[EWS] Identifiers in Exchange

Summary

Recently in the way of using EWS to develop the mailbox service, including writing e-mail, view the details of a message, reply, all replies and forwarding functions. The question about the unique identifier when getting the inbox. Also a little confused, in each mail item, there is an identity of ChangeKey and UniqueID. The difference between the two is to look at MSDN to find the results.

EWS Identifiers in Exchange

Original address: https://msdn.microsoft.com/en-us/library/office/dn605828 (v=exchg.150). aspx

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Find out the identifiers in exchange, how to use them in the EWS APIs and references.

In Exhange storage, each object has a unique identity. You can use object identifiers to refer to the object or to distinguish it from other objects. The folder and item identifiers are the most common identifiers.

To understand the identifier and its importance to your application, it is helpful to understand the relationships between objects. When your ews Managed API or EWS app is communicating with Exchange, you will use different levels of objects, including mailboxes, folders, and item objects. One store may be any of them. Typically, he is a mailbox on an Exchange server, but it may also be a folder that is exposed on the Exchange server. (Remember, online Exchange is part of Office 365 in online exhange, and many exhcnage versions start with exchange2013, exposing files that are just another type of mailbox, not a different kind of storage.) ）

The store includes folders, folders include items, and each folder and item has an identity. As shown in the following:

EWS identifiers

The identifiers used in folders and items in EWS are either EWS identifiers or called Ewsids. Ewsids can be seen in many different objects of EWS. Just different objects are called different. Because, you might use these objects in your application, and you want to understand how to identify and ewsids related objects.

These identifiers in Ews also apply to the EWS Managed API. In the EWS Managed API, identifiers are properties of objects that are used to map EWS elements.

The following table lists the object identifiers in Ews.

Object	Identity	Relationship with Ewsid
Calendaritem	The corresponding child element contains a unique identifier for the calendar item.	The child elements corresponding to the Itemid are the same as the entries identified by the Ewsid.
Conversationid	Its ID property contains the identity of the item that is part of the meeting.	The id attribute is the same as the item with the EWSID identity
Attachmentid	Provides a unique identifier for the attachment. The Rootitemid property contains the unique identity of the item that the attachment of the root store belongs to.	The attachment can be an additional items in the Exchange store, in this case, the same as Ewsids. Rootitemid is ewsid because it refers to the item in the store.
Personalid	The ID property returns a string containing the person's identity.	The id attribute is the same as the person Ewsid identified.
ContactId	The ID property returns the string of the contact's identity.	The id attribute is the same as the contact that Ewsid identifies.
GroupId	The ID property returns the string identifying the group.	The D property is the same as the group identified by Ewsid.
Associatedcalendaritemid	The id attribute identifies the calendar item, which is related to Meetingmessage,meetingrequest,meetingresponse or meetingcancellation.	The D property is the same as the calendar item that Ewsid identifies.
Userconfigurationproperties	The identity value of this element specifies the identifier attribute.	This identifier is not directly mapped to Ewsid, and it is not a property identifier.
Occurrenceitemid	The Recurringmasterid attribute identifies the master of a recurring item.	He Occurrenceitemid value does not maps directly to the EwsId, but the Recurringmasterid does because it references The top-level object of the recurring item.
Storeentryid	A exhange storage identity that contains a single item	This identifier does not directly map the large ewsid, but it provides the identity that the item saves in the store.

Attention

1. The value of the element that corresponds to the folder and item is case-sensitive. If you look at a folder or item that is returned by the FindItem operation (or the Finditems EWS managed API method), you may think that this is the ID of another item that is duplicated; however, the ID of one or more characters in these two items will have different situations.
2. If the item ID that you want to store is retrieved in the database, the recommended field size is 512 bytes, so it is large enough to hold the GUID.
3. Do not assume that your ID will always be valid if you need to retrieve the item at a later time. If an item is moved in the store, the ID can be changed because of the way the move is handled. A project is actually copied, and a new ID is generated, and then the original item is deleted.
4. Identifiers in exchange are opaque, for example, Ewsid is created from some information, but not important to developers, but important for exchange.
5. When you use items in exchange, you need to remember the ChangeKey property, which is used to track project status in addition to the project identity. Any time a project has changed will produce a new changkey. When you perform a updateitem operation, for example, you can use the ChangeKey property to let the server know that your update is being applied to the latest version of the item. If another application changes the item you are updating, the changes will not match and you will not be able to perform the update operation.

[EWS] Identifiers in Exchange