## 6 Key Challenges and Future Directions
### Limitations of Current WebAssembly Implementations  
* **Lack of Garbage Collection** One of the major hurdles when dealing with Wasm in the context of IoT is the lack of native support for garbage collection. Garbage collection is a form of automatic memory management that can greatly simplify programming, and is a critical feature in many high-level programming languages. Wasm does not directly support garbage collection, which can complicate things for developers. * **Understanding the Problem** Garbage collection is the process of identifying and freeing up memory that is no longer in use by the program. It is used in many modern programming languages, including JavaScript, Python, Java, and Go. The absence of native garbage collection support means languages that rely on it cannot be fully or effectively compiled to Wasm. In IoT scenarios, where devices often have constrained memory resources, efficient memory management is essential. Without garbage collection developers have to manually manage memory, which is more challenging and error-prone as well as time-consuming. * **Current Solutions and Workarounds** For languages such as C and C++, which do not use garbage collection and allow developers to manually manage memory, this is not an issue. However, for languages that depend on garbage collection there are a few solutions and workarounds. * **Compile the Garbage Collector** One approach is to compile the garbage collector of the source language into Wasm along with the program itself. This can make the resulting Wasm module self-contained and capable of doing its own garbage collection. However, this can significantly increase the size of the resulting module, which might not be suitable for IoT devices with limited memory. * **Use WASI** The WASI provides a capability-oriented system interface that allows Wasm modules to interact with system resources, including memory management. * **Use Linear Memory** Wasm's linear memory can be manipulated manually from within Wasm code (or from JavaScript, if running in a browser environment). However, this places the burden of memory management onto the programmer, increasing complexity. * **Interoperability Challenges*
* Interoperability refers to the ability of different systems or applications to communicate, exchange, and utilize data effectively. It is a critical aspect of modern technology stacks, in which multiple languages, libraries, and services often need to work together seamlessly. There are certain interoperability challenges that emerge when considering Wasm in the context of IoT, predominantly due to the varying nature of IoT devices and Wasm's unique operational dynamics. * **Communication between JavaScript and WebAssembly*
* While Wasm was designed to coexist with JavaScript in a web environment, communication between the two is not always straightforward. Currently, interaction between JavaScript and Wasm is mainly restricted to numeric data types. This constraint means that transferring more complex data types such as strings or objects between JavaScript and Wasm requires them to be broken down into simple numeric components or transferred using shared memory. The process of data conversion adds an extra layer of complexity to application development, and can introduce a performance overhead. It requires careful management to ensure data integrity, and can lead to errors if not properly implemented. While proposals such as Wasm Interface Types aim to improve this, the problem remains a significant challenge for developers. * **Compatibility With Various Devices*
* IoT devices come in various forms and use a range of software and hardware configurations. Certain IoT devices might use different architectures and operating systems, creating a need for additional layers of abstraction in the application code. Wasm's goal of \"write once, run anywhere\" promises to ease this problem by providing a universal binary format. However, the Wasm runtime needs to be ported to each new system architecture, which can require considerable effort.