Multi tier Architecture utilities (NLOG)

see these Related topics:

1. Multi tier basics
2. A best practice for multi tier architecture
3. A sample code based on best practice
4. Examine utilities to speed up Multi tier programming- NLog

Please download the second version of Multi tier code

In previous lessons I talked about basic concepts of Multi tier and a best practice Architecture. Also I examine a sample code about that Architecture in this lesson I am going to review ”NLOG” one of the best tools that with no doubt you better use in that architecture to Log both errors and interaction with application.
What is NLOG?
NLOG is a free tool could be used to log into different resources like file, event viewer, database, Memory, Console, MSMQ, Mail and Web Service and etc. Meanwhile it can be configured to different level of log. Moreover, it can be switched off or on. Also you can have different source of log. Above of all it is open source application. Should you need any changes you will be able to make it.
How NLOG works?NLog gives you a class library to call its services. Also it has a configuration file called NLog.config where you set which log sources you need for instance file or database. Also you can configure the source for example for a file you probably configures the file name. You can have multiple sources. Take look at this sample:

this configuration file will be in UI application then other layers in Multi tier architecture do not need extra Nlog.config file all of them will use this configuration file. If you look at the logDirecotry in above code you will see that actually nlog will create a folder called Logs inside application folder and it will log data for each day. I just showed you logging in files. Log in other data sources like database has its own configuration variables.
It you look at the rules tag you will find two logger tags where you define each one of these logger
1- which class will represents them (“name”)
2- what is the minimum level of log also you can disable log by setting this value to debug for a release version of application (“minLevel”)
3- Which target this logger is using to log information

In a multi tier application we always put our logger in Common Layer because we need this library in other layers. Also I highly recommend you to write a rapper class to simplify using NLog. Take a look at the DataLogger code:

In above code simply two methods are written Info and Warn to log information. If you look at the parameters you see multiple parameters. To save these parameters an xml structure is being used.
Please see the next version of multi tier code with logging
I remind you that I used very simple logging here you may change it and adapt it to your requirements. So this is not a best practice however, it is a good practice using Nlog in your projects. Nlog is really a lot more than I show you here. If you need any extra information or you think it is worth to have more detail information about NLOG let me know and raise some comments here. Do not underestimate this fabulous tool. I believe it needs at least 20 posts to show its capability!
In next lesson I am going to talk about my favourite tool Code Smith to generate code. Please download the next version of the code.

Please download the second version of Multi tier code

sending configurable email in Asp.net (Best practice)

Sending email is very common in Asp.net application. In most of asp.net applications I was asked to send email to client or admin etc. Meanwhile, almost always I was asked to change content of email many times. Like change a sentence, put space between sentences. Sometimes to create email the way client needs I had to change email content 10 times. Finally I come up with the idea that I need to make this process configurable and allow clients change the content themselves easily. Another issue is that since email is dependent to other factors like mail server sometimes your application may not be successful to send email so you need detect unsuccessful emails and send email in later steps. This Post will talk about best practice to send email to client. please download the Code

Understanding the issue:

We are going to send email to users. We need these functionalities:

1- The Email content should be configurable

2- We may need to have a link in our email to somewhere in our site or in other sites

3- If sending email is not successful we need to log that email in database to be able to send email in future

You can send email in .net using System.Web.Mail.SmtpMail which is obsolete. Also you can use System.Net.Mail.SmtpClient I highly recommend the second one also try to use System.Net.MailMessage which is new class in .Net 2.0 unless you are using .net 1.1 By using SmtpClint class you can configure your smtp server information in web.config take a look at this code:

Quick look to class diagram:

I need to remind you that I did not use multi tier architecture here. I highly recommend that Accessing to database should be done through DataAccessLayer you can find more information about DataAccessLayer and multi tier programming in my blog.

EmailHelper, EmailLog, EmailLogProvider, DataAccessHelper:

UI will call EmailHelper class methods to send email in our case we have just one type of email if I had 10 different emails (of course with different content) I would have 10 methods to send Emails. All of those 10 methods would use SendEmail method (a private method) to send email. Also in this class there is another method called LogException used to Log the exception in database. Meanwhile, the email information is being saved so we can send email in later step to client. In this method an object of email log is being created then it is passed to EmailLogProvider Insert method to insert into database. DataAccessHelper is a utility class that you may use to add parameter to a command and to run a storedprocedures. In our example it is being used by EmailLogProvider class.

EmailReader, EmailLinkLoader:

When a method of EmailHelper is being called to send an email first a MailMessage object is created afterwards, it is passed to EmailReader class to prepare the body and other information. In this method we load information form an Xml file. So it is highly maintainable because as long as client gets back to us to change content of email we can apply those changes in this xml file not to our code. Take a look of this xml file.

As you see we even have "from emai"l and "from email display name" also as many as required bcc email can be configured. A very nice trick in this code is that if you look closer to the xml file you will find $firstName$ . This is a key for our code and we will replace this value in EmailLoader.LoadRegistration .So the email can have dynamic information for example another good example is that you may want to send username and password to a user but this information may vary from one user to another user so we use other keys and we replace this information in our code exactly the same way for $firstName$. In most of the sites that I worked I had more than one email also many of them had some special links like Terms and Condition link that should be placed into email. A good practice always suggests that never put a link hard coded as long as you have more than one email content connecting to the same link. So imagine you have 5 email and all of them somewhere in their content have a link to Terms and condition. You better make this link configurable because when this link changes you need change just one configuration rather than looking for this link in all emails. So EmailLinkLoader actually load another xml file and find the link address then cache this information. So next time it does not need to look up link again. This link information is passed to EmailReader to be applied to body content.

Important (how to run the code)

Open Visual studio and form file menu select open web site and form file system select the project folder. Afterwards you can run the project. You need to apply smtpserver address. A good test is without applying smtpserver if you run application then application ask your first Name and your email address. Afterwards since sending email is not successful the email information is saved into database. And it shows you unsuccessful message. In later steps we can use EmailLogProvider class and load all EmailLog objects so we can retry and resend email.

please download the Code