MCSE Training Kit Exam 70-224(c) Microsoft Exchange 2000 Server Implementation and Administration
Authors: Unkroth K.
Published year: 2001
Almost a decade ago, Microsoft began its development of a powerful enterprise messaging system, which years later became known as Microsoft Exchange Server. The first Visual Basic demo of the Exchange Administrator program was shown at computer fairs in 1994. However, the market had to wait until July 1996, when Microsoft finally released Exchange Server version 4.0, which relied on a full-featured X.400 (88) message transfer agent. In the early 1990s the X.400 standard was widely recognized as the framework for global messaging.
Today, the Internet is the single most important global messaging environment, so Microsoft Exchange 2000 Server focuses entirely on Internet technologies. It is Microsoft's most recent answer to the demand for a high-end, Internet-aware messaging and collaboration system. When you take a closer look, you will find that Exchange 2000 Server opens new avenues for exciting technologies and eliminates some of the limitations of earlier Exchange Server versions.
This chapter discusses basic messaging features and describes Microsoft's design goals for Exchange 2000 Server. It also covers in brief Exchange 2000 Server's support for industry messaging standards and interoperability issues.
To complete this chapter:
A new messaging system cannot expect to find an uncultivated market segment. Messaging is one of the most popular network applications, available virtually everywhere. Why should your organization, which most likely has a messaging solution in place, consider Exchange 2000 Server?
This lesson provides basic guidelines for evaluating messaging systems. It will help you if you are considering Exchange 2000 Server. If you have decided to use Exchange 2000 Server, this lesson will give you the confidence that you have made the right choice.
At the end of this lesson, you will be able to:
Estimated time to complete this section: 75 minutes
Shared-file messaging systems maintain a structure of directories and files at a centralized location—usually on a file server. These centralized structures are often called post offices . Every user who wants access to e-mail messaging needs to access a mailbox within a post office. The post office serves as the mailbox repository for multiple users. Typical messaging systems that use shared-file post offices are Microsoft Mail for PC networks and Lotus cc:Mail.
To send messages, users must write their data into the directories (mailboxes) of the post office. The users on the receiving end recognize the written data as incoming messages. The post office itself is a passive file structure, meaning that the client programs must perform all processing of sending and receiving themselves . To check for new messages, clients must poll the post office at regular intervals (see Figure 1.1).
Figure 1.1 A shared-file messaging system
When one client opens common files for writing, these files must be locked to prevent accidents. All other clients must wait until one client has completed its write operation. The more clients that access the same post office, the more often these common files will be locked and all other clients will have to wait. This effect can be worsened if the underlying network operating system is not optimized for fast input/output operations. It is not advisable to create a very large number of mailboxes on one server. Microsoft Mail post offices, for instance, are limited to 500 users.
Table 1.1 lists the general advantages and disadvantages of shared-file messaging systems.
Table 1.1 Advantages and Disadvantages of Shared-File Messaging Systems
|Advantages of Shared-File Messaging Systems||Disadvantages of Shared-File Messaging Systems|
|Messaging systems are independent of the underlying network operating system as long as read-write access to the post office is guaranteed .||The client must perform all the work to download messages. Client polling generates a high volume of network traffic.|
|A shared- file-based e-mail system doesn't need a very powerful machine on the server side because all processing is accomplished at the client side.||The passive character of the post office does not support processing of mailbox rules (such as out-of-office notifications).|
|Shared-file-based e-mail systems are easy to install. The administrator must simply grant read-write access for the post office data structure to all users who have mailboxes.||
A shared-file-based e-mail system provides only limited scalability. It is not advisable to create numerous mailboxes (more than 500) on one server, for instance, because each polling client is a drain on system resources.
The direct read-write access to and within the post office allows users to damage the internal structure of a post office by deleting files either inadvertently or intentionally.
In this exercise you will evaluate the characteristics of a client sending and polling for e-mail messages. You can simulate client polling when configuring Microsoft Outlook 2000 for offline and remote use. For this purpose, you need to configure a personal folder store (.pst) file, which requires some advanced configuration steps. Follow the steps outlined here; Chapter 8, "Microsoft Outlook 2000 Deployment," and Chapter 9, "MAPI-Based Clients," contain more information about Outlook 2000 and the configuration of messaging services.
To view a multimedia demonstration that displays how to perform this procedure, run the EX1CH1.AVI file from the Exercise_Information\Chapter1 folder on the Supplemental Course Materials CD.
To simulate client polling with Microsoft Outlook 2000
Figure 1.2 Configuring Outlook 2000 for offline usage
At this point you have successfully configured Outlook 2000 for offline usage.
At this point, notice that your test message remains in your Outbox and is not sent to the server, as shown in Figure 1.3.
Figure 1.3 Messages remain in Outbox until Outlook 2000 works online
At this point, Outlook checks for new messages and downloads the nondelivery report that was generated automatically as a response to your test message sent to a nonexistent recipient, as shown in Figure 1.4. This indicates that messages are only received after the next polling interval.
Figure 1.4 Messages are received after the next polling interval
The preceding experiment illustrates one of the most important disadvantages of shared-file messaging systems. Messages may be waiting, yet the recipients will not be aware of them until the clients are polling their message repositories. Even system processes, such as message transfer agents , which transfer messages between post offices, can be seen completely as clients (see Figure 1.1). These systems also do not recognize new messages until they perform their next polling. Consequently, message delivery in shared-file messaging systems is generally slow. To increase delivery performance, you would have to decrease the polling interval on all client systems, which in turn increases the network load. To make matters worse , polling always happens at regular intervals, even if there are no new messages to retrieve.
Overcoming the limits of the passive post office structure requires active server components or services. These active services interact with the clients and will process the client requests to return the results only (see Figure 1.5). The client program only has to inform the server, "Here is a message for you. Please deliver it to Paul," and the server services will take care of that request. After completion, the server services return only the result to the client: "Done. Looking forward to servicing you again soon." The client does not need to perform the actual server-side processing, access any file server resources directly, or poll the server anymore because the active server services are able to contact the client themselves when new messages arrive : "Hey, aren't you Paul's Outlook client? Here's a new message for you."
Figure 1.5 A client/server messaging system
In a client/server messaging system, the bulk of the work is shifted to the active server. This requires more powerful and expensive server hardware than what is needed by a shared-file-based messaging system. To give an example, it is very common to install Exchange 2000 Server on dual-processor machines, with at least 256 MB of RAM and a well-designed high-performance Small Computer System Interface (SCSI) disk system. You might go along with less, yet the more the better.
Table 1.2 lists the advantages and disadvantages of client/server messaging systems.
Table 1.2 Advantages and Disadvantages of Client/Server Messaging Systems
|Advantages of Client/Server Messaging Systems||Disadvantages of Client/Server Messaging Systems|
|Higher security, because the client does not need read-write permission in a post office. The server services are the actual components that write messages into and read messages from the server's messaging databases. No other components require direct read-write access.||The need for powerful server hardware, which is required due to the amount of processing performed by the server.|
|Reduced network traffic, because the active server can inform the client about the arrival of new messages (making polling unnecessary).||Increased complexity that may be excessive for small organizations.|
|Improved scalability, which makes client/server messaging systems suitable for the needs of large and quickly growing organizations. Clients do not poll the active messaging server and files will not be opened directly by any messaging client.|
In this exercise you will use Outlook 2000 online and compare the resulting performance to the outcome of Exercise 1. This will emphasize the reasons to decide in favor of a powerful client/server messaging system, such as Exchange 2000 Server, for your environment.
To view a multimedia demonstration that displays how to perform this procedure, run the EX2CH1.AVI file from the \Exercise_Information\Chapter1 folder on the Supplemental Course Materials CD.
To configure Microsoft Outlook 2000 for online usage and compare the results with the outcome of Exercise 1
Figure 1.6 Configuring Outlook 2000 for online operation
At this point, you should notice that the message leaves your Outbox immediately and that a nondelivery report is returned in a relatively short period of time, as shown in Figure 1.7.
Figure 1.7 Sending and receiving messages takes only seconds
Exchange 2000 Server is strictly a Windows 2000 Server system comprising various active Windows 2000 services, which are typically launched when the operating system starts. Examples are the Microsoft Exchange System Attendant and the Microsoft Exchange Information Store. It is the Information Store that handles message processing on behalf of client programs. This service assists the clients in sending and receiving messages and accessing public folders. You can read more about the purpose and tasks of the Exchange 2000 Server services in Chapter 3, "Microsoft Exchange 2000 Server Architecture."
Your future messaging system should have capabilities beyond plain messaging. It should provide you with powerful workgroup and workflow capabilities. It should be a collaboration or groupware system that allows your users to interact efficiently , find and share information conveniently, publish information quickly, and track how information is used. Even better, automated processes on the active server can deliver information to you when the system determines it may be helpful or relevant.
Outlook 2000 provides numerous items you can customize easily (Appointments, Tasks, Journal, and Contacts). Basically, you only need to place the desired standard module in a public folder and your work is done. It is really that easy. In Chapter 21, "Microsoft Outlook Forms Environment," you will learn how to customize Outlook's standard modules.
The following are types of collaboration solutions based on Exchange 2000 Server and Outlook 2000:
In this exercise you will take a first glance at the extensive collaboration capabilities of Exchange 2000 Server. The following procedure suggests a public phone book for business contacts. You will set up the repository as a moderated resource according to the process illustrated in Figure 1.8.
To view a multimedia demonstration that displays how to perform this procedure, run the EX3CH1.AVI file from the \Exercise_Information\Chapter1 folder on the Supplemental Course Materials CD.
Figure 1.8 A collaboration example using a moderated public folder
To set up a public phone book for business contacts
At this point, you have set up the public contact repository and specified a folder moderator, as shown in Figure 1.9.
Figure 1.9 Specifying a folder moderator
At this point, the new object does not appear in your public folder yet. Instead you have received a standard notification that your submission has been received and is reviewed. Open your inbox to read the response from Business Contacts, as shown in Figure 1.10.
Figure 1.10 A standard response from the Business Contacts folder
At this point, your contact object is publicly available. Optionally, you may log off and back on as Administrator to verify the result, as shown in Figure 1.11.
Figure 1.11 Moving an item into a public folder
Exchange 2000 Server provides an excellent set of workgroup and workflow features. Following the steps just outlined, you created an instant collaboration solution with basic routing capabilities in which users contribute new information, which is then forwarded automatically to a central moderator for approval. After approval, the information is made available to all users in the organization. A moderator can guarantee that only valid information is published. You can read more about public folders and their configuration in Chapter 17, "Public Folder Management."
MCSE Training Kit Exam 70-224(c) Microsoft Exchange 2000 Server Implementation and Administration
Authors: Unkroth K.
Published year: 2001