Sunday, June 16, 2013

Microsoft Exchange Architecture continued

Microsoft Exchange Architecture
We will look at the Exchange Server Architecture in detail here:
1) Unified Messaging: The unified messaging server role enables unified messaging for an Exchange Server organization.
Features included are :
a) Outlook voice access : user logs onto the mailbox and accesses it via  a voice user interface. An associated UM server checks Active Directory for addresses and access information.
b) Call answering : UM Server plays the individual's greeting and captures voice mail message which is then sent to Hub transport server for delivery
c) Play on Phone: User receives a voice mail message and selects play. Outlook uses https to communicate with the UM web services to fetch the appropriate message.
d) One Inbox: Unified messaging puts all the voice, video and audio content in the same mailbox for the users to pull it from different devices.
e) The Active Directory UM objects has a dial plan comprising of an auto-attendant and user dictated Mailbox policies. A UM IP gateway communicates with the external PBX switchboard.

2) The Mailbox server role: includes the following features:
a) Resource Booking Attendant: This enables conference room booking, enforces duration, who can book, delegates for approval and provides conflict information. The policies and resources for auto-accept are booked using OWA or Exchange management shell.
b) Generate Offline Address Book: OAB files are generated, compressed and placed on a local share. Administrators can configure how the address books are distributed.
c) Outlook Client Connection : Clients inside the mailbox server can access the mailbox server directly to send and retrieve messages.
d) Exchange administration : Administrator-only computer retrieves active directory topology information from the corresponding AD service.
e) Mailbox and Public Folder Databases: Private user database as well as public folder information are stored in Exchange databases as logical containers
f) Exchange Search : generates fulltext index and indexes new message and attachments automatically
g) Calendar attendant : automatically puts new meetings as tentative appointments and deletes out of date meeting requests.
i) Messaging records management: This is a managed folder.

3) Client Access Server Role: includes the following features:
1) Exchange web services : These web services comprise of the autodiscover service, exchange data service, availability service, synchronization service, notification service, and managed folder service. Clients using EWS communicate over the https and SOAP / REST and these services are hosted in the IIS.  The autodiscover service lets the clients find the exchange server via AD or DNS. The Exchange data service provides read or write access to mailbox and public folder mail, contact, tasks and calendar data. The synchronization and notification services alerts changes to mailbox and synchronizes public folders. The availability service retrieves free/busy information and meeting time suggestions.
2) Exchange Active Sync : Used mainly by the handheld devices, this service is used to push messages from the intranet to the devices using cellular / wireless network and SSL. Remote device wipe can also be initiated.
3) Outlook web access : A variety of authentication schemes together with light and full feature clients enable mailbox to be accessed via browser.
4) CAS Proxy and redirection. Proxy enables another CAS server to be made available when one is not. Redirection informs the user the correct OWA url when user tries to access another.
5) Intranet features include Sharepoint, file share integration, conversion of pdf and office attachments to HTML, single sign on for mailbox server access, mailbox server access and most OWA configuration settings are stored in Active Directory.

4) High Availability includes features such as
1) no replication : Failover cluster is built using shared storage array and Microsoft Cluster service.
2) replication to a local disk set : partitions data for performance and recovery and adds data redundancy without service redundancy
3) replication to a standby server : Source server can be standalone. Target must be stand-alone and passive. Logs are copied, verified and replayed. Database is copied. There is a built-in delay for log replay activity.
4) replication within a cluster : Failover cluster built using Microsoft Windows cluster service with log replay and copying database. Hub Transport Server acts as the file share witness.

5) Hub Transport Server includes features such as :
1) directly delivers message between the source server and the target server by reducing the hops. Internally, it has a pickup/replay directory, a submission queue,  a categorizer that takes the messages from the submission queue and processes the message  by resolving recipients, routing, converting content, processing routed messages, and message packaging before delivering it to the delivery queue.
Courtesy : MSDN
 

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