Update documentation

Author: jan-janssen

docs/source/development.md

@@ -1,10 +1,27 @@
 # Development
 The `pympipool` package is developed based on the need to simplify the up-scaling of python functions over multiple 
 compute nodes. The project is under active development, so the difference between the individual interfaces might not 
-always be clearly defined. The `pympipool.Pool` interface is the oldest and consequently currently most stable but at 
-the same time also most limited interface. The `pympipool.Executor` is the recommended interface for most workflows but
-it can be computationally less efficient than the `pympipool.PoolExecutor` interface for large number of serial python
-functions. Finally, the `pympipool.MPISpawnPool` is primarily a prototype of an alternative interface, which is available
-for testing but typically not recommended, based on the limitations of initiating new communicators.
+always be clearly defined. 
 
-Any feedback and contributions are welcome. 
+## Contributions 
+Any feedback and contributions are welcome. 
+
+## Integration
+The key functionality of the `pympipool` package is the up-scaling of python functions with thread based parallelism, 
+MPI based parallelism or by assigning GPUs to individual python functions. In the background this is realized using a 
+combination of the [zero message queue](https://zeromq.org) and [cloudpickle](https://github.com/cloudpipe/cloudpickle) 
+to communicate binary python objects. The `pympipool.communication.SocketInterface` is an abstraction of this interface,
+which is used in the other classes inside `pympipool` and might also be helpful for other projects. It comes with a 
+series of utility functions:
+
+* `pympipool.communication.interface_bootup()`: To initialize the interface
+* `pympipool.communication.interface_connect()`: To connect the interface to another instance
+* `pympipool.communication.interface_send()`: To send messages via this interface 
+* `pympipool.communication.interface_receive()`: To receive messages via this interface 
+* `pympipool.communication.interface_shutdown()`: To shutdown the interface
+
+## Alternative Projects
+[dask](https://www.dask.org), [fireworks](https://materialsproject.github.io/fireworks/) and [parsl](http://parsl-project.org)
+address similar challenges. On the one hand they are more restrictive when it comes to the assignment of resource to 
+a given worker for execution, on the other hand they provide support beyond the high performance computing (HPC)
+environment.