Alasdair, Thanks for taking the time to write a test that answers my question. I had a suspicion that this sort of thing would happen. It needs to be possible for the blueprint bundle to behave consistently whether JEXL is installed or not.
Regards, Tim > Date: Thu, 8 Sep 2011 23:26:18 +0100 > Subject: Re: [Release Discussion] ship maintenance releases of > application-0.2.2 / util-0.2.1 / blueprint-0.3.2 ? > From: [email protected] > To: [email protected] > > Hi, > > So lets get real with an example to start illustrating my issues. We have a > release already and the release is used by people, quite a few people. We > don't know what they are doing. I have written a test. The test uses the > sample blueprint bundle. It contains the following blueprint xml: > > <bean id="bar2" class="org.apache.aries.blueprint.sample.Bar"> > > <property name="value" value="${a+b}"/> > > </bean> > > The setValue method takes a String. I have run these tests in two ways. The > first with jexl and the second without. If jexl isn't installed I get: > > ${a+b} > > when jexl is installed I get: > > 0 > > Irrespective of how useful this is to people who want the behaviour it is a > huge problem for those people who do NOT want this behaviour. It is easy to > say "well don't install jexl then", but consider this. I have written a > blueprint bundle that expects to have ${a+b} injected. I deploy it in one > runtime and it works the way I expect. Now I drop it into Geronimo and I get > 0 instead. So I now need to go back and rewrite my bundle to work in > geronimo and I have two different bundles for each environment. This is > wrong. > > As said before I think we need this enabled via a namespace handler and an > attribute. I would require the following to be added to the blueprint > element: > > <blueprint jexl:enable="true" xmlns:jexl=" > http://aries.apache.org/blueprint/xmlns/blueprint-jexl/v1.0.0"/> > > any existing application will then behave consistently irrespective of what > is installed in the surrounding framework. Even the one I just created. If > the jexl bundle isn't installed then the jexl namespace handler is not > installed so the blueprint bundle will not be processed until it is in the > normal way. The code in question can remain where it is, but it would only > be enabled if the jexl namespace is configured. Ideally we would be able to > parameterise the value processing in a pluggable way, but as long as the > externals are right we can refactor the internals at our leisure. > > We are creating a programming model for OSGi here and that means we need to > get the modularity right. Currently it is not right, not only is the > modularity wrong but this makes a breaking change to the way a blueprint.xml > is processed in what is a bug release. Irrespective of how useful this is I > do not think it is important enough to warrant a breaking change when we can > make it work without breaking existing bundles. > > To address your question of "Do you think it is a good idea to support > this?" I do think it is a good idea, if I didn't I would have -1ed the > commit rather than engaged in an email discussion to get it right. > > Thanks > Alasdair > > On 8 September 2011 14:35, Rex Wang <[email protected]> wrote: > > > 2011/9/8 Alasdair Nottingham <[email protected]> > > > > > On 8 September 2011 10:10, Rex Wang <[email protected]> wrote: > > > > > > > 2011/9/8 Timothy Ward <[email protected]> > > > > > > > > > > > > > > Hi, > > > > > > > > > > I'm afraid I've not been paying as much attention as I should to this > > > > > thread. Reading back over the issues. I would currently vote -1 on > > this > > > > > release. I am not at all happy with the fact that users of this > > support > > > > will > > > > > see different, potentially erroneous, behaviour depending on the > > > presence > > > > or > > > > > absence of an optional dependency. Our previous statement has always > > > been > > > > > "If a blueprint bundle wants to use some non-standard function it > > > should > > > > > declare that using an additional namespace". > > > > > > > > > Do you mean the statement in spec 121.4: > > > > "The Blueprint XML resources in a bundle are the definitions. Each > > > > definition can include multiple > > > > namespaces. Implementations of the Blueprint core namespace must > > strictly > > > > follow this specification, > > > > if they add additional behavior they must add additional namespaces > > that > > > > are > > > > actually used in > > > > the definitions to signal the deviation from this specification."? > > > > > > > > We are improving the blueprint-ext, which has been already an > > additional > > > > namespace to blueprint core schema. Why must we add a new namespace to > > > > extend the ability of blueprint-ext? > > > > > > > > > > > Blueprint ext is a part of our core implementation. Adding it to > > > blueprint-ext means that if you want to use ANY part of blueprint ext you > > > MUST have apache-jexl even if you don't wan to use the ${a+b} syntax. > > This > > > is wrong. > > > > > > > Hi Alasdair, > > The itests passes without adding the commons-jexl bundle now. > > If you don't have commons-jexl installed, the current code can work as > > before. Unless you want to use ${a+b}, you need guarantee the commons-jexl > > is present. Otherwise it will record this exception in logger. I know this > > is not that convenient, but at least user can know what he need to do to > > get > > things right from the log.. > > > > On the other hand, Java EE EL supports such style of calculation natively, > > I > > think we should support it in blueprint-ext directly to keep the consistent > > of the current development experiences. In other words, if we don't use > > commons-jexl to implement such ability, instead, we write codes by > > ourselves > > to do that. Do you think it is a good idea to support this? After all, > > there > > is no spec for blueprint-ext. > > > > thanks, > > -Rex > > > > > > > > > > > > > > > > > > > > > > > > > > > > > In my view this new function should only be available if the optional > > > > > dependency is satisfied, and blueprint bundles must enable this > > > function > > > > > using a custom namespace. Otherwise I see two problems. > > > > > > > > > > > > > > > I want this new support, but have no way to ensure it is present, as > > a > > > > > result I am sometimes injected with "1+2" instead of "3". This leads > > to > > > > > intermittent NumberFormatExceptions > > > > > > > > > I do not want this new support, but as the dependency is available I > > am > > > > > injected with "3" instead of "1+2". This leads to inconsistent and > > > > confusing > > > > > behaviour. > > > > > > > > > I am not sure I understand this.. > > > > If you want 3, you need <xxx value="${1+2}"> > > > > If you want 1+2, you should use <xxx value="1+2"> > > > > Only the expression in ${..} will trigger the calculation, no matter if > > > the > > > > dependency if available. > > > > > > > > > > > I think tim is saying you want the string literal "${1+2}" not the string > > > 1+2. With your change if I had ${1+2} I now get 3 rather than ${1+2}. > > This > > > is a change in behaviour and should be enabled using a new namespace. Of > > > course you could just reversion the namespace from v1.x to v2 as a > > breaking > > > change, but we would need to support both versions of the schema. > > > > > > As with Tim I would currently -1 any release of blueprint 3.2 until this > > is > > > addressed. > > > > > > Alasdair > > > > > > -Rex > > > > > > > > > > > > > > > > > > > > > > > Adding a namespace for this function elegantly solves both these > > issues > > > > in > > > > > a way that is consistent with other blueprint extensions, and I think > > > is > > > > > essential before this function can be released. > > > > > > > > > > Regards, > > > > > > > > > > Tim > > > > > > > > > > > > > > > > From: [email protected] > > > > > > Date: Thu, 8 Sep 2011 11:58:22 +0800 > > > > > > Subject: Re: [Release Discussion] ship maintenance releases of > > > > > application-0.2.2 / util-0.2.1 / blueprint-0.3.2 ? > > > > > > To: [email protected] > > > > > > > > > > > > I still think adding a new namespace only for such simple > > calculation > > > > is > > > > > too > > > > > > heavy and not consumalbe for users.. > > > > > > > > > > > > Anyway, could anybody help with the release of * > > > > > > org.apache.aries.application/0.2.2-SNAPSHOT* *and > > > > > > org.apache.aries.util/0.2.1-SNAPSHOT* first? or chould anyone help > > > > check > > > > > why > > > > > > I can not deploy artifacts to apache.snapshot? Maybe I can try > > > release > > > > > the 2 > > > > > > components. Geronimo does not have much time targeting the 3.0-beta > > > > > release. > > > > > > > > > > > > thanks, > > > > > > > > > > > > -Rex > > > > > > > > > > > > > > > > > > > > > > > > 2011/9/7 Alasdair Nottingham <[email protected]> > > > > > > > > > > > > > If we release blueprint as is we will never be able to make the > > > > change > > > > > as > > > > > > > we > > > > > > > would cause a major breaking change. I think we need to get this > > > > right > > > > > > > before a release is done. > > > > > > > > > > > > > > On 6 September 2011 04:37, Rex Wang <[email protected]> wrote: > > > > > > > > > > > > > > > 2011/9/6 Alasdair Nottingham <[email protected]> > > > > > > > > > > > > > > > > > On 1 September 2011 07:41, Valentin Mahrwald < > > > > > [email protected] > > > > > > > > > >wrote: > > > > > > > > > > > > > > > > > > > Comments inline :) > > > > > > > > > > > > > > > > > > > > Kind regards, > > > > > > > > > > > > > > > > > > > > Valentin > > > > > > > > > > > > > > > > > > > > On 31 Aug 2011, at 20:02, Alasdair Nottingham wrote: > > > > > > > > > > > > > > > > > > > > > I'm sorry for being slow I'm on holiday with limited > > access > > > > to > > > > > > > email. > > > > > > > > > > > > > > > > > > > > > > The goal (I thought) was to ensure that the support for > > > > ${a+b} > > > > > > > would > > > > > > > > be > > > > > > > > > > > optional. When we make it optional we have two problems: > > > > > > > > > > > > > > > > > > > > > > 1. How do we make it optional (usually gate any call > > with > > > a > > > > > > > > > > > Class.forName check to ensures we can load a class. > > > > > > > > > > > 2. How do we fail when the support isn't there and > > > someone > > > > is > > > > > > > using > > > > > > > > > it. > > > > > > > > > > > > > > > > > > > > > > The first problem is trivial to fix, the latter is harder > > > to > > > > > > > define. > > > > > > > > It > > > > > > > > > > > isn't until you build the bean that you find the ${a+b} > > > > doesn't > > > > > > > work > > > > > > > > > and > > > > > > > > > > > with lazy activation that could take a while. I would > > > suggest > > > > > that > > > > > > > if > > > > > > > > > we > > > > > > > > > > > have ${a+b} in use, and the apache-jexl bundle is not > > > > present, > > > > > then > > > > > > > > the > > > > > > > > > > bean > > > > > > > > > > > creation would most likely fail (or you would get the > > wrong > > > > > > > > behaviour). > > > > > > > > > > This > > > > > > > > > > > is obviously not desirable. > > > > > > > > > > > > > > > > > > > > > > An alternative would be to make use of the default > > > behaviour > > > > of > > > > > > > > > blueprint > > > > > > > > > > > for namespace extensions. By using a separate namespace > > to > > > > > indicate > > > > > > > > the > > > > > > > > > > > desire to use this behaviour blueprint will delay > > > > > initialisation of > > > > > > > a > > > > > > > > > > > bundle's blueprint container until the namespace is > > > > available. > > > > > The > > > > > > > > > result > > > > > > > > > > > would be if apache-jexl is not present the namespace > > > handler > > > > > would > > > > > > > > not > > > > > > > > > be > > > > > > > > > > > registered and the blueprint container would not be > > > > configured. > > > > > In > > > > > > > > > > addition > > > > > > > > > > > you can now register the namesake when apache-jexl > > becomes > > > > > > > available > > > > > > > > > > > allowing it to be brought up later. > > > > > > > > > > > > > > > > > > > > I think that this definitely the right way to go. In > > > practical > > > > > terms > > > > > > > > > though > > > > > > > > > > it might be quite a bit tricky to implement. > > > > > > > > > > In particular I am wondering how to link the usage of the > > > > > extended > > > > > > > > > property > > > > > > > > > > replacement syntax to a namespace reference. I can think of > > > > > > > > > > the following ways to do this: > > > > > > > > > > > > > > > > > > > > a) Have two different property placeholder brackets like > > > > ${...} > > > > > for > > > > > > > > the > > > > > > > > > > non-arithmetic one and $[...] for the one doing arithmetic. > > > The > > > > > > > second > > > > > > > > > > one is defined via a tag from the new namespace. > > > > > > > > > > b) Support property placeholders only if we can support the > > > > whole > > > > > > > > shebang > > > > > > > > > > (which is kind of step back?) > > > > > > > > > > c) Have a kind of unrelated namespace import which we check > > > for > > > > > when > > > > > > > we > > > > > > > > > > decide whether to do arithmetic (that could be quite > > > > non-obvious > > > > > to > > > > > > > the > > > > > > > > > > user). > > > > > > > > > > > > > > > > > > > > > > > > > > > > > The blueprint specification says any non-standard extensions > > to > > > > > > > blueprint > > > > > > > > > must be enabled via namespace handlers. I don't like the ext > > of > > > > cm > > > > > > > > > namespaces to require apache-jexl since it means more > > > > dependencies > > > > > are > > > > > > > > > pulled in when they may never be used. > > > > > > > > > > > > > > > > > Hi Alasdair, > > > > > > > > Since the current code does not hard depend on the > > commons-jexl, > > > > and > > > > > I > > > > > > > > think > > > > > > > > the only difference from your desire is adding a new namespace > > > > which > > > > > can > > > > > > > > delay the blueprint container initialization if the > > commons-jexl > > > is > > > > > not > > > > > > > > present, > > > > > > > > I consider this as an improvement to the current solution. And > > I > > > > > think it > > > > > > > > would be better to let user hold the option that if he would > > use > > > > the > > > > > new > > > > > > > > namespace, and if he don't use it, the ${a+b} can still work. > > > Hope > > > > > the > > > > > > > > current solution meets the criteria to start release.. > > > > > > > > > > > > > > > > BTW, seems Aries community is not that active in last two > > month. > > > Is > > > > > there > > > > > > > > still a release manager help the release works? > > > > > > > > > > > > > > > > -Rex > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Looking at your options a) doesn't work because it isn't > > using > > > > > > > namespace > > > > > > > > > handlers, b) sucks big time and would mean to meat the spec > > we > > > > > would > > > > > > > > need > > > > > > > > > apache-jexl and the whole point is to allow the spec to be > > > > > implemented > > > > > > > > > without apache-jexl being required. So I think something > > like > > > > > option c > > > > > > > > > should be gone for. For instance you could add an attribute > > in > > > a > > > > > > > > > non-standard namespace that says to enable this capability. > > > > > > > > > > > > > > > > > > > > > > > > > > > > Is any of that what you were thinking of? > > > > > > > > > > > > > > > > > > > > > Does that make any sense? > > > > > > > > > > > > > > > > > > > > > > Alasdair > > > > > > > > > > > > > > > > > > > > > > On 30 August 2011 07:36, Rex Wang <[email protected]> > > > wrote: > > > > > > > > > > > > > > > > > > > > > >> Sorry, I will add the corresponding tests. But I am not > > > > quite > > > > > > > > > > understanding > > > > > > > > > > >> your suggestion in Aries-727 of "use a different > > > namespace > > > > to > > > > > the > > > > > > > > ext > > > > > > > > > > >> one". The current implement add the ability to > > > > blueprint-ext > > > > > and > > > > > > > > also > > > > > > > > > > >> blueprint-cm, because the CmPropertyPlaceholder is the > > > > > subclass of > > > > > > > > the > > > > > > > > > > >> PropertyPlaceholder. Could a different namespace handle > > > > this? > > > > > > > > > > >> After the change is final, will definitely port it to > > the > > > > > trunk. > > > > > > > > > > >> > > > > > > > > > > >> thanks, > > > > > > > > > > >> -Rex > > > > > > > > > > >> > > > > > > > > > > >> 2011/8/30 Alasdair Nottingham <[email protected]> > > > > > > > > > > >> > > > > > > > > > > >>> Hi, > > > > > > > > > > >>> > > > > > > > > > > >>> I'm not happy with the current fix for ARIES-727. There > > > are > > > > > no > > > > > > > > tests > > > > > > > > > > and > > > > > > > > > > >> as > > > > > > > > > > >>> I commented on the bug the dependency on jexl is not > > > > optional > > > > > > > when > > > > > > > > it > > > > > > > > > > >> should > > > > > > > > > > >>> be. It also doesn't exist in trunk which is dangerous. > > > This > > > > > > > affects > > > > > > > > > the > > > > > > > > > > >>> programming model so it needs to be right. > > > > > > > > > > >>> > > > > > > > > > > >>> Alasdair Nottingham > > > > > > > > > > >>> > > > > > > > > > > >>> On 29 Aug 2011, at 23:17, Rex Wang <[email protected]> > > > > wrote: > > > > > > > > > > >>> > > > > > > > > > > >>>> Hi Devs, > > > > > > > > > > >>>> > > > > > > > > > > >>>> Geronimo 3.0-beta has passed the Java EE 6 full > > profile > > > > tck, > > > > > and > > > > > > > > is > > > > > > > > > > >>> going > > > > > > > > > > >>>> to release soon. But some dependencies are from Aries > > > > > project, > > > > > > > so > > > > > > > > we > > > > > > > > > > >> are > > > > > > > > > > >>>> requesting your supports to release the following 3 > > > > > components > > > > > > > > with > > > > > > > > > > the > > > > > > > > > > >>>> important fixes to our users. Could anybody please > > help? > > > > > > > > > > >>>> > > > > > > > > > > >>>> *1. **org.apache.aries.application/0.2.2-SNAPSHOT* > > > > > > > > > > >>>> ARIES-521: handles zip files without directory entries > > > > > > > > > > >>>> ARIES-635: Move the resource bundle to the right > > > directory > > > > > > > > > > >>>> ARIES-638: Logging improvements for > > > > > AriesApplicationManagerImpl > > > > > > > > > > >>>> ARIES-667: OBRAriesResolver can return bundle > > > information > > > > > for > > > > > > > > > bundles > > > > > > > > > > >>> with > > > > > > > > > > >>>> higher version than expected > > > > > > > > > > >>>> ARIES-689: Application OBR resolution fails for > > optional > > > > > imports > > > > > > > > > > >>>> ARIES-734: Back port improvements made to resolution > > > error > > > > > > > > messages > > > > > > > > > in > > > > > > > > > > >>> OBR > > > > > > > > > > >>>> application resolver > > > > > > > > > > >>>> > > > > > > > > > > >>>> *2. org.apache.aries.util/0.2.1-SNAPSHOT* > > > > > > > > > > >>>> ARIES-667: OBRAriesResolver can return bundle > > > information > > > > > for > > > > > > > > > bundles > > > > > > > > > > >>> with > > > > > > > > > > >>>> higher version than expected > > > > > > > > > > >>>> > > > > > > > > > > >>>> *3. org.apache.aries.blueprint/0.3.2-SNAPSHOT* > > > > > > > > > > >>>> ARIES-727 support syntax : ${a+b} in blueprint-ext > > > > > > > > > > >>>> > > > > > > > > > > >>>> regards, > > > > > > > > > > >>>> -- > > > > > > > > > > >>>> Lei Wang (Rex) > > > > > > > > > > >>>> rwonly AT apache.org > > > > > > > > > > >>> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > > >> -- > > > > > > > > > > >> Lei Wang (Rex) > > > > > > > > > > >> rwonly AT apache.org > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > > Alasdair Nottingham > > > > > > > > > > > [email protected] > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > Alasdair Nottingham > > > > > > > > > [email protected] > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > Lei Wang (Rex) > > > > > > > > rwonly AT apache.org > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > Alasdair Nottingham > > > > > > > [email protected] > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > Lei Wang (Rex) > > > > > > rwonly AT apache.org > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > Lei Wang (Rex) > > > > rwonly AT apache.org > > > > > > > > > > > > > > > > -- > > > Alasdair Nottingham > > > [email protected] > > > > > > > > > > > -- > > Lei Wang (Rex) > > rwonly AT apache.org > > > > > > -- > Alasdair Nottingham > [email protected]
