I am new to J2ME development, so i am having some problems regarding storing images in RMS.
What is the diffrence between storing image in a package and storing it in RMS, is it the same thing or having any difference. Moreover, if i store image on RMS, then ultimately i would i have to keep it in package too so it consumes space at two different places.
Please help me out with this issue and assist me with the best approach to be used.
RMS is used to store data that needs to be loaded again later, like e.g. variables that is input by the user, or highscores achieved in a game.
In my opinion it would only make sense to store images in RMS, if they have been edited by the user. But even then, I'd probably go with saving them on the file-system instead.
A MIDlet cannot come with data pre-defined in RMS. In order to put data into RMS, you need to get that data from somewhere first, e.g. inside the jar file resources folder, or downloaded from the web.
Related
I'm using intake to access the catalog catalog.ocean.GFDL_CM2_6.GFDL_CM2_6_control_ocean_surface.
At the moment I only work with small patches of that data, but accessing that data every single time is still quite costly (it's on Google Cloud Storage). So I want to use the persist option of intake to store that data locally. However as far as I've understood from the docs, it looks like one can only persist the whole dataset. For that specific dataset that would amount to almost 400 dollars if I take a cost of 0.1$ per GB, since the total data is 3976GB.
Hence my questions:
Is there a way (especially for a zarr file which in theory should make this quite easy) to persist only parts of the data (for instance only a subset of the variables)
This is probably more complicated, but can I push things further, by persisting regions of data I'm interested in (in terms of coordinates values for instance)?
There is no direct Intake way to do what you are asking for. Intake was conceived as a way to get your data into a format that you can then manipulate as you normally do, i.e., deal with only the loading part, so that a persisted data-set is the same as the original.
However, it is not hard to accomplish manually: you should grab the xarray, filter for the region you need, and call to_zarr to save the new dataset. You can then point a simple catalogue entry like the old one at the new location.
You could have done this manipulation in a driver directly if this was a specific pattern that would repeat a lot. In fact, we have mooted the idea of whether/how to implement such processing steps in Intake, but there is no plan yet. In the end, we may take the work on pipelines in Holoviews to describe processing steps.
I'm creating a RESTful API with node, express, and mongodb and the book I'm using as a reference recommends using GridFS (namely gridfs-stream) for cases where one needs to handle files larger than the MongoDB cut-off (16MB)
I'm not sure if my app will ever need to handle files that size, but I'm wondering if there are cons to using it anyways in case I may need that feature later.
Are there any cons (i.e. significant unnecessary performance penalties, stability issues) that I should be aware of to help make this decision?
I'm also open to suggestions for alternate file management solutions that you may have.
Thanks!
dont use Gridfs for small binary data
GridFS requires two queries: one to fetch a file’s metadata and one to fetch its contents
Therefore, if you use GridFS to store small files, you are doubling the number
of queries that your application has to do. GridFS is basically a way of breaking up large
binary objects for storage in the database.
GridFS is for storing big data—larger than will fit in a single document. As a rule of best practice anything that is too big to load all at once on the client is probably not something
you want to load all at once on the server. Therefore, anything you’re going to
stream to a client is a good candidate for GridFS. Things that will be loaded all at once
on the client, such as images, sounds, or even small video clips, should generally just
be embedded in your main document
Furthermore, if your files are all smaller the 16 MB BSON Document Size limit, consider storing the file manually within a single document instead of using GridFS. You may use the BinData data type to store the binary data. See your drivers documentation for details on using BinData.
see https://docs.mongodb.com/manual/core/gridfs/
please mark correct if this helped
I am building a personal project in Node, and I want my users to be able to upload 'cover' photos. The approach I am using right now is to save these images to my fs, and just add the path to that image in a MongoDB database. So if a user adds an image I add that image to my images folder with the name lets say userID.jpg, and I save "/public/images/userID.jpg" as a string in my database. I have a feeling that this approach might not be the most efficient. Should I be directly saving it to the database? What are the advantages or disadvantages ?
Storing your images as files is actually pretty efficient (unless we're talking about 10's of K's of images, but still). Also, on the serving side, the images would probably be handled by something like express.static() (assuming that you're using Express), which is also quite lightweight.
However, if you eventually want to be a bit more scalable, you can take a look at using GridFS, which implements a file-system like storage on top of MongoDB. I use gridfs-stream for something similar (uploads/downloads) and it works fine.
If the images are small enough (smaller than about 16MB, which is the size limit for BSON documents), you might not even need to use GridFS and just store the images as Binary type.
I am trying to store a plist and several binary files (let's say images) as part of an UIManagedDocument. The name of the binary files are an attribute in Core Data and I don't need to enumerate them, just access the right one when showing the related entity.
The file structure that I want to have is:
- <File yyyyMMdd-HHmmss>.extdoc
- StoreContent
- persistentStore
- AdditionalContent
- ListStatus.plist (used to store per document defaults)
- Images
- uuid1.png
- uuid2.png
- ...
- uuidn.png
So far, I have successfully followed the instructions in How do I save additional content into my UIManagedDocument file packages?, but when I try to add the binary files there are some things that I don't know how to do.
Should I treat the URL /the/path/File yyyyMMdd-HHmmss.extdoc/AdditionalContent (the default one provided with readAdditionalContentFromURL:error:) as a NSFileWrapper? Are there any advantages/disadvantages vs just using the URLs? I find it more complicated to use the file wrapper, since the plist has to be read using the file wrapper accessors and NSCoder (I guess), and the files, I have to store the file wrapper for the Images directory and then obtain the corresponding node with objectForKey (I assume). But Apple's Document-Based Apps Programming Guide for iOS regarding custom formats instead of NSData or NSFileWrapper, states "Keep in mind that your code will have to duplicate what UIDocument does for you, and so you must deal with greater complexity and a greater possibility of error." Am I misunderstanding this?
Per document defaults are declared as properties: the setter modifies the NSDictionary that maps the plist and marks the document as updated, and the getter accesses the dictionary with the proper key. How do I expose the ability to read/write the binary files? Should I add a method to my subclass of UIManagedDocument? - (void)writeImage:(NSString*)uuid; and -(UIImage *)readImage:(NSString *)uuid; And should I keep this data in memory until the document is saved? How?
Assuming that NSFileWrapper is the way to go, if I plan to use this document with iCloud should I use file coordinators with the file wrapper? If so, how?
Any source code for each question will be greatly appreciated. Thank you.
P.S.: I know that I could save some binary data inside of Core Data, but I don't feel comfortable with that solution. Among other reasons, I rather store the PNG data for image files that a serialized version of UIImage that won't be compatible with NSImage if I want to create a desktop app.
I'd like to say that, in general I rather like UIManagedDocument. It has a few advantages over raw Core Data. For example, it sets up the entire core data stack for you automatically. It also sets up nested managed object contexts for you, so you get free background saving. None of that is particularly earth-shattering, but it's a lot of functionality from a tiny amount of code.
I haven't played around with saving additional information...but here are my thoughts.
First, you shouldn't need to treat the new URL as a file wrapper. You should just be able to do regular file operations on the provided URL. Just make sure you have everything implemented properly in additionalContentForURL:error:, writeAdditionalContent:toURL:originalContentsURL:error: and readAdditionalContentFromURL:error:. The read and write operations need to be symmetric. And you should probably snapshot your data in additionalContentsForURL:error: so that everything will be saved in a known, good state (since the save operations are asynchronous).
As an alternative, have you considered using the Store in External Record File flag in your data model instead of saving it manually? This should force Core Data to (depending on the size of the binary data) automatically store them externally. I looked at the release notes, and I didn't see anything saying you couldn't use this feature with iCloud. That might be the easiest fix.
Attacking a side point for the moment (as I have not had ANY good experience with UIManagedDocument).
You can save the binary inside of Core Data for a iOS 5.0+ application using the external file reference. Then you can save the PNG of the image to Core Data directly and not need to worry about a UIManagedDocument or about bloating the sqlite file.
There is nothing stopping you from storing the PNG instead of a UIImage.
One other thought. You may need to use an NSFileCoordinator for the read and write operations. Technically, any read or write operations in the iCloud container need to use a file coordinator (to coordinate with the iCloud sync service--this prevents accidentally corrupting a file by reading it while another process is writing to it).
I know that UIDocument wraps most of its input and output methods automatically. I'd guess that these methods are similarly wrapped (since they give you a URL to use)--However, the docs aren't very clear.
tl;dr : Should I store directories in CouchDB as a list of attachments, or a single tar
I've been using CouchDB to store project documents. I just create documents via Futon and upload them directly from there. I've also written a script to bulk-upload directories. I am using it like a basic content repository. I replicate it, so other people on my team have a copy of the repository.
I noticed that saving directories as a series of files seems to have a lot of storage overhead, so instead I upload a .tar.gz file containing the directory. This does significantly reduce the size of the document but now any change to the directory requires replicating the entire tarball.
I am looking for thoughts or perspective on the matter.
It really depends one what you want to achieve. I will try and provide some options for you to consider.
Storing one tar.gz will save you space, but it does make it harder to work with. If you are simply archiving it may work for you.
Storing all the attachments on one document works well for couchapps. The workflow is you mess around with attachments until you are ready to release the application, then there is not a lot of overhead for replication, because it is usually one time. It is nice that they are one one document because they all move/replicate as one bundle. Downsides for using this approach for a content management system are that you can get a lot of history baggage that you have to compact on your local couch. Also you will get a lot of conflicts during replication between couches, and couch will keep conflicts around for you to resolve. Therefore if you choose this model, you should compact frequently to reduce disk size.
For a content management system, I might recommend using one document per attachment. That would give you less conflicts. There will be a slight overhead as each doc will have some space allocated for the doc itself, but the savings in having to do frequent compaction and/or conflict resolution will be better.
Hope that gives you some options to weigh out.