Updated Architecture (markdown)

Architecture.md

@@ -13,6 +13,18 @@
   **File API**, where testing inputs and corresponding outputs for each task and 
   other required files are stored. It's possible to upload files, too.
 
+The worker has to:
+
+- Download the archive containing the submission and an isoeval configuration 
+  file
+- Download any supplementary files based on the configuration file, such as test 
+  inputs or helper programs (This can be done on demand, using a `fetch` command
+  in the assignment configuration)
+- Download the source codes of the student's submission
+- Evaluate the submission according to the assignment's configuration
+- Upload the results of the evaluation to the file server
+- Notify the broker that the evaluation is finished
+
 ### Internal Worker architecture
 Picture below is overall internal architecture of worker, which shows its defined classes with private variables and public functions. Vector version of this picture is available [here](https://github.com/ReCodEx/GlobalWiki/raw/master/images/Worker_Internal_Architecture.pdf).
 ![Internal Worker architecture](https://github.com/ReCodEx/GlobalWiki/blob/master/images/Worker_Internal_Architecture.png)