Can Opensource Exchange My World

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VOORTGEZETTE OPLEIDING GAS

DEPARTEMENT WETENSCHAPPEN

Can Open source eXchange My World?

Academiejaar 2005-2006 Verhandeling aangeboden tot het verkrijgen vande graad van Master in IT:

Roel De Meester

Downloadable versions of this document can be found at http://users.pandora.be/develOOp/thesis/Thisdocument (except for the logo) is licensed under the Creative Commons Attribution License. This means thathe licensor, Roel De Meester, permits others to copy, distribute, display, and perform the work. In return,licensees must give the original author credit. For the full license, visithttp://creativecommons.org/licenses/by/1.0/legalcode/or send a letter to Creative Commons, 559 NathanAbbott Way, Stanford, California 94305, USA.
http://users.pandora.be/develOOp/thesis/http://creativecommons.org/licenses/by/1.0/legalcode/http://users.pandora.be/develOOp/thesis/http://users.pandora.be/develOOp/thesis/http://creativecommons.org/licenses/by/1.0/legalcode/http://creativecommons.org/licenses/by/1.0/legalcode/http://creativecommons.org/licenses/by/1.0/legalcode/http://users.pandora.be/develOOp/thesis/


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Table of Contents

1.Introduction ....................................................................................................................................................

2.can open source exchange my [WORLD] ......................................................................................................

2.1. E-mails ...................................................................................................................................................

2.1.1.Wikipedia definition ........................................................................................................................

2.1.2.E-mail information ..........................................................................................................................

2.1.3.Applications......................................................................................................................................

2.2. Address books ........................................................................................................................................

2.2.1.Techweb definition ..........................................................................................................................

2.2.2.Address book information................................................................................................................

2.2.3.Address book file format................................................................................................................

2.2.4.Applications ...................................................................................................................................

2.3. Calendar.................................................................................................................................................

2.3.1.Definition .......................................................................................................................................

2.3.2.Information .....................................................................................................................................

2.3.3.File Format .....................................................................................................................................

2.3.4.Applications ...................................................................................................................................

2.4. Notes .....................................................................................................................................................

3.can open source exchange [MY] world .........................................................................................................1

3.1. Securing E-mail ....................................................................................................................................

3.1.1.SSL .................................................................................................................................................

3.1.2.Digital Signatures ...........................................................................................................................

3.1.3.Bundled security .............................................................................................................................

3.2. Securing synchronization of information .............................................................................................2

4.can open source [EXCHANGE] my world ...................................................................................................2

4.1. E-mail ....................................................................................................................................................2

4.1.1.SMTP (Simple Mail Transfer Protocol) .........................................................................................2

4.1.2.POP (Post Office Protocol) ............................................................................................................2

4.1.3.IMAP ..............................................................................................................................................2

4.2. Calendar ................................................................................................................................................2


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4.3. Address book .........................................................................................................................................2

4.3.1.Requirements ..................................................................................................................................2

4.3.2.Microsoft exchange Server ............................................................................................................2

4.3.3.LDAP .............................................................................................................................................2

4.3.4.SyncML ..........................................................................................................................................2

4.3.5.Plaxo.com .......................................................................................................................................2

4.4. Exchange Server Alternatives ...............................................................................................................2

4.4.1.Open source Microsoft Exchange replacements ............................................................................2

4.4.2.From a different angle ....................................................................................................................2

5.5can [OPEN source] exchange my world ......................................................................................................2

5.1. Open source software ............................................................................................................................2

6.CAN open source exchange my world? ........................................................................................................3

6.1. the breakdown........................................................................................................................................3

6.2. (Pessimistic) conclusion .......................................................................................................................3

6.3. (Optimistic) conclusion..........................................................................................................................3


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Woord vooraf

Deze verhandeling heeft lang op zich laten wachten. Een samenloop van professionele (bvba opgestart) enfamiliale (welkom Joris, Tinne en Wouter) omstandigheden hebben ertoe geleid dat dit werk zichvoornamelijk in mijn hoofd heeft ontwikkeld, en pas op papier heeft kunnen ontstaan door de vrijheid vanmijn partner Christa. Het is omdat zij de zorgende factor verschillende weekends en weken volledig op haar

schouders heeft genomen dat ik er in geslaagd ben om al mijn ideeen neer te schrijven.

Antwerpen, nazomer 2006


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1. Introduction

This thorough study has started as a result of my own problems keeping my address book synchronizedbetween my work PC, 2 home PC's, a PDA and some web mail address lists. While trying to figure out a wato do this in an automated way I learned a lot on open standards, xml formats, server and web services.

I have split up the work in 4 major parts.

1. What information is commonly relevant to keep synchronized? In other words what makes up theworld of information.

2. How can this be done in a secure way? How can we make sure that any information stays in myhands.

3. How can (or should) the information be shared orexchanged between applications, which protocolsshould be used?

4. Are there already open standards oropen sourced applications (client or server) available that can beused for the synchronization task?

5. Joining these parts together leads to the overall question: Can open source exchange my world?

2. can open source exchange my [WORLD]

The optimist proclaims that we live in the best of all possible worlds; andthe pessimist fears this is true.

James Branch Cabell (1879 - 1958), The Silver Stallion, 1926

An important part in the whole synchronization story is defining what world of information is relevant toshare between different desktop/web applications.

Nowadays PDAs1 have already clarified what most people see as important information. Most owners ofPDA's use it for it's PIM2 functions, as digital alternative for their filo-fax.

Watching at the personal information items that those PIMs support we already have a good list to start with

1. E-mails

2. Address books

3. Calendars

1 Personal Digital Assistant: hand helddevices that were originally designed as personal organizers

2 Personal Information Manager: Personal Information Management functionality started with the Filofax, with all your persondata held in paper form in a single package. The personal organizer came along to store the data electronically with the abilityto store the same information on your PC and synchronize the two. The same functionality is now finding its way into mobile

phones, which also have the synchronization capability.
http://en.wikipedia.org/wiki/E-mailhttp://en.wikipedia.org/wiki/Address_bookhttp://en.wikipedia.org/wiki/Calendarhttp://en.wikipedia.org/wiki/PDA_(Computer)http://en.wikipedia.org/wiki/PDA_(Computer)http://en.wikipedia.org/wiki/Handheld_devicehttp://en.wikipedia.org/wiki/Handheld_devicehttp://en.wikipedia.org/wiki/Handheld_devicehttp://en.wikipedia.org/wiki/Personal_information_managerhttp://en.wikipedia.org/wiki/Personal_information_managerhttp://en.wikipedia.org/wiki/PDA_(Computer)http://en.wikipedia.org/wiki/PDA_(Computer)http://en.wikipedia.org/wiki/PDA_(Computer)http://en.wikipedia.org/wiki/Handheld_devicehttp://en.wikipedia.org/wiki/Handheld_devicehttp://en.wikipedia.org/wiki/Handheld_devicehttp://en.wikipedia.org/wiki/Personal_information_managerhttp://en.wikipedia.org/wiki/Personal_information_managerhttp://en.wikipedia.org/wiki/Personal_information_managerhttp://en.wikipedia.org/wiki/E-mailhttp://en.wikipedia.org/wiki/E-mailhttp://en.wikipedia.org/wiki/E-mailhttp://en.wikipedia.org/wiki/Address_bookhttp://en.wikipedia.org/wiki/Address_bookhttp://en.wikipedia.org/wiki/Address_bookhttp://en.wikipedia.org/wiki/Calendarhttp://en.wikipedia.org/wiki/Calendarhttp://en.wikipedia.org/wiki/Calendar


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4. Task lists

5. Wish lists

6. Task scheduling (invitations etc)

7. Notices

But since the start of the Internet a lot of other valuable personal information has become available that helppeople to organize their virtual world. (There are even tools being developed to organize that newinformation into one single environment. eg. Jetbrains' Omea). Some parts of that newer information :

8. Websites and bookmark lists

9. newsgroups

10.eZines

11.Blogs

12.Instant Messages

13.RSS/Atom Feeds

We need to precise what uniquely defines those different information items, and of what atomic data they arbuild up. The definitions of all above terms are already clarified on the largest free encyclopedia on the net:Wikipedia[wiki]

2.1. E-mails

2.1.1. Wikipedia definition

Electronic mail, abbreviated e-mail orE-mail, is a method of composing, sending, and receiving messagesoverelectronic communication systems. The term e-mail applies both to theInternete-mail system based ontheSimple Mail Transfer Protocol(SMTP) and to work group collaboration systems allowing users withinone company or organization to send messages to each other.

2.1.2. E-mail information

There are 3 components to an E-mail message

1. The envelope : is used internally by the Message Transfer Agent (MTA) (eg. Sendmail, Exim, Qmaiand Postfix )

2. The headers : The most interesting part of an E-mail - to systems administrators and engineersanyway.

KEY: VALUE pairs that conform toRFC 822.
http://en.wikipedia.org/wiki/Task_listhttp://en.wikipedia.org/w/index.php?title=Wish_list&action=edithttp://en.wikipedia.org/w/index.php?title=Notice&action=edithttp://www.jetbrains.com/omea/http://en.wikipedia.org/http://en.wikipedia.org/http://en.wikipedia.org/wiki/E-mailhttp://en.wikipedia.org/wiki/Electronichttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocolhttp://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocolhttp://www.faqs.org/rfcs/rfc822.htmlhttp://www.faqs.org/rfcs/rfc822.htmlhttp://en.wikipedia.org/wiki/Task_listhttp://en.wikipedia.org/wiki/Task_listhttp://en.wikipedia.org/wiki/Task_listhttp://en.wikipedia.org/w/index.php?title=Wish_list&action=edithttp://en.wikipedia.org/w/index.php?title=Wish_list&action=edithttp://en.wikipedia.org/w/index.php?title=Wish_list&action=edithttp://en.wikipedia.org/w/index.php?title=Notice&action=edithttp://en.wikipedia.org/w/index.php?title=Notice&action=edithttp://en.wikipedia.org/w/index.php?title=Notice&action=edithttp://www.jetbrains.com/omea/http://www.jetbrains.com/omea/http://www.jetbrains.com/omea/http://en.wikipedia.org/http://en.wikipedia.org/http://en.wikipedia.org/http://en.wikipedia.org/wiki/E-mailhttp://en.wikipedia.org/wiki/E-mailhttp://en.wikipedia.org/wiki/E-mailhttp://en.wikipedia.org/wiki/Electronichttp://en.wikipedia.org/wiki/Electronichttp://en.wikipedia.org/wiki/Electronichttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocolhttp://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocolhttp://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocolhttp://www.faqs.org/rfcs/rfc822.htmlhttp://www.faqs.org/rfcs/rfc822.htmlhttp://www.faqs.org/rfcs/rfc822.html


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Each header transmitted as a single line of text.

Some are Mandatory: Date From, To, (or BCC).

Others are optional but widely used: Subject, Cc, Reply-To, Received, Message-Id.

Any others are ignored by the mail system but all headers are propagated, recognized or not.

Headers starting with 'X-' are for personal application or institution use.

3. The message body :

The actual content of the E-mail message.

MUST be plain text: binary content must be encoded into ASCII text.

The body is separated from the headers by a single blank line.

sometimes containing asignature blockat the end

2.1.3. Applications

a) Desktop:

Most widely spread in windows world are the outlook series and outlook express mail clients.

Both have been known to handle E-mail in a rather insecure way.

One of Microsofts goals is for the E-mail client to be easy to use. However, the embedded automation andlack of security features compared to competitors have been repeatedly exploited by malicioushackers usinE-mail viruses. These typically take the form of an E-mail attachment which executes on the users machineand replicates itself by mass-mailing the users or Exchange servers address list. Examples of such virusesare the Melissaand Sobigworms. Other programs have exploited OutlooksHTML E-mail capabilities toexecute malicious code or confirm that E-mail addresses are valid targets forspam. The notoriety of theworms and other viruses has gained Outlook a reputation as a highly insecure E-mail platform.

Other alternatives are the (free) eudora. Eudora is a classic, powerful, flexible and efficient E-mail client thacans spam precisely, too, and shows nary a weakness.

Other well known E-mail clients are Lotus Notes, Mozilla Thunderbird, Mulberry and The Bat!.3

3 For a thorough comparison see :

http://en.wikipedia.org/wiki/Comparison_of_E-mail_client

http://www.engin.umich.edu/caen/E-mail/emailchart.html

http://E-mail.about.com/od/emailclients/
http://en.wikipedia.org/wiki/Signature_blockhttp://www.absoluteastronomy.com/encyclopedia/h/ha/hacker.htmhttp://www.absoluteastronomy.com/encyclopedia/h/ha/hacker.htmhttp://www.absoluteastronomy.com/encyclopedia/c/co/computer_virus.htmhttp://www.absoluteastronomy.com/encyclopedia/a/at/attachment.htmhttp://www.absoluteastronomy.com/encyclopedia/m/me/melissa_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/m/me/melissa_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/s/so/sobig_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/c/co/computer_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/c/co/computer_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/h/ht/html3.htmhttp://www.absoluteastronomy.com/encyclopedia/h/ht/html3.htmhttp://www.absoluteastronomy.com/encyclopedia/s/sp/spam.htmhttp://en.wikipedia.org/wiki/Comparison_of_email_clienthttp://www.engin.umich.edu/caen/email/emailchart.htmlhttp://email.about.com/od/emailclients/http://en.wikipedia.org/wiki/Signature_blockhttp://en.wikipedia.org/wiki/Signature_blockhttp://en.wikipedia.org/wiki/Signature_blockhttp://www.absoluteastronomy.com/encyclopedia/h/ha/hacker.htmhttp://www.absoluteastronomy.com/encyclopedia/h/ha/hacker.htmhttp://www.absoluteastronomy.com/encyclopedia/h/ha/hacker.htmhttp://www.absoluteastronomy.com/encyclopedia/c/co/computer_virus.htmhttp://www.absoluteastronomy.com/encyclopedia/c/co/computer_virus.htmhttp://www.absoluteastronomy.com/encyclopedia/c/co/computer_virus.htmhttp://www.absoluteastronomy.com/encyclopedia/a/at/attachment.htmhttp://www.absoluteastronomy.com/encyclopedia/a/at/attachment.htmhttp://www.absoluteastronomy.com/encyclopedia/a/at/attachment.htmhttp://www.absoluteastronomy.com/encyclopedia/m/me/melissa_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/m/me/melissa_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/m/me/melissa_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/s/so/sobig_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/s/so/sobig_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/s/so/sobig_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/c/co/computer_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/c/co/computer_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/c/co/computer_worm.htmhttp://www.absoluteastronomy.com/encyclopedia/h/ht/html3.htmhttp://www.absoluteastronomy.com/encyclopedia/h/ht/html3.htmhttp://www.absoluteastronomy.com/encyclopedia/h/ht/html3.htmhttp://www.absoluteastronomy.com/encyclopedia/s/sp/spam.htmhttp://www.absoluteastronomy.com/encyclopedia/s/sp/spam.htmhttp://www.absoluteastronomy.com/encyclopedia/s/sp/spam.htmhttp://en.wikipedia.org/wiki/Comparison_of_email_clienthttp://en.wikipedia.org/wiki/Comparison_of_email_clienthttp://en.wikipedia.org/wiki/Comparison_of_email_clienthttp://www.engin.umich.edu/caen/email/emailchart.htmlhttp://www.engin.umich.edu/caen/email/emailchart.htmlhttp://www.engin.umich.edu/caen/email/emailchart.htmlhttp://email.about.com/od/emailclients/


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b) Web4:

Web-based E-mail service is a web application that allows the users to access their mailboxes by using anyweb browser. One can than read mails that are on the server or write emails. Since the user is workingdirectly on the server, deleting an E-mail will be irreversible. (desktop clients often leave a copy of themessage on the server when downloading, Deleting an E-mail will only delete the local copy). Since theintroduction of the Gmail webmail [2GB] which discourages deleting emails but rather encourages users to

archive them, a strong battle has started between competitors (hotmail[250MB], yahoo[1GB], aol[2GB]) togive more storage to their users.

FastMail is a another great free E-mail service. It only gives the user 10MB of storage but comes with IMAPaccess and few ads.

POP6/IMAP access?

Gmail does not offer IMAP, only POP access it also and provides Mail Forwarding

Fastmail offers both IMAP and POP access and can be used to other E-mail services through POP

Yahoo does not offer POP nor IMAP access. It can however download mail from other POP account

AOL uses an proprietary client/server E-mail system. No POP or IMAP support

2.2. Address books

2.2.1. Techweb definition

A database of names and addresses and other personal information that is maintained in a personal

information manager (PIM), contact manager or other application that deals with people's addresses.

2.2.2. Address book information

The software address book are derived from their real alternatives which often live close to the telephone ankeeps contact details (e.g. name, address,telephone number, mobile phone number) in place. The softwareversion does not has the problem of getting rather chaotic when people start moving around, lose theirmobiles or get married. Each user has different needs, wants to store his data in a different order, and wantsto store different things (not everyone wants to store birthdays or first names). A good address book formatshould be able to contain as much contact information as possible.

1. Naming info

4 Only Free webmail services are discussed here.

5 IMAP: (Short for Internet Message Access Protocol) a mail protocol that provides management of received messages on aremote server. The user can review headers, create or delete folders and messages, and search contents remotely without havinto download the mail. It includes more functions than the similar and popular POP mail protocol.

6 POP : (Short for Post Office Protocol, a protocol used to retrieve e-mail from a mail server. Most e-mail applications(sometimes called an e-mail client) use the POP protocol, although some can use the newer IMAP (Internet Message AccessProtocol). There are two versions of POP. The first, called POP2, became a standard in the mid-80's and requires SMTP to senmessages. The newer version, POP3, can be used with or without SMTP.
http://en.wikipedia.org/wiki/Address_bookhttp://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Address+(geography)&gwp=8&curtab=2222_1http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Address+(geography)&gwp=8&curtab=2222_1http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Telephone&gwp=8&curtab=2222_1http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Mobile+phone&gwp=8&curtab=2222_1http://en.wikipedia.org/wiki/Address_bookhttp://en.wikipedia.org/wiki/Address_bookhttp://en.wikipedia.org/wiki/Address_bookhttp://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Address+(geography)&gwp=8&curtab=2222_1http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Address+(geography)&gwp=8&curtab=2222_1http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Address+(geography)&gwp=8&curtab=2222_1http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Telephone&gwp=8&curtab=2222_1http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Telephone&gwp=8&curtab=2222_1http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Telephone&gwp=8&curtab=2222_1http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Mobile+phone&gwp=8&curtab=2222_1http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Mobile+phone&gwp=8&curtab=2222_1http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Mobile+phone&gwp=8&curtab=2222_1


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Title [Dr., Mr., Mrs., ..]

First, Middle, Last Name

Suffix [Sr., Jr.]

2. Category [Business, Friends, Family, Client, ..]

3. Fax like numbers [fax, computer name, ip-address, ftp-site; telex]

4. Phone info: zero or more

Category [Home, Business, Company, Mobile, Assistant, Parents, ...]

5. Country code

6. City code

7. Local number

8. Extension

9. E-mail info: zero or more

Category [home, work, news, web-mail, ...]

local-part : before the @ sign, often the username

domain name : after the @ sign is looked up in DNS 7 to deliver the e-mail

10.Physical or postal address8 is best stored as free text but would often contain:

Category [home, work, parents, ]

block, street-name, number, apartment, room

city/code

country/province/state

11.Job information

7 DNS :Domain Name System is name resolution system that lets computers locate other computers on a Unix network or theInternet (TCP/IP network) by domain name. This information is stored and replicated in distributed servers. When one of thosDNS servers does not have the requested information, it will ask it's neighbours for that information. This is done recursivelyuntil an answer is found and given back to the requester. At the same time, all contributing servers update their own databaseswith the new information. This process uses highly advanced recursive learning mechanisms.

8 Postal conventions vary widely from country to country. Eg. The US term block is highly connected to the grid-like city maof USA cities and is not usable in most European organically grown (mostly circular) cities. Frank da Cruz has put a lot ofeffort in his COMPULSIVE GUIDE TO POSTAL ADDRESSESwhich contains postal schemes for nearly all countries in theworld.
http://en.wikipedia.org/wiki/Domain_Name_Systemhttp://www.columbia.edu/kermit/postal.htmlhttp://www.columbia.edu/kermit/postal.htmlhttp://en.wikipedia.org/wiki/Domain_Name_Systemhttp://en.wikipedia.org/wiki/Domain_Name_Systemhttp://en.wikipedia.org/wiki/Domain_Name_Systemhttp://www.columbia.edu/kermit/postal.htmlhttp://www.columbia.edu/kermit/postal.htmlhttp://www.columbia.edu/kermit/postal.html


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Job title

Company

Department

Office

Profession

Manager's Name

Assistant's Name

Secretary's Name

Home page

12.Personal information

Nickname

Spouse's name

Birthday

Anniversary

Children's names

Picture

Gender

Hobbies

13.Instant messaging

service type

username

14.Notes

15.User defined Fields


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2.2.3. Address book file format

There is NO uniform format to store address book information. So when switching between address booksoftware and E-mail software a conversion of the propriety format is needed. But most software is able toimport/export its data to a more open format. Examples of these open interchange formats are

"Title","First Name","Middle Name","Last

Name","Suffix","Company","Department", ..."Dr.","Frits","","De

Dokter","",,,"Orthodontist",,,,,,,,"Grote Baan

7",,,"Landen",...

"","Ken","","Barbie","","Happy land",,,"DollStreet

14",,,"Zulte 123",,,"USA","",,,,...

Comma Separated Value (CSV): A file containin

all contacts in a table like format. The first lineoften contains the names of the columns; theother lines contain one record per line. Columninformation is either separated by ; or ,

BEGIN:VCARD

VERSION:2.1

FN:Firstname Lastname

N:Lastname;Firstname

ADR;WORK;PREF;QUOTED-PRINTABLE:;Footown

12345=0AFooland;Bar Street 99

LABEL;QUOTED-PRINTABLE;WORK;PREF:Bar Street 99=0AFootown

12345=0AFooland

TEL;CELL:+358-40-123456

EMAIL;INTERNET:[email protected]

UID:

END:VCARD

vCard (VCF) : is a digital counterpart of abusiness card. It only contains a single contactsinformation. The main advantage of these vCardis that most E-mail software can automaticallyattached the senders vCard to emails whensending. When receiving an E-mail containing a

vCard the receiver can automatically add thevCard information into its address book.

dn: cn=John Doe,dc=example,dc=com

cn: John Doe

givenName: John

sn: Doe

telephoneNumber: +1 555 6789

telephoneNumber: +1 555 1234

mail: [email protected]

manager: cn=Barbara Doe,dc=example,dc=com

objectClass: inetOrgPerson

objectClass: organizationalPerson

objectClass: person

objectClass: top

LDIF: is a LDAP Interchange Format used tocommunicate with LDAP (Lightweight DirectoryAccess Protocol) content. It can contain one ormore entries. Each record is represented by a

block of name:value lines

There are some web-based converters which can handle propriety formats used in common mail-clients likeWindows Address Book, Outlook, Opera, Pine,

A famous converter is found at http://www.interguru.com/.Another option is to use Dawn (the Address Converter and Manager) which can be downloaded fromhttp://www.joshie.com/projects/dawn/features.html
http://www.interguru.com/http://www.joshie.com/projects/dawn/features.htmlhttp://www.interguru.com/http://www.interguru.com/http://www.interguru.com/http://www.joshie.com/projects/dawn/features.htmlhttp://www.joshie.com/projects/dawn/features.htmlhttp://www.joshie.com/projects/dawn/features.html


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3rd party mail providers to sync their address book with Plaxo.

2.3. Calendar

2.3.1. Definition

In the digital world a calendar is able to keep track of events, free and busy time, meetings, to-dos. Thesecalendars can be completely private and stored on a desktop machine or a PDA. Calendar information canalso be stored on a server which results in the benefit of sharing information to other users. Taking this onestep further would imply that people can subscribe to that calendar so that the (read-only) content can beviewed within the calendar client application. This is useful for distributing timetables, tour calendars, andrecurring events.

Another way to share calendar info is to send a calendar to another. This can be done using ordinary E-mailand a special mime content text/calendar, or by using a propriety exchange mechanism like is used inOutlook and Lotus Notes. In companies that system is heavily relied on to setup and schedule meetings,checking for free time of colleagues, and can be even used to schedule a meeting room. Most often the E-

mail application is used to share the information but the file format of the attached calendar is not fixed.

In a typical company environment any event or meeting that a user enters in his shared calendar will also bestored on the server. Once on the server there are two options. Either the calendar info is only used tocalculate free/busy times so that other can easily schedule a meeting with the user, another option is to alsoshare the content of the meeting. In that case any other authorized user can look into the shared calendar. This typically used by secretaries that keep track of the calendar of their boss.

2.3.2. Information

By scheduling an event in any calendar application we can easily derive the needed information in a calendaitem. There are mainly three types of calendar items, which share a lot of fields but are still to be used fordifferent situations

1. Meeting (requests) with other people within your digital connection. Colleagues, friends, within anon-profit environment

2. Appointments contains same information as a meeting but does not expect response from invitees

3. Task typical puts less focus on time (except a due date) and often contains a field to define the % ofcompletion. Some applications allow a task to have sub-tasks.

Content

Subject : short descriptive title

Description: a longer text area containing a meeting agenda, driving directions,

Category: can be used to group information in different areas of interest

Invitees: A list of people that will receive an invitation to this meetingA mail will be sent to those people and some mail applications are able to add the meeting totheir own calendar and each invitee is able to accept or reject the invitation


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Start time and End time of the event

Optionally mark an event as a all day event

Reminder : an alert will be given to the user to remind the upcoming event

A timing can be given

Type of alerts (beep, OS notification, E-mail, SMS, ..)

Optionally mark an event as private : other people using the same exchange server areunable to see the details of the event, but during the time of the event the calendar is mark asbusy

Schedule recurring events. Some events take place every week at the same time, or every yeaor a few days in a row. Instead of copying the same event information to all these other dates(and having the problem of making a change to all recurring events), it is possible to define aevent as recurring and provide recurring info

Recurrence pattern : daily/weekly/monthly/yearly

Range of recurrence :

No end date

End after X occurrences

End at given date

2.3.3. File Format

a) vCalendar

The traditional calendaring and scheduling information found in paper day-planners and calendars have beecaptured in a flexible, electronic format in the vCalendar specification. It is suitable as an interchange formabetween applications or systems and is defined independent of the particular method used to transport it.

On http://www.imc.org/pdi/pdiproddev.html the specification is outlined and explains the content of eithervTodo and vEvent data-objects; They contain about thirty Properties upon which the most important are :

Attendee

Categories and Classification

Due Date, Start Date, End Date, Date Created and Date completed

Location

Description, Summary and Status
http://www.imc.org/pdi/pdiproddev.htmlhttp://www.imc.org/pdi/pdiproddev.htmlhttp://www.imc.org/pdi/pdiproddev.htmlhttp://www.imc.org/pdi/pdiproddev.html


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i.e. roughly all content information that we need as defined in 2.3.2 are represented in the vCalendarspecification.

b) iCalendar

iCalendar is essentially version 2.0 of vCalendar. It has some features that v1.0 does not support and is

defined in RFC 2245: http://www.ietf.org/rfc/rfc2445.txtthe specification of iCal (vCal 2.0) is outlined and

While vCalendar is the older standard, developed by the Internet mail consortium in 1996. iCalendar is anewer and more robust version of vCalendar, capable of transferring more information, and first wasdocumented in 1998. It is based on the earlier work of the vCalendar specification. iCalendar is essentiallyversion 2.0 of vCalendar. The basic difference is the types of data each can transmit. Both handle therudiments of time, date, place and attendees, but iCalendar also handles e.g. alarm type and RelationshipComponent.

The following example specifies a scheduled meeting that begins at 8:30 AM EST on March 12, 1998 andends at 9:30 AM EST on March 12, 1998.

BEGIN:VCALENDAR

BEGIN:VEVENT

UID:guid-1.host1.com

DTSTAMP:19980309T231000Z

DESCRIPTION:Project XYZ Review Meeting

SUMMARY:XYZ Project Review

DTSTART:19980312T133000Z

DTEND:19980312T143000Z

LOCATION:1CP Conference Room 4350

END:VEVENTEND:VCALENDAR

c) Microsoft .Cal

Reverse engineering the the binary file format used by Microsoft Windows Calendar (CALENDAR.EXE)produced the document at

http://mediasrv.ns.ac.yu/extra/fileformat/windows/cal/calendar.txt

A Calendar binary file contains information about file content, dates, days, and appointments. It is onlysupported by some older Ms distributions.

d) hCalendar

While the above specification are used to define how a calendar event should be stored in a file for archivinor for exchanging, the micro-formats site contain a hCalendar9 format (open standard) for embedding suchcalendar events inside XHTML documents. The iCalendar example above will than deliver the following

9 http://microformats.org/wiki/hcalendar
http://www.ietf.org/rfc/rfc2445.txthttp://mediasrv.ns.ac.yu/extra/fileformat/windows/cal/calendar.txthttp://microformats.org/wiki/hcalendarhttp://www.ietf.org/rfc/rfc2445.txthttp://www.ietf.org/rfc/rfc2445.txthttp://www.ietf.org/rfc/rfc2445.txthttp://mediasrv.ns.ac.yu/extra/fileformat/windows/cal/calendar.txthttp://mediasrv.ns.ac.yu/extra/fileformat/windows/cal/calendar.txthttp://mediasrv.ns.ac.yu/extra/fileformat/windows/cal/calendar.txthttp://microformats.org/wiki/hcalendarhttp://microformats.org/wiki/hcalendarhttp://microformats.org/wiki/hcalendar


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xhtml snippet

Web 2.0 Conference:

October 5-

7,at the Argent Hotel, San Francisco, CA

which could be displayed as:

Web 2.0 Conference: October 5-7, at the Argent Hotel, San Francisco, CA

The main objective of the hCalendar format is to augment the capabilities of a simple html page to become aWeb2.0 page. This allows the page to not only be readable by humans but also by computer software.

2.3.4. Applications

a) Desktop

For windows OS the most common calendar application is integrated within Ms Outlook. It providesdifferent views (day/week/month) on the calendar events. When used in combination with an Ms ExchangeServer the software allows checking whether invitees for a meeting have a free slot for a next event bysharing busy/free times of colleagues.

Another runner-up is the Mozilla Sunbird/Lightning duo. They provide roughly the same functionality butthe Lightning application is integrated in the Thunderbird E-mail client. The main advantage of this duo isthat it is Open Source and it supports the Caldav exchange open standard.

b) Web

There are currently several free web applications for sharing calendar information. Most known are thosefrom yahoo and hotmail, but they both online keep track of a single users calendar, they do not providesharing/exchanging of information. The Google calendar does provide a way to share calendar with otherusers and even allows promoting a calendar to public so that every-one is able to view the calendarinformation. It also allows sending invites through Gmail. And as a last positive point, the Google calendar

allows publishing the calendar as an iCal file.

2.4. Notes

An interesting review on Electronic Calendars can be found athttp://aspen.ucs.indiana.edu/project/cctools/Calendars.doc and addresses the following calendar standards

Calendaring data interchange standard (vCalendar/iCalendar)
http://www.web2con.com/http://aspen.ucs.indiana.edu/project/cctools/Calendars.dochttp://www.web2con.com/http://www.web2con.com/http://www.web2con.com/http://aspen.ucs.indiana.edu/project/cctools/Calendars.dochttp://aspen.ucs.indiana.edu/project/cctools/Calendars.dochttp://aspen.ucs.indiana.edu/project/cctools/Calendars.doc


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Calendaring interoperability protocol (iTIP/iMIP/iRIP)

Calendar access protocol (CAP)


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3. can open source exchange [MY] world

"Bless us and splash us, my precioussss! I guess it's a choice feat; at least a

tasty morsel it'd make us, gollum!" And when he said gollum he made ahorrible swallowing noise in his throat. That is how he got his name, thoughhe always called himself 'my precious'

The Hobbit, "Riddles in the Dark"

Most information discussed in the previous chapter is typically private information which is not supposed tobe visible to other people. There are of course company wide address books but even them are not supposedto be visible by other companies and most often not including all personal info like birthdays, private mobilphone, etc.

The same applies to Calendar entries, task lists and notes. But not so for bookmark lists, Rss feeds, etc.People dont seem to mind to share that info with others. Web services like http://del.icio.us/andhttp://share.opml.org/are there just for that reason.

In any case, we need to make sure that information that is private should not be seen by others. This is whersecurity and encryption comes in. Since we are mainly interested in exchanging and synchronizinginformation we will not discuss the security of data-storage ON the desktop. It is the security of the operatinsystem and of each particular desktop application that needs to ensure that the data on disc is save. We willfocus on security and authentication when sending information like emails, calendar updates, address booksearches/updates over the Internet.

3.1. Securing E-mail

Default E-mail sending is a secure as sending postcards by snail mail. Why?

The protocol for routing mail around the Internet (SMTP) is typically implemented without any type oftransport encryption. The same counts for standard POP or IMAP protocols that are used to retrieve emailsfrom server.

This means that anyone listening to these lines can read the emails if they are unencrypted. There are twooptions here. Either you make sure that your transport layer become secure which can be done by connectinto the SMTP and POP/IMAP server using SSL. Or you make sure the message itself is encrypted.

The latter is preferred since SSL only protect data in transit over a network, a mechanism is needed to protedata in long-term data storage such as disk files on desktop and server machines.

And there is still the issue of authentication. The current situation is that receivers of emails can be identifie(they have to enter user-name and password to retrieve their mail), but the senders are not. Anyone can in fasend an E-mail and fill in any address on the sender field. A way to authenticate the emails and even putdigital signatures is needed.
http://del.icio.us/http://share.opml.org/http://del.icio.us/http://del.icio.us/http://del.icio.us/http://share.opml.org/http://share.opml.org/http://share.opml.org/


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3.1.1. SSL

SSL(Secure Sockets Layer) ensures that all data that travels the line from the sender or receiver to the SMTPor POP/IMAP server is encrypted. Any-one eavesdropping this line will only see encrypted data.

SSL10 consists of 2 sub-protocols, one for setting up a connection and one for transmitting data over theconnection. The protocol act as a new layer between the network transport layer (e.g. TCP/IP) and the

application layer (HTTP), which in that case is called HTTPS and is often used in secure web applicationslike web mail clients and web based banking. But in fact any application can use the secure layer so SMTPand IMAP can also float on it.

3.1.2. Digital Signatures

There are three common reasons for applying a digital signature to communications:

1. Authentication: The receiver will be confident that the message was indeed send by the personclaiming to be the sender.

2. Integrity: Both the sender and the receiver can be confident that the content of the message has notbeen altered

3. Non-repudiation: the sender cannot claim that the message was send by someone else.

It is most common to use a private key to sign the message. Signing in this case means: calculating the hashof the message and using the private key to encrypt that hash, that encrypted hash is attached to the message[Note that the message itself is not encrypted in this process].

The receiver on the other hand uses the public key of the sender to decrypt the hash and compares it to theself calculated hash.

In practice it is not needed to sign each message send during a communication. In fact only the final decisioshould be signed. E.g. during negotiations with a future employer, all communication should be encrypted(but not necessarily signed), only when the employee decides to sign a contract he should digitally sign thatmessage.

3.1.3. Bundled security

When all of the pieces of the security puzzle are available one can build a security solution that ensuresprivacy, authentication, digital signing, encryption and compression. The first pretty good solution came froPhil Zimmerman in the form of PGP11 (Pretty Good Privacy). It was an open source solution implemented oall major OS-platforms andCryptographerBruce Schneiercharacterized an early version as being "the

closest you're likely to get to military-grade encryption" (Applied Cryptography, 2nd ed., p587).

Because of political issues (US considered the open sourcing of PGP software as military export) and patentproblems. Both symmetric RSA algorithm and the asymmetric IDEA algorithm had been patented and had tbe replaced by unpatented algorithms.

10 http://en.wikipedia.org/wiki/Transport_Layer_Security and A. Tanenbaum in (Computer netwerken, 4th ed., p822).

11 Pretty_Good_Privacy
http://en.wikipedia.org/wiki/Cryptographerhttp://en.wikipedia.org/wiki/Cryptographerhttp://en.wikipedia.org/wiki/Bruce_Schneierhttp://en.wikipedia.org/wiki/Bruce_Schneierhttp://en.wikipedia.org/wiki/Transport_Layer_Securityhttp://en.wikipedia.org/wiki/Pretty_Good_Privacyhttp://en.wikipedia.org/wiki/Transport_Layer_Securityhttp://en.wikipedia.org/wiki/Transport_Layer_Securityhttp://en.wikipedia.org/wiki/Transport_Layer_Securityhttp://en.wikipedia.org/wiki/Pretty_Good_Privacyhttp://en.wikipedia.org/wiki/Pretty_Good_Privacyhttp://en.wikipedia.org/wiki/Pretty_Good_Privacyhttp://en.wikipedia.org/wiki/Cryptographerhttp://en.wikipedia.org/wiki/Cryptographerhttp://en.wikipedia.org/wiki/Cryptographerhttp://en.wikipedia.org/wiki/Bruce_Schneierhttp://en.wikipedia.org/wiki/Bruce_Schneierhttp://en.wikipedia.org/wiki/Bruce_Schneier


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A successor for the PGP program is the S/MIME12 standard which provides the following cryptographicsecurity services for electronic messaging applications:

authentication,

message integrity

non-repudiation of origin (using digital signatures)

privacy and data security (using encryption).

It is currently build into the majority of E-mail clients and can only be used after installing a key/certificatefrom a free or paying Certificate Authority like www.certipost.be

3.2. Securing synchronization of information

The needs to have a secure synchronization of personal information are a lot less than when sending emails.

We need

1. Integrity of the information. We need to be sure if data that the requested changes (update/delete/addis correctly applied on the receiver side. This can easily be done by calculating a check-sum andadding that to the message. The receiver can than verify that the request has not been altered

2. Privacy of the information. We suppose that the storage of the information is secured either bymaking sure that accessing the information is only feasible by the authorized user or by encrypting ainformation with a key that is only know by the user. The only weak link is than the communicationchannel. We have explained above that by using the SSL on top of the transport layer any application(web services, remote procedure calls, http requests) can benefit from this secure channel. It can alsobe used to tunnel an entire network stack to create aVPN. In that case all communication becomesencrypted.

4. can open source [EXCHANGE] my world

Discussion is an exchange of knowledge; argument an exchange ofignorance.

Robert Quillen (1887- 1948)

4.1. E-mail

E-mail originated in the mid 60s as a way to communicate between users of the same Time-sharing system(TSS). Users left files in a common folder To tom containing a message. In the late 60s most TSS had aninternal mail system and linking them was the one of the first applications of ARPANET. After some

12 MIME (Multipurpose Internet Mail Extensions)
http://www.certipost.be/http://en.wikipedia.org/wiki/Virtual_Private_Networkhttp://en.wikipedia.org/wiki/Virtual_Private_Networkhttp://en.wikipedia.org/wiki/Virtual_Private_Networkhttp://en.wikipedia.org/wiki/1887http://en.wikipedia.org/wiki/1948http://www.google.be/url?sa=t&ct=res&cd=1&url=http%3A%2F%2Fwww.mhonarc.org%2F~ehood%2FMIME%2F&ei=SYFfRa2KG6L0nQOFl4G2Bg&usg=__pPBSpptRR3Mj6-ekkT6GJa-D8Rk=&sig2=qDJSOOgP7NI4z-7_lCn69Qhttp://www.google.be/url?sa=t&ct=res&cd=1&url=http%3A%2F%2Fwww.mhonarc.org%2F~ehood%2FMIME%2F&ei=SYFfRa2KG6L0nQOFl4G2Bg&usg=__pPBSpptRR3Mj6-ekkT6GJa-D8Rk=&sig2=qDJSOOgP7NI4z-7_lCn69Qhttp://www.certipost.be/http://www.certipost.be/http://www.certipost.be/http://en.wikipedia.org/wiki/Virtual_Private_Networkhttp://en.wikipedia.org/wiki/Virtual_Private_Networkhttp://en.wikipedia.org/wiki/Virtual_Private_Networkhttp://en.wikipedia.org/wiki/1887http://en.wikipedia.org/wiki/1887http://en.wikipedia.org/wiki/1887http://en.wikipedia.org/wiki/1948http://en.wikipedia.org/wiki/1948http://en.wikipedia.org/wiki/1948


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iterations a protocol for sending mail came to life in the beginning of the 70s. Also the @-sign to separateusername from computer system was invented at that time. This led to the SMTP protocol as we know itnowadays for delivering mail from a sender to the receivers Mail server. The receiver itself has to pick uphis mail from that mail server. This can be done in several ways.

He logs into his mail server to open his mailbox and read his mails directly at the server. Typicalthrough a telnet session and using old mail software like pine, elm or mutt.

He uses a web mail application which retrieves the E-mail from the server and displays it as a html.

He uses a mail client on his desktop PC which retrieves the E-mail using either POP or IMAP

We have already addressed (2.1.2) the format of emails as they float over the Internet and even discussed amore secure format (3.1) which is an extension to the original MIME format.

4.1.1. SMTP (Simple Mail Transfer Protocol)

It is a text based protocol which first defines the list of recipients followed by the message in plain text. The

protocol is used to deliver mail from the senders desktop to the mail transfer service of the ISP, but is alsoused to send the mail to other MTAs until it finally is delivered in the mailbox of the receivers ISP.

There are typically three steps to deliver a mail from a senders desktop to a receivers mail server.

1. The client application looks at the domain name in the E-mail address to find a server that accepts thmessage

2. That server request the DNS of the receivers domain for the MX record in its table, which response bgiving the name of any mail server that accepts messages for the receivers domain.

3. The senders server delivers the message using SMTP to the receivers mail server

SMTP is not used to deliver the mail to the desktop of the receiver. The receiver itself must initiate the pickup process.

4.1.2. POP (Post Office Protocol)

While the SMTP protocol is used to push e-mail from sender to receivers mail server. POP is used to pulle-mail from the mail server to the receivers desktop mail client. POP3 is the version that is currentlyimplemented by desktop mail client applications, and has been designed for dial-up connections that are notalways online. It is used to connect to the mail server, download all or selected messages to the desktop, andtypically go back offline. The messages that are successfully downloaded to desktop are by default removedfrom the server. This has an advantage because the receiver can now read the message without going onlineBut as a result when he switches to another desktop machine he will no longer be able to read thedownloaded message. As a result most clients now support the leave message on serveroption which will ndelete the message after successful download. This puts some extra burden on the client because it now needto keep track which messages have already been downloaded and which havent. To be able to do that POP3supports UIDL (Unique IDentification Listing) command which attaches a unique number to each message

4.1.3. IMAP

IMAP (Internet Message Access Protocol) is gradually replacing POP as the main protocol used by E-mail


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clients in communicating with E-mail servers. Using IMAP an E-mail client program can not only retrieve Email but can also manipulate message stored on the server, without having to actually retrieve the messagesSo messages can be deleted, have their status changed, multiple mail boxes can be managed, etc. All this isoff course only possible with an always online connection. But it can also be used to download messagesoffline so it can also be used by dial-up connections.

A very interesting feature of IMAP is the Push e-mail. When both the server and the client support the idle

command, a message that reaches the server is immediately pushed to any connected clients. The client nolonger has to poll the server every few minutes to check if new mail has arrived. It has the same effect as e.gBlackBerry telephones which immediately retrieve new mail when it reaches the Blackberry server. Thispush technology is mainly interesting for Phone devices which have rather low bandwidths and are usingcostly GPRS/UMTS connection to stay online. A good mobile E-mail client will generate a "poll" event(leave IDLE - re-enter IDLE), that can be as little as 20 characters each way.2(up-down) x 20(character) x 24(2 times an hour for 12 hours) x 30 = 28.8k a month which is not that muchtraffic in order to keep an IMAP continuously alive for receiving push e-mails within seconds after arrival othe server.

4.2. Calendar

When using Ms Exchange server, calendaring and scheduling within the company is relatively easy incombination with Ms Outlook as client application. The main problem is that a closed protocol is used totransmit calendaring information from client to server machines.

There are several open standards regarding the exchange of calendaring information.

The oldest standard is rfc2445 (iCalendar). But this standard only defines the format in which calendarinformation should be transmitted. It does not state what protocol should be used to query a server forcalendar information.

Webdav

The simplest implementation of calendar sharing is based on Webdav which is an extension to the httpprotocol allowing users to collaboratively edit and manage files on remote web servers. In this case the fileswould be iCalendar files stored on a Webdav supporting server. When the address of this calendar file isshared to other people they can subscribe to this calendar and view the events in their own client applicationWhen the maintainer of the calendar makes changes, the client application will then publish a new version othe .ical file to the Webdav server and thus pushing the change to any other listeners. Several clientapplications (Apple's iCal, Mozilla Sunbird, ) support this type of calendar sharing.

Caldav

Another rather new protocol for sharing calendar is CalDav, it is based on the way that Webdav was used bysome client applications for sharing calendars, but where the Webdav way of working was based on simplystoring iCal files on on a network drive, It takes over some already existing advantages of WebDAV forCalendar Access13like

Using existing HTTP URLs for Calendar objects. No new format is needed

13See http://greenbytes.de/tech/webdav/draft-dusseault-caldav-01.html#advantages for more info on these advantages
http://greenbytes.de/tech/webdav/draft-dusseault-caldav-01.html#advantageshttp://greenbytes.de/tech/webdav/draft-dusseault-caldav-01.html#advantageshttp://greenbytes.de/tech/webdav/draft-dusseault-caldav-01.html#advantageshttp://greenbytes.de/tech/webdav/draft-dusseault-caldav-01.html#advantageshttp://greenbytes.de/tech/webdav/draft-dusseault-caldav-01.html#advantages


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Webdav provides info as XML which makes it easy to use in web-application and web-services

Support locking of objects [events,todo,..]

Authorization of users can be supported through Webdav ACL14

Security can be provided through SASL15and TLS16

Some work has been to have Webdav support offline functionality and synchronization on reconnectCaldav could benefit from this work

The required calendaring features that are still missing in Webdav should be provided by the calDavextension of webdav

Fan-out: This allows clients to perform simple operations (send a single schedule request to theserver) and have the server perform complex and possibly time consuming processing

Recurrence: Should be provided by a single object containing recurrence info, all the instances of are-currency will than become a VIEW/REPORT of the recurrence data. Changing the title in thesingle object would affect all instances.

Notifications: HTTP has no way to interact with client, so some mechanism e.g XMPP17 or SIP18 isneeded to provide 2-way communication

4.3. Address book

4.3.1. Requirements

Before going into the detail of exchanging address books, lets first rumble down over the requirements fosuch a service from the perspective of an end-user.

the service should be accessible from different client applications

the service should preferable be accessible through a web application

it should be possible to access the service from multiple clients at the same time

e.g a pc at home and a pc at work still online

14Access Control Protocol

15Simple authentication and Security Layer

16Transport Layer Security

17Extensible Messaging and Presence Protocol

18Session Initiation Protocol
http://tools.ietf.org/html/rfc3744http://en.wikipedia.org/wiki/Simple_Authentication_and_Security_Layerhttp://en.wikipedia.org/wiki/Transport_Layer_Securityhttp://en.wikipedia.org/wiki/Extensible_Messaging_and_Presence_Protocolhttp://en.wikipedia.org/wiki/Session_Initiation_Protocolhttp://tools.ietf.org/html/rfc3744http://tools.ietf.org/html/rfc3744http://tools.ietf.org/html/rfc3744http://en.wikipedia.org/wiki/Simple_Authentication_and_Security_Layerhttp://en.wikipedia.org/wiki/Simple_Authentication_and_Security_Layerhttp://en.wikipedia.org/wiki/Simple_Authentication_and_Security_Layerhttp://en.wikipedia.org/wiki/Transport_Layer_Securityhttp://en.wikipedia.org/wiki/Transport_Layer_Securityhttp://en.wikipedia.org/wiki/Transport_Layer_Securityhttp://en.wikipedia.org/wiki/Extensible_Messaging_and_Presence_Protocolhttp://en.wikipedia.org/wiki/Extensible_Messaging_and_Presence_Protocolhttp://en.wikipedia.org/wiki/Extensible_Messaging_and_Presence_Protocolhttp://en.wikipedia.org/wiki/Session_Initiation_Protocolhttp://en.wikipedia.org/wiki/Session_Initiation_Protocolhttp://en.wikipedia.org/wiki/Session_Initiation_Protocol


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e.g. an address-book application and an E-mail application accessing the service at the sametime from the same pc

changes made in one client should ripple through to all other attached clients

this synchronization can become very hard in some situation, eg. A user having a pc at homeand work, a mobile phone and online address book service19

preferable make use of open standards

4.3.2. Microsoft exchange Server

Although Microsoft exchange Server supports the concept of having a company-wide public address book,which can be searched through by any outlook client, it is not open standard, not free, and difficult to installfor most of the computer users.

4.3.3. LDAP

Another option could be to install a personal LDAP server and use it to share address books.20

We will go inthe details of a LDAP server later on, but we can already reveal that setting up a LDAP server is not an easytask and requires good knowledge about Active Directories. LDAP is not limited to contact information, oreven information about people. LDAP is used to look up encryption certificates, pointers to printers and othservices on a network, and provide "single sign-on" where one password for a user is shared between manyservices. LDAP is appropriate for any kind of directory-like information, where fast look-ups and less-frequent updates are the norm.

Because LDAP can be used for a lot more than keeping track of contact information it is like using a RoyceRolls only to go to the market. You are allowed to do it, but it has so much more to offer.

LDAP (Lightweight Directory Access Protocol) is a protocol running over TCP/IP to query a LDAP server.

The LDAP server (aka. Directory server) are databases heavily optimized for read performance.

LDAP directory servers store their data hierarchically in a tree of entries

An entry consists of a set of attributes

An attribute has a name and one or more values

An example of such an entry represented in LDIF format has already been provided in sectio2.2.3, as an example of an address book file format.

4.3.4. SyncML

A third option is using some synchronization mechanism like SyncML to synchronize address books inseveral client applications or devices.

19 Read more about these difficulties on a blog titled : the-holy-grail-of-synchronization

20 See http://www.sudleyplace.com/LDAP/ andhttp://kb.mozillazine.org/Sharing_address_books#LDAP
http://engtech.wordpress.com/2006/08/11/the-holy-grail-of-synchronization-how-to-synchronize-microsoft-outlook-multiple-locations-google-calendar-gmail-ipod-and-mobile-phone-with-funambol-scheduleworld/http://engtech.wordpress.com/2006/08/11/the-holy-grail-of-synchronization-how-to-synchronize-microsoft-outlook-multiple-locations-google-calendar-gmail-ipod-and-mobile-phone-with-funambol-scheduleworld/http://www.sudleyplace.com/LDAP/http://kb.mozillazine.org/Sharing_address_books#LDAPhttp://kb.mozillazine.org/Sharing_address_books#LDAPhttp://engtech.wordpress.com/2006/08/11/the-holy-grail-of-synchronization-how-to-synchronize-microsoft-outlook-multiple-locations-google-calendar-gmail-ipod-and-mobile-phone-with-funambol-scheduleworld/http://engtech.wordpress.com/2006/08/11/the-holy-grail-of-synchronization-how-to-synchronize-microsoft-outlook-multiple-locations-google-calendar-gmail-ipod-and-mobile-phone-with-funambol-scheduleworld/http://engtech.wordpress.com/2006/08/11/the-holy-grail-of-synchronization-how-to-synchronize-microsoft-outlook-multiple-locations-google-calendar-gmail-ipod-and-mobile-phone-with-funambol-scheduleworld/http://www.sudleyplace.com/LDAP/http://www.sudleyplace.com/LDAP/http://www.sudleyplace.com/LDAP/http://kb.mozillazine.org/Sharing_address_books#LDAPhttp://kb.mozillazine.org/Sharing_address_books#LDAPhttp://kb.mozillazine.org/Sharing_address_books#LDAP


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SyncML is an open standard used to synchronize contact and calendar information between some handhelddevice (mobile phone, pda , ) and a computer (personal, or network-based service).

The protocol is especially aimed at mobile phones, but can in fact also be used to synchronize contact andcalendar information from eg. outlook with a SyncML server. There are some open source server solutionsthat adhere to this synchronization standard like open-xchange and funambol but more on those in the nextchapter

4.3.5. Plaxo.com

A last option is to use the Plaxo.com web service which synchronizes several mail clients (outlook,Thunderbird, mac address book) with the online address book. It even provides API calls to integrate it intoanother web application. But sadly it does not support any open standard to search through the contactinformation

4.4. Exchange Server Alternatives

In the above section separate way of sharing/synchronization Personal Information have been provided, eachof the provided solutions tries to solve a different task of the complete exchange mechanism.

To ease maintenance it would be extremely helpful if there was a single solution that would solve all theseproblems at once. Again preferable we are looking at open source solutions supporting as many openstandards as possible. In this section a few groupware solution are listed that solve the exchange problem innon-standard way. Most of the provided solution are free and support a lot of open standard(mapi,ldap,syncml, ldap,) but most often the company maintaining the open source projects charge forconnector with eg. outlook

4.4.1. Open source Microsoft Exchange replacements

a) www.open-xchange.com

Open-Xchange is the star of the new generation of messaging and collaboration servers, and a sterlingexample of the power of free and open source development methodologies. It is based on the usual best-of-breed FOSS suspects: Postfix, OpenLDAP, Apache, Cyrus IMAP, Tomcat, and PostgreSQL, as well asvarious other bits and pieces. 21

Individually, these are all first-class applications. Knit them together, add nice graphical administration anduser interfaces, and presto! Instant superpower messaging suite.

Of course, it isn't quite that easy, and much credit goes to the developers. Open-Xchange Server 5, the latestrelease, packs in many improvements and boasts a comprehensive feature set:

E-mail and Webmail

Calendaring, both individual and group

Meeting coordination

21 According to http://www.serverwatch.com/sreviews/article.php/3603776
http://www.open-xchange.com/http://www.serverwatch.com/sreviews/article.php/3603776http://www.open-xchange.com/http://www.open-xchange.com/http://www.open-xchange.com/http://www.serverwatch.com/sreviews/article.php/3603776http://www.serverwatch.com/sreviews/article.php/3603776http://www.serverwatch.com/sreviews/article.php/3603776


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Contact management, both shared and group

Document sharing

Cross-platform domain controller

Project management capabilities

Searchable knowledge base

Shared "Pin Board"

Personalizable to-do lists

PDA synchronization

Forums

The main benefits of the commercial version over the open source are

support

easy installation

connectors for outlook, syncML devices

b) other alternatives

There are a lot of other linux alternatives that have roughly the same feature set as Open-Exchange and ofteinclude a lot of similar libraries. All of them are to be installed/maintained by experienced systemadministrators.

We will not go into details but here's a list of some of these solutions in alphabetical order

www.egroupware.org

www.exchange4linux.org

www.opengroupware.org

www.scalix.com/products/opensource.html

4.4.2. From a different angle

The above solutions all try to mimic the Ms Exchange Server and do their best to provide connectors so thatend users using Ms Outlook do not notice the difference
http://www.egroupware.org/http://www.exchange4linux.org/http://www.opengroupware.org/http://www.scalix.com/products/opensource.htmlhttp://www.egroupware.org/http://www.egroupware.org/http://www.egroupware.org/http://www.exchange4linux.org/http://www.exchange4linux.org/http://www.exchange4linux.org/http://www.opengroupware.org/http://www.opengroupware.org/http://www.opengroupware.org/http://www.scalix.com/products/opensource.htmlhttp://www.scalix.com/products/opensource.htmlhttp://www.scalix.com/products/opensource.html


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a) www.kolab.org

The special Idea behind Kolab is the usage ofIMAPas an underlyingprotocolnot only for E-mail, but forcontact- and calendar entries, too. An entry is simply saved in a special IMAP-folder using XML and theIMAP-server takes care of the storage. The configuration and maintenance of Kolab is entirely controlled bythe extensive use of LDAP.22

The architecture of kolab is based on open standards. Chapter 2 of their lengthy architecture draft23

discussethe protocols and file formats used

The protocols were selected with the following criteria in mind:

proper standardization e.g. by the Internet Engineering Task Force (IETF, http://www.ietf.org) open standard in the sense that a Free Software implementation is available existing Free Software implementations must scale very well

This leads to the following protocols used in the project:

LDAP, FTP, SSL, SMTP, IMAP, POP3, HTTP, HotSync

And the following file formats:

MIME E-mail, iCalendar and vCard, Kolab-XML an open storage format

Any standard client can connect to the various services a Kolab Server provides, e.g. E-mail (SMTP, POP3,IMAP), iCalendar services (E-mail), Address-book/Management (LDAP) or Freebusy lists (HTTP).

For an integrated groupware experience, more is needed. Clients must understand the Kolab2 storage formaand have necessary features, like setting access controls dealing with iCalendar emails and freebusy lists.Any non-web client must also offer offline support and should do electronic signatures. Following clients arcurrently known

KDE client (Kontact) free - GPL Ms Outlook, Trolltec connector - proprietary, with 30 day evaluation Horde webmail Thunderbird plugin: Sync kolab

b) www.funambol.com

Formerly known as the Sync4j project, Funambol is an open source mobile application server that provides

push E-mail, address book and calendar (PIM) data synchronization, application provisioning, and devicemanagement for wireless devices and PCs, leveraging standard protocols. For users, this meansBlackBerry-like capabilities on commodity handsets.24

Funambol is mainly targeted to mobile clients and uses synchronization through syncMl as the heart of all

22 http://en.wikipedia.org/wiki/Kolab

23 The architecture draft can be found in the pdf document :http://www.kolab.org/doc/concept-draft-cvs20060921.pdf

24 http://en.wikipedia.org/wiki/Funambol
http://www.kolab.org/http://en.wikipedia.org/wiki/Internet_Message_Access_Protocolhttp://en.wikipedia.org/wiki/Communications_protocolhttp://www.funambol.com/http://en.wikipedia.org/wiki/Push_emailhttp://en.wikipedia.org/wiki/Personal_information_managerhttp://en.wikipedia.org/wiki/BlackBerryhttp://en.wikipedia.org/wiki/Kolabhttp://www.kolab.org/doc/concept-draft-cvs20060921.pdfhttp://www.kolab.org/doc/concept-draft-cvs20060921.pdfhttp://en.wikipedia.org/wiki/Funambolhttp://www.kolab.org/http://www.kolab.org/http://www.kolab.org/http://en.wikipedia.org/wiki/Kolabhttp://en.wikipedia.org/wiki/Kolabhttp://en.wikipedia.org/wiki/Kolabhttp://en.wikipedia.org/wiki/Internet_Message_Access_Protocolhttp://en.wikipedia.org/wiki/Internet_Message_Access_Protocolhttp://en.wikipedia.org/wiki/Internet_Message_Access_Protocolhttp://en.wikipedia.org/wiki/Communications_protocolhttp://en.wikipedia.org/wiki/Communications_protocolhttp://en.wikipedia.org/wiki/Communications_protocolhttp://www.kolab.org/doc/concept-draft-cvs20060921.pdfhttp://www.kolab.org/doc/concept-draft-cvs20060921.pdfhttp://www.kolab.org/doc/concept-draft-cvs20060921.pdfhttp://www.funambol.com/http://www.funambol.com/http://www.funambol.com/http://en.wikipedia.org/wiki/Funambolhttp://en.wikipedia.org/wiki/Funambolhttp://en.wikipedia.org/wiki/Funambolhttp://en.wikipedia.org/wiki/Push_emailhttp://en.wikipedia.org/wiki/Push_emailhttp://en.wikipedia.org/wiki/Push_emailhttp://en.wikipedia.org/wiki/Personal_information_managerhttp://en.wikipedia.org/wiki/Personal_information_managerhttp://en.wikipedia.org/wiki/Personal_information_managerhttp://en.wikipedia.org/wiki/BlackBerryhttp://en.wikipedia.org/wiki/BlackBerryhttp://en.wikipedia.org/wiki/BlackBerry


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operations.

c) www.scheduleworld.org

Another project using syncML as core exchange mechanism iswww.scheduleworld.org. It is service enablinits users to schedule events, and keep track of contacts.

To contact the server a user has several options. There is a web-interface25 (which can even be synchronizedwith Google calendar), a java client using webstart26, a J2ME client for cell phones27 and there isInteroperability with standard clients like Outlook, Thunderbird, Sunbird and recently syncEvolution andBlackberry support has been added.

Although the software still has active development on freshmeat and seems to support a lot of openstandards, the project is maintained only by a single developer and is not open source (but a trial version canbe obtained).

d) http://osafoundation.org/

OSAF is a non-profit organization developing next-generation inter-personal information managementsoftware. Their current projects include a desktop PIM application code-named "Chandler", a server code-named "Cosmo"and a web calendar code-named Scooby. The project is still under heavy development anseeks to become a complete all-in-one package providing small businesses and universities and interestingplatform for collaborative working.

There is an active development in this project and the foundation recently (September 06) welcomed twonew members to their team.

Another reason for monitoring the progress of this project is that the board of directors28 includes some very

well known technological people from Mozilla Foundation, Lotus Development, Electronic FrontierFoundation, and University of Berkeley.

5. 5can [OPEN source] exchange my world

The trouble with having an open mind, of course, is that people will insiston coming along and trying to put things in it.

Terry Pratchett

25 http://www.ScheduleWorld.com/tg/

26 http://www.ScheduleWorld.com/sw/ScheduleWorld.jnlp

27 http://www.scheduleworld.com/j2me.html

28 See bottom ofhttp://osafoundation.org/people.htm
http://www.scheduleworld.org/http://www.scheduleworld.org/http://www.scheduleworld.org/http://osafoundation.org/http://chandler.osafoundation.org/http://cosmo.osafoundation.org/http://scooby.osafoundation.org/http://www.scheduleworld.com/tg/http://www.scheduleworld.com/sw/ScheduleWorld.jnlphttp://www.scheduleworld.com/j2me.htmlhttp://osafoundation.org/people.htmhttp://osafoundation.org/people.htmhttp://www.scheduleworld.org/http://www.scheduleworld.org/http://www.scheduleworld.org/http://www.scheduleworld.org/http://www.scheduleworld.org/http://www.scheduleworld.org/http://www.scheduleworld.com/tg/http://www.scheduleworld.com/tg/http://www.scheduleworld.com/tg/http://www.scheduleworld.com/sw/ScheduleWorld.jnlphttp://www.scheduleworld.com/sw/ScheduleWorld.jnlphttp://www.scheduleworld.com/sw/ScheduleWorld.jnlphttp://www.scheduleworld.com/j2me.htmlhttp://www.scheduleworld.com/j2me.htmlhttp://www.scheduleworld.com/j2me.htmlhttp://osafoundation.org/http://osafoundation.org/http://osafoundation.org/http://chandler.osafoundation.org/http://chandler.osafoundation.org/http://chandler.osafoundation.org/http://cosmo.osafoundation.org/http://cosmo.osafoundation.org/http://cosmo.osafoundation.org/http://scooby.osafoundation.org/http://scooby.osafoundation.org/http://scooby.osafoundation.org/http://osafoundation.org/people.htmhttp://osafoundation.org/people.htmhttp://osafoundation.org/people.htm


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Why Open?

The basic point is to understand the difference between open source (which allows you to change code orcontent) and open standards (which enable components to work together because the specifications areknown).

In the course of this paper it comes down to checking if

Client applications (E-mail, browser, synchronization software) are Open Source

Application protocols (smtp, pop, imap, ical, rpc) are Open Standard

File formats (mime, ical, mbox) are Open Standard

Algorithms (encryption, handshaking) are Open Standard and its implementations Open Source

5.1. Open source software

There are currently 2 different definitions that cover the meaning of 'Open Source'

a) Open source definition by OSI:

Open source doesn't just mean access to the source code. The distribution terms of open-source softwaremust comply with the 10 criteria defined by the Open Source Initiative.

The most important requirements are

Free Redistribution : The license shall not require a royalty or other fee for sale. Source Code available : The program must include source code, and must allow distribution in sourc

code as well as compiled form. Derived Work must be allowed to be created and distributed under the same terms as the license of th

original software.

b) Free Software definition by GNU:

According to GNU ("GNU's Not UNIX) the free software definition shows clearly what must be true aboua particular software program for it to be considered free software.

Free software is a matter of liberty, not price. To understand the concept, you should think of free as in freespeech, not as in free beer.

Free software is a matter of the users' freedom to run, copy, distribute, study, change and improve thesoftware. More precisely, it refers to four kinds of freedom, for the users of the software:

The freedom to run the program, for any purpose (freedom 0). The freedom to study how the program works, and adapt it to your needs (freedom 1). Access to the

source code is a precondition for this. The freedom to redistribute copies so you can help your neighbour (freedom 2).
http://opensource.antifork.org/docs/definition.phphttp://opensource.antifork.org/index.phphttp://www.gnu.org/philosophy/free-sw.htmlhttp://www.gnu.org/http://opensource.antifork.org/docs/definition.phphttp://opensource.antifork.org/docs/definition.phphttp://opensource.antifork.org/docs/definition.phphttp://opensource.antifork.org/index.phphttp://opensource.antifork.org/index.phphttp://opensource.antifork.org/index.phphttp://www.gnu.org/philosophy/free-sw.htmlhttp://www.gnu.org/philosophy/free-sw.htmlhttp://www.gnu.org/philosophy/free-sw.htmlhttp://www.gnu.org/http://www.gnu.org/http://www.gnu.org/


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The freedom to improve the program, and release your improvements to the public, so that the wholecommunity benefits (freedom 3). Access to the source code is a precondition for this.

c) Licences

Open source software is distributed under a license, just like regular proprietary software is. An open source

license is a license with a difference: instead of keeping or expanding the software developer's rights, it givethem away. There is no single open source license; to date, more than 30 exist. The OSI web site lists andlinks toall the OSI-certified open source licenses. But all those licences can be grouped into 4 main classes

strong copyleft licenses (example Gnu Public Licence) weak copyleft licenses (example Mozilla Public Licence) no copyleft licenses (example BSD) other open source licenses

An article onONLAMP explains these differences very well but to summarize we could state thatstrongcopyleftforces you to give up private ownership on modifications made to the source code, while no copylefleaves you free to distribute your changes.These licensing issues are becoming more and more important. In the Java world many companies are usingOpen Source Libraries (e.g apache-commons, hibernate, berkeleydb,..) in their final product, and it is veryimportant for them to check in advance how these libraries can be used. The matter has become that complethat deciding to pick an Open Source Product in the project should not be left to a single developer. There artechnical attorneys which can help manager in finding their way in the legal labyrinth.29

6. CAN open source exchange my world?

In the previous chapters we covered different parts of a general problem: Is it possible to use only software

(both client and server), released with an open source license and based only on open standards, to exchanginformation between different people, and have that information available from different location (web,client, pda).Much to my regret i think i must conclude that the full-blown solution ( a simple to install exchange serversolution based only on open standards and which can be synchronized with different clients/devices) iscurrently not yet available.There are some solution (see chapter 4) which come close but none is capable to give a solution for allrequirements.Let's break this down to the smaller pieces.

6.1. the breakdown

a) E-mail

E-mail is a very important part of information. We have see that the IMAP standard provides a very goodsolution which is easy to install and there are even free/paying services available. Combined with recentdevelopment around the IMAP IDLE command which even allows to provide a push E-mail service which iinteresting for mobile devices that are always online.

29 groklaw ,slashdot ,news.com ,linuxjournal
http://www.opensource.org/licenses/http://www.opensource.org/licenses/http://www.opensource.org/licenses/gpl-license.phphttp://www.opensource.org/licenses/gpl-license.phphttp://www.opensource.org/licenses/mozilla1.1.phphttp://www.opensource.org/licenses/mozilla1.1.phphttp://www.onlamp.com/pub/a/onlamp/2004/11/18/licenses.htmlhttp://www.onlamp.com/pub/a/onlamp/2004/11/18/licenses.htmlhttp://www.groklaw.net/index.phphttp://interviews.slashdot.org/article.pl?sid=01/06/05/122240http://interviews.slashdot.org/article.pl?sid=01/06/05/122240http://news.com.com/Lawyer+Open-source+risks+overblown/2100-7344_3-5929015.htmlhttp://news.com.com/Lawyer+Open-source+risks+overblown/2100-7344_3-5929015.htmlhttp://www.linuxjournal.com/article/5073http://www.linuxjournal.com/article/5073http://www.opensource.org/licenses/http://www.opensource.org/licenses/http://www.opensource.org/licenses/http://www.opensource.org/licenses/gpl-license.phphttp://www.opensource.org/licenses/gpl-license.phphttp://www.opensource.org/licenses/gpl-license.phphttp://www.opensource.org/licenses/mozilla1.1.phphttp://www.opensource.org/licenses/mozilla1.1.phphttp://www.opensource.org/licenses/mozilla1.1.phphttp://www.groklaw.net/index.phphttp://www.groklaw.net/index.phphttp://www.groklaw.net/index.phphttp://interviews.slashdot.org/article.pl?sid=01/06/05/122240http://interviews.slashdot.org/article.pl?sid=01/06/05/122240http://interviews.slashdot.org/article.pl?sid=01/06/05/122240http://news.com.com/Lawyer+Open-source+risks+overblown/2100-7344_3-5929015.htmlhttp://news.com.com/Lawyer+Open-source+risks+overblown/2100-7344_3-5929015.htmlhttp://news.com.com/Lawyer+Open-source+risks+overblown/2100-7344_3-5929015.htmlhttp://www.linuxjournal.com/article/5073http://www.linuxjournal.com/article/5073http://www.linuxjournal.com/article/5073http://www.onlamp.com/pub/a/onlamp/2004/11/18/licenses.htmlhttp://www.onlamp.com/pub/a/onlamp/2004/11/18/licenses.htmlhttp://www.onlamp.com/pub/a/onlamp/2004/11/18/licenses.html


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b) Contacts

Contacts management is also considered as a base necessity for many users. In a company environment itcould be possible to setup an LDAP-server. There are a few Open Source implementations but it appears thasetting up a LDAP server is not an easy task. More experienced administors are needed, and it is typically nworth the effort for single end-users. To my knowledge there aren't any ISP that provide this service for freeor as a paying service.

Although there are open standards (vCard, iCard,LDIF) to exchange contact information not much work isdone to design a working server which is capable of doing the simple CRUD-operations(CreateReadUpdateDelete) on contacts. Recently the syncML standard is being implemented using WebDavstandards, this seems like a good direction but this synchronization technology is not yet mature.

c) Calendar & Tasks

Calendar and Tasks management is yet another story. Unless that one chooses for a full blown exchangeserver which gives support for shared calendars; setting busy times, and use E-mail as a way to subscribe toevents and invite other people. It does not seem to work outside the exchange network. The 'protocol' used ithe emails is not proven to work when sending mails to people in another (exchange) network. The syncMLstandard is used here also to provide the same functionality over HTTP and by using webdav as a means ofstoring event-items. But again we must conclude that the technology is rather young and not wide spread.There are some internet services allowing people to maintain a web-based calendar/tasklist, and there areeven plugins (plaxo.com) allowing to synchronize that information with other clients/devices, but again, ..these services do not rely on any open standards

d) Bookmarks

Bookmarks and RSS-feeds: There is NO standard yet to be able to store,query or exchange this type ofinformation. There are some well-known Internet Services (Google reader/delicious/..) which allow to

maintain this information in a single location on a server. And there are even plug-ins (Google synchronize,sitebar client) that allow to 'synchronize' that information with client browsers, but alas, .. again theseservices are not build on some open standard. Just because there aren't any standards in this field.

6.2. (Pessimistic) conclusion

Although there is again some momentum in the technological world in order to provide a solution to ourproblem. We must conclude that the All-In-One solution does not yet exist. Either because there are nodecent open source implementations of the existing exchange standards, or worse, there aren't any standardsyet to solve some parts of the exchange problem. Several years will pass (if it will happen at all) before a

grant unified solution will emerge.


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6.3. (Optimistic) conclusion

It is not all gray and rainy in exchange land. Due to the rise of several Web2.0 services the exchange problemhas gained some interests from big companies like Plaxo, Yahoo, Google who all try to solve some part ofthis big puzzle. If a solution will come, it will definitely come from that direction, and hopefully result in anexchange standards that are open for anyone. Let it be even through web services, or another high levelRemoteProcedureCalling mechanism, as long as the API for these services are open to anyone (and not

licensed or owned by a single company), the future is still bright.

Documents

Can Opensource Exchange My World