Frank, SilverStream uses the conversion approach and it has a very reach user interface based on Java Object generating the Java Script. Recently we developed a tag which generates some JavaScript from Java in order to simluate some events like SilverStream does. It is a good idea to control the DHTML and javaScript from Java and vis versa
Cheers Alan > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Sent: 29 October 2004 21:13 > To: [EMAIL PROTECTED] > Subject: Re: Proposal: Javascript-to-Java object conversions > > > I do have some experience with Rhino, I actually integrated it > into DataVision a few weeks ago for Javascript formula support > (new release coming at some point!). I hadn't considered it for > this... I'll have to think about it a bit. Off the top of my > head it seems like it might be a little heavyweight for this > application, meaning it's one more dependency if this whole idea > ever got added to Struts, something I'd bet everyone (certainly > me) tries to avoid as much as possible. But that's just my gut > reaction, I'll consider it a bit more. > > As far as use cases go, this is actually based on something a > user posted a few hours ago, not something I'd ever thought of... > He was asking about how he could have a Javascript object on a > page and get that into a Java object on the server. I think his > basic thought was that since he's structured his pages to use > objects to store and manipulate data, it might be nice to be able > to easily convert that to a class in his Actions to work with. I > just took it a step further and considered the other path... what > if you have a Java object and you want to get yourself a > Javascript object with the same state as the Java object? > > Especially when dealing with richer user interfaces as I'm sure > you know, you tend to get into client-side scripting and dynamic > HTML more... I do a tremendous amount of that here at work > because I'm kind of known for being able to make web apps look, > feel and work like a fat client, but that comes at the cost of > complexity on the client-side. Many of us like to use OOP > techniques on the client-side as we do on the server-side, so > being able to convert objects from the client to the server and > vice-versa with a minimum of fuss is an attractive idea. The > alternative is of course extra code on the pages (or in taglibs) > to render values into Javascript variables, and then munging > Javascript variables into form fields to be submitted and than > manually populating any objects that might need to be on the > server. A standard way of doing such a thing might be quite helpful. > > -- > Frank W. Zammetti > Founder and Chief Software Architect > Omnytex Technologies > http://www.omnytex.com > > On Fri, October 29, 2004 4:01 pm, David Graham said: > > Have you looked at Rhino http://www.mozilla.org/rhino/ ? It lets you > > access Java from JS and JS from Java so you might not need to > handle types > > if you just pass the JS into the Rhino interpreter. > > > > I'm not sure I understand the use cases for your proposal though. > > > > David > > > > --- [EMAIL PROTECTED] wrote: > > > >> Craig (and everyone else), based on what you mentioned on the User's > >> list, I'd like to make the following proposal, get some feedback from > >> everyone and go off and work on it... I prefer getting at least some > >> level of buy-in from you guys before I spend any time on it... > >> > >> The basic idea is being able to convert a Javascript object to a Java > >> object, and vice-versa. Let's deal with it in two steps... > >> > >> To convert from Javascript to Java, I propose we add a new form tag to > >> the HTML taglib called 'html:jsObject'. This would act like an > >> html:hidden element, but with some differences. > >> > >> The 'styleId' element would always render the HTML id attribute as > >> 'jsoXXXX' where XXXX is the name as specified in 'styleId' for an > >> html:jsObject tag. This would be needed to avoid name > conflicts with an > >> object named the same thing as the form field. > >> > >> The html:form element would need to have a new attribute added, > >> 'jsoAware'. When set to true, an added onSubmit handler would be > >> rendered that grabs Javascript objects in page scope named according to > >> the 'styleId' of the html:jsObject tags and sets the value of the > >> corresponding html:jsObject tag for each one. > >> > >> So, a developer has to (a) set jsoAware true on html:form and > (b) add an > >> html:jsObject element for each object they wish to serialize. As I > >> understand it, the browser will create a string out of the object (I > >> need to verify this frankly, but I'm taking it on faith at this point), > >> so that becomes the value of the jsObject field. That gets us > >> serialization on the client-side integrated with the taglibs. > >> > >> Next, as Craig said, we create a new JSJavaConverter. Pass this the > >> class to convert to (maybe an ActionForm? maybe something else?) and > >> the string as submitted as the jsObject field... > >> > >> ...and here's the first problem I see... what about data types? > >> Javascript is typeless, Java obviously isn't. My thought here is that > >> we put a restraint on any Javascript class to be converted: you as a > >> developer must provide a dataTypeXXXX field for each data field, where > >> XXXX is the name of the field. These would be set to one of a set of > >> known values (i.e., string, double, etc). I'm thinking we can add > >> another tag, maybe html:jsObjectConstants, that will render Javascript > >> defining the data type constants. A developer can throw this tag into > >> their class (or at page-level, whichever) and use them in the class to > >> define the data types. > >> > >> I think that gives us enough information to attempt conversions on the > >> fields of the Javascript class. The converter I don't think would be > >> terribly difficult to write, once I know the structure of the > >> serialization the browser performs (hopefully it's name/value pairs and > >> is delimited in some way, then it's almost cake). > >> > >> Now, moving on to converting a Java object to Javascript... > >> > >> That should be even easier... Just write a converter to call toString() > >> on all class fields. I'm thinking I'd write a generic > >> 'JavascriptObjectClass' for use in the converter as the target class. > >> This would probably be as simple as a class with nothing but a HashMap > >> in it that contains the field names and values. Heck, maybe just > >> passing it a HashMap class is sufficient, I'll have to think about that > >> a bit (if it is, even simpler and better!) > >> > >> Then we'd need a new html:renderJSObject tag that would, you > guessed it: > >> accept the name of an object (in the response? not sure...) and render > >> the Javascript for it based on the HashMap. > >> > >> Obviously this will only reconstitute an object's state, not it's > >> methods. I think that's perfectly logical but it does place some > >> limitations on the usefulness of this potentially... I could see an > >> attribute of html:renderJSObject that says either (a) render an entire > >> Javascript class, i.e., the state is all I'm interested in, or (b) just > >> render variable declarations... this would assume that the developer is > >> writing Javascript and basically wants the tag to "insert" the state > >> code into the rest of the class definition. > >> > >> So, if you have a JSP that you want to have a Javascript object in that > >> contains data retrieved from a database for example, in your Action you > >> get your data in some class (some DTO for instance) and then ask the > >> converter to convert that to a JavascriptObjectClass (or a HashMap, > >> whichever way thatgoes). In your JSP you have html:renderJSObject and > >> lo and behold, you have your class! > >> > >> Does this all make sense? Does it sound useful? What problems do you > >> see that I'm not? As I said, I wouldn't mind doing this, but if > >> everyone thinks it's a stupid idea then I don't want to waste time. > >> Thanks all! > >> > >> -- > >> Frank W. Zammetti > >> Founder and Chief Software Architect > >> Omnytex Technologies > >> http://www.omnytex.com > >> > >> On Fri, October 29, 2004 2:23 pm, Craig McClanahan said: > >> > That's a pretty interesting idea. > >> > > >> > If you registered a Converter (in BeanUtils) that knew how to convert > >> > a String to a TestObject (and back), I'll bet you could get > >> > BeanUtils.populate() to do what you want. > >> > > >> > Craig > >> > > >> > > >> > On Fri, 29 Oct 2004 13:07:49 -0400, Ed DeMaio <[EMAIL PROTECTED]> > >> wrote: > >> >> I have a javascript object that I store in a hidden form field. It > >> >> seems to be submitted to the servlet as an array of strings, where > >> the > >> >> indices are the values of the properties of the javascript Object. > >> >> > >> >> Basically I'm wondering how I can have a javascript object mapped to > >> a > >> >> java object, instead of simply into an array of strings. > It seems to > >> >> have something to do BeanUtils.populate(), but really I'm not sure. > >> If > >> >> anyone can even point me in some vaguely helpful direction it would > >> be > >> >> much appreciated, as I have been searching for days. > >> >> > >> >> Below is an example in case my description was unclear... > >> >> > >> >> my jsp file includes: > >> >> > >> >> <script type="javascript"> > >> >> var test = new Object(); > >> >> test.property1 = "qwerty"; > >> >> test.property2 = 7; > >> >> > >> >> window.onload = function() { > >> >> > document.getElementById('form1').test.value = > >> >> test; > >> >> } > >> >> </script> > >> >> > >> >> <html:form styleId="form1"......> > >> >> <html:hidden property="test" styleId="test" /> > >> >> <html:submit property="submit" /> > >> >> </html:form> > >> >> > >> >> my ActionForm class contains the following getter and setter method: > >> >> > >> >> public TestObject getTest() { return testObj; } > >> >> public void setTest(TestObject test) { this.testObj > = test; } > >> >> > >> >> and my TestObject class contains the following getter and setter > >> >> methods: > >> >> > >> >> public String getProperty1() { return prop1; } > >> >> public void setProperty1(String s) { this.prop1 = s; } > >> >> > >> >> public Integer getProperty2() { return prop2; } > >> >> public void setProperty2(Integer i) { this.prop2 = i; } > >> >> > >> >> and when the form is submitted, i would like the test object in my > >> >> action form populated with the properties from the javascript test > >> >> object that was submitted. > >> >> > >> >> > --------------------------------------------------------------------- > >> >> To unsubscribe, e-mail: [EMAIL PROTECTED] > >> >> For additional commands, e-mail: [EMAIL PROTECTED] > >> >> > >> >> > >> > > >> > --------------------------------------------------------------------- > >> > To unsubscribe, e-mail: [EMAIL PROTECTED] > >> > For additional commands, e-mail: [EMAIL PROTECTED] > >> > > >> > > >> > >> > --------------------------------------------------------------------- > >> To unsubscribe, e-mail: [EMAIL PROTECTED] > >> For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > > > > > _______________________________ > > Do you Yahoo!? > > Express yourself with Y! 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