I managed to make some arbitrary signals manually, but I want to define them in a database and at the define signal part from the Arbitrary signal properties I would like to take the values from a DB.
I have never worked with DB in Labview, and I'm a labview noob. Do you know some tutorials or schemas for what I'm trying to do? Thanks.
http://performancemicrowave.com/sql_LV.html
http://www.jeffreytravis.com/lost/labsql.html
Free alternatives to NI's DB kit. Without knowing more about your DB, whether it is already set up or not, what type of DB it is, etc, it's hard to provide more help than this.
Related
I need to write a piece of software which collects signals from different bus systems (e.g. CAN Bus, Ethernet) and then saves the data in a data storage.
Another piece of software then uses the data in the database to operate.
So basically i need constant write access on the one side and constant read access on the other side.
I thought about using SQLite because i had good experience with it because its ease of use. But i also experienced problems with two processes simultaniously using the database file.
So my question is: Is SQLite still the right thing for a use case like this or are there alternatives? Like a whole SQL Server thingy? Or some completely other approach? I can't think of a practical one.
Thanks in advance!
I'm still in college and I'm trying my hand at designing my own applications, for practice and also for funsies, but I'm having some big questions.
Currently, I'm attempting to design an application that uses a relational database backend to store records related to a pen-and-paper RPG that a friend and I have been designing. It will need to store characters, weapons, items, etc. Since it's based off of a sci-fi universe, there are guns, etc.
Now, I'm stuck in the conceptual stages here because I'm not sure how I would store some of the weirder to grasp types of information here. Since it's a tabletop RPG, there are dice involved, typically referred to as D4, D6, D10, D20, etc. and a lot of these weapons, for example, have several kinds of attacks each (they're guns, so it's like firing modes, etc.) and a typical attack would be something like "D20 + 20."
Now, I know that I could just store it as a string variable, but I was hoping to design this in such a way that I could actually add some dice-rolling/etc. functionality to it. Is there a simple or effective way of storing a Math.random variable (not the result, mind you, but the actual range number) in a SQL record so that I could just grab it and use it real quick?
For extra context, I was hoping to have one table of the actual weapon templates & stats and another table of just actual instances of those weapons, so I could keep track of ammo in each gun, who owns it, etc.
I'm using Netbeans and a Derby database. Thanks for any help you guys.
As stated above, I don't know why you just wouldn't create a java/C#/any programming language application that can simulate the dice rolls for you. I mean, you could integrate the database into the application to retrieve information. Otherwise just simply make the ability to input information on weapons/Armour into the application in the form of popup dialog boxes (Or something along those lines).
A database is primarily used to store information in a structured way and automatically updates this information as needed. What you are suggesting to do is more dynamic and has nothing to do with storing information and more so with actually playing the game. Not wanting to change your idea about creating it. Just creating an actual application that utilizes a database can be written in a language other than SQL. (And much easier to do it this way as well.)
Your question is very broad, but I would not store a descriptive characteristic like "D20 + 20" in your database only yo parse it out in the app. Instead store that as two or three (depending on what it represents) attributes (columns) in your database, and let the app display it appropriately.
I don't know exactly what you mean by storing "equations" and "RNGs" in your database, but those belong in the application, not the database. You can store inputs or parameters that guide those equations, but not the equations themselves.
I understand what serialized is. I simply do not know when I would use it. I have seen the discouraged practice of session data in a database and things like that but other than that I do not know.
What kind of objects state would I save in a database, file system, anything that needs persistence? Why would I use it for a non-"permanent" reason?
I do not have a context per se. All I really do are client server web apps. I may get to use a Java stack for it, but I'd really like to understand this part of things, should I need it.
I have asked similar questions. I'm just not understanding.
In a sentence, using a generic serialiser is a reasonable way to save stuff to disk, move stuff over a network in a manner which doesn't require you to design a data format, write code that emits data in that format, and write a parser for that format (all error-prone) by hand.
Any time you want to persist an object (or object hierarchy) beyond its existence inside a single execution on a single machine, you are going to want to serialise and deserialise.
Some scenarios that come to my mind are
Caching: when you want to offload in-memory objects to disk (the caching framework can serialise the object to disk)
For thick clients (either a desktop application or an app using RMI) you'll need to transfer objects from one JVM to another, and this is done by serialising them
I can't think of any other scenarios from the top of my head.
I know ! The "proper" way to read STXL.CLUSTD is through SAP ABAP function. But I'm sorry, we are suffering badly from performance problem. We have already make our decision to go directly to the database (Oracle), and we don't have any plan to revert our decision yet since everything goes so much better so far.
However, we've came across this issue. The text in STXL.CLUSTD field was stored in an incomprehensible format. We cannot find any information about its encoding format via google. Anybody can hint me how to decode text from STXL.CLUSTD ?
Thanks
Short version: You don't. Use the function module READ_TEXT.
Long version: You're looking at a so-called cluster table. See http://help.sap.com/saphelp_47x200/helpdata/en/fc/eb3bf8358411d1829f0000e829fbfe/frameset.htm for the details. The data you see is an internal representation of the text, somehow related to the way the ABAP kernel handles the data internally. This data does not make any sense without the metadata. If you change the original structure in an incompatible way, the data can no longer be read. Oh, and did I mention that the data does not contain a reference to the metadata? When reading the contents of these tables, even in ABAP, you need to know the original source data structure, otherwise you're doomed. Without the metadata and the knowledge of how the kernel handles these data types at runtime, you'll have a hard time deciphering the contents.
Personal opinion: Direct access to the database below the SAP R/3 system is a really bad idea since this not only bypasses all safety measures, but it also makes you very vulnerable to all structural changes of the database. The only real reason for accessing the database directly is not lack of performance, but lack of (ABAP) knowledge, and that should be curable :-)
You can definitely read clusters and pools without running any ABAP code, or invoking RFC's or BAPI's, etc. it is a very good approach, highly performant, and easy to use.
I don't like people flogging their products in StackOverflow, but the information that you must use ABAP to access SAP data has been outdated for over 7 years now.
Thanks,
Bill MacLean
I just noticed this thread and I work for Simplement. Snow_FFFF is correct (BTW, that user is not me, and ASFAIK is not anyone in our company). The Data Liberator product has been de-clustering and de-pooling tables (and many other things) for our customers since 2009.
What am I trying to do?
A UI process that reads data from a Core Data store on disk. It wouldn't need to edit the data, just read and display the data.
A command line process that writes to the same data store as accessed by the UI.
Why?
So that the command line process can be running all the time but the user can quit the UI process and forget about the app until they need to look at the data it's captured.
What would be the simplest and most reliable way of achieving this?
What Have I Tried?
I've read up on sharing a data store between threads and implemented this once before, but I can't find anything in the docs or on the web indicating how to share a store between processes.
Is it as simple as pointing both processes at the same data store file? I've experimented with this briefly. It appeared to work OK, but I'm worried I might run into problems with locking etc when it's really put under stress.
Finally
I'd really appreciate someone giving me pointers on what direction to go with this. Thanks.
This might be one of those situations in which you'll simply have to Try It And See™.
Insofar as I can remember, SQLite (which is the data store you'll most likely want to be using) has built in mechanisms for file locking and so on; so the integrity of the file is likely to be assured. If, on the other hand, you use the CoreData/XML approach, you might run into problems.
In other words; use the SQLite backing for your file, and you should likely be fine.
You can do exactly what you want, you probably want to use the SQLite store otherwise saving and committing every time you want to synch out data will be horrifically slow. You just need to use some sort of IPC doorbell between the apps so that you can inform one app it needs to recheck the persistent store on disk and merge in its data.
Apple documents using multiple persistent store corindators as a valid option in Multi-Threading with Core Data (in "General Guidelines", open 2). That happens to be discussing completely parallel CD stacks in the same process, but it is valid if they are in completely separate address spaces as well.
Nearly two years on, and I've just found a much better way of doing this.
The answer seems to lie with Sync Services. I didn't even realise it existed! There's an excellent post about this at:
http://www.timisted.net/blog/archive/core-data-and-sync-services/
I've not tried this with my app yet, but it seems like an excellent way of sharing a core data store between two processes or applications.
If I experience any performance issues, I'll update this answer accordingly, but this seems like the Apple recommended way of doing it.
You need to re-think your architecture. If you want a daemon to own the data store, then have your GUI app connect to the daemon. Trying to share the data store is a can of worms you don't want to open.