OpenWP Project
OpenWP state and limitations
As said in the introduction, OpenWP is in its very early stage of development and has a bunch of limitations, some that will soon be resolved, some that probably won't. Here are some of the limitations we can think of:
- for now only sequence, parallel split, and synchronize are handled. OpenWP doesn't yet handle parallel sections explicitely (just parallel loops), but a similar effect is obtained by indicating dependencies of the parallel tasks. It's just less formal and should be resolved soon. Choices and merges aren't handled yet.
- data must be Serializable as it's stored in distant location, usually in files. This probably won't change.
- arrays that are intended to be split will be on one dimension only (this should be resolved)
- in parallel loops computation is done on sub-arrays, and for now the index value should not be part of the computation itself. for example, a simple init : for (int i = 0 ; i < u.length ; i++){ u[i]=i } will result in an incorrect value for u because each sub array will have a value ranging from 0 to u.length/number of subarrays.
- arrays can't be accessed in a random way and, more important, can't be updated in a random way. So arrays must be split into smaller arrays, each task handling one piece of array.
- openWP generated method must be static
- for now CompileAndLaunch program only handles a single java program file, which should contain only one class
- the execution can't be dynamic (can't handle dynamic excution without a priori knowledge, see workflow patterns site)
Next steps
The next steps of development are toward taking care of memory access. For now data is stored directly into the DHT, we have to add an indirection level to put URIs into the DHT, then implement accessors to retreive/store data into the storage. We also have to find a definitive way to split loops, even if openWP is not primarily intended to handle such loops (which will be preferably handled with OpenMP).