# AzureQstor <img src="man/figures/logo.png" align="right" width=150 />

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An R interface to [Azure queue storage](https://azure.microsoft.com/en-us/products/storage/queues/), building on the functionality provided by [AzureStor](https://github.com/Azure/AzureStor).

The primary repo for this package is at https://github.com/Azure/AzureQstor; please submit issues and PRs there. It is also mirrored at the Cloudyr org at https://github.com/cloudyr/AzureQstor. You can install the development version of the package with `devtools::install_github("Azure/AzureQstor")`.

Azure queue storage is a service for storing large numbers of messages that can be accessed from anywhere in the world via authenticated calls using HTTP or HTTPS. A single queue message can be up to 64 KB in size, and a queue can contain millions of messages, up to the total capacity limit of a storage account. Queue storage is often used to create a backlog of work to process asynchronously.

AzureQstor uses a combination of S3 and R6 classes. The queue endpoint is an S3 object for compatibility with AzureStor, while R6 classes are used to represent queues and messages.

```r
library(AzureQstor)

endp <- storage_endpoint("https://mystorage.queue.core.windows.net", key="access_key")

# creating, retrieving and deleting queues
create_storage_queue(endp, "myqueue")
qu <- storage_queue(endp, "myqueue")

qu2 <- create_storage_queue(endp, "myqueue2")
delete_storage_queue(qu2)
```

The queue object exposes methods for getting (reading), peeking, deleting, updating, popping (reading and deleting) and putting (writing) messages:

```r
qu$put_message("Hello queue")
msg <- qu$get_message()

msg$text
## [1] "Hello queue"

# get several messages at once
qu$get_messages(n=30)
```

The message object exposes methods for deleting and updating the message:

```r
msg$update(visibility_timeout=30, text="Updated message")
msg$delete()
```

You can get and set metadata for a queue with the AzureStor `get/set_storage_metadata` generics:

```r
get_storage_metadata(qu)
set_storage_metadata(qu, name1="value1", name2="value2")
```

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