CHAPTER
3
MICROSOFT EXCHANGE 2000 SERVER
ARCHITECTURE
Active modules running on the server machine performs dedicated tasks, such as storing e-mail
messages, routing messages to the correct destinations, and so forth. To fulfill their particular
tasks, these components have to communicate with each other and with services provided by
Windows 2000, such as the Active Directory directory service and the extended Simple Mail
Transfer Protocol (SMTP) service.
By default, users can send e-mail messages and share information through public folders.
Lesson 1:
Exchange 2000 Server Components
To make the best of Exchange 2000 Server’s capabilities, a general understanding of the essential
services and their interaction is absolutely necessary. The essential components in conjunction
with various Windows 2000 services provide the basic messaging facilities.
Essential Components for Exchange 2000 Server
Exchange 2000 Server comes with numerous services. If you start the Services tool from the
Administrative Tools program group on a fully installed Exchange 2000 Conferencing server,
you can find 17 services that have names starting with Microsoft Exchange: See page 69 for
the list, but here are a few:
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SMTP Service
Unlike previous versions of Exchange Server, Exchange 2000 Server always requires message
processing through the SMTP transport.
Information Store
You can consider the Information Store service and its databases the most important Exchange
2000 Server component because it maintains the structured repository of all server-based user
data, such as e-mail messages. The executable file of the Information Store is STORE.EXE,
which resides in a default
installation in the \Program Files\Exchsrvr\Bin directory.
Mailbox and Public Stores
The information store service divides user data into two categories: private and public. Private
messages are maintained in private mailboxes, and public data can be shared among users
through public folders.
The two components of the information store are as follows:
Public Store. Maintains information stored in public folders.
Mailbox Store. Maintains all messages sent to an individual or a selected group of
addresses in private folders.
NOTE: When Information Store and Active Directory are in an operational state, users can gain
access to their messages and other data stored in mailboxes and public folders using a Messaging
Application Programming Interface (MAPI)-based client, such as Outlook 2000.
Storage Groups
The information store is organized in storage groups, which in turn can hold mailbox stores, public
stores, or both. You can manage up to four individual storage groups on a single computer running
Exchange 2000 Enterprise Server, and each storage group is capable of holding up to five
individual stores.
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System Attendant
IMPORTANT, if this is down, you will loose the EXCHANGE SERVER. The executable file
is a “MAD.EXE” located in the \Program Files\Exchsrvr\Bin Directory. The SA starts the
efragmentation routines of the Information Store and handles the DSProxy process to forward
MAPI-based address lookups to a Global Catalog server.
System Attendant Responsibilities
You can look at the various categories the SA may use to write events into the Windows 2000
application event log.
Look in the Application log in Event Viewer and click View, select FIND. Select MSExchange
SA, and then open the Category list box.
NOTE: The Microsoft Exchange SA must be running before several other Exchange 2000 Server
services can start.
Exchange 2000 Server Shutdown
The SA can assist you in the task of shutting down Exchange 2000 Server, which might be
necessary if you want to perform an offline backup or accomplish other maintenance tasks.
NOTE: Shutting down the Exchange 2000 server service, via SA does not stop the SMTP service,
the NNTP service, or the IIS process (INETINFO.EXE).
Exchange 2000 Server Startup
The file is called EMSSTART.BAT on the Exchange 2000 Server.
Exercise Summary:
very few such as Information Store and SMTP service) are required to provide the basic
messaging functionality to Outlook users.
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Internet Information Services for Exchange 2000 Server
Exchange 2000 Server is seamlessly integrated with IIS 5.0 to support SMTP, NNTP, IMAP4,
POP3, and HTTP/Web Distributed Authoring and Versioning (WebDAV). Finally, HTTP/WebDAV
is a solution that gives you the ability to work with mailboxes and public folders using almost any Web
browser.
IIS Process and Internet-Based Client Access
Integrating Internet-based client access protocols with the IIS process offers the advantages of
providing best performance and allowing you to control all Internet access protocols via IIS 5.0.
IIS Service Dependencies
*** IMPORTANT ***
Under these service depend on “IIS admin Service”, you will see a
Listing of other services that cannot be run without first starting IIS
And they are:
IIS Metabase
When you check the Windows 2000 Registry for advanced IIS
Configuration settings, you will be disappointed.
Metabase Update Service
Exchange 2000 Server stores it configuration information primarily in Active Directory, relies on the
SMTP service, and may use additional Internet services to extend its functionality.
The SA hosts a process known as the Metabase Update service implemented in DS2MB.DLL.
DM2MB.DLL resides in the \Program Files\Exchsrvr\Bin directory by default.
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NOTE: IIS configuration changes are only replicated in one direction, from Active Directory to
he IIS metabase.
Exchange Interprocess
Communication Layer
All Internet transport and access protocol engines need to communicate with the Information Store
service to access and store messaging-related information in mailbox and public stores.
You can use the command-line utility IISRESET.EXE to restart the IIS. The command
iisreset/restart/status, for instance, restarts the services and provides status information at
the command prompt.
Examining Metabase Settings for
the Internet-Based Exchange 2000 Services
The metabase resides on the local hard disk of each IIS server in a file named METABASE.BIN,
which is located in the \Winnt\System32\Inetsrv directory, by default.
**** See the process
page 78 ****
NOTE: Using the MetaEdit 2.0 utility allows you to configure properties in the metabase. Configuring
the metabase incorrectly can cause problems and may damage the IIS.
Additional Components for Exchange 2000 Server
Additional components can be used to connect to previous Exchange Server versions or foreign mail
systems, or to implement extra features such as advanced security or online conferencing.
Message Transfer Agent
The MTA is a real X.400 system that conforms to the 1984 and 1988 CCITT (International
Telecommunications
Event Service
The Event Service supports server-based scripting agents developed for Exchange Server 5.5.
Site Replication Service and Active Directory Connector
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SRS and Active Directory Connector (ADC) provide directory interoperability between Exchange
2000 Server and Exchange Server 5.5. If you need to integrate Exchange 2000 Server with an
environment running previous versions of Exchange Server, you need to configure and use these
services to handle directory replication with the legacy Exchange directory service.
MS Mail Connector
The MS Mail connector provides connectivity to MS Mail postoffice. Acts as a connector or
a gateway.
Directory Synchronization with MS Mail (DXA)
Or DXA is the active component that exchanges addresses information between Exchange 2000
Server and MS Mail by using the MS Mail DirSync protocol. The MS Mail addresses are
maintained as mail-enabled contact objects in Active Directory as usual.
Connector for Lotus cc:Mail
If you plan to integrate Exchange 2000 Server in a Lotus cc:Mail messaging network, use the
Connector for Lotus cc:Mail. This connector allows you to send messages between both systems,
but it can connect to only one cc:Mail post office directly.
Connector for Lotus Notes
The Connector for Lotus Notes provides connectivity to a Lotus Notes network by means of
message transfer and directory synchronization.
Connector for Novell GroupWise
The Connector for Novell GroupWise is a complete messaging solution for connecting Exchange
2000 Server and Novell GroupWise environments.
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Key Management Server
The Key Management server operates in conjunction with Microsoft Certificate Server to maintain
X.509 version 3 certificates and encryption keys.
Outlook Web Access
Outlook Web Access (OWA) is installed as part of the default setup of Exchange 2000 Server and
supports HTTP-based access to mailbox and public folder resources.
Exchange Chat
Exchange Chat Service allows you to configure chat rooms on your server to support real-time
collaboration using any standard Internet Relay Chat (IRC) or Extended IRC (IRCX) client.
Instant Messaging
Instant Messaging integrates with the IIS 5.0 Web Publishing service.
Video and Data Conferencing
Conferencing Server of Exchange 2000 Server is primarily a centralized reservation system that
allows your users to schedule and join meetings from Outlook or Web Browser.
Lesson 2:
Communication Between Essential Server
components
The Information Store is responsible for the mailbox and public folder stores. The IIS process and
its information services pull configuration information primarily from their metabase.
Interprocess Communication Mechanisms
They rely on lightweight remote procedure calls (LRPCs) and simultaneously support Windows
Sockets.
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Windows Sockets
Sockets is a de facto standard for accessing datagram and session services over TCP/IP. Windows
Sockets, however, is not limited to TCP/IP. Windows Socket 2 provides a protocol-independent
interface supported over both TCP/IP and Internetwork Packet Exchange/Sequenced Packet
Exchange (IPX/SPX).
Basically, every Exchange 2000 Server service supports communication over Windows Sockets.
Socket – is made up of IP address and port number.
Windows Sockets is a protocol-independent networking API
offering the following
advantages:
Familiar networking API to programmers using Windows or UNIX
Binary compatibility between Windows-based TCP/IP stacks and utilities from different vendors.
Support of connection-oriented and connectionless protocols (such as TCP and UDP).
No protocol overhead added to the data packet (NetBIOS interface and mapping layers are not required)
Supported on workstations running only TCP/IP without NetBIOS support.
Remote Procedure Calls
RPCs are an application-layer communication mechanism, which means that RPCs use other
interprocesses communication mechanisms, such as NetBIOS, named pipes, or Windows
Sockets, to establish the communication path.
However, RPCs, have several disadvantages, including the following:
as the client program execution stops until the server function returns results).
add significant overhead to the network packet.
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Shared Memory, Files and E-Mail Messages
Exchange 2000 Server processes can share information through shared memory, files, and e-mail
messages. Shared memory can only be used on the local computer, files are used primarily for
interprocess communication on the local machine, and e-mail messages are used for communication
over unreliable network links.
There is a redirectory used so there is only one copy of a running process open at a time.
Clients and Administrative Interfaces
Messaging clients and administrative utilities communicate with various server components to
perform their tasks. Clients prefer RPCs and management utilities rely primarily on LDAP to
communicate with Windows 2000 Server’s directory service, although RPCs are also used
when necessary.
Messaging Clients. Client-based communication is straightforward and less complex
than communication through administrative interfaces. Outlook 2000 and other
MAPI-based clients also need to communicate with Active Directory to log on to
mailboxes and retrieve recipient information from address lists, which is often accomplished
using the DSProxy component of the SA Service.
Administrative Tools. The Exchange System Manager allows you to manage most
aspects of the server configuration, so it must communicate with many server components.
Active Directory Directory Services. When you administer Exchange 2000 Server,
the Exchange System Manager communicates with the nearest Active Directory (a domain
controller) via LDAP.
Information Store. The Information Store service the Exchange System Manager’s
communication partner. Used primarily for troubleshooting.
System Attendant. The SA service is contacted in the event you attempt to examine
dynamic information maintained by the SA service, such as the Domain Controller Used
by Services on This Server.
Transport Components. To view messages awaiting delivery in the message queues of the
SMTP service, the MTA, or installed connectors, communication with the corresponding
service is required.
Additional Components. The Exchange System Manage also communicates with other
components when they are installed, configured, and active, for instance, to display status
information, such as information about current user sessions. The KMS or Key
Management Service must be accessible through RPCs if you want to create security
tokens or designate additional security administrators.
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Exercise Summary:
and additional components, if they are installed.
communicate directly with other server components, such as the information store for mailbox
and public folder statistics.
Component-to-Component Communication
Which is the busiest component in any Exchange 2000 Server environment? As figure 3.8 page
91, suggests, almost every Exchange 2000 Server component retrieves information from Active
Directory, such as configuration information or information about recipients, or at least
communicates with Active Directory for validation of access permissions.
Active Directory Directory Service
With so many components, plus MAPI-based clients and the administrative utilities accessing
directory information, Exchange 2000 Server has the potential for monopolizing Active Directory.
The Global Catalog represents an especially precious resource. By default, only the
first domain controller installed in a forest is a Global Catalog server, so you should manually
configure additional Global Catalogs in each site and monitor their workload carefully. At least
one Global Catalog should be available in each domain.
NOTE: With the exception of address book lookups from MAPI-based programs and the
SMTP routing process, all directory access goes through DSAccess.
System Attendant
Active Directory is not the only component involved in component-to-component communication.
The System Attendant (SA), for instance, contacts the Information Store and the KMS is installed.
The SA contacts several server components for the following reasons:
Active Directory. The SA communicates with Active Directory to build routing tables and
generate proxy e-mail addresses for newly created recipient objects.
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Information Store. The SA service communicates with the Information Store whenever you
configure a monitor to check the conditions of server services and messaging links. The SA
owns a hidden mailbox in the Information Store to send the monitor messages.
IIS Process. The SA service communicates with the IIS to update the IIS metabase.
KMS. The SA service performs important tasks in the background if the KMS has been
installed in your organization. The SA receives the requests of users in the form of e-mail
messages from the Information Store to enable the advanced security that the administrator
has configured form them. For the SA has to “unwrap” the e-mail messages to retrieve the
requests. It then communicates with the Exchange KMS to take over the users’ security
keys and X.509 certificates.
Information Store
The Information Store works primarily with the messaging clients, the SMTP service, and the
SA as messages are sent and delivered within an organization.
The Information Store communicates with the following components:
Active Directory. The information store communicates with Active Directory to retrieve
security-related information (such as access permissions) and information about the
configuration of its resources.
Connectors for Lotus cc:Mail, Lotus Notes, and Novell GroupWise. The IS
communicates with gateways to foreign systems to announce the presence of new mail
awaiting transfer in message queues.
MAPI-based clients. The IS communicates with MAPI-based clients to notify them
that newmessages are arrived.
MTA. The IS communicates with the MTZ to announce the presence of new mail
awaiting transfer through X.400 connectors or connectors to foreign messaging systems.
SA. The IS communicates with the SA to request the creation of and provide information
for tracking log files to be used by the message tracking center.
SMTP transport. The IS communicates with the SMTP transport to submit messages for
delivery.
Third-party gateways and connectors. The IS communicates with 3rd party gateways
in much the same way as with the connectors for Lotus cc:Mail, Lotus Notes, and Novell
GroupWise to announce the presence of new mail awaiting transfer.
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SMTP Transport Service
The SMTP service receives every individual message from the Information Store to determine
whether the recipients reside on the local computer or on remote systems.
NOTE: In a native Exchange 2000 Server environment, the SMTP service is the only component
directly communicating with its counterparts on remote Exchange 2000 server. All other Exchange
2000 Server components rely on the SMTP message transport for their server-to-server
communication.
The SMTP service communicates with the following components:
Active Directory. The SMTP service communicates with Active Directory to look up
address information to resolve recipients and expand distribution groups.
Information Store. The SMTP communicates with the IS to obtain messages from and
place messages into the Information Store.
Remote SMTP Services. The SMTP service communicates with other SMTP
services over the network to transfer e-mail messages.
MTA and Messaging
Gateways (Foreign)
It is important to note that the SMTP service does not directly communicate with the MTA or
any gateways installed on the local computer. If a message is sent to a foreign X.400 system,
for instance, the SMTP service uses the MTA by means of the IS to transfer the messages.
The MTA is also involved in the communication through the MS Mail Connector.
All MAPI-based messaging connectors, such as the connectors, such as the connectors for
Lotus cc:Mail, Lotus Notes, and Novell GroupWise, are not accessed by the MTA because
they communicate directly with the Information Store where their messages queues reside.
OTHER Components ***
See page 98 & 99 ****
Exchange 2000 Server Message Handling
The central control station of all native Exchange 2000 Server message transfer is the SMTP
service, the Exchange 2000 Server Extensions of the SMTP service, to be exact.
SMTP Transport and the MTA
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If your environment contains connections to the Internet, X.400 systems, MS Mail, Lotus cc:
Mail Lotus Notes, Novell GroupWise and legacy PROFS connection through a computer
running Exchange Server 5.5, a popular fax gateway, and not to forget an exotic pager
gateway, then a distribution group called Cosmopolitan may contain recipients from all these
environments.
SMTP Transport Components
Several SMTP components are involved in message handling and transfer. The store driver,
for instance, allows the SMTP transport to directly interact with the Information Store. As
soon as the IS indicates to the store that new mail has arrived, the store driver informs the
advanced queuing engine that a message must be routed.
Message Handling
Exchange 2000 Server handles messages as follows:
A remote SMTP system connects to the local SMTP service and transfers a message.
The SMTP service creates a temporary file for each incoming message on the file system
and streams the messages into this file.
Alternatively:
Outlook users on the local server sends messages, which are placed in the information store
first. Figure 3.13, page 101 also shows a path for messaging that arrive through the MTA
(for example, via an X.400 connector) that are directly transferred to the Information Store
service.
For each message, the message store driver informs the advanced queuing engine that a new
message requires processing.
IN BOTH CASES:
The advanced queuing engine needs to pas the incoming messages to the categorizer to
determine how to process the messages further.
Destination-domain queues.
The advanced queuing engine now allows any custom event sinks installed on the server to
process the message.
Messages in the destination-domain queues are passed to the routing engine, which returns a
next-hop identifier for each message destination.
The store driver informs the IS and the IS retrieves the messages from the local delivery queue
to deliver them to local recipients or the MTA for further processing.
The SMTP service transfers the messages from the destination-domain queues to the next hop
in the routing infrastructure.
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Message Categorization
Each recipient may require specific message handling.
The exchange 2000 Categorizer performs the following steps: (new for 2000)
Attempts to resolve the originator address using Active Directory.
Expands any distribution groups to determine all recipients, provided that local group expansion
is allowed on the server.
Resolves all recipients that exist in Active Directory and marks the remaining recipients as
unknown.
Checks if delivery restrictions and other limits exist for the originator and recipients.
Creates Multiple copies of the message if recipients require separate processing, such as
local and remote recipients, or recipients with restrictions.
Places the individual copies of the message in the appropriate delivery queue.
Informs the advanced queuing engine that the message categorization is complete.
The Exchange 2000 Categorizer is implemented in PHATCAT.DLL which is in \Program
Files\Exchsrvr\Bin Directory.
Chapter Summary:
collaboration system that includes Active Windows 2000 services.
controls the SMTP transport.
with the Information Store through memory rather than through RPCs or other communication
methods.