ToDo Server Module Documentation
Author: Maksim Noy <mnoy@cs.washington.edu>

Snapshot
---------
Since there is nothing to bound the snapshot, server will send back all the ToDo items for the 
user when an update is called for.

Updates
--------
* Addition: server expects a sequence of <text> and <priority> tags, one of each for every new 
record. Sends back updates with IDs
* Modification: server expects a sequence of <text>, <priority>, <id>, <done> tags (all are 
required but in any order). Sends back nothing.
* Deletion: server expects a sequence of <id> tags. Sends back nothing.


Examples of complete and valid messages to the server:
-------------------------------------------------------
* Snapshot: 
<snapshot><todo_app></todo_app></snapshot>

* Addition: 
<update><mode>add</mode><todo_app><priority>1</priority><text>Finish Project</text></todo_app></update>

* Modification: 
<update><mode>modify</mode><todo_app><id>9</id><done>0</done><priority>5</priority><text>Finish Project</text></todo_app></update>

* Deletion: 
<update><mode>delete</mode><todo_app><id>9</id></todo_app></update>


DTD
----
<!DOCTYPE snapshot [
  <!ELEMENT snapshot (todo_app)>
]>


<!DOCTYPE update [
	<!ELEMENT update (mode,todo_app)>
	<!ELEMENT mode   (#PCDATA)>
	<!ELEMENT todo_app   ((priority?,id?,text?,done?)+)>
	<!ELEMENT priority   (#PCDATA)>
	<!ELEMENT id         (#PCDATA)>
	<!ELEMENT text       (#PCDATA)>
	<!ELEMENT done       (#PCDATA)>
]>