Goh Kondoh

Annotation-based Web content transcoding

Abstract Users are increasingly accessing the Internet from information appliances such as PDAs, cell phones, and set-top boxes. Since these devices do not have the same rendering capabilities as desktop computers, it is necessary for Web content to be adapted, or transcoded, for proper presentation on a variety of client devices. In this paper, we propose an annotation-based system for Web content transcoding. First, we introduce a framework of external annotation, in which existing Web documents are associated with content adaptation hints as separate annotation files. We then explain an annotation-based transcoding system with particular focus on the authoring-time integration between a WYSIWYG annotation tool and a transcoding module. Finally, after giving an example of content adaptation using a page fragmentation module for small-screen devices, we compare our approach with related work.

Finding bugs in java native interface programs

In this paper, we describe static analysis techniques for finding bugs in programs using the Java Native Interface (JNI). The JNI is both tedious and error-prone because there are many JNI-specific mistakes that are not caught by a native compiler. This paper is focused on four kinds of common mistakes. First, explicit statements to handle a possible exception need to be inserted after a statement calling a Java method. However, such statements tend to be forgotten. We present a typestate analysis to detect this exception-handling mistake. Second, while the native code can allocate resources in a Java VM, those resources must be manually released, unlike Java. Mistakes in resource management cause leaks and other errors. To detect Java resource errors, we used the typestate analysis also used for detecting general memory errors. Third, if a reference to a Java resource lives across multiple native method invocations, it should be converted into a global reference. However, programmers sometimes forget this rule and, for example, store a local reference in a global variable for later uses. We provide a syntax checker that detects this bad coding practice. Fourth, no JNI function should be called in a critical region. If called there, the current thread might block and cause a deadlock. Misinterpreting the end of the critical region, programmers occasionally break this rule. We present a simple typestate analysis to detect an improper JNI function call in a critical region. We have implemented our analysis techniques in a bug-finding tool called BEAM, and executed it on opensource software including JNI code. In the experiment, our analysis techniques found 86 JNI-specific bugs without any overhead and increased the total number of bug reports by 76%.

An authoring technology for multidevice Web applications

The rapid proliferation of mobile computing devices has increased the complexity and cost of cross-platform application development. Multidevice authoring technology (MDAT) lets developers build a generic application common to multiple devices and customize it for specific devices. We developed MDAT an end-to-end development methodology and toolset, to reduce the complexity of creating interactive, form-based Web applications that execute on heterogeneous devices. Web application refers to conventional, servlet-based Web applications as well as portlet applications. A portlet is a Web application component that a Web portal server aggregates with other portlets.

Dynamic binary translation specialized for embedded systems

This paper describes the design and implementation of a novel dynamic binary translation technique specialized for embedded systems. Virtual platforms have been widely used to develop embedded software and dynamic binary translation is essential to boost their speed in simulations. However, unlike application simulation, the code generated for systems simulation is still slow because the simulator must replicate all of the functions of the target hardware. Embedded systems, which focus on providing one or a few functions, utilize only a small portion of the processors features most of the time. For example, they may use a Memory Management Unit (MMU) in a processor to map physical memory to effective addresses, but they may not need paged memory support as in an OS. We can exploit this to specialize the dynamically translated code for more performance. We built a specialization framework on top of a functional simulator with a dynamic binary translator. Using the framework, we implemented three specializers for an MMU, bi-endianness, and register banks. Experiments with the EEMBC1.1 benchmark showed that the speed of the specialized code was up to 39% faster than the unspecialized code.

JSP splitting for improving execution performance

Splitting a JSP (JavaServer Pages) page into fragments can improve the execution performance of JSP pages when the Web application server can separately cache the Web page fragments obtained by executing the JSP fragments. If a JSP page is split into fragments according to the update frequency of each portion of the Web page obtained by executing the JSP page, all of the split JSP fragments do not need to be executed again when only a single cached part of a Web page expires. In addition, the fragments of a JSP page can be reused by other JSP pages. In both cases, the execution results of all of the JSP fragments split from the JSP page must be the same as from the JSP page before it was split. In this paper, we propose JSP splitting, which is a method of splitting a JSP page into fragments maintaining the data and control dependences existing in the original JSP page. JSP splitting automatically detects the portions needed to maintain the data and control dependences of a JSP page for the portions that developers want to split from the JSP page. We implemented JSP splitting with a GUI tool, and confirmed that the split JSP fragments were executed in the same as the way as the JSP page before the split. Experimental results show that the response time to access a Web page can be reduced by splitting a JSP page into fragments and setting different caching periods for the Web page fragments obtained by executing the JSP fragments.