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diff --git a/kdecore/README.kstartupinfo b/kdecore/README.kstartupinfo new file mode 100644 index 000000000..233ccde1e --- /dev/null +++ b/kdecore/README.kstartupinfo @@ -0,0 +1,282 @@ +$Id$ + + +Application startup notification +Lubos Lunak <l.lunak@kde.org> +-------------------------------- +-------------------------------- + + + When a new application is started in KDE, together with it a startup +notification is sent, which is used to show a startup entry in taskbar, +the busy icon next to the cursor and put the window of the started app +on correct desktop. + This application startup notification ( ASN for short in the following +text ) usually works fine without problems, but some applications and +some special cases may need special handling. + Right now, this is only an internal KDE standard, but since a toolkit +support would improve the results a bit, I'll try to discuss this +on http://www.freedesktop.org . + + +Starting apps with ASN : +------------------------- + + When an application is started from the K-Menu or the minicli, and from other +places, ASN is sent automatically for it, assuming a matching .desktop file +is found for the starting application. Application without a .desktop file +don't get ASN ( this may change, but it's unlikely as it creates too many +ASNs which will stay too long until a timeout ). For improving the quality +of ASN and reducing the number of ASNs that don't detect when the application +has started, some .desktop file entries may be helpful ( see below ). + If you want to start an application in your code, prefer using KRun or +KApplication::startServiceByXXX() calls. Classes like KProcess don't create +ASN, so if you need to use it, you have to send it manually ( only in case +ASN is useful in this case, it shouldn't be sent e.g. for system processes ). + + +.desktop files : +----------------- + +These following .desktop file entries affect ASN : + +X-KDE-StartupNotify=<bool> + - if true, this app/service will get app startup notify + - if false, this app/service will _not_ get app startup notify + - if not set + - if it's service, it will _not_ get app startup notify + - if it's app, it will get app startup notify, but + X-KDE-WMClass will be assumed to be "0" ( non-compliant ) +X-KDE-WMClass=<string> + - if set, and it's different from "0" ( without quotes ), this + is the WMClass value for startup notification + - if it's "0" ( without quotes ), such app is considered non-compliant, + and the startup notification will stop + - either if its windows is correctly detected using the default + WMClass value ( the name of the binary ) + - or if a window is mapped that is not recognized ( doesn't have + neither _KDE_STARTUP_ID nor _NET_WM_PID property /*CHECKME*/), + it's assumed this window belongs to the started app; + the start-on-desktop feature won't work then too + - if not set, it defaults to the binary name of the app ( ok for most apps, + including KDE ones ) + - to get the WMCLASS value for any app, run 'xprop' and click on the app's + window, WMCLASS value for this app should be any of the strings listed + in the WM_CLASS property ( it's usually the same as the name of the + app's binary file, in such case it doesn't need to be explicitly set ) +MapNotify=<bool> + - this key is obsolete + - true is equivalent to X-KDE-StartupNotify=true and no X-KDE-WMClass set + - false is equivalent to X-KDE-StartupNotify=true and X-KDE-WMClass=0 + - many .desktop files in KDE ( especially in kdebase/kappfinder ) + seem to have MapNotify=false even though it's not needed, this + needs to be checked and replaced by the needed X-KDE-* values, + often just X-KDE-StartupNotify=true should be enough + + The best way to check if the entries are set correctly is to start +the application and switch to other desktop. If the startup notification +disappears and the application appears on the desktop on which it was +started, it's correct ( with X-KDE-WMClass=0, the start-on-desktop +feature may not work ). + + Ideally, every .desktop file should have X-KDE-StartupNotify set to the correct +value, and for apps which need it also X-KDE-WMClass should be set. This +sometimes gives slightly better behavior than when these entries are not set. + + +The KStartupInfo classes : +-------------------------- + + In some cases, or if you are interested in getting the ASN information, you +have to use the KStartupInfo classes in kdelibs/kdecore. + +Receiving the application startup notification information : +------------------------------------------------------------ + + Create an instance of class KStartupInfo and connect to its slots, they +will be emitted whenever a ASN info is received. + The clean_on_cantdetect argument to the constructor means whether all +ASN info for non-compliant apps should be removed when a window is mapped +which cannot be identified ( it's not possible to say if it belong to one +of the starting applications or not ). If the argument is true, it is +assumed that the window does belong to one of the starting applications, +and all ASN info for non-compliant apps must be removed, otherwise the ASN +info would timeout ( e.g. kdesktop sets it to true, otherwise the busy +icon would sometimes stay for too long, which is oftern annoying ). +On the other hand, KWin, which maps the first window of the starting apps +to the given virtual desktop, sets it to false, because there's no visual +representation and if a window for a starting non-compliant application is +detected later, it still will be successfully places on the correct virtual +desktop. + Note that the ASN info is often send in several messages, and the slots +will be therefore emitted several times, with the updated info ( e.g. the +binary name or PID is not know from the beginning ). + +Sending the application startup notification information : +---------------------------------------------------------- + + Before an application is started, ASN info for it must be sent ( unless +it's done by classes like KRun ). See e.g. KRun sources for details. + During the starting of the application, the info may need some updating +( e.g. right after starting the app, the PID with hostname may be sent, +or a PID change when KUniqueApplication forks into background ). + When it's detected that the started process exited, it an ASN info +about the finished process should be sent. Since the application may +have forked into background, the finish info should include the PID +and hostname, and the notification will be stopped only if there's +no other PID for it. On the other hand, if you simply really need +to stop ASN, send only the identification ( KStartupInfo::sendFinish() +with only KStartupInfoId argument ). + + + +Implementation details : +------------------------ + + The ASN info data is sent using X ClientMessages as text ( see below ), +this is mainly in hope also non-KDE people will start using it, and +they wouldn't be very happy with DCOP. + Before starting an application, and environment variable called +KDE_STARTUP_ENV is added to it's environment, and it's set to unique +identifier of its startup notification, or "0" for disabled ASN. +Ideally, the application should read it, and set a window property +called _KDE_STARTUP_ID ( type XA_STRING ) at least on its first mapped +toplevel window to this value. It should also unset it, so it doesn't get +propagated to other applications started from it. It should also +update the ASN info when necessary, e.g. when KUniqueApplication +forks into background, it sends the PID change. That's how compliant +applications should work, and this support for ASN should be provided +by toolkits. All KDE application should be compliant by now, since +kdelibs do all the necessary things. The KDE_STARTUP_ENV variable +is read and unset in KApplication constructor, and _KDE_STARTUP_ID +is set on every toplevel window in KApplication::setTopWidget(). + However, majority of applications aren't compliant now, and even +if I succeed making this thing a standard ( part of NETWM_SPEC +or whatever ), there still will be old applications that won't behave +this way. Not unsetting KDE_STARTUP_ENV is not a big problem, since +the ASN for its value will usually timeout, and when the app starts +a new application, this ASN identification value will get reused without +problems. The other problem is detecting, which newly mapped windows +belong to which starting application. If a newly mapped window doesn't +have _KDE_STARTUP_ID property, the code tries to read its _NET_WM_PID +property, and if it's set, it tries to match it ( together with +WM_CLIENT_MACHINE ) with PIDs of all ASN infos. And if the window +doesn't have even the _NET_WM_PID property, WM_CLASS property is used +then. It's usually set to two strings, and at least one of them is +usually the binary name of the application, so it's converted +to lowercase and compared. For applications, where such comparison +would fail, the X-KDE-WMClass .desktop file entry should be set +to the correct WMClass value ( e.g. for XEmacs, the binary name +is 'xemacs', but WM_CLASS is 'emacs', 'Emacs', so its X-KDE-WMClass +in its .desktop file should be set to 'emacs' - the case doesn't +matter ). + The ASN identification string must be a unique string for every ASN. +In KStartupInfo class, it's created as 'hostname;tm.sec;tm.usec;pid', +tm being the current time. If the identification string is set to "0", +it means no ASN should be done ( e.g. for things like kio_uiserver, +which shouldn't get ASN ). Empty identification string means the same +like "0", except for the call to KStartupInfoId::initId(), where it means +to create a new one. + + +Format of the text messages : +----------------------------- + +There are 3 types of messages : + - new: message + - this message announces that a new application is being started, + if there is not ASN info for this ASN identification, it should be + updated, otherwise it will be created + - the text of the message starts with 4 characters 'new:', followed + by the text entries ( see below ) + - change: message + - this message is like new: message, but it's only for updating existing + ASN info, if there's no ASN info for the given identification, it won't + be created. This is used e.g. in KUniqueApplication when it forks + into background and sends info about the PID change - it should update + any existing ASN info, but mustn't create a new one, otherwise there + could appear ASN even for applications which shouldn't have ASN + - the text of the message starts with 4 characters 'change:', followed + by the text entries ( see below ) + - remove: message + - this message is sent for stopping ASN with the given identification. + If the only item in the message is the identification string, the ASN + info should be removed. If there are also the PID and HOSTNAME entries + ( see below ), the matching ASN info should be only removed if this + given PID is the only PID for it ( in this case, the identification + string may be omitted ). + - the text of the message starts with 4 characters 'remove:', followed + by + - only ID entry + - only ID, PID and HOSTNAME entries + - only PID and HOSTNAME entries + + +Text entries in the messages : +------------------------------ + +Every entry is of the form <name>=<value>. Value may be either a number +or a string. If the string contains spaces, it must be quoted ("), all +backslashes and quotes (") must be escaped by backslashes. If this ever +becomes more than an internal KDE standard, non-standard entry names should +start with an underscore. + +Entries : + +- ID - string + - the identification string of the startup notification + - it must be present in all messages except for the remove: + message with only PID and HOSTNAME +- BIN - string + - the binary name of the starting application + - usually used as a fallback value if WMCLASS is not present + - e.g. 'kcontrol' +- NAME - string + - the name of the starting application + - usually used only for displaying it when indicating that + the application is starting + - e.g. 'Control Center' +- ICON - string + - the icon for this startup notification + - it should be handled like the Icon= entry in .desktop files + - e.g. 'kcontrol' +- DESKTOP - number + - the virtual desktop on which the application should appear + - if the application's first window has _NET_WM_DESKTOP already + set when the window is mapped, it shouldn't be changed +- WMCLASS - string + - the WMCLASS value used for matching newly mapped windows + of non-compliant applications + - useful only if it's different from the binary + name of the application +- PID - number + - the PID of a process that belongs to this startup notification + - there may be several PIDs for one notification + - value 0 is also valid, meaning that there's a process + with unknown PID for this notification ( is used e.g. + by kfmclient when it sends a DCOP message to already running + konqueror instance to create a new window and exits immediately, + without adding the zero PID to the notification, process + that started kfmclient could detect it exited and would send + a remove: message for the notification with kfmclient's PID, + which would cause the notification to stop if there wasn't also + PID=0 for it +- HOSTNAME - string + - the hostname of the machine on which the application is being + started + - this is used together with the PID entry + +-------------------- + + Well, I guess that's all. The KDE2.2 release will show if the users like it +or not ( it's quite good IMHO, even though there are probably some minor +details to fix or improve ). The only big thing remaining is to make also +non-KDE people agree on using something like this. My first attempt +https://listman.redhat.com/pipermail/xdg-list/2001-May/000083.html +didn't get much attention, but now that there's a working implementation, +I hope it will get better, when I try again sometime in the future. + + + + Lubos Lunak <l.lunak@kde.org> + |