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Quality Open Source Calendaring / Scheduling? 492

Jim R. Wilson writes "In past jobs, I've used Microsoft Outlook/Exchange, Novell Groupwise, and Google Calendar for handling business appointments. I'm sorry to say it, but I have yet to see a rival to Microsoft's scheduling features. On Slashdot I have occasionally read rumblings that there are better open source email and calendaring solutions out there. Can anyone substantiate this claim? What are the OSS alternatives? Can any compete with Microsoft's resource scheduling?"
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Quality Open Source Calendaring / Scheduling?

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  • no (Score:5, Informative)

    by Anonymous Coward on Thursday November 29, 2007 @12:32PM (#21520305)
  • Haven't found much (Score:4, Informative)

    by cbreaker ( 561297 ) on Thursday November 29, 2007 @12:32PM (#21520309) Journal
    I haven't found much, either. It's either some half-done web-based solution or it's got seriously missing features.

    Evolution works great with Exchange; all they need now is to create their own back-end =)

    PS. Public folders have gone away in Exchange 2007; big mistake if you ask me. It was a selling point for Exchange.
    • Re: (Score:2, Interesting)

      by Wicked187 ( 529065 )
      I believe the removal of Public Folders in Exchange 2007 is a result of integration with Sharepoint. The functionality is supposed to still exist, just outside of Exchange, itself. I haven't tried it out yet, as I do not have a 64-bit server to install on, but I do like a lot of the features in Sharepoint, and I can see how they would be better than Public Folders (and considering that Outlook pulls data in from Sharepoint, it should be fairly seamless from the user perspective).
      • Re: (Score:2, Insightful)

        by cbreaker ( 561297 )
        Yea, that's what I've been seeing - use Sharepoint. But Sharepoint is a whole 'nother beast. I think they should have improved the functionality of Public Folders. Sharepoint can't do a lot of things that PF's can, and Sharepoint itself is a bit of a pain in the ass.

        It's going to seriously slow the adoption of E2k7 because many companies really use them. One company I contracted at a couple years ago had over 25,000 public folders, many of which were used daily.

        Outlook integration isn't quite as sea
    • by Anonymous Coward on Thursday November 29, 2007 @12:51PM (#21520683)
      Sure about public folders? []

      Q. What is happening with Public Folders?

      Public Folders are included and supported in Exchange Server 2007. Microsoft has communicated that future releases of Exchange Server may not include public folders. If you use Public Folders, read the Exchange Team Blog on the topic of public folders for more guidance.
    • Re: (Score:3, Funny)

      I wrote a calendaring web app a few years back, and it was certainly a half-done web-based solution some seriously missing features. I wish you had included mine in your survey, because I still don't have any customers for it.
    • by ibi ( 61235 ) on Thursday November 29, 2007 @12:58PM (#21520823)
      It's worth looking at Chandler (fat client) and Cosmo (server) from []

      It's been a long time coming, but it's finally approaching a useable release and it's quite interesting. I think it will be a real choice in 2008...
    • Re: (Score:2, Informative)

      by sharkey ( 16670 )

      Public folders have gone away in Exchange 2007

      They are in there, just disabled by default. If you use Outlook 2003 or older they are required, so Exchange 2007 includes them.

    • by samkass ( 174571 ) on Thursday November 29, 2007 @01:32PM (#21521377) Homepage Journal
      The best candidate I've seen for the full calendaring "infrastructure" is the open CalDAV [] spec, but it's only really used commercially by Apple at this point. But since Apple has released their reference implementation as open source [], perhaps we'll get more implementations and a snowball effect of support.
  • by Anonymous Coward on Thursday November 29, 2007 @12:33PM (#21520321)

    Application: Pen and Paper.

    • by PrescriptionWarning ( 932687 ) on Thursday November 29, 2007 @12:55PM (#21520753)
      Unfortunately its not chicken scratch resistant
    • by Eberlin ( 570874 ) on Thursday November 29, 2007 @01:06PM (#21520957) Homepage
      As much as I love the Y2K compliant Office App...

      0) Geeks will argue which pen and which paper is the best.
      1) The Gentoo crowd will make their own paper from pulp.
      2) Where's the ^H on Pen?
      3) There are some serious latency issues
      4) Sometimes the output is so horrible that others can't read the file.
      5) Sometimes the output is so horrible that I can't read my own file.
      6) You can backspace on a word processor. You can shake an etch-a-sketch. If you mess up on paper, you need new hardware.
  • How about an OSS software package that actually WORKS with Outlook's calendar system properly? I'm not talking about OWA via Firefox, I'm talking about something that supports all the pretty colors and features of the calendar.
  • Compatibility (Score:5, Insightful)

    by WPIDalamar ( 122110 ) on Thursday November 29, 2007 @12:34PM (#21520337) Homepage
    I think the main problem is we can't really come up with an open source scheduling system that's compelely new and innovative because you need compatibility with people outside your organization.

    If we're not coming up with something new and innovative we're stuck making outlook clones. People don't like writing software like that.
    • two words "backward compatibility". You can make something new and invoative while keeping outlook compatability. Thats how Microsoft gets dominate. Imbrase a technology, saying this is good. Extend while keeping all the old features put new ones in so there is little risk in adopting. Extinguish once you have dominace make your product incompatible with the rest to force the rest to go to you.
    • I think the main problem is we can't really come up with an open source scheduling system that's compelely new and innovative because you need compatibility with people outside your organization.

      That's not all that true of the companies I've worked for. I'd be kind of annoyed if someone outside of my company sent me a meeting invite. You're not in my company; don't make assumptions about my scheduling.

      • Re:Compatibility (Score:5, Interesting)

        by forrestt ( 267374 ) on Thursday November 29, 2007 @01:06PM (#21520947) Homepage Journal
        How is that an assumption about your scheduling? It's an invitation to a meeting, if you can't make it or don't want to, you are free to decline the invitation or even just ignore it. But, it would be nice if your dentist could send you an appointment reminder with a link that would put it in your calendar so when your boss is wondering where you are he can look at the calendar (no, telling your boss has no effect on them knowing where you are when they want you). Or perhaps your friend could send you an email to go do something that would require you to take off early Friday and include a link to update your calendar. Or maybe some vendor could send you an invitation to meet them for lunch with multiple times for the event and you could pick one. Or maybe a customer needs to meet you to schedule a time they can call you so you send them a meeting invite, Or maybe even the people from SANS sending you an email after you register with a link to update your calendar to say you won't be at work for that week.

        Being in your company has nothing to do with wanting information in your calendar, and you are the person that gets to decide if it is worth putting in the calendar or not.
        • Re: (Score:3, Insightful)

          by brunascle ( 994197 )
          you can just put them in the calendar yourself. that's what i do.

          if my dentist sent me a meeting invite, it will not be how i want it. he'll likely mark it as "busy" or "out of office" for the exact time of the meeting, with the default 15 mins reminder. that's not how i want it. i'll need it to expand much further than that, because it takes at least an hour to get from work to there; and i'll want a 1 week reminder.

          i agree with the GP. sender-created meeting invites work fine for the office, but not
      • I'd be kind of annoyed if someone outside of my company sent me a meeting invite. You're not in my company; don't make assumptions about my scheduling

        You apparently don't work on a team that requires interaction with lots of clients and/or vendors and require $time_interval meetings to coordinate the development efforts of tech teams from each company involved.
      • Re: (Score:3, Funny)

        by toleraen ( 831634 )

        You're not in my company; don't make assumptions about my scheduling.
        Yeesh, I take it you don't get too many party invitations in the mail? Your Friday nights are booked up all the way through 2009? How dare someone try to include you in a gathering that might be relevant to your interests!

        That's why, at least in Outlook, there are "Propose New Time" and "Decline" buttons. We should get together next Tuesday at 1330 so I can show you these features.
    • Re: (Score:3, Funny)

      by Jamie Zawinski ( 775 )
      • If we're not coming up with something new and innovative we're stuck making outlook clones. People don't like writing software like that.

      What are you talking about?? Writing clones of commercial software is the prime directive of open source! I'm going to go out on a limb and say that actually there are quite a lot of people who like nothing more than doing exactly that.

  • I've used the php web calendar from for a number of clients and for personal usage as well. It's nice because it has very nice print friendly pages for printing your calendar, multi-user support, group support, public access calendar, rss feeds, and webdav support for keeping in sync with sunbird or icalendar. Sam
  • by guysmilee ( 720583 ) on Thursday November 29, 2007 @12:35PM (#21520367)
    Citadel is the best i know of: []
  • What features? (Score:5, Insightful)

    by Spy der Mann ( 805235 ) <> on Thursday November 29, 2007 @12:35PM (#21520369) Homepage Journal
    It's hard to expect the developers to write a feature they haven't been asked about, and/or don't even know it exists.

    In other words, what features do you use in MS products that you haven't found in the free/open source applications?
    • Re:What features? (Score:5, Informative)

      by jimbojw ( 1010949 ) <> on Thursday November 29, 2007 @12:58PM (#21520817) Homepage

      In other words, what features do you use in MS products that you haven't found in the free/open source applications?

      Sorry I wasn't clear enough in my initial question. What really impresses me about Outlook/Exchange is when you go to schedule a meeting, it allows you to see when all the participants, rooms and resources (like projectors) are available in a horizontal chart of sorts. People who are busy are marked off in blue, out of office is purple, etc. To find a time that works for everyone, you just scan across until you see a vertical bar of white (everyone free), or try to minimize conflicts.

      I don't know of MS holds a patent on the UI, but I haven't seen it anywhere else. Also, with respect to calendaring, in Outlook you can open up several calendars (yours and others) side-by-side in order to see who's free when. It's a pretty simple bit of eye candy, but nonetheless, I've only seen it in Outlook.

      • Re:What features? (Score:5, Informative)

        by 99BottlesOfBeerInMyF ( 813746 ) on Thursday November 29, 2007 @01:27PM (#21521311)

        I don't know of MS holds a patent on the UI, but I haven't seen it anywhere else.

        This function is available with the CalDav server standard and that particular feature is available in the implementations in the open source Zimbra client/server and the 10.5 version Apple's iCal server/client. I don't know about other implementations, but I imagine most other ones either include this or will soon, as Caldav has really taken of in adoption by major projects. Zimbra even offers that feature via the Web interface to their server.

        Also, with respect to calendaring, in Outlook you can open up several calendars (yours and others) side-by-side in order to see who's free when.

        I think Evolution has an interface like this (works with CalDav), but if I recall Zimbra allows you to overlap as many calendars as you want in one window, making the comparison quite a bit easier IMHO.

        I'd definitely look at Zimbra if you're serious about a OSS solution with lots of features and compatibility with both standards and proprietary interfaces (they have a full featured Exchange plug-in so users can still use Exchange as their client if they want). The server will run on all the popular Linux distros, OS X, and as a VMWare appliance.

  • WebCalendar (Score:3, Interesting)

    by DaGoodBoy ( 8080 ) on Thursday November 29, 2007 @12:35PM (#21520377) Homepage
    We use this: []

    Works well for our needs.
    • Seconded. Been using for our (small) office needs for over 2 years now. Even a host migration in the middle went off fairly well, considering I'd never had to install it manually before.

      Yes, it looks a little low-rent, and there are some features I would love to see, but it gets the job done.
  • The KDE organizer/calendaring system is extremely good -- I use it all the time. It supports multiple calendars as well as calendar export and sharing (although I don't use those features).

    Apparently there's an enterprise info sharing server available based on it too.

  • by narrowhouse ( 1949 ) on Thursday November 29, 2007 @12:37PM (#21520397) Homepage

    I hate to say this, but unless you give us a few reasons why some of the solutions you have looked at are not sufficient I doubt you will get any meaningful response.It's a pretty common problem when people ask for an open source replacement for a program they have used and were reasonably happy with.

    Without some starting point for comparison you will just get dozens of stories about how product X works fine for them.
    • by whoever57 ( 658626 ) on Thursday November 29, 2007 @01:47PM (#21521665) Journal
      How about this:
      1. It needs to have a client/server architecture (for mobile clients who don't have always-on connectivity). Pure web-based calendars don't do this.

      2. It needs to have Windows and Linux clients.

      3. Outlook plug-ins don't work. This is a limitation of Outlook. The plug-in can't be the default calendar, and Outlook will only pop up reminders for the default calendar. Also, my experience of OpenGroupware's plug-in is that it is unstable.

      4. It needs to have a means for one person to schedule an event on someone-else's calendar (if the appropriate permissions are given).

      5. It needs to have a way for people to view the details of other people's calendars (if the appropriate permissions are given). Free/Busy information is not enough in some cases.

      If someone can tell me of a calendar system that meets these requirements, I would be thrilled!

      Oh, one more -- it desn't need to try to replace other things, such as email servers, etc..

  • This is Slashdot. (Score:4, Interesting)

    by jellomizer ( 103300 ) * on Thursday November 29, 2007 @12:37PM (#21520407)
    Just because it is by microsoft people hate the product even if they never used it before. They will say Some Obscure Open Source tool is better even though they never really used the microsoft one... After so they just may realize that they are missing someting. That is the last thing they want to hear. It would be like someone from an other political party saying someone from the other party actually made a big difference and the world is better because of him/her. It just wont happen.
    • Oh, I love Outlook for Calendering. When you get a group of people who know how to use it it's really useful. You can use the thing to replace a CRM, and you can easily invite people to meetings. It's fast when working in a corporate environment with Exchange. All of that is great. The part I'd like to cut out is paying money to Microsoft for it. Not because I have some sort of vendetta against them. But because it shouldn't cost as much as it does.
    • Re: (Score:3, Insightful)

      by orclevegam ( 940336 )

      I've used Outlook before. I used it for over four years as it's the official corporate e-mail/scheduling client. The scheduling they did a pretty good job on, I'll give them that, but as an e-mail client I've never cared for it. I much prefer thunderbird or the web interface on gmail. Really the question people are looking for is, how do we replace the scheduling portion of Outlook and still retain all it's nice features while using the e-mail client of our choice?

      This is particularly tricky because one of

    • What it really comes down to is choice, if Microsoft were the only clear choice then I'd say you were right. However some of these alternatives aren't that obscure and are really quite capable of holding their own without needing to stand beside MS for direct comparison. The largest problem is their _relative_ obscurity to most people... hence the reason for this topic's existence: to find information!
    • Re: (Score:3, Interesting)

      by srussell ( 39342 )

      Just because it is by microsoft people hate the product even if they never used it before.

      I have to use Exchange at work every day. It sucks. My main gripes are:

      • It doesn't integrate very well with anything but Outlook
      • It often has problems with timezones and/or time changes. We get a week or two of screwed up scheduling twice a year, right around the daylight savings time change.
      • Resource scheduling is just stupid. If you forget and add a room as a required participant instead of a resource, it doesn
  • CalDav (Score:5, Informative)

    by jlittle ( 122165 ) <jlittle@cis.stan ... edu minus author> on Thursday November 29, 2007 @12:38PM (#21520423) Homepage
    CalDav is the wave of the future, with most calendaring clients supporting it (but not MS), and many servers commercial and otherwise also supporting it (Zimbra). The real coming out party was the commercial release of both OSX Server 10.5 and the client, which have both ends. But guess what, the server is open source: calendar server [] can be gotten and put on any platform. If you want something today, Zimbra or OSX Server are there for the taking. RedHat has a Messenging product coming out based on Zimbra for this exact purpose.
    • Yeah, I'm really hoping the rest of the non-Microsoft world will center around the standard, and it will end up that CalDav:calendars::IMAP:mail.

      • Yeah, I'm really hoping the rest of the non-Microsoft world will center around the standard, and it will end up that CalDav:calendars::IMAP:mail.

        That's not saying much, considering how many mail hosts still only support POP3.

    • Re: (Score:3, Insightful)

      by zoontf ( 64411 )
      I just attended the Mac OS X Leopard Server seminar Apple is touring through the country with... in Boston... and during the talk about CalDAV, the Apple tech reps said that Microsoft had a plugin available to Office for using CalDAV to some degree. I don't know more than that, but at least some Apple people think that MS is on board with CalDAV. Actually, they listed the steering committee members for CalDAV on a big screen, and buried among the 50-some-odd names was Microsoft.

      So, CalDAV maybe worth more i
    • Re: (Score:3, Insightful)

      by wodgy7 ( 850851 )
      CalDAV is indeed the holy grail. Finally we have something open source that supports all the major user-visible features of Exchange (time visibility, resource scheduling, etc.), is standards-based, and is supported by multiple vendors. There has been nothing like this for far too long.
  • by SuperKendall ( 25149 ) on Thursday November 29, 2007 @12:38PM (#21520429)
    Apple provides a nice calendar server [] with Leopard server - but it works with Linux (any anything else running Python) as well...

  • by Anonymous Coward
    Is there some particular reason you need to replace Outlook for an Open Source alternative?

    This makes no sense to dump something that works and is clearly the best solution right now.

    Unless you just want to save a couple of bucks, there's nothing magical about an Open Source product that makes it better.
    • by Pr0Hak ( 2504 )
      The magic comes in when you have some in-house programming talent and the open source software doesn't do *quite* what you want it to in some particular area (and neither does the commercial alternative).

      An organization that is using an open source package has some chance of making a tweak to the application to make that one little piece fit their needs and environment better. An organization using a closed source solution is essentially at the mercy of the software publisher in this regard.

      (That isn't to
      • by Retric ( 704075 )
        We have done the same thing with closed source software.

        EX: A coworker was having major issues with a closed source DLL so he decompiled it fixed the bug and then sent the update back to the company. We used his copy until they sent out and update.

        However, IMO extending open or closed source software is mostly a waste of time, because minor tweaks to software you don't really understand tend to create more issues than they solve.

    • A couple of bucks? Have you ever seen the bill Microsoft sends you for licenses for Exchange 2003 or 2007 and 50 licenses for Office 2007?
    • Re: (Score:3, Insightful)

      by orclevegam ( 940336 )
      It's also nice to be able to eliminate Windows machines off your network that you're not really using for anything but hosting a few select applications that require it. Having to have an entire server running just to host exchange server is a pain in the butt when you already have plenty of Linux servers around that could do the job if there was a cross-platform alternative to Exchange open source or otherwise.
    • by dbrutus ( 71639 )
      The universe of people who can use your calendering product is bounded at the bottom by the cost per user. If you have a nice solution that has zero cost per user like the Darwin Calendering Server, entrepreneurial startups everywhere end up with a marginally lower burn rate and a small number of them who would have run out of money right before they produced something useful will end up surviving and adding to the material goodness that is free market capitalism. It's part of a larger process of squeezing
    • by 99BottlesOfBeerInMyF ( 813746 ) on Thursday November 29, 2007 @01:51PM (#21521729)

      s there some particular reason you need to replace Outlook for an Open Source alternative? This makes no sense to dump something that works and is clearly the best solution right now.

      Up until a few years ago, I would have agreed it was the best solution for most businesses, but times have changed. I don't know what industry you're in, but a lot of larger companies are introducing more Linux and Macs on their networks and the ability to function cross-platform and across a variety of clients is a huge feature for a lot of companies.

      Unless you just want to save a couple of bucks, there's nothing magical about an Open Source product that makes it better.

      According to MS, in order to license the current version of exchange it will cost you $4000 per server + $97 per user + some unnamed fee if you want to interconnect with other companies servers. So, assuming you have 1000 people and two servers, you're looking at over $100K. And for that price you can only use all the functionality if all your clients are on Windows, so your advertising people on Macs and your software development team on Linux both end up running their own little calendaring servers or using a shitty Web interface that has not kept up with the regular client. People with smartphones also end up costing you extra for connectors that allow them to access some of the functionality of your Exchange server, instead of all the functionality of a CalDav server.

      To summarize, the failures of Exchange are:

      • licensing costs
      • future licensing costs for upgrades to support new clients
      • lousy cross platform support
      • added expense to support smartphones
      • lack of choice for clients
      • lack of choice for server platform (only Windows and VMWare) Whereas CalDav servers like Zimbra also support OS X, Linux, Solaris, etc.
      • lack of choice for support and customization and services, only MS instead of RedHat, Zimbra Inc, IBM, etc. (If MS does not fix a security hole tht is a problem for you, you're screwed, whereas with CalDav you can hire someone else to fix it or even fix it using internal programming resources)

      ...there's nothing magical about an Open Source product that makes it better.

      Umm, not magical, but being OSS is a feature, one that Exchange is lacking. It is not the only feature that matters, but it does bring significant benefits, including reduced risk and protection from vendor lock-in.

      • Re: (Score:3, Insightful)

        by Meorah ( 308102 )
        "or using a shitty Web interface that has not kept up with the regular client"

        The OWA client for Exchange 2007 is so good that there are companies who are getting rid of Outlook for all normal mail users and having everyone use the web client. The only people who get Outlook 2007 are Exchange Admins and special case-by-case basis (usually execs). So heterogenous environments are better from a client perspective (plus its easier to administer the web client anyway).

        "licensing costs"

        marketing websites and r
  • Not really (Score:5, Informative)

    by initdeep ( 1073290 ) on Thursday November 29, 2007 @12:39PM (#21520453)
    Zimbra []

    Scalix []

    are the two closest, but honestly, neither is a perfect replacement.

    • Re: (Score:3, Interesting)

      by HermMunster ( 972336 )
      Zimbra is INCREDIBLY COMPLEX TO INSTALL. It was sold to Yahoo who essentially is going to abandon all open source and take it out of that market. Do NOT trust Yahoo on this one.

      Zimbra's programmers were daft. They would only make installs for certain releases of the OS and then they would get rude to those who were seeking support. They essentially created a product and abandoned those in the open source arena, and they don't care about you.

      Their install requirements, their installer script, and their a
  • Mozilla has an active callender project with Sunbird and Lightening []
  • Can any compete with Microsoft's resource scheduling?"

    Um. Yeah. They all compete somehow.

    If you'd say what feature you wanted and what you wanted to do, someone could tell you how that feature in program X competes with Outlook. Short of that, I think the best answer is "Um. Yeah."
    • I obviously can't speak directly for the OP's needs but resource scheduling out in real IS/IT world - you know, where we can't just magically make all those MSFT installations disappear, no matter how much we'd like to - usually means booking conference rooms. Exchange 03's implementation isn't that great; most ppl just set their rooms to auto-accept any invite, then some lucky soul gets to go digging through all those when something goes bonkers (on Exchange 03, something always does).

      I'm moving us to Cal
  • Zimbra (Score:5, Interesting)

    by sg_oneill ( 159032 ) on Thursday November 29, 2007 @12:42PM (#21520509)
    Zimbra pretty much does it all. The web client is top notch, and makes a perfectly fine outlook replacement (Yeah, I know. Just try it, seriously), and its got some serious scaling capacitys (Its used by some of the biggest ISPs around). Yahoo now owns it, so its got some name backing. The catch is the outlook compatible one ISNT so open source, but its pretty cheap.

    Citadels pretty nice too, and Ignatius foobar is a cool guy, but its a pretty eccentric product. I think they've kinda been fucked around a bit with outlook compatibility, but I admit I havent checked in a long time.
    • Have to second Zimbra. We just finally got a proper mail / calendering server (after limping along with vanilla Imap and google calendars... ug). There's an Evolution plugin in beta but it seems to be flaky. However, I was surprised on how much I liked the web client. Not perfect, but pretty damn useful. If the Evolution plugin is ever completed I may switch the client back to that, but in the meantime I'm quite happy with the web client.
      • Re: (Score:3, Informative)

        Zimbra is, arguably, not Open Source.

        It comes under an 'attribution license' and hence cannot be forked. Its 'badgeware'.

        Ie: you cannot take the source code of Zimbra and produce your own version *without* the Zimbra logos.
  • Its not Free or Open, and far from free, but Steltor/Oracle's Corporate Time is at least available on Mac, Linux, and Windows and works well....
  • I use it as a personal mail/calendar server, I don't use a frontend with it much, but it does integrate nicely with evolution and with thunderbird and lightning.

    It has resource scheduling (even in the free version) I just don't use it, so I really can't comment on its quality. The email and scheduling is nice, its compatible with iCal, so there's tons of public calendars out there to help keep track of generic stuff too.

    Check it out.
  • by dominux ( 731134 ) on Thursday November 29, 2007 @12:55PM (#21520763) Homepage
    in the mean time I am using webcalendar which works great. Lotus Domino runs on Linux and would be my preferred choice of proprietary solution, I am trying to get IBM to make Domino a CalDAV server, anyone who has an IBM rep is encouraged to beat them up about CalDAV support. looks quite good now. Might have to re-evaluate that one.
  • Take a look at Citadel []. It does Groupdav, Kolab1, and a few others as well. Calendar, Contacts, and Email. And it's 100% GPL.
  • Citadel is the best kept secret on the internet. Installs in no time and does everything: []
  • Can any compete with Microsoft's resource scheduling?

    Google calendar handles resource scheduling, if you go with the Professional (paid) version.

  • eGroupware with Kontact. All F/OSS with outlook compatibility, LDAP Integration, MySQL Backend. Its just missing Kerberos then it would be perfect.

    It uses XML-RPC to transfer Addresses, Calendaring, etc. It even talks to Outlook, It would be the perfect Exchange replacement except that for the love of god, it doesn't support Kerberos! God damn it!
  • iCal Server (Score:5, Informative)

    by HiredMan ( 5546 ) on Thursday November 29, 2007 @01:00PM (#21520859) Journal
    Apple's iCal Server is Open Source PHP (with Twisted Framework) and based on the new CalDAV open standard. Everyone (with the possible exception of Microsoft) is moving to CalDAV as the open standard. Many big companies (Oracle, IBM, Google) are involved with the committee and hopefully the holy grail of inter-operable calendaring systems - including free/busy, invitations etc - is finally on the horizon.

    The server just officially went gold with Leopard but has actually been done for a while now. Apple's iCal Server and (closed source) Client are currently the most polished products but now that there is a solid CalDAV server I expect that the various clients with gain alot of polish and other CalDAV servers should start to roll out as well.

    Check out the CALCONNECT standards body for more information: []


    PS Microsoft is finally a member but their commitment level is not that of the other partners.
    • Re: (Score:3, Informative)

      by Erskin ( 1651 ) *

      Apple's iCal Server is Open Source Python (with Twisted Framework) and based on the new CalDAV open standard.
      (It's probably an innocent slip of the brain, but figured I'd mention it for anybody unfamiliar with the tech so they don't get confused.)
      • by HiredMan ( 5546 )
        Absolutely right - Python not PHP. Sorry, serious lack of caffeine this morning....

    • Re: (Score:3, Informative)

      by MouseR ( 3264 )
      It should be noted that

      - Apple's Calendar Server is indeed open source [], unlike mentioned above.
      - Apple's current implementation of recurring events in their CalDav server has some issues.

      It should also be noted that I work for Oracle in the very same division responsible for the calendaring stuff and that my intent is not to diminish Apple's offering. Oracle aims for full interoperability with other CalDAV-compliant offerings, including that of Apple.
  • Zimbra (Score:3, Interesting)

    by hackus ( 159037 ) on Thursday November 29, 2007 @01:04PM (#21520921) Homepage []

    We are replacing all of our Exchange users and dumping exchange by the end of the year.

    It is an open source free replacement for Exchange.

    Very nice and integrates well with Sunbird (Thunderbird Calander).

  • My bugaboo with calendaring has been devices. We're a introspective enough shop that we get away with a lot of open source. But, for calendars? Blackberrys, Symbians, PalmOS, Windows Mobile for Smartphones and PDAs, iPhones... and the list grows. I hope CalDAV picks up soon, because even Exchange isn't 100% on syncing with all these devices.
  • How about Meldware [] from Bunisoft? They have
    a calendaring module. I haven't used it, but it might be worth a look.
  • I rely on Google Calendar for my day-to-day needs. Can an enterprise implement Zimbra and still send out messages that auto-trigger Google Calendar to update itself like Outlook does? Conversely, can a business implement a Zimbra solution to interface with someone else's Outlook solution?

    I really don't know the answer to these questions. I have a number of clients who use Outlook/Exchange for calendaring but I am pretty much all-Linux on my end. The thing that seems to work is they schedule events on my Go

  • The biggest problem with the calendar system now is that there is no standard 2 way communication platform. I do all of my scheduling online then pull it down to Outlook on my PC, iCal on my Macbook Pro, then sync my blackberry with iCal so that IT pulls down google calendar.

    If there was a good 2-way platform that would allow me to upload AND download (safely! I know there are hacks) from a service like Google Calendar I would be more likely to use it.

    I am thinking of getting a hosted Exchange server but I
  • There are essentially two options out there that I would be willing to use: Zimbra and iCal Server (Darwin Calendar Server). Zimbra is sort of in limbo right now due to the Yahoo! acquisition, and Apple has not yet released a packaged version of iCal Server outside of Mac OS X Server 10.5 (you can, however, get it from the Subversion system).

    I hope that Yahoo follows through on their stated intention to keep the open source version of Zimbra.

    The other problem is clients. Right now, there aren't many clients
  • by IGnatius T Foobar ( 4328 ) on Thursday November 29, 2007 @01:15PM (#21521133) Homepage Journal
    You really want to check out Citadel []. It has a very comprehensive feature set -- not just calendars but also email, address books, message boards, instant messaging, access via all standard protocols plus a gorgeous ajax-style web user interface.

    The best part about Citadel is that it is very easy to install. There's an automatic installer script right on the web site. No fuss, no muss, just enter the install command and watch it go. No tedious mucking about with integrating all of the pieces yourself, as the entire Citadel system is self-contained.

    And the whole thing is GPL, unlike solutions such as Zimbra and Scalix which claim to be open source, but when you actually go there you find out that to get the full feature set you have to buy a commercial version. The Citadel project makes its very best work available to everyone on the same terms.
  • by Arrogant-Bastard ( 141720 ) on Thursday November 29, 2007 @02:25PM (#21522315)

    It makes my short list, along with ZImbra, Scalix, and Openchange (so far).

    The nice things about JES are (a) it's rock-solid (b) it works well with many mail clients, even horribly broken ones like Outlook (c) while it doesn't have every possible calendar feature in the world, it has all of the ones that people actually use (d) it scales amazingly well -- it's really no problem to get it to support millions of users (e) because it's been around for a while (including a prior incarnation as a Netscape product) there's a pretty solid support community for it (in addition to Sun) (f) it's flexible enough to support integration with other products.

    The bad things about JES are (a) the install is complicated, even if you're very accustomed to complex installs (b) the documentation, like much of Sun's documentation, is poorly written, verbose, uses opaque terminology, and lacks cohesion (c) the log files are inscrutable (d) it's somewhat bloated (somebody needs to trim all the legacy code out of it) (e) it's overkill for anyone who just needs a mail server (i.e., no calendaring).

    But...given that you get mail, calendaring, LDAP, all rolled up in one package -- it's at least worth looking at. I'm aware of any number of places that have migrated from Exchange to JES, so at least their requirements were met.

"Everything should be made as simple as possible, but not simpler." -- Albert Einstein