UI Control such as LISTVIEW or Tree or ... comes with model that is observable.
When one make a change to that model, I suppose JavaFX knows how to refresh it automatically in the display.
However my question here is as follows:
Is it the intent way, that someone who wants to update and not replace this model, do so in a background thread with a platform.runlater.
In other words, one has some serious computation to do, and needs to to update an ObservableList as a result. Is it the intended way, to do the heavy work in a background thread and at the end of it, run the update in a platform run later?
I'm asking this because this is what I have been doing so far without problem. But from my reading here and there, in particular in
http://docs.oracle.com/javase/8/javafx/api/javafx/concurrent/Task.html
It seems that some other mechanism shall be used. One should rather return a full list instead of updating the observable list.
But this works only if things comes from the GUI. In case the update is triggered from the back end, there is no way to do so.
The solution that I have used so far, was always to hold a reference to the observable list and updating it by means of platform.Runlater.
Is there any other way ?
The link you give has an example (the PartialResultsTask) that does as you describe: it updates an existing ObservableList as it progresses via a call to Platform.runLater(). So this is clearly a supported way of doing things.
For updating from the back end (i.e. from a class unaware that the data are being used in a UI), you'd really have to post some code for anyone to be able to help. But you might have a look at the techniques used in this article. While he doesn't actually update lists from the backend in the examples there, the same strategy could be used to do so.
Related
Our plugin maintains some instance parameter values across many elements, including those in groups.
Occasionally the end users will introduce data that activates an unused Category,
so we have to update the document parameter bindings, to include those categories. However, when we call
doc.ParameterBindings.ReInsert()
our existing parameter values inside groups are lost, because our VariesAcrossGroups flag is toggled back to false?
How did Revit intend this to work - are we supposed to use this in a different way, to not trigger this problem?
ReInsert() expects a base Definition argument, and would usualy get an ExternalDefinition supplied.
To learn, I instead tried to scan through the definition-keys of existing bindings and match those.
This way, I got the document's InternalDefinition, and tried calling Reinsert with that instead
(my hope was, that since its existing InternalDefinition DID include VariesAcrossGroups=true, this would help). Alas, Reinsert doesn't seem to care.
The problem, as you might guess, is that after VariesAcrossGroups=False, a lot of my instance parameters have collapsed into each other, so they all hold identical values. Given that they are IDs, this is less than ideal.
My current (intended) solution is to instead grab a backup of all existing parameter values BEFORE I update the bindings, then after the binding-update and variesAcrossGroups back to true, then inspect all values and re-assign all parameter-values that have been broken. But as you may surmise, this is less than ideal - it will be horribly slow for the users to use our plugin, and frankly it seems like something the revitAPI should take care of, not the plugin developer.
Are we using this the wrong way?
One approach I have considered, is to bind every possibly category I can think of, up front and once only. But I'm not sure that is possible. Categories in themselves are also difficult to work with, as you can only create them indirectly, by using your Project-Document as a factory (i.e. you cannot create a category yourself, you can only indirectly ask the Document to - maybe! - create a category for you, that you request). Because of this, I don't think you can bind for all categories up front - some categories only become available in the document, AFTER you have included a given family/type in your project.
To sum it up: First, I
doc.ParameterBindings.ReInsert()
my binding, with the updated categories. Then, I call
InternalDefinition.SetAllowVaryBetweenGroups()
(after having determined IDEF.VariesAcrossGroups has reverted back to false.)
I am interested to hear the best way to do this, without destroying the client's existing data.
Thank you very much in advance.
(I'm not sure I will accept my own answer).
My answer is just, that you can survive-circumvent this problem,
by scanning the entire revit database for your existing parmater values, before you update the document bindings.
Afterwards, you reset VariesAcrossGroups back to its lost value.
Then, you iterate through your collected parameters, and verify which ones have lost their original value, and reset them back to their intended value.
One trick that speeds this up a bit, is that you can check Element.GroupId <> -1. That is, those elements that are group members.
You only need to track elements which are group members, as it's precisely those that are affected by this Revit bug.
A further tip is, that you should not only watch out for parameter-values that have lost their original value. You must also watch out for parameter-values that have accidentally GOTTEN a value, but which should be left un-set.
I just use FilteredElementCollector with WhereElementIsNotElementType().
Performance-wise, it is of course horrible to do all this,
but given how Revit behaves, I see no other solution if you have to ship to your clients.
I would like to implement CQRS and ES using Axon framework
I've got a pretty complex HTML form which represents recruitment process with six steps.
ES would be helpful to generate historical statistics for selected dates and track changes in form.
Admin can always perform several operations:
assign person responsible for each step
provide notes for each step
accept or reject candidate on every step
turn on/off SMS or email notifications
assign tags
Form update (difference only) is sent from UI application to backend.
Assuming I want to make changes only for servers side application, question is what should be a Command and what should be an Event, I consider three options:
Form patch is a Command which generates Form Update Event
Drawback of this solution is that each event handler needs to check if changes in form refers to this handler ex. if email about rejection should be sent
Form patch is a Command which generates several Events ex:. Interviewer Assigned, Notifications Turned Off, Rejected on technical interview
Drawback of this solution is that some events could be generated and other will not because of breaking constraints ex: Notifications Turned Off will succeed but Interviewer Assigned will fail due to assigning unauthorized user. Maybe I should check all constraints before commands generation ?
Form patch is converted to several Commands ex: Assign Interviewer, Turn Off Notifications and each command generates event ex: Interviewer Assigned, Notifications Turned Off
Drawback of this solution is that some commands can fail ex: Assign Interviewer can fail due to assigning unauthorized user. This will end up with inconsistent state because some events would be stored in repository, some will not. Maybe I should check all constraints before commands generation ?
The question I would call your attention to: are you creating an authority for the information you store, or are you just tracking information from the outside world?
Udi Dahan wrote Race Conditions Don't Exist; raising this interesting point
A microsecond difference in timing shouldn’t make a difference to core business behaviors.
If you have an unauthorized user in your system, is it really critical to the business that they be authorized before they are assigned responsibility for a particular step? Can the system really tell that the "fault" is that the responsibility was assigned to the wrong user, rather than that the user is wrongly not authorized?
Greg Young talks about exception reports in warehouse systems, noting that the responsibility of the model in that case is not to prevent data changes, but to report when a data change has produced an inconsistent state.
What's the cost to the business if you update the data anyway?
If the semantics of the message is that a Decision Has Been Made, or that Something In The Real World Has Changed, then your model shouldn't be trying to block that information from being recorded.
FormUpdated isn't a particularly satisfactory event, for the reason you mention; you have to do a bunch of extra work to cast it in domain specific terms. Given a choice, you'd prefer to do that once. It's reasonable to think in terms of translating events from domain agnostic forms to domain specific forms as you go along.
HttpRequestReceived ->
FormSubmitted ->
InterviewerAssigned
where the intermediate representations are short lived.
I can see one big drawback of the first option. One of the biggest advantage of CQRS/ES with Axon is scalability. We can add new features without worring about regression bugs. Adding new feature is the result of defining new commands, event and handlers for both of them. None of them should not iterfere with ones existing in our system.
FormUpdate as a command require adding extra logic in one of the handler. Adding new attribute to patch and in consequence to command will cause changes in current logic. Scalability is no longer advantage in that case.
VoiceOfUnreason is giving a very good explanation what you should think about when starting with such a system, so definitely take a look at his answer.
The only thing I'd like to add, is that I'd suggest you take the third option.
With the examples you gave, the more generic commands/events don't tell that much about what's happening in your domain. The more granular events far better explain what exactly has happened, as the event message its name already points it out.
Pulling Axon Framework in to the loop, I can also add a couple of pointers.
From a command message perspective, it's safe to just take a route and not over think it to much. The framework quite easily allows you to adjust the command structure later on. In Axon Framework trainings it is typically suggested to let a command message take the form of a specific action you're performing. So 'assigning a person to a step would typically be a AssignPersonToStepCommand, as that is the exact action you'd like the system to perform.
From events it's typically a bit nastier to decide later on that you want fine grained or generic events. This follows from doing Event Sourcing. Since the events are your source of truth, you'll thus be required to deal with all forms of events you've got in your system.
Due to this I'd argue that the weight of your decision should lie with how fine grained your events become. To loop back to your question: in the example you give, I'd say option 3 would fit best.
I'm preparing the sequence diagram for a project. I made the following sequence diagram for a retailer updating his inventory
It's confusing to me because this is the first time I use this technique with a real project.i have used database as an object here and i don't know whether its right or wrong. And another thing i need to clarify is by using Updating i meant for both editing/add new item To the inventory. Is it wrong to do like that way? or else can we draw it separately?
The following image is part of the updating process, would any one take a look and correct me if I did any mistake.(UpdateUI- User interface).Thanks in Advance.
It does not look right. There are a couple of issues:
Your database will likely never issue any messages
Actions inside a DB are usually not exposed. You normally only call CRUD from outside for a DB.
You mix synch/asynch (likely unwillingly). Filled arrows are synch, unfilled ones as asynch.
Main Page is likely the V in MVC and UpdateUI the C. So the controller will act on a click from the user and interact with the DB.
So just from my guts here is a more reasonable sketch:
This is a rather generic question, but I'll try to be as precise as possible:
quite often I'm asked by customers for proper implementations of LotusScript's
continue = false
in Notes' Query* events. One quite common situation is a form's QueryOpen event where we actually can stop the process of opening the document in question based on some condition, e.g based on the response from a user dialog.
For some Xpages events like querySaveDocument there are quite obvious solutions, whereas with others I only can recommend re-thinking the entire logic like preventing code execution at a much earlier stage. But of course most people in question would prefer a generic approach like "re-write those codes using...". And - to be honest - I'd like to know myself ;)
I'm more or less familiar with the Xpages / JSF lifecycle, but have to admit that I don't have a proper idea how I could stop execution at any given phase.
As always, any hint is welcome.
EDIT (to clarify my question, but also in response to Tim's answer below):
It's not just the QuerySave but also the QueryModeChange and QueryRecalc that somehow need to be transformed together ith an existng application's logic but that don't have their equivalent in the Xpages logic. Are both concepts (forms based and xpages based) just too different at this point?
As an example think of a workflow application where we need to check certain conditions before we allow opening an existing doc in edit mode for a potential author. In my Notes client application I add some code to 2 events, i.e. QueryOpen, where I check the "mode" arg, and 2nd QueryModeChange, where I check the current doc mode. In both cases I can prevent the doc from being edited by adding my continue = false, if necessary. Depending on the event the doc will either not change its mode, or not open at all.
With an Xpage I can use buttons for changing a doc's edit mode, and I can "hide" those buttons, or just add some checking code or whatever.
But 17 years of Domino consulting have tought me at least one lesson: there'll always be users that'll find the hidden ways to reach their goals. In our case they might find out that a simple modification of the page's URL will finally allow them to edit the doc. To prevent this I could maybe use the "beforeRenderResponse" event, I assume. But then, beforeRenderResponse is also called in other situations as well, so that we have to investigate the current situation first. Or I could make sure that users don't have author rights unless the situation allows it.
Again, not a huge problem, but when making the transition from a legacy Notes application this means re-thinking its entire logic. Which makes the job more tediuos, and especilly more expensive.
True? Or am I missing some crucial parts of the concept?
Structure your events as action groups and, when applicable, return false. This will cause all remaining actions in the group to be skipped.
For example, you could split a "Save" button into two separate actions:
1.
// by default, execute additional actions:
var result = true;
/* execute some logic here */
if (somethingFailed) {
result = false;
}
return result;
Replace somethingFailed with an evaluation based on whatever logic you have in place of the block comment to determine whether it's appropriate to now save the document.
2.
return currentDocument.save();
Not only does the above pattern cause the call to save() to be skipped if the first action returns false, but because save(), in turn, returns a boolean, you could theoretically also add a third action as a kind of postSave event: if the save is successful, the third action will automatically run; if the save fails, the third action will be automatically skipped.
All queryModeChange logic should be moved to the readonly attribute of a panel (or the view root of an XPage or Custom Control) containing all otherwise editable content... you would basically just be flipping the boolean: traditionally, queryModeChange would treat false (for Continue) as an indication that the document should not be edited (although this also forces you to check whether the user is trying to change from read to edit, because if you forgo this check, you're potentially also preventing a user from changing the mode back to read when it's already in edit), whereas readonly should of course return true if the content should not be editable.
Since the queryModeChange approach was nearly always an additional layer of "fig leaf" security, in XPages it's far better to handle this via actual security mechanisms; the readonly attribute is explicitly intended for enforcing security. Additionally, in lieu of using readonly, you could instead use the acl complex property that is also available for panels, XPages, and Custom Controls to provide different permissions to different subsets of users; anyone with a certain role, for instance, would automatically have edit, whereas the level for the default entry can be computed based on item values indicating the current "status" and/or "assignee". With either (or both) of these mechanisms in place, it doesn't matter what the user does to the URL... the relevant components cannot be editable if the container is read only. They could even try to hack in by running JavaScript in Chrome Developer Tools, attempting to emulate the POST requests that would be sent if they could edit the content... the data they send will still not get pushed back to the model, because the targeted components are read-only by virtue of the attributes of their container.
Attempting to apply all Notes client patterns directly to the XPages context is nearly always an exercise in frustration -- and, ultimately, futility. While I won't divulge specifics here, I (and some of the smartest people I know) learned this lesson at great cost. While users may say (and even believe) that they want exactly what they already have... if they did, they would be keeping what they already have, not paying you to turn it into something else. So any migration from a Notes client app to an XPage "equivalent" is your one opportunity to revisit the reason the code used to do what it did, and determine whether that even makes sense to retain within the XPage, based not only on the differential between Notes client and XPage paradigms, but also on any differential between what the users' business process was when the Notes client app was developed and what their process is now.
Omitting this evaluation guarantees that the resulting app will be running code it doesn't need to and fail to make the most of the target platform.
queryRecalc is a perfect example of this: typically, recalculation was blocked to optimize performance when the user's desktop and network resources were responsible for performing complex and/or network-intensive recalculations. In XPages this all happens on the server, so a network request from the browser that returns a page where everything has changed is typically no more expensive for the end user than a page where nothing has changed (unless there's an extreme differential in the amount of markup that is actually sent). Unless the constituent components are bound to data that is expensive for the server to recalculate, logical blocking of recalculation offers little or no performance benefit for the user. Furthermore, if you're trying to block recalculation in an event, you're too late: XPages uses a "lifecycle" that consists of 6 phases, so by the time your event code runs, any recalculation you're trying to block has already occurred. So, if the reason for blocking recalculation was to optimize performance, implement a scope caching strategy that ensures you're only pulling fresh data when it makes sense to do so, and the end user experience will be sufficiently performant without trying to prevent the entire page from recalculating. If, on the other hand, queryRecalc was being used as another fig leaf (something has changed, but we don't want to show the user the updates yet), that logic should definitely be revisited to determine whether it's still applicable, still (if ever) a good idea, and which portions of the platform are now the best fit for meeting the business process objectives.
In summary, use the security mechanisms unique to XPages for locking down portions or all of a page, and use the memory scopes that we didn't have in the Notes client to ensure the application performs well. Porting an event that used to contain this logic to an XPage event that continues to contain this logic will likely fail to produce the desired result and squander some of the benefits of migrating to XPages.
I have a requirement to add fields onto a form based on data from another set of entities. Is this possible using an event script or does it require a plugin?
Given that I understand your assignment correctly, it can be done using JavaScript as well as a plugin. There is a significant difference that you need to take into consideration.
Is the change to the other entities to be made only when an actual user loads a form? If so, JS is the right way.
Or perhaps you need to ensure that those values are written even if a console client or system process retrieves the value of the primary entity? In that case, C# is your only option.
EDIT:
Simply accessing the values from any entity in the onload event can be done using a call to oData. I believe someone else asked a similar question recently. The basic format will look like this.
http://Server:Port/Organization
/XrmServices/2011/OrganizationData.svc
/TheEntityLogicalNameOfYoursSet()?$filter=FieldName eq 'ValueOfIt'
Some extra remarks.
If you're targeting on-line installation, the syntax will differ, of course, because the Schema-Server-Port-Organization are provided in a different pattern (https, orgName.crm4.something.something.com etc.). You can look it up on Settings.
Perhaps it should go without saying and I'm sure you realize it but for completeness' sake, TheEntityLogicalNameOfYours needs to be substituted for the actual name (unless that is your actual name, in which case I'll be worried, haha).
If you're new to this whole oData thingy, keep asking. I got the impression that the info I'm giving you is appreciated but not really producing "aha!" experience for you. You might want to ask separate questions, though. Some examples right off the top of my head.
a. "How do I perform oData call in JavaScript?"
b. "How do I access the fetched data?"
c. "How do I add/remove/hide a field programmatically on a form?"
d. "How do I combine data from...?"