Develop Reference

Creating Agents from Agent Base Type during the simulation

I try to explain my problem as short as possible:
I got an AgentTypeOnly called customer, the data of the customer is in a database. I dont wan't to create all my agents at the beginning of the simulation. They should appear after a defined time, then they have to do a task and after the task is finished they have to dissapear (sink). At the moment i am creating them with a source block, but i am quite sure, that there is a better way to do it. For example a code in the main.
Thanks for the help, I hope u get my question

depending on the modeling technique you use, you can do it in different ways. When you use agent type only, you can only create agents using the source from the process modeling library.
If you use agent-based then instead of agent-type you have to use a population initially empty. then, for example if your agent population is called customers, you can create an agent whenever you want using the code add_customers();
None of these techniques is better than the other and it depends on your application

Dynamically build java/scala method body at runtime and execute it

Suppose I have the following Interface in java:
public interface DynamicMethod {
String doit();
}
I would like to build an Object during runtime which conforms to the above interface such that I inject doit method body in it and then execute it? Is this possible with Java Reflection API, or any other way? Or probably in some way in Scala?
Note that doit body for my objects would be dynamic and are not known a priori. You can assume that in run-time an array CodeArray[1..10] of Strings is provided and each entry of this array holds the code for each doit method. I would appreciate if you could answer with a sample code.
The context:
I try to explain the context of the problem; nonetheless, the above question still remains independent from the context.
I have some commands say C1,C2, ...; each command has certain parameters. Based on a command and its parameters the system needs to perform a certain task (which is expressible using a java code.) I need that these commands are stored for future execution based on user demand (so the CodeArray[1..10] in the above holds this list of java codes). For example, a user chooses a command from the list (i.e., from the array) and demands its execution.
My thought is that I build an engine that based on the user selection, loads the corresponding command code from the array and executes it.

With your context that you added, it sounds to me like you have an Interpreter..
For example, SQL takes input like "SELECT * FROM users", parses and builds a tree of tokens that it then interprets.
Another example: Java's regex is an interpreter. A string like "[abc]+" is compiled into tokens, and then interpreted when executed. You can see the tokens (called Nodes) it uses in the source code.
I'll try to post a simple example later, but the Interpreter Pattern doesn't use dynamically generated code. All of the tokens are concrete classes. You do have to define all possible (valid) user input so that you can make a token to execute it however. SQL and regex has a defined syntax, you will need one also.

I think Byte Buddy would be helpful in your case. It's an open source project maintained by a very well respected Java developer.
Take a look at the Learn section, they have a very detailed example there:
http://bytebuddy.net/#/tutorial

Currently it's not very clear what's your aim. There are many approaches to do this depending on your requirements.
In some cases it would be enough to create a Proxy and an InvocationHandler. Sometimes it's reasonable to generate Java source, then invoke JavaCompiler in runtime and load the generated class using URLClassLoader (probably that's your case if you're speaking about strings of code). Sometimes it's better to directly create a bytecode using libraries like ASM, cglib or BCEL.

Cascading method calls in FitNess?

I'm new to FIT and FitNess and I'm wondering if is possible to cascade method calls without defining special fixtures.
Background: we are testing our web based GUI with Selenium WebDriver. I have created a framework based on the PageObject pattern to decouple the HTML from the page logic. This framework is used in our JUnit tests. The framework is implemented in a Fluent API style with grammar.
Something like this:
boolean connectionTest =
connectionPage
.databaseHost( "localhost" )
.databaseName( "SOME-NAME" )
.instanceNameConnection()
.instanceName("SOME-INSTANCE-NAME")
.windowsAuthentication()
.apply()
.testConnection();
Some testers want to create acceptance tests but aren't developers. So had a look to FIT. Would it be possible to use my framework with FIT as is without developing special fixtures?

I don't believe you can use the existing code with 'plain-vanilla' Fit, it would at least require a special fixture class to be defined. Maybe 'SystemUnderTest' could help?
Otherwise Slim's version might be something to get it to work for you.
As a side note: I've put a FitNesse baseline installation including features to do website testing with (almost) no Java code on GitHub. In my experience it's BrowserTest will allow non-developers to create/modify/maintain tests easily, and integrate those tests with you continuous integration process (if you have one). I would suggest you (or your testers) also have a look at that.

I know you asked about Java but in case any .NET developers see this, it's possible with the .NET implementation, fitSharp:
|with|new|connection page|
|with|database host|localhost|
|with|database name|some-name|
etc.
See http://fitsharp.github.io/Fit/WithKeyword.html

I have solved my problem by writing a generic fixture which receives the target methods and their arguments from the fitness table and uses Java reflection to invoke the appropriate framework methods.
So I have one fixture of all different page objects that are returned from the framework.

Save object in debug and than use it as stub in tests

My application connects to db and gets tree of categories from here. In debug regime I can see this big tree object and I just thought of ability to save this object somewhere on disk to use in test stubs. Like this:
mockedDao = mock(MyDao.class);
when(mockedDao.getCategoryTree()).thenReturn(mySavedObject);
Assuming mySavedObject - is huge enough, so I don't want to generate it manually or write special generation code. I just want to be able to serialize and save it somewhere during debug session then deserialize it and pass to thenReturn in tests.
Is there is a standard way to do so? If not how is better to implement such approach?

I do love your idea, it's awesome!
I am not aware of a library that would offer that feature out of the box. You can try using ObjectOutoutStream and ObjectInputStream (ie the standard Java serialization) if your objects all implement Seriablizable. Typically they do not. In that case, you might have more luck using XStream or one of its friends.

We usually mock the entire DB is such scenarios, reusing (and implicitly testing) the code to load the categories from the DB.
Specifically, our unit tests run against an in-memory database (hsqldb), which we initialize prior to each test run by importing test data.

Have look at Dynamic Managed Beans - this offers a way to change values of a running java application. Maybe there's a way to define a MBean that holds your tree, read the tree, store it somewhere and inject it again later.

I've run into this same problem and considered possible solutions. A few months ago I wrote custom code to print a large binary object as hex encoded strings. My toJava() method returns a String which is source code for a field definition of the object required. This wasn't hard to implement. I put log statements in to print the result to the log file, and then cut and paste from the log file to a test class. New unit tests reference that file, giving me the ability to dig into operations on an object that would be very hard to build another way.
This has been extremely useful but I quickly hit the limit on the size of bytecode in a compilation unit.

How to find static method calls in large Java project?

I'm refactoring some Java code to be more decoupled by changing some static method calls to non-static calls, for example:
// Before:
DAO.doSomething(dataSource, arg1, ..., argN)
// After:
dao.doSomething(arg1, ..., argN)
My problem is that in a large project, it can be hard to find where static method calls are being made. Is there an easy way to do this, either from the command line or in Eclipse?
Such a tool would need to let me ignore "benign" static method calls such as these (either by not finding them in the first place, or by allowing them to be easily deleted from the search results):
String.valueOf(...)
Integer.parseInt(...)
MyClass.someBenignStaticMethod(...)
Some clarifications:
I'm not interested in finding method calls made via reflection
I don't know what static methods currently exist in this project, so it's not as simple as searching for their callers using Eclipse's "Open Call Hierarchy" command (Ctrl-Alt-H), although an easy way to search for non-private static methods would let me use this approach
I'm also interested in finding calls to static methods located outside my project, e.g. javax.mail.Transport#send
I'm looking for a free (as in beer) solution

Do you really need to search? Why not comment out the static method calls one by one? When you compile it then it will flush out the references.

I'd use grep (-R on Linux) to search for initial caps-dot-camel case-open (I don't use it enough to give you the full command line). And then grep -v to get rid of some of the rubbish.
Well, really what I'd do is refactor incrementally. Changes a method, and see what breaks (if nothing breaks, delete the code).
Theoretically you could search through the class files looking for invokestatic. The FindBugs infrastructure would probably help out here (there may be better starting points).

Some IDEs provide support for refactoring. You can refactor every static method one-by-one.
In Eclipse, you can view the call hierarchy to see all the callers of such method. To view the call hierarchy you can select the method name and press Command-Alt-H, or Right-Click on symbol and choose 'Open Call Hierarchy).

We have a product called nWire for Java which might just help. nWire analyzes your code and builds a database of your code components and associations. You can see a brief demo on our web site.
We plan to have reporting capabilities added in the future. In the mean while, if you have some basic experience with databases, you can tap into the nWire repository and, with a simple SQL query, get a list of all your static methods (you can also see the invocations there). nWire uses the H2 database engine which is open-source and free.
I can assist in accessing the database. Drop me a line to support [at] nwiresoftware.com.

I've written a small Java program that uses the excellent ASM library. It lets you exclude packages like java.lang, and produces output that looks like this:
+ java
+ io
- File
# createTempFile(java.lang.String, java.lang.String)
+ javax
+ imageio
- ImageIO
# read(java.io.InputStream)
# write(java.awt.image.RenderedImage, java.lang.String, java.io.File)
+ mail
- Transport
# send(javax.mail.Message)
+ internet
- InternetAddress
# parse(java.lang.String, boolean)
+ xml
+ parsers
- DocumentBuilderFactory
# newInstance()
I'd prefer something that's more easily built into my existing build process, which uses CheckStyle, but this is the best solution I've come up with so far.

A possible solution could be a custom CheckSyle or PMD or ... warning. Currently I have the same challenge and trying it with CheckStyle. It seems to be right easy to write such an extention.