Creating multiple prototypes facilitates comparative reasoning, grounds team discussion, and enables situated exploration. However, current interface design tools focus on creating single artifacts. This paper introduces the Juxtapose code editor and runtime environment for designing multiple alternatives of both application logic and interface parameters. For rapidly comparing code alternatives, Juxtapose introduces selectively parallel source editing and execution. To explore parameter variations, Juxtapose automatically creates control interfaces for “tuning ” application variables at runtime. This paper describes techniques to support design exploration for desktop, mobile, and physical interfaces, and situates this work in a larger design space of tools for explorative programming. A summative study of Juxtapose with 18 participants demonstrated that parallel editing and execution are accessible to interaction designers and that designers can leverage these techniques to survey more options, faster. Author Keywords Design alternatives, prototyping, design tools.

Structured program editors can lower the entry barrier for beginning computer science students by preventing syntax errors. However, when editors force programs to be executable after every edit, a rigid development process results. We explore the use of a separate edit-time grammar that is more permissive than the runtime grammar. This helps achieve a balance between structured editing and flexibility, particularly in live development environments. JPie is a graphical programming environment that applies this separation to the live development of Java applications. We present the design goals for JPie’s edit-time grammar and describe how its implementation supports a balance between structure and flexibility. As further illustration of the benefits of a relaxed edit-time grammar, we present “mixed-mode editing, ” an integration of textual and graphical editing for added flexibility. 1.

We present middleware for a Client Development Environment that facilitates live development of client applications for SOAP or CORBA servers. We use JPie, a tightly integrated programming environment for live software construction in Java, as the target platform for our design. JPie provides dynamic classes whose signature and implementation can be modified at run time, with changes taking effect immediately upon existing instances of the class. We extend this model to automate addition, mutation, and deletion of dynamic server methods within dynamic clients. Our implementation simplifies distributed application development by masking technical differences between local and remote method invocations. Moreover, the live development model allows server-side changes to be dynamically integrated into a running client to support simultaneous live development of both the client and server. 1.

JPie is a visual programming environment supporting live construction of Java applications. Class modifications, such as declaring instance variables and overriding methods, take effect immediately on existing instances of the class to encourage experimentation in an educational setting. Because programs are edited live, editing gestures must transform the program from one well-formed state to another, without intermediate ambiguous states. To accomplish this, JPie’s visual representation provides capsules, which represent logical code units, and semantic regions, which represent different aspects of a program. A capsule’s meaning depends upon its containing semantic region. Similarly, a gesture, which involves manipulation of a capsule, is interpreted on the basis of the semantic region in which it occurs. This paper describes how capsules and semantic regions visually expose the structure of JPie programs and support live program editing through natural atomic gestures.

Class hierarchy design is central to object-oriented software development. However, it is sometimes difficult for developers to anticipate all the implications of a design until implementation is underway. To support experimentation with different designs, we extend prior work on live development environments to allow run-time modification of the class hierarchy. The result is a more fluid objectoriented development process, in which immediate feedback from the executing program can be used to guide hierarchy design. This paper presents a framework and developer support for run-time modification of class inheritance relations in JPie, a live visual programming environment for Java. Most notably, the framework supports class reloading without modification of the Java Virtual Machine. 1.