Mobile messaging in Exchange 2003 (Part 1): Introduction to Microsoft's DirectPush technology

This article is one of the five-part series that we want to talk about Exchange 2003 (SP2) and mobile devices running Windows Mobile 5.0 with Messaging and Security Feature Pack (MSFP) installed, and now we will take into consideration a specific new DirectPush technology.

Introduce

With Exchange 2003 SP2, you have two options for synchronizing mobile devices with mailboxes: you can configure ActiveSync on a mobile device to create a schedule-based synchronization, or you can use Always. -up-to-date (AUTD). The problem with scheduling synchronization is that you can't split them into time periods shorter than 5 minutes, which means you won't always get the latest information on your device. The other problem here is that you (depending on the mobile activity) will be responsible for each session set up when new data is transmitted, each time a new session is established.

AUTD can keep your device up-to-date by creating an Exchange storage event in the user's mailbox. When the archive event detects a change in the mailbox it will generate a Short Message Service (SMS) short message service control message, which is then sent to the user's mobile device. . When the user device receives the SMS message it will initiate synchronization with the Exchange server. The idea behind AUTD technology is very good but unfortunately it does not work well in real terms because there are very few mobile activities that support AUTD. Microsoft was aware of this problem when they deployed Exchange 2003 based mobile messaging in their own organizations.

Based on customer feedback that concerns the limitations of using SMS, Microsoft has improved AUTD in Exchange Server SP2 based on the following objectives:

1. A standard data plan is only registered if you need to sync with Exchange
2. No need to deploy additional infrastructure in your Exchange environment
3. No need for SMS notifications or other 'out-of-band' schemes.
4. No special configuration is required on the device.

These are the basic issues in Exchange DirectPush technology. Microsoft tested this new technology on their servers and the results were very good. DirectPush technology allows your mobile device to stay up to date by sharing email, schedules, contacts and tasks directly with the device, which allows you to interact quickly to replace change in the mailbox. AUTD v1 has done the same thing but DirectPush has some other benefits.

Note : When enabling DirectPush in Exchange 2003 Server, devices currently configured to use AUTD v1 will automatically switch from AUTD to DirectPush. That means you don't need to reconfigure anything on the device after enabling this feature.

One new directing technology of DirectPush is that it has the ability to maintain HTTPS connectivity between the Exchange server and the mobile device, each session maintained by the clock. In this way, the Exchange server can notify the mobile device whether it is necessary to change the linked mailbox and if there is a change in the mailbox, the server can instruct a synchronization.

When the device keeps an open session for the Exchange server, some people may think this is quite a luxury. However, here the device simply sets and waits for response, it does not need to send or receive data in this state. In other words, no data exchange is required unless a change is detected in the mailbox or clock has expired. To see more about how DirectPush technology works through images you can see in Figure 1 below.

Since the mobile device does not send a blank sync as is the case with manual or scheduled synchronization, it reduces its energy consumption thereby increasing the life of the power supply. In addition, the data that needs to be transmitted also decreases significantly. In addition, synchronous data between mailbox and devices is also compressed with GZIP.

DirectPush requirements

The server side

DirectPush is a new technology in Exchange 2003 SP2, which requires you to apply Exchange 2003 SP2 at least on Exchange 2003 front-end servers in the organization. Note that referring to 'front-end' servers is because your back-end servers can run anything from Exchange 2003 RTM, SP1 to SP2 as long as you have one or several servers' front-end 'has Exchange SP2.

However, although DirectPush does not require it, we still recommend that you upgrade back-end servers to SP2, because you will not only benefit from the DirectPush technology, but also the SP2 package. New features and improvements and lots of error correction tools.

Note : In addition to the above requirements, you need to adjust the time-out values ​​for HTTPS connection in the firewall.

To ensure Exchange ActiveSync properly, our best advice and advice is to use the ISA Server 2004 firewall, see Figure 2 below.

On the client side

Another requirement to use this DirectPush technology is that mobile devices need to run on Windows Mobile 5.0. In addition, devices need to have Messaging and Security Feature Pack (MSFP) installed. Although Microsoft has launched a basic MSFP program for mobile device manufacturers since August 2005, the basic program offered for MSFP is still delayed. Until March 2006, they began to be implemented. Both i-mate and Qtek as well as Orange have finally launched a new program, although only for a few of their new models.

Note : Messaging and Security Feature Pack (MSFP) - the security and mail feature package is also known as Adaption Kit Update 2 (AKU2).

Enable DirectPush on Exchange 2003 servers

With Exchange 2003 SP2, the DirectPush feature will be enabled by default. This feature can also be found on the Mobile Services object properties page in Exchange System Manager (see Figure 3 below).

Note that even if the DirectPush feature is enabled, mobile devices that do not have the MSFP installed will still be able to perform synchronization using either a scheduled or manual method, or via AUTD.

Time-out value of Pulse 2003 Server pulse

To maintain a continuous connection between Exchange server and mobile device, DirectPush uses clock intervals. These intervals are used for the server to be able to keep an open connection to the device at any time, even when no changes appear in the mailbox. The Exchange server automatically adjusts this distance, it keeps the last clock interval received from a device. However, you can also configure this value in the set of registry keys on the Exchange server (usually it is not necessary). For more details on this issue, you can refer to the end of the article.

Consider issues related to firewalls

To maximize performance and provide user experience, we recommend increasing the time-out value for HTTPS connections in the firewall. Depending on what type of firewall is used in your organization, this is done differently. The steps you can refer to in the lower part of the article.

Note : If setting the time-out on the firewall at least 15 minutes (Microsoft recommends 30 minutes) will make the power life of the mobile devices decrease as well as increase the amount of data transferred.

Activate DirectPush on mobile devices

Now we need to see what requirements are on the mobile devices so that it can synchronize with the Exchange server via DirectPush. Nothing new when configuring ActiveSync on a mobile device, you just need to activate Microsoft DirectPush under Comm Manager as shown in Figure 4 below.

When DirectPush is enabled on a mobile device, an icon consisting of two small arrows appears on the top right corner of the screen (see Figure 5). When a change is detected in the mailbox or if the clock expires, the server will issue a response back to the device, which will then perform synchronization for the corresponding mailbox or re-issue. an HTTP request.

DirectPush performance counter

When installing Exchange 2003 SP2 on the Exchange server, some performance counters for DirectPush will be added to the server. These counters can be found under the Microsoft Exchange ActiveSync object as you can see in Figure 6.

Note that all these counters are also called Ping commands. Ping (you should not mistake this Ping with the normal Ping command), it is a command or request sent by a mobile device to the server via an HTTP (S) connection. This request will be placed in the waiting state until a change appears in the mailbox, or until the clock period expires.

Other performance counters can refer to their detailed descriptions by marking and then clicking the Explain button (Figure 6).

Conclude

DirectPush technology has brought a much richer feel to users, though DirectPush is not a boost to true technology (as is the case with RIM's Blackberry product), users can also feel. The problem occurs in seconds when a change occurs in the mailbox (email, schedule, contacts and tasks) synchronized to the mobile device

Thanks to DirectPush technology built into Exchange 2003 Servers SP2, it has reduced the number of essential words to a minimum, and the only thing you need to invest in mobile devices is Windows Mobile 5.0 and MSFP.

To configure time-out values ​​for Exchange Direct Push, follow these steps:

1. In the tree view of ISA Server Management, click Firewall Policy .

2. On the Toolbox tab, click Network Objects .

3. Open the Web Listeners button, and then view the appropriate Web Listener attribute.

4. Click the Preferences tab, and then click Advanced .

5. Change Connection Timeout from default value of 120 seconds (2 minutes) to 1800 seconds (30 minutes).

6. Click OK twice to apply this change

7. Click Apply .

The table below contains values ​​that can be changed because they are related to the clock interval. These registry values ​​are not reflected in the Exchange Server 2003 SP2 installation. The server can be converted back to the default code if the registration value is lost. Administrators often have to create these registry values ​​if they want to set the value. These values ​​can be set according to the following registration key:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesMasSyncParameters

Note:

1. In this table, the value "1 - MaxHearbeatInterval" represents the value between 1 and the maximum value MaxHearbeatInterval. Also, the "MinHeartbeatInterval -3540" value indicates the smallest value between MinHeartbeatInterval and 3540.
2. If one of the values ​​is set in the register and the specific value is outside the value listed for that parameter, Exchange ActiveSync will initialize the default value. In addition, an event will be written to the application event log. However, an event will not be logged if the value is set to 0. When a value is set to 0, it is considered to be non-existent. In other words, the default code will be used.
3. Exchange ActiveSync reads those values ​​every time it starts. So if an administrator decides to change the values, the IIS Admin Service must be restarted for those changes.