ASP.Net MVC Book Review and musings

ASP.Net MVC musings

• ASP.Net MVC is a CoC MVC framework, it’s not a “full stack” framework. You still need to implement some type of database layer.
• Traditional ASP.net web forms attempts to hide the core parts of web development HTML, JS, CSS. ASP.Net MVC does not.
• Learning a pattern like MVC in web framework that allows developers to be aware of HTML, JS, CSS will only benefit you as a web developer.
  • If you actually understand how web pages work it makes you a better debugger and a more well rounded programmer. You are able to more easily apply your knowledge and skill set to other languages/platforms. I know that some web form developers do know the details of web development, but in my opinion most do not.
• The fact that ASP.Net MVC makes it easier to test will not appeal to people who have never written a unit test in their life. You have to convince such people by showing a real world example demonstrating how test coverage can save you loads of time and money in the maintenance phase of application development. But at that point you will only get architects and project managers to buy in, the lazy developers that fear learning anything new will still avoid ASP.Net MVC like the swine flu.
• The fact that the MVC pattern is a common pattern among other web development environments such as Java and PHP will also not appeal to most Microsoft developers. However the really smart ones will realize that more common knowledge will only help if you ever have to do any type of development other than microsoft development

Book Review – Pro ASP.Net MVC Framework – Steven Sanderson

Book on Amazon I am a Java, PHP, and .Net developer which may make my opinion worthless to some Microsoft zealots but I thought I would type up my thoughts on this book anyway. Overall I found this book to be a great way to learn ASP.Net MVC. It has great examples and enough background material to bring people new to the MVC pattern up to speed. Below are my pros and cons along with notes on chapters 1-13.

Note about the cover.

One thing I found interesting is that the cover says “Discover the biggest innovation in Microsoft web development since asp.net 1.0″. I find it amusing that something as old as MVC web frameworks can be called an innovation for asp.net development since MVC frameworks are nothing new to web development. Heck they are not even new to ASP.Net development. See MonoRail .

Pros

• Provides good definition of MVC and explains why you want to use it
• Overall all the examples are clear and concise
• Gives examples of how to test every part of ASP.Net MVC
• Moves quick enough for someone with MVC experience and slow enough for someone with no MVC experience
• Great chapter on web site security
• Book often demonstrates C# 3 language features

Cons

• Database examples use LINQ to SQL.
  • As many have noted this isn’t a major con. It was probably used to keep the examples shorter. Whether you like LINQ to SQL or not that is a good thing.
• No mention of Mono project or any hints of how to get ASP.Net working with Mono.
• Book examples are for the “real” version of VS2008 not the free VWDE2008.
• Does not provide a good example of using a validation utility such as XVal or Data Annotations

Chapter 1

• An adequate history lesson for those unfamiliar with MVC.

Chapter 2

• A great chapter that quickly and easily shows you the basics of ASP.Net MVC

Chapter 3

Book on Amazon

Read HTML with Java – Then 7 Fun Things to do to It

There are several ways to get the HTML content of a URL from Java. There are even more ways to get the HTML using open source java libraries. Last week Lars Vogel shared how to get the HTML using nothing but the SDK.

SDK

final URL url = new URL("http://blog.codehangover.com");
final InputStream inputStream = new InputStreamReader(url);
final BufferedReader reader
             = new BufferedReader(inputStream).openStream();

String line;

while ((line = reader.readLine()) != null) {
   System.out.println(line);
}

reader.close();

Apache Commons HttpClient

You can also use the Apache Commons HttpClient for a slightly easier to use library.

HttpClient client = new HttpClient();
HttpMethod method = new GetMethod("http://blog.codehangover.com");

try {
 client.executeMethod(method);

 byte[] responseBody = method.getResponseBody();

 System.out.println(new String(responseBody));

} catch (Exception e) {

 e.printStackTrace();

} finally {

 method.releaseConnection();
}

But the real fun comes after you get the HTML. Now you get to work with it.

7 Things to do with HTML Source in Java

1. Extract the Text from the Markup

I worked on a web application that was similar to a feed reader. One of the features that we supported was searching the pages. To do this I needed to extract the text from the markup. I use the CyberNeko HTML Parser for this task.

private String getHtmlFilteredString(Reader reader)
{

  // create element remover filter
  ElementRemover remover;
  remover = new ElementRemover();
  remover.removeElement("script");
  remover.removeElement("link");
  remover.removeElement("style");
  remover.removeElement("CDATA");
  remover.removeElement("<!--");
  remover.removeElement("meta");

  OutputStream stream = new ByteArrayOutputStream();

  try
  {
    String encoding = "ISO-8859-1";
    XMLDocumentFilter writer = new Writer(stream, encoding);

    XMLDocumentFilter[] filters = {remover, writer};

    XMLInputSource source = new XMLInputSource(null, null, null, reader, null);

    XMLParserConfiguration parser = new HTMLConfiguration();
    parser.setProperty("http://cyberneko.org/html/properties/filters", filters);

    parser.parse(source);

  } catch (Exception e) {

    e.printStacktrace();
  }

  String content = stream.toString().trim();

  return content;
}

2. Extract Links

To find all of the links in an HTML fragment, maybe for your own spider, or to extract email addresses, you can use HtmlParser

Collection<String> links = new ArrayList<String>();

try {

  URI uriLink = new URI(url);
  Parser parser = new Parser();
  parser.setInputHTML(htmlBody);
  NodeList list = parser.extractAllNodesThatMatch(new NodeClassFilter (LinkTag.class));

  for (int i = 0; i < list.size (); i++){
    LinkTag extracted = (LinkTag)list.elementAt(i);
    String extractedLink = extracted.getLink();
    links.add(extractedLink);
  }

} catch (Exception e) {

  e.printStackTrace();
}

3. Change Links

Using the previous code, instead of calling getLink, you can call setLink to change the href. For example, this might be used by any type of analytics software that needs to track hits.

4. Collect Email Addresses

Using the previous code, before adding the link to the Collection, chech to see if it uses the mailto protocol by calling the boolean method isMailLink()

  for (int i = 0; i < list.size (); i++){

    LinkTag extracted = (LinkTag)list.elementAt(i);

    if (extracted.isMailLink())
    {
      String extractedLink = extracted.getLink();
      links.add(extractedLink);
    }
  }

5. Collect Images

Still using HtmlParser, you can extract images by filtering on the ImageTag.

Collection<String> imageUrls = new ArrayList<String>();

try {

  URI uriLink = new URI(url);
  Parser parser = new Parser();
  parser.setInputHTML(htmlBody);
  NodeList list = parser.extractAllNodesThatMatch(new NodeClassFilter (ImageTag.class));

  for (int i = 0; i < list.size (); i++){
    ImageTag extracted = (ImageTag)list.elementAt(i);
    String extractedImageSrc = extracted.getImageUrl();
    imageUrls.add(extractedImageSrc);
  }

} catch (Exception e) {

  e.printStackTrace();
}

6. Add Syntax Highlighting

If you’re going to present the source on screen you have to add syntax highlighting. If you’re displaying on a web page, I would highly recommend using something like SyntaxHighligher, which is what we use on this blog. If you are displaying an a Swing app, you can use a tool called  Syntax which is now several years old.

try {

     ToHTML toHTML = new ToHTML();

     toHTML.setInput(new FileReader("Source.java"));
     toHTML.setOutput(new FileWriter("Source.java.html"));
     toHTML.setMimeType("text/x-java");
     toHTML.setFileExt("java")

     toHTML.writeFullHTML();

 } catch (Exception e){

    e.printStackTrace();
 }

7. Diff Two Sources

Once you get the HTML source of two URLs, or you have an old version of the HTML stored somewhere, you might want a nicely formatted diff output.

Madlep wrote his own method to handle the diff and output the results over on Stackoverflow.com

Given some simple input, his code gives simple output.

String one = "" +
    "<ul>" +
    "  <li>item 1</li>" +
    "  <li>item 2</li>" +
    "</ul>";

String two = "" +
    "<p>This is text</p>" +
    "<ul>" +
    "  <li>item 1</li>" +
    "  <li>item 2</li>" +
    "  <li>item 3</li>" +
    "</ul>";

System.out.println(diffSideBySide(one, two));

Outputs

                     >  <p>This is text</p>
<ul>                    <ul>
 <li>item 1</li>          <li>item 1</li>
 <li>item 2</li>          <li>item 2</li>
                     >    <li>item 3</li>
</ul>                   </ul>

3 More Things to do with the HTML

This list sure feels incomplete at only 7 of a nice even 10 things. What else could you you do with the HTML? Ill pick the top three from the comments and finish this blog post with them.

Getting friendly with Spring, JUnit and EasyMock.

Here are some steps that can get you using Spring, JUnit and EasyMock all together in some Test Driven Development hotness.

Start by adding the following lines to the top of your unit test. Specifying Autowire by name ensures you get the injection you want and will stop those Spring errors that there are more than one of the same type of mock objects in your mock-applicationContext.xml. When you specify the Spring Junit runner you must provide one ore more context configurations with @ContextConfiguration.

MyClassUnitTest.java

...
@Configurable(autowire = Autowire.BY_NAME)
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:com/some/domain/someproject/resources/mock-applicationContext.xml"})
public class MyClassUnitTest {
...
     @Autowired private Collaborator mockCollaborator;

     @Before
     public void setup() throws Exception {
     ...
     }

     @After
     public void teardown() throws Exception {
     ...
     }

     @Test
     public void testMyClass() throws Exception {

          //Set your mock behavior here
          ....

          EasyMock.replay(mockCollaborator);

          MyClass myClass = new MyClass(mockCollaborator);
          myClass.run();
          EasyMock.verify(mockCollaborator);

          // Other JUnit assertions
          ...
     }
 }

Then add your mocks to your mock-applicationContext.xml (an applicationContext in your test resources just for providing your unit tests with spring injection dependencies):

mock-applicationContext.xml

...
<bean id="mockCollaborator" name="mockCollaborator" class="org.easymock.EasyMock" factory-method="createStrictMock">
     <constructor-arg value="com.some.domain.someproject.Collaborator"/>
</bean>

<bean id="mockOtherCollaborator" name="mockOtherCollaborator" class="org.easymock.EasyMock" factory-method="createStrictMock">
     <constructor-arg value="com.some.domain.someproject.OtherCollaborator"/>
</bean>
...

Ensure your maven pom has the following test-scoped dependency:

pom.xml

...
<dependency>
     <groupId>org.springframework</groupId>
     <artifactId>spring-test</artifactId>
     <version>2.5.6</version>
     <scope>test</scope>
</dependency>
...

Then use your mocks as normal. Make sure you call EasyMock.reset(mock) in your @After teardown() method so that each of your mocks are reset for each test. You can also tell Spring to reset the context after a test if needed with @DirtiesContext.

For official documentation and tutorials check out these links.

Spring

http://www.springsource.org/documentation

JUnit

http://www.junit.org

EasyMock

http://easymock.org/Documentation.html

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