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Read: 37 - S3

What is Amazon S3?

• Amazon Simple Storage Service (Amazon S3) is storage for the Internet. It is designed to make web-scale computing easier.

• Amazon S3 has a simple web services interface that you can use to store and retrieve any amount of data, at any time, from anywhere on the web. It gives any developer access to the same highly scalable, reliable, fast, and inexpensive data storage infrastructure that Amazon uses to run its own global network of web sites. The service aims to maximize benefits of scale and to pass those benefits on to developers.

• Advantages of using Amazon S3

1. Creating buckets – Create and name a bucket that stores data. Buckets are the fundamental containers in Amazon S3 for data storage.
2. Storing data – Store an infinite amount of data in a bucket. Upload as many objects as you like into an Amazon S3 bucket. Each object can contain up to 5 TB of data. Each object is stored and retrieved using a unique developer-assigned key.
3. Downloading data – Download your data or enable others to do so. Download your data anytime you like, or allow others to do the same.
4. Permissions – Grant or deny access to others who want to upload or download data into your Amazon S3 bucket. Grant upload and download permissions to three types of users. Authentication mechanisms can help keep data secure from unauthorized access.
5. Standard interfaces – Use standards-based REST and SOAP interfaces designed to work with any internet-development toolkit.

Buckets

A bucket is a container for objects stored in Amazon S3. Every object is contained in a bucket. For example, if the object named photos/puppy.jpg is stored in the awsexamplebucket1 bucket in the US West (Oregon) Region, then it is addressable using the URL https://awsexamplebucket1.s3.us-west-2.amazonaws.com/photos/puppy.jpg.

Objects

Objects are the fundamental entities stored in Amazon S3. Objects consist of object data and metadata. The data portion is opaque to Amazon S3. The metadata is a set of name-value pairs that describe the object. These include some default metadata, such as the date last modified, and standard HTTP metadata, such as Content-Type. You can also specify custom metadata at the time the object is stored.

Keys

A key is the unique identifier for an object within a bucket. Every object in a bucket has exactly one key. The combination of a bucket, key, and version ID uniquely identify each object. So you can think of Amazon S3 as a basic data map between “bucket + key + version” and the object itself. Every object in Amazon S3 can be uniquely addressed through the combination of the web service endpoint, bucket name, key, and optionally, a version. For example, in the URL https://doc.s3.amazonaws.com/2006-03-01/AmazonS3.wsdl, “doc” is the name of the bucket and “2006-03-01/AmazonS3.wsdl” is the key.

Regions

You can choose the geographical AWS Region where Amazon S3 will store the buckets that you create. You might choose a Region to optimize latency, minimize costs, or address regulatory requirements. Objects stored in a Region never leave the Region unless you explicitly transfer them to another Region. For example, objects stored in the Europe (Ireland) Region never leave it.

• Amazon S3 provides strong read-after-write consistency for PUTs and DELETEs of objects in your Amazon S3 bucket in all AWS Regions. This applies to both writes to new objects as well as PUTs that overwrite existing objects and DELETEs. In addition, read operations on Amazon S3 Select, Amazon S3 Access Control Lists, Amazon S3 Object Tags, and object metadata (e.g. HEAD object) are strongly consistent.

• Amazon S3 achieves high availability by replicating data across multiple servers within AWS data centers. If a PUT request is successful, your data is safely stored. Any read (GET or LIST) that is initiated following the receipt of a successful PUT response will return the data written by the PUT. Here are examples of this behavior:

1. A process writes a new object to Amazon S3 and immediately lists keys within its bucket. The new object will appear in the list.
2. A process replaces an existing object and immediately tries to read it. Amazon S3 will return the new data.
3. A process deletes an existing object and immediately tries to read it. Amazon S3 will not return any data as the object has been deleted.
4. A process deletes an existing object and immediately lists keys within its bucket. The object will not appear in the listing.
5. If you delete a bucket and immediately list all buckets, the deleted bucket might still appear in the list.
6. If you enable versioning on a bucket for the first time, it might take a short amount of time for the change to be fully propagated. We recommend that you wait for 15 minutes after enabling versioning before issuing write operations (PUT or DELETE) on objects in the bucket.