I'm trying to figure out a way to serialize an activejdbc model from a server application running on a JVM across the wire to another JVM that is running a GUI application. The GUI application does not have access to the database, since it is not on the same machine. On the GUI, when I try to set the properties on that model instance via a setter, to update some fields to send the model back to the server to be updated, I obviously get exceptions about not having a database connection.
I have a way to get around this by overriding the getMetaModeLocal() method, but was wondering if there was a cleaner solution to this?
The exception is as follows:
Caused by: org.javalite.activejdbc.DBException: Failed to retrieve metadata from DB, connection: 'default' is not available
at org.javalite.activejdbc.Registry.init(Registry.java:133)
at org.javalite.activejdbc.Model.getMetaModel(Model.java:67)
I expect to be able to update the model without having to have a database connection until saveIt() has been called.
You have two options for this:
Do not use models in your GUI app. On the server side you can serialize models into Maps by using a Model.toMap() method and simply sending a map to the UI. If you need to make updates, you can set new values to that same map and then send it back to the server side, where you can use a model.fromMap(map).save() approach. In other words, no need to send models across the wire.
Wait till this is fixed: Add ability to use model classes without connecting to the DB. This new feature is currently in active development, and completion is projected within a couple of weeks. It will allow you to pass models from one JVM to another without the database because the DB schema will be queried during the build rather than at run time.
Related
I would like to have two separate Parse servers (configured with a different app ID) connect to the same mongodb, so they can see the same set of users, so that I can create 2 different apps that share the same userbase.
Is this something Parse would support? Are there any expected conflicts or config caveats? I was unable to find info about this on Parse's github..
thanks
There's nothing to do, besides setting the database URL option to the same value on both servers, and that your database is accessible from both servers.
I'm not sure why you would need two different applicationId's as you want the same data and likely, logic running on both apps.
No, Parse Server does not support sharing classes between applications.
What you could do is have one of the instances or maybe a third one handle authentication and store your user information. I am pretty sure this would mean you will have to manually set user info on your requests and objects to save on the other two instances.
Another option is for each of the instances have an afterSave hook on the user class that saves and updates the info at the other instance. This seems easier to do and maintain.
I would choose the second option.
I want to have single FakeApplication for all my test.
My final goal is to set up database and use it in all test. They should access single database and share data in it. I can not use H2, because I use some MySQL features(fulltest search, for example). But if there is no started application, I can't call "DB.withTransaction" because there is started application yet. But it should start once, because it drops all tables and create new ones.
How can I do it?
I am using scala and JUnit. I solved my problem next way: I just created singleton for my fake application, which is retrieved as an implicit val. So, all work about creating and cleaning database is done on first fetch.
Let me explain in more detail:
1st: I'm running endeca 3.1, so Endeca Server here refers to 3.0's Data Domain.
I'm required to use an Endeca Server currently present on Endeca (Downloaded a Demo VM). All the info on it, including, groups, attributes and data, must be merged into out Endeca Server. (It can also be the other way around, i could merge my Endeca Server into this one.)
So far, i've tried to do the following:
1) Clone the Endeca Server
2) use the putCollection sconfig operation to create a collection on it with the same name i have on mine.
3) Load configurations using the LoadCollection & LoadAttributes graphs from OEID POC Template 3.1. I point to the new collection on the Configuration.xls file.
This is where i encounter an issue. The LoadAttributes graph gets a T/O message from the server's WS. Then the config WSDL becomes inaccesible for a while. I can't go beyond this point.
I've been able to load data into the collection, but i need to load the attributes first.
THanks in advance for your replies.
Regards
There are a few techniques.
Have you tried exporting the data domain and then importing it?
You can use the endeca-cmd tools to export to a file, and then import from that file. This would enable you to add 2 datastores into one server.
If you want to combine 2 datastores then that is a different question.
The simplest approach in 3.1 if the data collections are small. Extract then as CSV (via a data-table), convert to XLS and add them via self provisioning into separate collections within a single data store. If you are running in the VM this is potentially the easiest approach.
This can also be done using Integrator.
You don't need to load the attributes unless you are using multi-value types. You can call against the conversation web-service to extract data and then load it using 'bulk-load' I would not worry too much about creating the attributes unless this becomes essential due to their type or complexity. If you cannot call against the conversation web-service, then again extract as csv and load using Integrator.
I've been developing several iOS applications using Core Data and it has been an excellent framework to work with. However, I've encountered an issue whereby we more or less have distributed objects (synced) across multiple platforms. A web/database server backend and mobile devices.
Although it hasn't been a problem until now, the static nature of the data model used by Core Data has me a little stuck. Basically what is being requested is a dynamic forms system whereby forms can be created on a server and propagated to the devices. I'm aware of the technique for performing this with a set number of tables with something like:
Forms table
Fields table
Instance of Forms table
Instance Values table
and just linking everything together. What I'm wondering however is if there is an alternative system to Core Data (something above talking to an SQLite database directly) that will allow for a more dynamic object graph. Even a standard ORM would be good if there are options for modifying the schema at runtime. The main reason I want to go down this route is for performance in the sense that I don't want the instance values table exploding with entries (on the local device or server).
My other option is to have the static schema (object-graph) on the iOS devices but have a conversion layer on the server's side which fetches the correct object, populates the properties and saves it to the correct table. Then when the devices comes to sync, it does the reverse and breaks it down into instances. While this saves the server from having a bloated instance value table, it could still be a problem on the device.
Any suggestions are appreciated.
Using specific tables/entities for forms and fields, and entities for instances of each, is probably what I would recommend. Trying to manipulate the ORM schema on the fly if it's going to be happening frequently doesn't seem like a good idea in general.
However, if the schema is only going to change infrequently, you can probably do it with Core Data. You can programatically create and/or manipulate the NSManagedObjectModel prior to creating a NSManagedObjectContext. You can also create migration logic so data stored in an old model can be preserved when you update the model and need to recreate the context and stores.
These other SO posts may be helpful:
Customize core data model at runtime?
Handling Core Data Model Changes
You need to think carefully about what you are actually modeling.
Are you modeling: (1) the actual "forms" i.e. UI elements, (2) data that might be presented in any number of UI versions e.g. firstName or (3) both?
A data model designed to model forms would have entities like:
Form{
name:string
fields<-->Field.form
}
Field{
width:number
height:number
xPos:number
yPos:number
label:sting
nextTab<-->Field.priorTab
priorTab<-->Field.nextTab
form<<-->Form.fields
}
You would use this to store data about form as displayed in the user interface. Then you would have a separate entities and probably a separate model to store the actual data that would populate the UI elements that are configured by the first data model.
You can use Core Data to modeling anything you just need to know what you are really modeling.
I am using NHibernate for a project, and I am absolutely beginner. I am fetching some objects from a table and showing it to a form, where they can be edited. If an user inserts a new object into the table from some other window, I want to show this newly inserted object into the edit window. My application uses tabbed window interface, so user can simultaneously open insert window and edit window at the same time.
So basically what I need is a way to determine if a newly created object exists in the database which is not fetched before by ISession, and if not, then fetch that new object from the database. In other words, I need to synchronize my session with the database, just like flush method, but in the reverse way.
Can anyone help me?
Publish/Subscription method works well for this. Check out the Publishing Events part of Ayende's sample desktop application. Basically after you've added a new item, you publish that information and other parts of your application that subscribed can update their lists accordingly.
You are taking the path to NHibernate Hell.
Be sure to work your infrastructure (ie defining interfaces, defining session management patterns and notification pattern) and isolate these non-business utilies from the rest of your code before using NHibernate to implement them.
Good luck.