4th International Conference on Principles and Practices ... - MADOC

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traditional courses these properties should be - and were actually - assessed by looking into the source code and documentation of the student’s solution. Hence, the assessment of programming assignments usually took a lot of human corrector time. The automation of these reviews and quality assurance tests by our tool is described in the following section. 2. AUTOMATIC ASSESSMENT OF JAVA PROGRAMS In recent years we have developed an online Java course consisting of a tutorial that provides a high level of interaction and an assessment tool that analyses the code and enables the students to run a suite of predefined tests [2]. The hypertext tutorial can be navigated via a predefined learning path or by freely following the hyperlinks. It contains a lot of editable and executable examples and many exercises (from multiple choice and free text to programming exercises) to check the student’s progress. The solutions for the programming exercises, small or mediumsized programs, are uploaded to the assessment tool [4]. Thence, various electronic evaluators perform: • Formal tests We check if the program compiles, conforms to coding and naming conventions, and if appropriate comments are present such as Javadoc comments. • Structural tests The recommended usage of structured statements or data types is checked. Violation of these conventions may lead to hidden mistakes. It is e.g. possible to enforce that the statement following a loop or branch statement is a block or that case clauses are terminated by a break or a return statement. • Specification tests The specification requires that classes with predefined names or methods with given signatures are expected. Classes have to extend other classes or implement given interfaces. In a teaching environment it may be interesting to prohibit the usage of packages or classes. • Functional tests Comparison with a master solution or a set of JUnit tests are performed. 2.1 Functional Tests The common practice for functional tests is black box testing, using e.g. the JUnit framework. These tests check the solution for well known test cases and their expected results. Therefore these results must be known in advance, what might be problematic, if the way to compute the results is rather complex. Whereas the development of black box tests is or at least should be standard in a development team we also provide the opportunity to compare the results of the student solution with a master solution. The comparator provides a set of classes and methods that mirrors the structure of both solutions. The implementation then calls the respective constructs from the student’s and the master’s implementation, and compares the results. The comparison is done on the real objects, taking into account the internal structure of arrays and collections. Special methods for comparison can be provided such as a possible equality relation for floating-point numbers that only checks, is the student’s solution lies within a given interval. This simplifies the writing of tests tremendously, as (seemingly) standard manipulation of objects can be used, and no explicit checking needs to be done. Of course explicit checking is also possible, in case the implicit is not sufficient. 2.2 Combining Tests The tests can be configured and individually tuned for each specific exercise. The combination of different tests makes sense especially in a teaching environment where we are interested in more than results. We also want to know or prescribe the manner these results are produced. A method may have to be called recursively, another must not use a while loop and a third method has to advance an iterator of a data structure properly. The results have to be the same. Such conditions or requirements can easily be imposed by our tool by combining the appropriate (e.g. the structural and functional) tests. All tests may be mandatory, optional or even secret. A program is only accepted, if it passes the required checks. Since the automatic assessment is carried out immediately, the students do not need to wait for feedback and can fix problems and upload corrected versions immediately. The number of turn in tries usually is not limited, there is only a general submission deadline for an exercise. Having optional tests is especially important in courses, where programming is not the major objective. Here compliance to e.g. formal tests is often not enforced in order to allow students to concentrate on different matters. Often even some or all functional tests are configured as optional, so that partially incomplete solutions can be turned in, because rejecting those completely would be too strict. Yet, those tests are usually included, so that students remember, that their programs can still be improved. 3. EXAMPLE Let us illustrate the work of our tool by a simple exercise: Write a class StringReverse containing a method reverse(String) that reverses a string without using the method reverse() from the class java.lang.StringBuffer. In the following we mimic the upload and assessment of several attempts to solve this exercise. 1.Attempt: Uploaded program (shortened): public static String reverse(String s) { return new StringBuffer(s).reverse().toString(); } public static void main(String[] args) { for (int i=0; i
Results of online checks (shortened, translated from German): Check 1: compilation: passed Check 2: coding conventions: passed Check 3: signature and hierarchy: failed Invocation test checks whether prohibited classes or methods are used; call of method reverse from the prohibited class java.lang.StringBuffer 2. Attempt: Uploaded program (shortened): public static String reverse(String s) { if (s == null) return null; if (s.length()
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Edited by: Ralf Gitzel, Markus Alek
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Message from the Chairs Dear confer
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Sam Midkiff, Purdue University (USA
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Session F: Novel Uses of Java______
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The Project Maxwell Assembler Syste
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tomated assembler and disassembler
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memory address offset mnemonic argu
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5.2 Instruction Templates The assem
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ange for a very short restart/debug
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Tatoo: an innovative parser generat
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In the grammar file an error termin
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Figure 3: Push parsers and lexers L
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eturn visit((Expr)p1, param); } R v
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Session B Program and Performance A
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Table 1: Use of interfaces and deco
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Table 3: Comparison of the situatio
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will trigger the creation of many n
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Appendix A 10 9 8 7 6 5 4 3 2 1 0 1
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Throughout this paper, we make no a
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instrumented program and obtained t
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Figure 5: Investigation of garbage
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to the same category—again, this
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Investigating Throughput Degradatio
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Figure 1: Apache. Throughput degrad
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Minor GC Full GC Workload # of Avg.
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Figure 6: Comparing memory and pagi
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GenRC on the other hand, allows the
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Session C Mobile and Distributed Sy
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ing a continuous buffer for raw dat
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the data arrival speed is more impo
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public class StreamingClient { publ
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importance of β in our aggregation
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Enabling Java Mobile Computing on t
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A strongly mobile thread has the ab
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a context switch occur. The invoked
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above phases. Now, the new stack ha
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5 frames 15 frames 25 frames Pure d
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Juxta-Cat: A JXTA-based platform fo
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Figure 1: JXTA Architecture. 3. JUX
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• Send a discovery query to the p
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The best candidate is then the one
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Local Hosts=2 Hosts=4 Hosts=8 Hosts
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Session D Resource and Object Manag
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Enterprise Edition (J2EE). It enabl
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As pictured in Figure 4, JDOSecure
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Methods of a PersistenceManager, th
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Datenmodell abstrahiert user role,
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An Extensible Mechanism for Long-Te
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missing object references in the de
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4.2 Mapping the name spaces of the
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(a) (b) ColorSliderPanel0 color
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8. REFERENCES [1] Abu-Ghazaleh, N.,
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permission by process. In other wor
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The processor then refers to the en
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1: // Protection domain 2: struct p
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Table 3: Frequency of JNI calls tha
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[13] Intel Corporation. IA-32 Intel
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01 try { 02 ... 03 } finally { 04 t
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2. FRAMEWORK The Framework for Unif
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ManagedInputStream ResourceGroup Ma
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18. throw ‡ 1. release 17. cleanu
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3. FUTURE WORK The ability to split
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124
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UML sequence diagrams are among the
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diagrams, and behavioral (dynamic)
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the official scripting language for
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Apache's XML Graphics Project. A cu
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Java Debug Interface (JDI). In Revi
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1.3 JML 1.3.1 Overview JML, the Jav
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The Usage of CANAPA is fairly strai
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*@non_null@*/ String str = attribut
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142
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parallel and distributed versions o
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RingElem CextendsRingElem GenPolyno
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RingElem +isZERO():bolean CextendsR
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class constructors with the actual
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plemented via a distributed hash ta
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which are common nowadays. The reus
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Derivative Contract Component Repos
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Page 183 and 184: The idea of Java 5.0 type inference
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Page 187 and 188: 5. IMPLEMENTATION In order to prese
Page 189 and 190: Infinite Streams in Java Dominik Gr
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Page 195 and 196: Interaction among Objects via Roles
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Page 251: ISBN: 3-939352-05-5 ISBN: 978-3-939
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