = new Pop3Protocol( serverSBS.Name );
EmailProtocol protoSmtp = new SmtpProtocol( serverSBS.Name );
serverSBS.RegisterProtocol( protoPop );
serverSBS.RegisterProtocol( protoSmtp );
// 4.3) Register e-mail accounts
EmailAccount account = new EmailAccount( protoPop );
account.UserName = "alexk@artfulbits.com";
// SECURITY ISSUE: do not enter password here!!! file stored in SVN.
account.Password = "password-password";
serverSBS.RegisterAccount( account );
// 4.4) attach configured servers to the context
s_analyzer.Context.Servers.Add( serverOutside );
s_analyzer.Context.Servers.Add( serverSBS );
s_analyzer.Context.Servers.Add( serverFSRV );
#if SERIALIZATION_TEST
// ---> SERIALIZATION <---
// ---> 5) Save settings into configuration file
using( Stream stream = File.OpenWrite( "c:\\gsm_notification.config" ) )
{
WorkerContext.Serialize( stream, s_analyzer.Context );
}
// ---> DESERIALIZATION <---
using( Stream stream = File.OpenRead( "c:\\gsm_notification.config" ) )
{
WorkerContext context = WorkerContext.DeSerialize( stream );
Dump( context );
}
#endif
// ---> CHECK CYCLE <---
// --> 5) Run processing
s_analyzer.RunWorkerAsync();
s_sync.WaitOne();
System.Console.WriteLine( "Press ENTER to exit" );
System.Console.ReadLine();
}
Logic of work
Algorithm of work for application is not so trivial as it can
be.
For each registered server we should proceed following steps:
1) Check protocols of server for availability (connectivity). Failure of one protocol does not mean that server is broken;
1.1) On protocol failure start to count attempts from our side for recovering connectivity;
1.2) If connectivity restored then continue without any admins disturbing;
1.3) If we reach critical point then create message for SMS and put it into rules processing queue;
1.4) If after failure connectivity recovered then create message and also put it into rules processing queue;
1.5) Rules are the same as used in e-mail processing. So this step simply redirected to 2.2 point in this list;
2) Check e-mail accounts of the server:
2.1) If protocol OK then extract e-mails from server;
2.2) Check each e-mail on Rules match;
2.3) If we have match at least on one rule then required SMS sending.
Do you need a commercial solution?
This project has a commercial support now. If you are interesting in similar solution with support and customization from our side please contact ARTFULBITS sales. Thanks.
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