Exchange Web Services (EWS) is an XML-based protocol that is used to access Exchange servers from non-Microsoft platforms and applications. EWS serves as a successor to previous WebDAV approaches. EWS uses SOAP over HTTP and allows access to Exchange functionality like email, calendars, contacts from any platform or programming language. EWS was designed to provide a more high-level interface than MAPI and handles complex functions like recurrence and meeting requests. Clients use EWS because it provides cross-platform access and is easier to use than MAPI for developers. Zarafa implements an EWS gateway to allow clients to access Exchange functionality through EWS via Zarafa's MAPI implementation.

1. Exchange Web Services (EWS)
Steve Hardy

2. How are we going to pronounce it ?
• Eee-doubleyou-es
• Eee-wee-es
• you w’s ?

3. This is a ‘ewe’

4. What is EWS
- XML-based protocol (SOAP)
- Introduced in Exchange 2007
- Successor to previous WebDAV approach
- Used from introduction for OWA 2007 and later
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope>
<soap:Body>
<GetItem>
<ItemShape>
<t:BaseShape>Default</t:BaseShape>
<t:IncludeMimeContent>true</t:IncludeMimeContent>
</ItemShape>
<ItemIds><t:ItemId Id="AAAlAF" ChangeKey="CQAAAB" /></ItemIds>
</GetItem>
</soap:Body>
</soap:Envelope>

5. Who/what is using EWS at the moment?
• Outlook 2010
– Free/Busy
– Some minor features
• Mac
– Outlook 2011
– ‘Mail’
– ‘Addressbook’
– ‘Calendar’
• Other
– Various opensource projects for accessing exchange server from
opensource packages (eg. Evolution, Thunderbird, etc)
– Various closed source projects (eg. Archivers, Indexers, etc)

6. Relation to MAPI
EWS protocol
EWS Gateway
(IIS plugin)
MAPI
Exchange mail store message
database
(EMSMDB)

7. EWS: MAPI + CDO over XML
EWS protocol
MAPI -> XML engine
EWS Gateway Calendaring engine
(IIS plugin) (like CDO)
Meeting/Task request
engine (like CDO)

8. Why was it designed this way ?
• Much more high-level functions
– Easier for developers to use, less client-side code needed
– Solves most of the really hard stuff like recurrence and meeting request
handling
• XML/SOAP interface allows access from any platform
• XML/SOAP interface allows access from any programming
language (well, in theory …)
• Most easily built on top of MAPI since MAPI already provides many
features that you need for EWS

9. Why do clients use EWS?
• On non-MS platform
– You have no choice, except IMAP & CalDAV
• On MS platform
– It’s easier than MAPI, and usable from .Net applications
• Why not IMAP?
– Email only
– No handling of meeting requests, etc
• Why not CalDAV?
– Calendar/tasks only
– No easy handling of meeting requests, etc

10. EWS in Zarafa
EWS protocol
MAPI -> XML engine
EWS Gateway Calendaring engine
(Standalone server) (like CDO)
Meeting/Task request
engine (like CDO)

11. EWS in Zarafa: general design
• Forked processes (think ‘zarafa-ewsd’)
• Primarily in Python
– Rapid development possible
– Speed disadvantage compared to C++ is not important, since most real
processing is done by MAPI (C++)

12. EWS general development goals
In order of priority:
3.Support e-mail handling in Outlook 2011, Mac Mail
4.Support addressbook handling in Outlook 2011, Mac Addressbook
5.Support calendar handling
6.Support MR/TR handling
7.Management functions like setting OOF, etc.
Low priority:
-Bulk handling features of EWS
-Administration features

13. XML handling in Zarafa-EWS
• Always the question: pull or push XML ?
Push
- Read all XML at once, parse it all, then pass to processor
- Easy to code, clear overview
- Slow for large requests: high latency
Pull
- Read XML bit-by-bit, process when possible (before reading end of
XML request)
- Harder to code, sometimes makes the code less readable
- Low memory footprint, low latency

14. Demo