COVER STORY

Messaging Stand-Off: Lotus Notes 4.1 Battles Microsoft Exchange ServerIn A Clash Of Messaging Titans

Sidebars:
The Features Microsoft Exchange Still Needs
What Lotus Notes Won't Do

Notes and Exchange Screen Shots

In the fight for the messaging heavyweight crown, the bell has rung andfists are flying. It's not too late to place your bets.

Your messaging system choice has a major impact on your network: It maydefine your standard hardware and operating system platforms, determineWAN bandwidth requiremen ts and, most importantly, dictate user expectations.People live in e-mail and document-sharing systems, and they don't wantinadequate quarters.

Both Notes and Exchange can deliver e-mail and store documents; in otherwords, they use both "push" and "pull" communications.They can replicate documents across multiple servers, or down to individualclient workstations for offline access. They can handle customized forms,sort

items into folders and provide some form of intelligent rules processing.You can even create advanced applications using scripts, formulas or traditionalprogramming languages and APIs.

Matching the contenders head to head is tough. Vastly different environmentseme rge when communications meet applications. What fits your organization?A simple messaging interface that must be customized to be truly powerfulor a powerful applications platform that must be customized to be trulysimple? Should solutions be developed by end users or core programming teams?

The Differences Weigh In Lotus Notes puts vast power in the handsof the advanced developer. You can build world-class applications in Notes-applicationswhere a failure can cost millions of dollars. In contrast, Microsoft Exchangefocuses on intuitive features for the end user and system administrator,for those applications where you want to minimize development, installation,training and support costs.

These products are different to the core. Take database engines, for example.Notes uses a single-file storage structure, which it calls "multi-level,distribute and hierarchical." Exchange uses a radically different approach,streaming all updates sequentially into transaction logs and doing lazywrites into a relational B+ tree data structure when the server is free.

They both do replication, but the similarity ends there. Notes replicationcenters around synchronous communication via remote procedure calls (RPCs),ensuring immediate feedback when updates conflict, even dow n to the individualfield level. Replication can be set by document (think of Notes documentsas database records). In contrast, server-to-server replication in Exchangeis almost entirely based on store-and-forward messaging, even when RPCsare available. Update collisions are handled at the document level. Entirefolders must be moved, with all documents they contain.

These architectural differences aren't an accident. They're a result offundamental differences in focus. Notes is built for database distribution,where update conflicts must be tightly monitored, even down to the individualfield. Exchange is document- and discussion-oriented, designed for keepingentire libraries in sync across servers.

End Users Tak e It on the Chin The user interface for each productalso reflects its orientation. Notes Mail provides a cc:Mail-style interface,but you'll immediately need to learn the scripting language if you wantto customize a view. Microsoft took its queues from traditional e-mail systemswh en it built the Exchange interface. Most functions are simply obviousand natural. Any user can easily modify views.

While Lotus has attempted to simplify application development by introducingLotusScript, it's still most appropriate for the professional programmer.As a good Notes developer, you'll need an understanding of the Notes architecture,including database structures, field attributes, replication and security.Then you'll need to master formulas, a scripting language or other APIs.

To develop simple applications in Exchange, you'll needa mouse. OK, onceyou get beyond the simple things, you have to purchase and learn VisualBasic. For instance, if you'll be accessing ODBC data sources you'll needto use some VB code. But there are massive hordes of VB programmers, andtheir expertise is a lot cheaper than that of the Notes guru.

Tale of the Tape Plug-in, turn-on, drag and drop. Both of these systemsare programmable, but we chose to evaluate only those features that actuallys hip out of the box. Depending on how hard you're willing to work, you canbuild a feature in one to match almost anything that the opposing systemdoes. You could also commute on the New Jersey Turnpike via skateboard,if you're so inclined.

We brought both systems into our labs and pounded pretty hard on them. Weset up a moderate number of users (approximately 6,000), then proceededto fire messages between users and into document storage, primarily by usingnative rules and scripting languages. Both systems were hosted on a groupof Windows NT 3.51 servers, with two remote systems (Notes Named Networks/ExchangeSites) connected over a routed ISDN link.

Once we had messages moving across the system, we looked at storage effici encyand network utilization. We evaluated the administrator's ability to viewand control what was going on in the system. We looked extensively at Microsoft'sInternet Mail Connector; the Notes SMTP MTA was not shipping at test time.We flagrantly abused these platforms, sending up to 2,000 messages intoa single mailbox or public storage folder, sometimes with 300-MB or largerfiles attached to them.

Neither system broke. We uncovered a couple of Exchange flaws, some of whichare substantial. Notes held up to the load. It's not surprising that bothcontinued to function well: Notes has many years of maturity, and Exchangeunderwent extensive user testing prior to its release.

In medium- and large-scale enterprises, you'll need a dedicated infrastructureto run either system. With Exchange, that means a big NT Server deployment,exclusively using Windows-based workstations (at least as of this writing).With Notes, you've got much more platform flexibility, both in clients andserver choices. Platform sizing, the actual number of users per server ormessages per gateway, is based on many variables: user traffic, rule typesand load, message size and type, network bandwidth, replication schedules,and more. Both have natural growth paths, vertically (to other hardwareplatforms, a t least) and horizontally (via automatic replication of directoriesand message stores across servers).

In the final analysis, Notes has the best architecture for building groupwareapplications, while Exchange has the best usability. Who will close thegap first? It's too soon to tell. While Lotus could enhance its user features,the underlying Exchange engine is set and as of yet unproven.

Lotus Notes Release 4.1

Notes remains the most powerful collaborative software available anywhere.Nothing else comes close to this comprehensive suite of tools for the applicationdeveloper and administrator, including Microsoft Exchange. It will do j ustabout anything you'd want to do with databases, forms and messaging. Ifyou don't want to do it all yourself, there are thousands of developersand hundreds of custom products to choose from.

Yet the power it gives to administrators and dev elopers is not extendedas effectively to end users. You'll need to work with it a while to getthe hang of it, or the administrator has to do massive customization tosimplify things.

Notes is database-centric, in contrast to Exchange's folder-centric approach.Documents (essentially database records) contain fields, views on the dataare created via forms and actions are taken using formulas or scripts. Thedata itself may be structured or unstructured. Database views use an expand-and-collapsemechanism similar to outlines, providing an intuitive drill-down mechanism.

Replication is used to move data close to the end user, conserve networkbandwidth or spread its load across servers for better performance. A replicacan contain a subset of the elements from the master database, unlike Exchange'srequirement to move entire folders. Updates are tracked at the field level,reducing the number of actual conflicts that have to be resolved. For example,if one user changes a phone number and another changes a salary field tothe same document, both updates occur across all replicas without conflict.

Communications, for replication or otherwise, is based on RPC mechanismsthat require live links between servers and/or clients. You can't replicateacross a store-and-forward network, and Lotus is adamant that you can'tinsure data consistency any other way. Costs are reduced by replicatingfield-level changes only, so you don't move a 2-KB record over the wireif only a 1-byte flag is changed in it.

Notes contains an extensive set of database administration tools. Unlikewith Exchange, the usage history of a database is easily viewed via a drill-downmechanism, letting you track an individual user's activity if you'd like.You can remove files based on their (un)popula rity, not just because they'reold (as with Exchange). For example, directions to company offices may bethe oldest documents in the system yet be the most used.

The Client Side The database-centric view is reflected in the useri nterface. Tabbed folders contain database lists, including the mail database.A special tab is reserved for replication. Users familiar with simple e-mailmay be confused by the interface, and they may be frustrated by the formulasthat are required even for view modifications.

The Notes Mail interface feels unfinished. It's really another Notes sampleapplication, and it seems incomplete. The online help is too general, offeringhigh-level discussions of Notes functions, instead of specific help on thecurrent field. Exchange's interface is far superior for typical users.

Notes Agents are one element that separates it from the pack. They're similarto rules capabilities in most e-mail systems, but they can be triggeredin different ways. Agents can execute on a scheduled basis, when a databasegets updated, when another agent executes or, of course, when a new messagearrives. Agents can be shared across multiple users. They can perform simpleactions (reply to, forward) or launch formulas and scripts. And formulasand scripts can control just about anything.

For all its power, Notes lacks many simple features. There's no integratedgroup scheduler. You can't send mail on behalf of another user, only asthat user. Launching an external document requires a two-step process. Youcan't locate a mail message that has been sent but not yet delivered. Youcan't set storage limits on an individual user. Granted, you could writeroutines that send notices to space hogs, but it's not already there foryou.

Strong Security, Internet Integration and Test Results The securityadministrator uses an internal public key distribution mechanism using X.509V1 certificates, and the security engine is based on RSA algorithms. Certificateauthorities can exist at multiple levels in an organization, and cross-certificationbetween organizations is possible. Access Control Lists and encryption canbe applied to individual fields or subforms. In contrast, Exchange reliesheavily on NT security supplemented with a vers ion of Nortel Entrust tomanage digital signature keys. There are vulnerabilities to each approach,but the Notes model is more distributed, more flexible and more scalable.

Notes 4 includes the InterNotes Web Navigator, an application-level gatewaythat converts HTML documents into Notes databases. Automated agents canmonitor Web documents and replicate them across the enterprise, even toclients for offline viewing. Since those sites are effectively cached atthe Notes server, commonly accessed Web documents don't fill Internet pipes.It could also be used to monitor or limit individual browsing. One big caveat:Lotus will forever be trying to keep up with the mainstream browsers. Javasupport is only being demonstrated, and plug-ins are not yet on the scope.InterNotes Web Navigator is not for everybody, but it can legitimatize corporateaccess to the Internet.

Notes performed well in our tests. With 6,000 users in the public addressbook, user lookups were instantaneous. We set up a common mail file to verifythat documents were efficiently shared by reference (they are). The default,however, is for each user to have their own mail file, which can eat upstorage fairly quickly. We created a simple discussion group and documentrepository. In all cases, user storage was compressed for both main documentsand attachments (unlike with Exchange).

Once several thousand messages were in the system, we viewed logs and monitoringsystems. We were impressed by the event monitoring, which requires lesswork to set up than with Exchange, yet is more flexible. Notes also hasmuch more replication event control and monitoring than Exchange.

Notes administration tasks can be executed from any client in the enterprise.The Administrative Control Panel is accessible to any client with the appropriateaccess. Logs and monitors are just Notes databases that can be added toany personal desktop. In contrast, Exchange Administrator will only executeon an NT Server. Online backups can be created with any utility that backsup open files, although it would be better practice to shut down activedatabases for this purpose (Lotus recommends periodic shutdowns for garbagecollection anyway). IBM ADSM can provide online incremental Notes backup,but otherwise it's difficult to find Notes-aware backup systems.

Development is integrated into Notes Workspace. Many simple functions areavailable through formulas, which read similar to spreadsheet formulas.LotusScript stands out as a development language, similar to BASIC but withobject classes and methods. Notes provides an integrated programming environmentwith a debugger. Source code is managed within Notes, so you won't needseparate processes to handle it as you would when using Visual Basic andExchange. If you really want to use Microsoft tools, the Lotus HiTest Toolsfor Visual Basic are available separately, along with tools that use OLEobjects or provide ActiveX components.

Performance from a remote client operating through a Shiva LANRover on a24-Kbps connection was good. Notes maintains a consistent interface forremote or local clients, and performs replication in the background. Replicationcan be initiated immediately or scheduled. Location assignments let youquickly change communications settings based on where you are. Overall,remote capabilities are superior to those of Exchange.

Microsoft Exchange Server

After years of anticipation, Microsoft Exchange has arrived. It raises thebar for electronic mail systems by introducing collaboration features thatyou don't find in traditional e-mail packages. Offering one of the mostusable interfaces we've seen, this client/server-based package is easy toset up, monitor and use. Exchange is certainly ahead of its traditionalcompetition-Lotus cc:Mail and Novell GroupWise-in features and und erlyingarchitecture. However, a few holes need to be filled before we'd considerit truly ready for the enterprise (see "TheFeatures Microsoft Exchange Still Needs," ).

Of co urse, Exchange is Windows centric: The server runs only on NT, andrelies heavily on NT services for administration. Clients for all Windowsplatforms are available, and for the first time a full MAPI 1.0 ServiceProvider for Windows 3.1 is available. Support for Macintosh and Unix arecoming. Despite an Exchange DOS client, Notes is still far ahead in multiplatformsupport.

A Brand New Architecture Exchange has a completely new architecturethat shouldn't be compared to the anemic Microsoft Mail. For example, theInformation Store has four main data structures: folders, message headers,messages and attachments. By separating the data in this way, Exchange maintainssingle instance storage. In other words, a message or an attachment thatis shared is only kept once on the server, even when forwarded. Unfortunately,disk space may be consumed by bloated file attachments.

Messages are not saved directly into the message database files. Instead,activity is streamed sequentially into log files and t hen written to themain store as the server has time. These logs serve double duty as transactionhistories, allowing for rollback or replay if a system failure occurs, aswell as letting archive utilities use the logs for incremental backups.Exchange ships with an enhanced version of NT Backup which works againstactive Exchange information stores. Third-party utilities must use the Exchangebackup API to allow for online backups. Cheyenne Database Agent for MicrosoftExchange and Seagate Backup Exec support online backups of Exchange data.

Transaction log integrity is critical to Exchange's operation, and sincestreaming is only effective when a single process controls a disk's read-writehead, each server needs a disk used exclusively to hold transaction logs.You won't need entirely separate disk channels, but Microsoft recommendsa battery-backed caching controller.

Servers are grouped together into Sites, which share a common network protocol.Connections between Sites can be made via the Site Con nector, which usesRPCs to set up communications but uses message-based communications acrossthese links. This is one of the major differences from Notes-servers don'thave immediate feedback between themselves, so replication conflicts requirelonger time spans to get resolved.

You can also use the Internet Mail Connector or X.400 Connector betweentwo Exchange sites, although Site Connectors are preferred between sitesfor performance and reliability. Unfortunately, Site Connectors requireNetbios names to communicate, which makes them difficult to set up overthe Internet. Information delivery between all connectors is neither compressednor encrypted.

Each Connector instance has an associated link cost, so you can define multipleroutes for fault tolerance. Costs are statically configured, so you can'tadjust routes based on time of day or other parameters.

Exchange Administration Almost all configuration and administrationis done via the Exchange Administrator program, which must be executed froma Windows NT server. From here you can manage any connected server, configuringconnections, directory replication, system policies and so forth, whichis all contained in the directory information tree.

Exchange leverages existing NT tools. When a new NT user account is setup in the NT User Manager, all associated Exchange mailbox information isautomatically set up. When a mailbox is deleted, the NT user account maybe automatically deleted. It uses Event Viewer for events and PerformanceMonitor to view statistics, such as traffic loads or queue sizes.

Unfortunately, this doesn't provide for a consistent system monitoring interface.You can't drill down from the Link or Server Monitors to view low-levelproblems. Instead, you have to view a collection of predefined NT PerformanceMon itor screens, each of which shows only "Performance Monitor"across the title bar.

You also don't have the extensive replication control that you find in Notes.Entire folders have to be r eplicated between sites. You have little exposureto the replication engine, so it's hard to monitor status.

Despite these limits, Exchange Administrator beats Notes in a few key areas.You can limit the maximum message size sent into the system, or across anyConnector. You can limit users' information store usage-they can keep receivingmail, but they can't send it when they cross the threshold.

We were able to locate individual messages across the system, by user ormessage ID. If you want to know what a user sent yesterday, you can getit. Or if a user complains that a message wasn't delivered, you can trackthe actual message down. Notes provides only a minimal trace capability.

Exchange provides extensive migration and coexistence tools for a varietyof platforms. You can read information directly from existing NT directoriesor NetWare binderies. Gateway templates are available for transparentlyaddressing MHS, IBM PROFS, SNADS, fax and AT&T Easylink mail. The Exchangeclient's pure MAP I interface makes it deployable as a client before you'veswitched over your servers, provided of course they have MAPI Service ProviderInterfaces. For example, MS Mail servers may be used with Exchange clients.

Likewise, Microsoft's supplemental tools are quite good. You can find loadsimulators, NT Domain and Exchange Server modelers, configuration managementtools and more. You have to search high and low to find this stuff: Someitems are on the Server CD, others on the Technical Resource CD, MS TechNetand the Microsoft Web site; others are third-party utilities. This scattershotapproach reflects Exchange's youth, and we hope Microsoft collects and integratessupplemental utilities better in later releases.

We pumped thousands of messages across thousands of users on multiple servers.Processor utiliz ation was fairly intense on our test systems, but Exchangealways kept up. Even the slowest queue-that of the Internet Mail connector-continuedto drain at a rate of at least 30 2-KB messages per sec ond, although thislimit may have been due to the remote SMTP gateway with which we were conversing.Nonetheless, this throughput is more than adequate for most.

Under heavy loads, the Exchange transaction files fill up fairly quickly.With local delivery of about 1,800 2-KB messages per minute (3,600 KB),a 5-MB log file was created every minute. Still, Exchange delivered allmessages in under a minute, across the three servers.

The Client Side The Exchange front end is full featured. You getthe advanced features you'd probably expect, such as folders, views andrules that execute on the server. But there is a lot more to say about theclient. You can connect the Exchange client to multiple MAPI services orPOP servers, even while it's also talking to the Exchange server. We usedit to connect to the Notes server, for example.

The Exchange client provides advanced features out of the box, and can becustomized by almost anybody in seconds. You can view several mailboxessimultaneously, and can "send as" or "send on behalf of"another user if you have permissions (it's an important distinction). Youcan block off hundreds of messages and forward them in a single command.Internet encoding defaults (that is, MIME or UUENCODE) set by the administratorcan be overridden on a per-message basis by the user.

Mail rules loops are automatically detected, so mailboxes can't play pingpongvia rules. The administrator can block rules execution over the InternetMail Connector, so your Out of Office messages can't create mail loops witha remote mailing list server.

Public folders are used for discussions, document storage, applications,and other "pull"-style communications. We dragged countless filesof various types into the public message store-spreadsheets, documents,and so on. External applications are launched automatically from the messagestore; for example, double-clicking on an HTML document will bring you intoyour favorite browser (even it's from Netscape ). Standard forms for nesteddiscussions are included, and various access levels can be assigned.

Users can develop simple applications using the built-in Exchange FormsDesigner. The EFD will create form applications that can be either simplemail send forms or folder applications. It's a good set of graphical tools.For advanced functions, such as access to a database, you'll have to pickup Visual Basic. In contrast, Notes will talk to ODBC sources using itsnative formula language. However, with the variety of custom controls available,and the vast amount of VB programmer talent available, this is not too bad.It just doesn't approach what Notes can do.

If you're working offline, you can pull folders down to your local clientby using offline folders. Remote access occurs over LAN protocols, WindowsDialup Networking/RAS, Shiva and so forth. Updates to any type of folder-publicor private-are synchronized, either on demand or on a timed basis. It won'tsynchronize in the background while you keep wor king. Using multiple servicessimultaneously is a little clumsy, and the remote client does not autosensenetwork availability.

Performance over a remote link was acceptable. We could download a 6,000-nameaddress book in less than three minutes over a 24-Kbps connection. Becausesecurity is based on NT, roving users connecting outside their home domainmust have a trust relationship to the domain to which they are connecting.

David Willis can be reached at dwillis@nwc.com.

Updated June 14, 1996