Is there any possibility to have a Restful method (Java EE) that returns back to the client a POJO serialized us bytes (using ByteArrayOutputStream, FlatBuffers or some other library)?
And the client to cast the bytes back to a POJO object by using jquery or javascript in general (us client side)?
What I had found until now, is receiving back a JSON/XML.
Directly converting POJO to bytes won't work as your client (javascript or so) won't know how to convert the bytes back to POJO. What you can do is this. Say your response is objA. The do this. Convert objA to String (JSON maybe) and then Base64 encode it to get byte[]. Put it inside a wrapper object objB. Return objB as a JSON from your service. Your client can just take that byte[] and since it knows that the byte[] is base64 it will be able to get the original information from there.
May I ask the intent of doing this instead of XML/JSON?
Related
I am typically transferring JSON objects from JavaScript and saving them with PHP.
I then append them to a specific text file like this:
$theFile = fopen("Data/" . FQ . ".txt", "a+");
fwrite($theFile, $data.PHP_EOL);
fclose($theFile);
Can I add code to save this information as an encrypted text file?
Ideally, I want:
All the files on my server to be encrypted
A secret key that is stored on my local computer
To decipher, I would:
Transfer data from server to local computer
Use my local secret key to decipher
I want this so that if my server is compromised, all data is gibberish without the secret key (which is NOT stored on the server anywhere).
You're going to want a symmetric encryption algorithm, such as AES. It turns out that there is a decent JavaScript implementation of it as part of Forge.
https://github.com/digitalbazaar/forge#aes
You'll want to use CBC mode to encrypt the payload and send it to your server.
If you're dead set on keeping this in a text file, you'll have to base64-encode this binary data. Do this server-side. Your client code shouldn't need to know or care how your server is actually storing the data. Plus, you'll save yourself 33% bandwidth, and some client-side CPU.
As a bonus to the base64-encoding, you'll be able to line-delimit the records in your text file.
When you return the data to your client, you should decode the base64 and send them the binary encrypted data. The client will then decrypt it using the key that only it knows.
I have an ArrayBuffer in angularjs that I am trying to send to my backend endpoint in c#, I thought it was a regular byte array but it's not mapping appropriately
What would an ArrayBuffer map to as an object in c# if not a byte[]?.
I have a PDF file represented as that ArrayBuffer but now I would like to send it to the server, or perhaps is there a way to convert that ArrayBuffer to a File type in JavaScript and send it o the endpoint so that I can use something like an IFormFile?.
Thank you
I had a situation of same some long days back. What I did was, I converted the array buffer data to base 64 string in the js side and sent it to the backend c# code using post method,and again I decoded it to array buffer to regenerate the file on server side. By this way I achieved the mapping.
I used this code which helps to convert the array buffer to base 64 string in JS.
and this api of .net framework to convert back the base 64 string to file buffer.
I hope this would help you.
I have a GraphQL server, hosted on express. I want to return images to the client by sending back nodejs buffer objects. How can i config graphql server, to return bytes, instead of json? I don't wish to do this through base64, as the image are large in size.
You have to return JSON, but there's still a way. We're using GraphQL to return images stored in Blob fields in a legacy sql database. We're using sequelize, graphql-sequelize, and graphql-js.
We've defined the Blob fields to be String types in our graphql schema and so they come through in the json reply just fine.
Then we convert to a buffer before delivering, like
const imgBuffer = new Buffer.from(imgObj.data, 'ascii');
The only problem is we're now having trouble saving image data back to the database via the graphql interface. Our mutation function gives us a syntax error when it finds certain bad unicode characters in the strings, like \U0000 and whatnot (so I found your question looking for a solution to that).
There's a way, but it's complicated, and very manual, and I'm only going to give you an overview of what I've done in ApolloServer, but I think it should be enough.
First, you need to use the "Accept" header in your request to send a binary mime type, and send a matching "Content-Type" in your response. This is nessisary to be efficient, but not nessisary to work, as you'll see (with EJSON).
To serialize and deserialize respecting the headers you may need to write an express middleware, and you'll need to handle base64 encoding with a {$data: "..."} encapsulating object (as EJSON does) or just (strangely) returning null, if someone makes a request for binary data using "application/json" for their "accept" header. You'll also want to choose what binary formats that you'll support. I only use 1: "application/x-msgpack", but I hear that "application/cbor" is becoming more popular. You can use a library for EJSON, MessagePack, and CBOR to do your serialization, so this isn't as hard as it sounds.
I would then strongly recommend using the #defer on any images. See this post for more information on #defer: https://www.apollographql.com/blog/introducing-defer-in-apollo-server-f6797c4e9d6e/
I've done it. It wasn't easy, and it would be better if ApolloServer worked this way "out of the box".
It's better to send a hashed & temporary link to download it
The URL can be hashed to be non-accessible by other users.
Backend can expire the link or remove the binary file on the static server.
There might be an answer to your question by using the node module found here.
All I have is <input type="file" name="myFileUpload" />.
After the user chooses a file (most likely an image), how do I obtain the actual contents of the file as a string? (If possible, please tell me anything about base 64 and url encoding/decoding.)
I was asked to obtain such a string and set it as a value of a JSON object, then such a JSON object would be posted to the server "as is", that is, application/json; charset=utf-8.
I'm not sure if the above is a common practice since I'm accustomed to just posting such data as multipart/form-data which I was told not to use.
The receiver of this gigantic JSON object is an ASP.net Web API Controller. I suppose there would be a problem with deserialization if such an object is potentially multi-megabytes large.
So again, how to obtain the image bytes as a string and what problems may I encounter if I try to post such a large JSON object especially when it's received the server-side.
I want to send data from Javascript to a WebSocket server and also from a WebSocket server to Javascript.
I want to send this:
Headers
-------
Field 1: 2 byte hex
Field 2: 2 byte hex
Field 3: 4 byte hex
Data
----
Field1 : 2 byte hex
Field1 : 8 byte hex
From Javascript, I can send a two-byte value via
socket = new WebSocket(host);
...
socket.send(0xEF);
But I want to send multiple fields, together...let's say 0xEF, 0x60, and 0x0042.
How do I do this?
And, how to I interpret via Javascript data containing multiple fields coming from the WebSocket server?
You can send data as a string. For example:
socket.send("hello world");
I recommend you to use JSON as data format. You can convert JSON strings directly into objects and vice versa. It's so simple and useful!
You can send data as JSON objects.
socket.send(JSON.stringify({field1:'0xEF', field2:'0x60',field3: '0x0042'}));
Sound like what you are asking is how to send binary data over a WebSocket connection.
This is largely answered here:
Send and receive binary data over web sockets in Javascript?
A bit of extra info not covered in that answer:
The current WebSocket protocol and API only permits strings to be sent (or anything that can be coerced/type-cast to a string) and received messages are strings. The next iteration of the protocol (HyBi-07) supports binary data is currently being implemented in browsers.
Javascript strings are UTF-16 which is 2 bytes for every character internally. The current WebSockets payload is limited to UTF-8. In UTF-8 character values below 128 take 1 byte to encode. Values 128 and above take 2 or more bytes to encode. When you send a Javascript string, it gets converted from UTF-16 to UTF-8. To send and receive binary data (until the protocol and API natively support it), you need to encode your data into something compatible with UTF-8. For example, base64. This is covered in more detail in the answer linked above.