HTTPS is recommended for Exchange on-premises and is required for Exchange Online.Īuthentication methods - EWS messages include basic, NTLM (Windows Integrated authentication), or OAuth authentication information as part of the HTTP payload. The SOAP XML message - An XML message, in a SOAP envelope, embedded in an HTTP/S message that conforms to the dl file on the Client Access server. If you use the EWS Managed API to develop the EWS application, the EWS Managed API assemblies have to be installed on the client and redistributed by your application. The following are the components that are shown in the diagrams:ĮWS application - This can be a client, portal, or service application and it can be installed on a client or on an Exchange on-premises Client Access server.
EWS application and the Exchange Online architecture EWS application and the Exchange on-premises architectureįigure 2 shows the same communication paths shown in Figure 1, as used by EWS applications when communicating with Exchange Online.įigure 2. From the EWS application perspective, the communication paths are identical and the authentication methods only vary slightly the main difference is the visibility you have into the Exchange backend.įigure 1. The following diagrams show the authentication methods and communication paths used by EWS applications when communicating with Exchange 2013 and Exchange Online. The SOAP message is embedded in an HTTP message when sent between the application and the server, which means that as long as your application can post XML through HTTP, it can use EWS to access Exchange. EWS applications can access mailbox items locally or remotely by sending a request in a SOAP-based XML message. Learn about how EWS works within the Exchange architecture, and find out which protocols EWS relies on.Įxchange Web Services (EWS) is a cross-platform API that enables applications to access mailbox items such as email messages, meetings, and contacts from Exchange Online, Exchange Online as part of Office 365, or on-premises versions of Exchange starting with Exchange Server 2007.