Holmes/lib/MaintainJ_4.2.0/com.maintainj.inst.wizard_4.2.0/help/whyMaintainJ.html

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<h1>2. Why should I use MaintainJ?</h1><p>

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Costs of software maintenance are well documented.
      <a href="http://www.cs.jyu.fi/~koskinen/smcosts.htm">This</a> compilation 
      puts maintenance cost at more than 90% of total software 
      cost. The same paper puts the cost of understanding the code at 50% of 
      maintenance cost.</font></p>
      <p>
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		Currently there are no good tools to understand 
      enterprise scale Java applications. Most of the reverse engineering tools 
      generate the class diagrams, a static time view of the system. But when a 
      developer is changing code, he/she is more interested in knowing how 
        classes 
      interact at runtime for a single use case.
      MaintainJ  generates runtime sequence and class diagrams for a single use 
      case.</font><font face="Verdana"> </font> </p>



<p><h2>2.1 Why should managers be interested?</h2></p> 

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Change is constant and everywhere - business 
      changes, development teams change, enhancements and bug fixes involve changes, interfacing with new applications need changes, etc.</font></p>
      <p><font face="Verdana">Change involves risk. Understanding reduces risk. 
      MaintainJ significantly reduces the effort spent in understanding large 
      Java applications. </font></p>
      <p><font face="Verdana">Typically, developers depend on debuggers to analyze 
      runtime interactions. Debuggers definitely help but diagrams are better 
      for the same reason that managers prefer graphs to numbers.</font></p>

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      <p><font face="Verdana" size="2">Most of the currently available reverse engineering 
      tools generate class diagrams and a static sequence diagrams. Generally, 
      the class diagrams generated are not for a single use case. They are more 
      for the entire system and are too cluttered to understand. Static sequence diagrams are generated from code and show the possible 
      call flows starting from a method. This helps to understand the code 
      structure to certain extent but do not help to understand the runtime 
      behavior.</font></p>
      <p><font face="Verdana" size="2">MaintainJ generates runtime diagrams for a use case and that is what 
      developers crave for while debugging a complex Java application.</font><font size="-1" face="Verdana">

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In agile development environments, MaintainJ can also be used to generate always 
up-to-date 
UML documentation from code.</font></p>
      <p><font face="Verdana">MaintainJ is based on open source 
Eclipse project and works on any IDE that is built on Eclipse platform. </font> 

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<p><h2>2.2 Why should developers be interested?</h2></p> 

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Any developer who has ever tried to change a large 
      Java application should not need much persuasion. For the remaining few, 
here are a few reasons :</font><p><font face="Verdana" size="2"><b>Dynamic Binding</b> - Dynamic or runtime binding 
in Java makes understanding code more difficult. Developers often need to 
understand the runtime object interactions for a specific use case either to 
debug or enhance the application. Dynamic binding helps in building very 
flexible systems but, at the same time it increases the time to understand the 
system. It is also common to employ multiple levels of dynamic binding, like a 
Vector containing another Vector, which further complicates the issue.</font></p>
<p><font face="Verdana" size="2"><b>Observer Pattern</b> - Many enterprise applications follow Observer 
Pattern for flexibility, where 'listener' (or observer) objects change model 
state besides 'listening' (or observing) for the state changes. When many 
such listener objects, which are often determined at runtime, change the model, 
it becomes hard to understand and debug a large application.</font></p>
<p><font face="Verdana" size="2"><b>Multi-threaded Applications</b> - Multi-threaded 
applications are always difficult to code and debug. Using MaintainJ, one can 
see the sequence of method calls happening in each thread in a neat sequence 
diagram. This makes debugging multi-threaded applications much easier.</font></p>
<p><font face="Verdana" size="2"><b>Externalized Data and Rules</b> - Externalizing configuration data as well 
as rule based logic to XML files is very commonly found in the present day Java 
applications. Very often, the logic to determine the runtime classes is 
soft-coded in xml files. In a not so well documented large-scale system, it is 
very hard to understand how the xml file drive the system.</font></p>
      <p><font face="Verdana" size="2"><b>Poor Design - </b>Designing robust and flexible systems at the same 
      time is hard. Maintaining them as the systems evolve is harder. If 
      poor design slips into this equation, it becomes very hard to understand a 
      system after 2-3 years from initial launch.</font><font face="Verdana">
      </font> </p>
      <p><font face="Verdana" size="-1">Here are some other scenarios where 
      MaintainJ helps developers.</font></p>
      <p><font face="Verdana" size="2"><b>Complements Debugger</b> - MaintainJ complements debugger rather than replacing it. By generating 
      the class and sequence diagrams for a use case, it reduces the time spent 
      in debugger. Unlike other reverse engineering tools, MaintainJ offers 
      uncluttered and focused UML&nbsp; diagrams. For sequence diagrams, which 
      get cluttered very easily, MaintainJ offers features like call 
      folding to generate crisp diagrams.</font></p>
      <p><font face="Verdana" size="2"><b>During Code reviews</b> - MaintainJ can also be used during code reviews. 
      Rather than reviewing the entire source code, one can review the diagrams 
      to find deviations from the design standards. Class diagrams 
      showing the dependencies help to weed out unwanted dependencies.</font><font face="Verdana">
      </font>
      </p>
      <p><font face="Verdana" size="2"><b>For Agile Teams</b> - For agile programming teams, 
      MaintainJ provides always up-to-date documentation of the system. Useful 
      UML diagrams 
      can be generated whenever one needs them.</font><font face="Verdana">
      </font>

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