EWS Managed API, EWS, and web services in Exchange

The EWS Managed API is the recommended interface for developing client applications that use EWS and Autodiscover to communicate with Exchange. You can use the EWS Managed API to work with email messages, calendar, task, and contact information, and allow programmatic access to mailboxes, public folders, and public folder mailboxes. The API enables programmatic access to most Exchange resources in a more intuitive format than the underlying EWS SOAP messages or the now deprecated generated proxy classes. Nearly all of the functionality available in the underlying EWS operations is available in the EWS Managed API, although there are minor differences.

The EWS Managed API is essentially a wrapper for EWS. EWS SOAP calls are sent by the EWS Managed API and the EWS SOAP responses are also parsed and handled by the EWS Managed API.

Note

The EWS Managed API is now available as an open source project on GitHub. You can use the open source library to: Contribute bug fixes and enhancements to the API. Get fixes and enhancements before they are available in an official release. Access the most comprehensive and up-to-date implementation of the API, to use as a reference or to create new libraries on new platforms. We welcome your contributions via GitHub.

EWS provides a set of operations that client applications use to access and manage Exchange store items. Just like the EWS Managed API, you can use EWS to work with email messages, calendar, task, and contact information, and allow programmatic access to mailboxes, public folders, and public folder mailboxes. With EWS, data is sent to and from the Exchange server by means of XML that is based on a schema definition. The client application creates an XML request, submits it to the server, and receives an XML response with data that is then parsed by the client.

The SOAP Autodiscover service was introduced in Exchange 2010. If you are targeting a version of Exchange starting with Exchange 2010, including Exchange Online, we recommend that you use the SOAP Autodiscover service, rather than the POX Autodiscover service, to get client configuration data from Exchange.

Like the POX Autodiscover service, the SOAP Autodiscover service provides configuration information, such as the EWS URL, but it allows for more granular control over the requested settings. The SOAP Autodiscover service also provides additional information about the federated status of an organization.

The "plain old XML" (POX) Autodiscover service enables applications to automatically configure user settings. You can use the Autodiscover service to determine client settings based only on a user email address. The end result of using the POX Autodiscover service is that a client can automatically get the EWS service URL.

You can use the POX Autodiscover service to configure client applications that target versions of Exchange starting with Exchange 2007, including Exchange Online. Note that the POX Autodiscover service does not enable you to specify which settings are returned in a response. We recommend that clients that target versions of Exchange starting with Exchange 2010 or Exchange Online use the SOAP Autodiscover service, because it provides for more granular control over requested settings.

The Mail, Calendar, and Contact REST APIs provide an easy-to-use way to access and manipulate Exchange Online data by using the OAuth and OData open standards. Because these APIs require OAuth version 2.0 for authentication, your application does not have to handle or store user credentials. OAuth also makes it possible to request tightly scoped permissions to user data.

The user photo REST API, introduced in Exchange Server 2013 and Exchange Online, enables you to retrieve a user's photo from either Exchange or Active Directory Domain Services (AD DS). You can use this service instead of the GetUserPhoto operation EWS operation.

The Unified Messaging (UM) web service provides a set of operations that enable a client to access UM functionality such as initiating and managing phone calls that play mailbox items (including voice mail messages) on telephony devices, UM PIN reset, enabling missed call notifications, turning on voice Out of Office (OOF) greetings, and getting UM settings. In versions of Exchange starting with Exchange 2010, including Exchange Online, EWS provides some UM functionality.

• Explore the EWS Managed API, EWS, and web services in Exchange – Contains conceptual and how to information that applies to the web services in Exchange.

• Web services reference for Exchange – Contains reference information for EWS, the EWS Managed API, Autodiscover, and the Unified Messaging web service.

• Get started with EWS Managed API client applications

• Get started with EWS client applications

• Exchange 2013 101: Code Samples