JavaScript what is “this”

Written by Welzie

June 11th, 2012 at 5:56 pm

Posted in JavaScript

With no comments

“this” in js functions

I am getting deeper into the JS rabbit hole and as a programmer with more experience with strongly typed languages I find some things hard to grasp in languages where functions are first class elements (learn more here). One thing that is not tricky but interesting is the different values for “this” in a function. What “this” is in a function depends on how it is used. These are my brief notes about functions and “this”, feel free to comment if you see something incorrect.

As a global function: honk();

As a method: myCar.honk()

As a constructor: new Car()

Function called with honk.apply(…) or honk.call(…)

Examples with console output

Console output for above code

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Track every Build Number with Maven

Written by MikeNereson

October 9th, 2010 at 12:42 pm

Posted in Software Tools, java, maven

Tagged with , ,

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Problem

You need to differentiate between build numbers. For example, you’ve just redeployed your application and need to ensure that the new version is what you are viewing. Or, you need to keep track of how many times you build. There could be many reasons why you want to know the build number that you are on. I use it for reporting bugs against specific builds.

Solution

maven-buildnumber-plugin. This Maven2 plugin will generate a unique build number each time your build your project. You can even configure which maven phase triggers the increment of the number. This plugin can also fetch data from SVN to ensure that a team of developers all get unique build numbers.

As a bonus, it generates a buildNumber.properties file so that you can read in this build number from anywhere in your project. Here is how I use the plugin.

First, update your pom.xml. You need to setup the build trigger.


<build>
  <plugins>
    <plugin>
      <groupId>org.codehaus.mojo</groupId>
      <artifactId>buildnumber-maven-plugin</artifactId>
      <version>1.0-beta-3</version>
      <executions>
        <execution>
          <phase>validate</phase>
          <goals>
            <goal>create</goal>
          </goals>
        </execution>
      </executions>
      <configuration>
        <doCheck>true</doCheck>
        <doUpdate>false</doUpdate>
        <format>${version}.{0,number}</format>
        <items>
          <item>buildNumber0</item>
        </items>
      </configuration>
    </plugin>
  </plugins>
</build>





Now, you’ll need the build number and append it to your artifact’s final name. Add this to your pom.xml

<build>
  <finalName>
    ${project.artifactId}-${project.version}.{buildNumber}
  </finalName>
</build>

Now you’re package goal will output a file named

projectname-1.0.1.war

This is a great start and now you can differentiate each and every build. However, I need to take this a step further.

I need to see the version on my application’s index page. To do this, I use an ant filter to write the version and timestamp to a version.html file, and then copy it to my project’ web app directory. Add this to your pom.xm.

<build>
  <plugins>
    <plugin>
      <artifactId>maven-antrun-plugin</artifactId>
      <executions>
        <execution>
          <phase>compile</phase>
          <configuration>
            <tasks>
              <!-- versioning -->
              <echo message="[build version]"/>
              <delete file="target/projectname/version.html"/>
              <tstamp>
                <format property="rightNow" pattern="d MMM yyyy" locale="en"/>
              </tstamp>
              <copy todir="target/projectname">
                <fileset dir="src/main/webapp">
                  <include name="version.html"/>
                </fileset>
                <filterset>
                  <filter token="VERSION" value="${buildNumber}"/>
                  <filter token="BUILTON" value="${rightNow}"/>
                </filterset>
              </copy>
              <echo message=" version is ${buildNumber}"/>
            </tasks>
          </configuration>
          <goals>
            <goal>run</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

Version.html is simple.

<p class="version">Version: @VERSION@</p>
<p class="built">Built on: @BUILTON@</p>

Finally, in my index page…

<jsp:include page="/version.html"/>

Almost everything you want to know about this plugin can be found on the plugin’s site: http://mojo.codehaus.org/buildnumber-maven-plugin/

Alternatives

As an alternative to writing and importing version.html, you can read buildNumber.properties in an MVC controller and put the version in your page model. This is what I for my login pages. I use a java class to read the build number, format it, and cache it. I start the first build number at 00100, then format that to 0.1.0. So the next build is 00101 which gets displayed as 0.1.1.





Update:Tips

Here is a usage tip. You can move the create goal into a build profile so that the build number only increments in specific situations. I use a profile for my Continuous Integration builds so that our version increments only when Hudson builds our apps. This also makes it possible to synchronize our Hudson build numbers to our module versions.

Feedback

What do you use to track build numbers? How do your format it?

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.Net Data Provider Overview

Written by Welzie

August 5th, 2010 at 4:40 pm

Posted in .Net

Tagged with ,

With no comments

Summary
This is a high level summary of the basic .Net API’s for interacting with a database. This includes a short description of each and how they relate to each other. As a developer with mainly a Java and PHP background I was unclear about how ADO.Net related to OleDb and I had no idea what was meant by the term “.Net Data Provider”. I created this because the msdn documentation is HEAVILY focused on ADO.Net and does not give a clear picture of how the many namespaces, interfaces, and classes interact. Please add comments to correct or enlighten. Note at this time the relation of .Net Providers to Nhiberante, LINQ to SQL, and Entity Framework is not covered in this post.

.Net Data Provider

System.Data

Four examples of System.Data Implementations

System.Data.SqlClient

System.Data.OleDb

System.Data.Odbc

IBM.Data.DB2.iSeries


http://msdn.microsoft.com/en-us/library/system.data.sqlclient.aspx

http://msdn.microsoft.com/en-us/library/system.data.oledb.aspx

http://msdn.microsoft.com/en-us/library/system.data.odbc.aspx

http://www-03.ibm.com/systems/i/software/access/windows/dotnet/index.html

Core Classes

  • SqlConnection
  • SqlCommand
  • SqlDataAdapter
  • SqlDataReader
Core Classes

  • OleDbConnection
  • OleDbCommand
  • OleDbDataAdapter
  • OleDbDataReader
Core Classes

  • OdbcConnection
  • OdbcCommand
  • OdbcDataAdapter
  • OdbcDataReader

Core Classes

  • iDB2Connection
  • iDB2Command
  • iDB2DataAdapter
  • iDB2DataReader

ADO.Net

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