Kyle Stiemann will also be commenting on the following issue in JIRA:
https://java.net/jira/browse/JAVASERVERFACES_SPEC_PUBLIC-1423
Again, please click on the "watch" link in JIRA if you are interested. Thanks.
> On Jun 27, 2016, at 7:12 AM, Bauke Scholtz <balusc_at_gmail.com> wrote:
>
> As to "render target", isn't PartialViewContext#getRenderIds() sufficient for the task? This returns a mutable collection of client IDs which need to be updated on current partial request.
>
> Cheers, B
>
>
> On Mon, Jun 27, 2016 at 11:56 AM, Leonardo Uribe <leonardo.uribe_at_irian.at> wrote:
> Hi
>
> 2016-06-24 10:35 GMT+02:00 Bauke Scholtz <balusc_at_gmail.com>:
> encodePartial() looks OK.
>
> I only don't understand how RequestViewContext, setRenderTarget() and getComponentsToRender() are useful as compared to UIViewRoot#addComponentResource()/getComponentResources().
>
>
> I haven't found good names for those ones but I'll explain the intention of them.
>
> setRenderTarget(...) is used to indicate a component inside a specified target needs to be updated on the client in the current partial request. In comparison, addComponentResource(...) is used to add the component to the tree.
>
> I know both methods look similar but they are not the same. The reason is addComponentResource(...) is used to affect the component tree, so it will be called each time the component tree is build (initial state, delta, ...), and setRenderTarget(...) is used as a flag to indicate how the current partial request must be rendered. Add a resource could cause the flag to be activated, but not every call to addComponentResource(...) cause the flag to be activated.
>
> Maybe a better name could be setRenderTargetComponent(...)
>
> getComponentsToRender(...) returns the list of the components bound to an specific target that needs to be rendered on the current ajax request. in comparison UIViewRoot.getComponentResources(...) return all components bound to an specific target in the view.
>
> Maybe a better name could be getTargetComponentsToRender(...)
>
> These two methods are in fact more bound to UIViewRoot than to FacesContext, but the data they manage is "transient", which means the data is discarded at the end of the request.
>
> I also don't understand "You can't use an eval block because the encoding does not work correctly". Which encoding exactly is problematic? (there's at least character encoding, html encoding and javascript encoding involved). Why couldn't that part be fixed instead?
>
>
> If you have a block like this:
>
> <h:outputScript target="head">
> script2 = function(){
> alert("script2");
> }
> </h:outputScript>
>
> you could try to do in code something like this:
>
> prwriter.startEval(....);
> renderChildren(...);
> prwriter.endEval();
>
> I tried but it doesn't work because you need to encode it properly, but since there is a ResponseWriter outside of your control, you can't encapsulate the script without do some nasty hacks over ResponseWriter/PartialResponseWriter.
>
> In this case eval(...) does not work, so we need to attach the node (well, if we want to fix this use case, which I think we should).
>
> regards,
>
> Leonardo Uribe
>
> Cheers, B
>
> On Thu, Jun 23, 2016 at 2:45 PM, Leonardo Uribe <leonardo.uribe_at_irian.at> wrote:
> Hi
>
> Since there is already a solution almost completed in MyFaces (which an small sample
> done some time ago) I did a prototype to see how it works and try to find other details
> that could give us a better idea about what to do.
>
> From spec perspective the relevant changes are:
>
> UIComponent: Add the following methods:
>
> public void encodePartial(FacesContext context) throws IOException
>
> Default implementation call startUpdate(), encodeAll(), endUpdate();
>
> UIComponentBase: Add the following methods:
>
> public void encodePartial(FacesContext context) throws IOException
>
> Default implementation if renderer found call Renderer.encodePartial, otherwise call
> super.encodePartial(...)
>
> Renderer: Add the following methods:
>
> public void encodePartial(FacesContext context, UIComponent component)
> throws IOException
>
> Default implementation call startUpdate(), encodeAll(), endUpdate();
>
> RequestViewContext: (it could be located in FacesContext)
>
> public void setRenderTarget(String target, boolean value,
> UIComponent component)
>
> public List<UIComponent> getComponentsToRender(String target);
> (it has an internal set to avoid duplicates, find a better name)
>
>
> The remaining tasks are implement encodePartial(...) for h:outputScript,
> h:outputStylesheet, and update the implementation in PartialViewContext to call
> encodePartial.
>
> This is a fragment of the generated response when the change
> is activated:
>
> <partial-response id="j_id__v_0"><changes><eval>
> <![CDATA[myfaces._impl.core._Runtime.loadScript(
> "/client-window-example/javax.faces.resource/script1.js.jsf", null, null,
> "UTF-8", false);]]></eval><update id="content"><![CDATA[ ...
>
> The main page look like this:
>
> <h:commandLink id="page1" value="Page 1" actionListener="#{ajaxContentBean.setPage1}">
> <f:ajax render=":content"/>
> </h:commandLink>
> ...
> <h:panelGroup id="content" layout="block">
> <ui:include src="#{ajaxContentBean.page}.xhtml" />
> </h:panelGroup>
>
> And the included page has something like this:
>
> <h:outputScript name="script1.js" target="head"/>
> <h:commandButton type="button" value="MSG" onclick="script1()"/>
>
> It works well for scripts but try to update something like this:
>
> <h:outputScript target="head">
> script2 = function(){
> alert("script2");
> }
> </h:outputScript>
>
> or this:
>
> <h:outputStylesheet name="style3.css"/> (target="head" is implicit)
>
> is the real problem. You can't use an eval block because the encoding does not work
> correctly, so you really need to insert the DOM node. But the current API in
> PartialResponseWriter is useless because head tag does not have an id or name where you
> can grab.
>
> Ok, we can try to "make cheat" a little in this part and try:
>
> prwriter.startInsertAfter("javax.faces.ViewHead");
>
> but strictly speaking this should insert the html markup after </head>, but we want
> the code inside. I just modified the js code to include it inside in this case, but for
> a real implementation it is required to add some methods to PartialResponseWriter like:
>
> public void startInsertFirst(String targetId) throws IOException
> public void startInsertLast(String targetId) throws IOException
>
> (find a better name, or maybe startInsertInsideAfter?, look in another framework how
> they name this?)
>
> There is also another problem: How do you know you need to insert the node instead of
> update it? The only clue is the node is processed specially in PartialViewContext like
> this:
>
> List<UIComponent> componentsToRender = rvc.getComponentsToRender("head");
>
> for (UIComponent resource: componentsToRender)
> {
> resource.encodePartial(_facesContext);
> }
>
> So, we need some flag or context attribute or something to indicate we are attempting
> to include something new on the tree. Something like JAVAX_FACES_INSERT_PARTIAL for
> example and something like JAVAX_FACES_UPDATE_TARGET, so the Renderer in encodePartial
> can decide how to update the view.
>
> The partial response markup looks like this:
>
> <changes><insert><after id="javax.faces.ViewHead"><![CDATA[
> <script type="text/javascript">
> script2 = function(){
> alert("script2");
> }
> </script>]]></after></insert>
>
> It should be better
>
> <changes><insert><last id="javax.faces.ViewHead"><![CDATA[<script type="text/javascript">
> script2 = function(){
> alert("script2");
> }
> </script>]]></last></insert>
>
> And that's it the proposal from MyFaces side. I think it is flexible enough to allow the
> algorithm using "two lists comparison", but also enough to allow the implementation
> inside MyFaces.
>
>
> But note the issue proposed here:
>
> JAVASERVERFACES_SPEC_PUBLIC-1404 Add UIViewRoot#getRenderedComponentResources()
>
> is still valid. But I'll send the comments related to that one in other email.
>
>
> Suggestions are welcomed.
>
> regards,
>
> Leonardo Uribe
>
>
>
> 2016-06-22 9:19 GMT+02:00 Cagatay Civici <cagatay.civici_at_gmail.com>:
> Sure, actually Thomas Andraschko, the reporter of JAVASERVERFACES_SPEC_PUBLIC-1423 has implemented it in PF, I’ve asked him for details and his response briefly is;
>> Have a look at:
>> org.primefaces.application.resource.DynamicResourcesPhaseListener - it collects the initial resources on the ajax request
>> org.primefaces.context.PrimePartialResponseWriter - ln 278; gets the resources again, creates a diff of the initial and new resources, render some JS to load the resources dynamically
> Regards,
>
> Cagatay Civici
> PrimeFaces Lead
> PrimeTek Informatics
> On Wednesday 22 June 2016 at 10:02, Bauke Scholtz wrote:
>
>> Cagatay, can you point out it in the PrimeFaces codebase? Then I will look at similarities and differences and if necessary optimize the standard solution based on that.
>>
>> Cheers, B
>>
>>
>> On Wed, Jun 22, 2016, 08:43 Cagatay Civici <cagatay.civici_at_gmail.com> wrote:
>>> We also have a custom solution to this in PrimeFaces as it is a very common case. A standard solution would be preferred for sure.
>>>
>>> Regards,
>>>
>>> Cagatay Civici
>>> PrimeFaces Lead
>>> PrimeTek Informatics
>>> On Tuesday 21 June 2016 at 22:34, Bauke Scholtz wrote:
>>>
>>>> Coming to it, a new encodeAjax() method in UIComponent and Renderer (I'd rather call it encodePartial(), in line with the existing API) is a great suggestion which could indeed solve this problem and has potential for solving/optimizing ajax based problems in a much more flexible way. This is indeed a small and easy change in the API (and impl).
>>>>
>>>> +1 from me.
>>>>
>>>> Cheers, B
>>>>
>>>>
>>>>
>>>>
>>>> On Tue, Jun 21, 2016 at 5:22 PM, Bauke Scholtz <balusc_at_gmail.com> wrote:
>>>>> As to writer.startEval(), as per https://java.net/jira/browse/JAVASERVERFACES_SPEC_PUBLIC-1412 I've added a PartialViewContext#getEvalScripts() for JSF 2.3. This could be used.
>>>>>
>>>>> I will think about encodeAjax() and reply later.
>>>>>
>>>>> Cheers, B
>>>>>
>>>>> On Tue, Jun 21, 2016 at 4:01 PM, Leonardo Uribe <leonardo.uribe_at_irian.at> wrote:
>>>>>> Hi
>>>>>>
>>>>>> I just wanted to repost a comment from MyFaces issue tracker in 2012 about the issue being discussed now:
>>>>>>
>>>>>>
>>>>>> Luciano Deiru:
>>>>>>
>>>>>> Thanks for the reply.
>>>>>>
>>>>>> I don't think it's going to be possible for me to migrate my app to JSF2 without a
>>>>>> complete re-write of the frontend. I did a little more digging to see if richfaces was
>>>>>> the issue and i can across this section of the richfaces 4.2.2 development guide...
>>>>>> ...
>>>>>>
>>>>>> "JSF 2 does not allow resources such as JavaScript or Cascading Style Sheets (CSS) to
>>>>>> be added if the element requiring the resource is not initially present in the JSF
>>>>>> tree. As such, components added to the tree via Ajax must have any required resources
>>>>>> already loaded. In RichFaces, any components added to the JSF tree should have
>>>>>> components with corresponding resources included on the main page initially. To
>>>>>> facilitate this, components can use the rendered="false" setting to not be
>>>>>> rendered on the page."
>>>>>> ...
>>>>>>
>>>>>> So the only workaround would be to add every possible richfaces and primefaces component
>>>>>> to the login page so it loads the JS and css. That's a bit depressing because you
>>>>>> can't create a "pure ajax"/dynamic application in JSF2 even tho i was possible in JSF1.
>>>>>> It seems like a widely used approach and there are a lot of forum posts about the
>>>>>> issue but no one is ever able to get it working without including the hidden components.
>>>>>>
>>>>>>
>>>>>> regards,
>>>>>>
>>>>>> Leonardo Uribe
>>>>>>
>>>>>> 2016-06-21 15:55 GMT+02:00 Leonardo Uribe <leonardo.uribe_at_irian.at>:
>>>>>>> Hi
>>>>>>>
>>>>>>> I see.
>>>>>>>
>>>>>>> BS>> Also, to avoid duplicates and/or unnecessary re-rendering, all so far rendered
>>>>>>> BS>> resources must be remembered in JSF state. AFAIC this is currently not the case.
>>>>>>>
>>>>>>> Well, this is information related to the view that is implicit there, but you want to
>>>>>>> avoid to put it in the state.
>>>>>>>
>>>>>>> That's the reason why I like the way it is working in MyFaces, because we just keep
>>>>>>> track of the change, rather than store that information in the state.
>>>>>>>
>>>>>>> Write the script directly into the <eval> is possible, but right now from spec
>>>>>>> perspective there are not the necessary "building blocks" available.
>>>>>>>
>>>>>>> Both h:outputScript and h:outputStylesheet are components that are supposed to be
>>>>>>> rendered as resources, but both components have Renderer instances, which are
>>>>>>> the classes who finally decide how they should be rendered. Even if you have a list,
>>>>>>> this list could include javascript/css or whatever and the resources could be rendered
>>>>>>> in different ways.
>>>>>>>
>>>>>>> For example an h:outputScript could have children that could be js code. Or a
>>>>>>> h:outputStylesheet could have a "media" property set.
>>>>>>>
>>>>>>> So if we want a "general" solution to the problem, which includes script, stylesheets
>>>>>>> or whatever, it is necessary to know the component instance that needs to be added
>>>>>>> or updated, and then ask the component how it should be rendered.
>>>>>>>
>>>>>>> The problem from the "building blocks" perspective, is there is no way the component
>>>>>>> can know the current request is an ajax update. encodeAll(...) just means encode
>>>>>>> everything and don't ask questions.
>>>>>>>
>>>>>>> I would like to have a method in UIComponent/Renderer called encodeAjax(...) for the
>>>>>>> component, which by default start and end an <update> section and call by default
>>>>>>> to encodeAll(...). Something like this
>>>>>>>
>>>>>>> public void encodeAjax(FacesContext _facesContext, PartialResponseWriter writer) {
>>>>>>> try
>>>>>>> {
>>>>>>> writer.startUpdate(target.getClientId(_facesContext));
>>>>>>> target.encodeAll(_facesContext);
>>>>>>> }
>>>>>>> finally
>>>>>>> {
>>>>>>> writer.endUpdate();
>>>>>>> }
>>>>>>> }
>>>>>>>
>>>>>>> This part is done in PartialViewContext implementation, but if we can move it here
>>>>>>> we could ask the component in a gentle way how it should be rendered. Then, from
>>>>>>> this location we could override the method and call writer.startEval(...), which is
>>>>>>> something is not possible in this moment, because there is no way right now to
>>>>>>> customize this step for each component.
>>>>>>>
>>>>>>> In this way, you could add an script to load the stylesheet and then use the eval
>>>>>>> to include it in the response.
>>>>>>>
>>>>>>> I have already mention this improvement in this mail some time ago:
>>>>>>>
>>>>>>> https://java.net/projects/javaserverfaces-spec-public/lists/jsr372-experts/archive/2015-04/message/41
>>>>>>>
>>>>>>> It looks we have yet another use case where this could be useful.
>>>>>>>
>>>>>>> regards,
>>>>>>>
>>>>>>> Leonardo Uribe
>>>>>>>
>>>>>>>
>>>>>>> 2016-06-21 14:51 GMT+02:00 Bauke Scholtz <balusc_at_gmail.com>:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> OmniFaces has 3 solutions to dynamically include a (script) resource:
>>>>>>>>
>>>>>>>> 1: Ajax#load() (just write script straight to <eval>)
>>>>>>>> 2: Components#addScriptResourceToHead()
>>>>>>>> 3: Components#addScriptResourceToBody()
>>>>>>>>
>>>>>>>> Which one to use depends on the moment (which isn't yet refactored into a single utility method, this is TBD). When the request is an ajax request with partial rendering (i.e. ajax with NO @all), then use #1. Else when the current phase is NOT render response, or the view is in BUILDING state, then use #2. Else use #3.
>>>>>>>>
>>>>>>>> This is implemented for the unload script associated with OmniFaces @ViewScoped and this works quite well.
>>>>>>>>
>>>>>>>> Also, to avoid duplicates and/or unnecessary re-rendering, all so far rendered resources must be remembered in JSF state. AFAIC this is currently not the case.
>>>>>>>>
>>>>>>>> Cheers, B
>>>>>>>>
>>>>>>>>
>>>>>>>> On Tue, Jun 21, 2016 at 2:37 PM, Leonardo Uribe <leonardo.uribe_at_irian.at> wrote:
>>>>>>>>> Hi
>>>>>>>>>
>>>>>>>>> I have seen this issue has been opened in the spec issue tracker
>>>>>>>>>
>>>>>>>>> https://java.net/jira/browse/JAVASERVERFACES_SPEC_PUBLIC-1423
>>>>>>>>> Dynamic resource loading in ajax requests
>>>>>>>>>
>>>>>>>>> I would like to contribute with some thoughts about the topic, since in MyFaces there
>>>>>>>>> is a solution that is not perfect (if PartialViewContext is overriden, the code will
>>>>>>>>> not work, so some third party libraries will not be able to use it), but it helps to
>>>>>>>>> identify the missing points in the spec, and specify it faster.
>>>>>>>>>
>>>>>>>>> This issue could be also relevant for portlets.
>>>>>>>>>
>>>>>>>>> The issue has been reported long time ago in:
>>>>>>>>>
>>>>>>>>> - https://issues.apache.org/jira/browse/MYFACES-3106
>>>>>>>>> Resources not loaded when using a dynamic ui:inlclude and rendered via ajax
>>>>>>>>>
>>>>>>>>> - https://issues.apache.org/jira/browse/MYFACES-3367
>>>>>>>>> Detect when to update head or body target when content has been updated dynamically
>>>>>>>>>
>>>>>>>>> - https://issues.apache.org/jira/browse/MYFACES-3659
>>>>>>>>> Conditional include of scripts and stylesheets
>>>>>>>>>
>>>>>>>>> The first thing to understand the problem is identify the possible use cases we have:
>>>>>>>>>
>>>>>>>>> - c:if, ui:include src="#{...}" or facelet tag that dynamically update the tree.
>>>>>>>>>
>>>>>>>>> For example:
>>>>>>>>>
>>>>>>>>> ...
>>>>>>>>> <f:ajax event="onclick" render="box"/>
>>>>>>>>> ...
>>>>>>>>>
>>>>>>>>> <div jsf:id="box">
>>>>>>>>> <c:if test="#{...}">
>>>>>>>>> <h:outputScript target="head" library="js" name="help.js" />
>>>>>>>>>
>>>>>>>>> ...
>>>>>>>>> </c:if>
>>>>>>>>> </div>
>>>>>>>>>
>>>>>>>>> Here we have a case when the components inside the c:if requires some javascript file,
>>>>>>>>> but the update comes from an ajax request. The algorithm just somehow put the
>>>>>>>>> h:outputScript on the head of the document, but the ajax does not trigger the head
>>>>>>>>> refresh, so the component was added to the tree, but the javascript file was not loaded
>>>>>>>>> and we finally have a broken panel.
>>>>>>>>>
>>>>>>>>> There are variants of the same example with h:outputStylesheet, or ui:include but the
>>>>>>>>> reason is the same.
>>>>>>>>>
>>>>>>>>> - Dynamic but the resource is added by a @ResourceDependency annotation.
>>>>>>>>>
>>>>>>>>> This is similar to the previous case, but the component is added indirectly when
>>>>>>>>> Application.createComponent(...) is executed.
>>>>>>>>>
>>>>>>>>> The important thing to keep in mind is there are 3 possible targets: "head", "body" and
>>>>>>>>> "form". But the only thing we can do with the current spec is just force a full update
>>>>>>>>> of each of these targets.
>>>>>>>>>
>>>>>>>>> So, in MyFaces there is a web config param called
>>>>>>>>> org.apache.myfaces.STRICT_JSF_2_REFRESH_TARGET_AJAX that when it is activated, and
>>>>>>>>> the previous situation happens, it just enable a flag so the target is updated with
>>>>>>>>> the ajax request. If the "head" needs to be updated, the whole "head" and the updated
>>>>>>>>> content is sent and so on.
>>>>>>>>>
>>>>>>>>> The processing is done on process partial render time, after the ajax request is
>>>>>>>>> rendered but before write the state token. Please note if the target is rendered before
>>>>>>>>> this code, the algorithm should be able to detect the condition and do not duplicate
>>>>>>>>> the response.
>>>>>>>>>
>>>>>>>>> The solution is not perfect because it force render the whole target, when we only
>>>>>>>>> need to render the html fragment of the added component (script/stylesheet/
>>>>>>>>> other js code). But there is no way to do it with the current API, because <head>
>>>>>>>>> or <body> could not have an id and without id, you can't insert. PartialResponseWriter
>>>>>>>>> contains these methods:
>>>>>>>>>
>>>>>>>>> startInsertBefore(String targetId)
>>>>>>>>> startInsertAfter(String targetId)
>>>>>>>>>
>>>>>>>>> But note these two are useless, because what we need is insert "inside" at the beginning
>>>>>>>>> or the end.
>>>>>>>>>
>>>>>>>>> For example:
>>>>>>>>>
>>>>>>>>> <head>
>>>>>>>>>
>>>>>>>>> <script .../>
>>>>>>>>> </head>
>>>>>>>>>
>>>>>>>>> <body>
>>>>>>>>> <script .../>
>>>>>>>>>
>>>>>>>>> </body>
>>>>>>>>>
>>>>>>>>> Please note there are some cases where the jsf third party library (for example
>>>>>>>>> primefaces) provides its own rules to to render the script at first, middle or last. But
>>>>>>>>> in this case it doesn't matter those rules, because what we really need is that the
>>>>>>>>> resource is added.
>>>>>>>>>
>>>>>>>>> The code that activates the flags to render head, body or form target is on
>>>>>>>>> h:outputScript and h:outputStylesheet, specifically in the listener attached to
>>>>>>>>> PostAddToViewEvent. This is the best place, because here is the place where
>>>>>>>>> UIViewRoot.addComponentResource is done.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> I think what's really important in this problem is provide the API where you can notify
>>>>>>>>> that the resource needs to be added. In MyFaces there is:
>>>>>>>>>
>>>>>>>>> class RequestViewContext {
>>>>>>>>>
>>>>>>>>> public boolean isRenderTarget(String target);
>>>>>>>>>
>>>>>>>>> public void setRenderTarget(String target, boolean value);
>>>>>>>>>
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> Which could evolve to something more complex, including the UIComponent instance and
>>>>>>>>> so on.
>>>>>>>>>
>>>>>>>>> I don't really like to do a list comparison, because it can introduce an unnecessary
>>>>>>>>> performance overhead. I would like an API that could have some methods to register the
>>>>>>>>> component for updated on the target and others to get the changes and do the necessary
>>>>>>>>> calculation in PartialViewContext.processPartial(...) (render response).
>>>>>>>>>
>>>>>>>>> regards,
>>>>>>>>>
>>>>>>>>> Leonardo Uribe
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>
>
>
>
>