Caching within the web application

In-memory application caches can reduce load on services and improve performance and scalability on the database tier by caching frequently used information. Amazon ElastiCache[9] is a web service that makes it easy to deploy, operate, and scale an in-memory cache in the cloud. The in-memory cache that we create can be configured to automatically scale with load and to automatically replace failed nodes. Amazon ElastiCache is protocol-compliant with Memcached, which simplifies migration from our current on-premises solution.

Database configuration, backup and failover Many web applications contain some form of persistence, usually in the form of a relational or NoSQL database. AWS offers both relational and NoSQL database infrastructure. Alternatively, we can deploy our own database software on an Amazon EC2 instance.

Table 4.2-The following table summarizes these options, which are then discussed in greater detail.

Amazon Relational Database Service (RDS)

Amazon RDS gives we access to the capabilities of a familiar MySQL, Oracle, or Microsoft SQL Server database engine. The code, applications, and tools that we are already using can be used with Amazon RDS. Amazon RDS automatically patches the database software and backs up our database, and it stores backups for a user-defined retention period. It also supports point-in-time recovery. We benefit from the flexibility of being able to scale the computer resources or storage capacity associated with our relational database instance by making a single API call. In addition, Amazon RDS Multi-AZ deployments increase we database availability and protect our database against unplanned outages. Amazon RDS Read Replicas provide read-only replicas of web database, so we can scale out beyond the capacity of a single database deployment for read-heavy database workloads. As with all Amazon Web Services, there are no up-front investments required, and we pay only for the resources we use.

Hosting a relational database (RDBMS) on an Amazon EC2 instance

In addition to the managed Amazon RDS offering, we can install our choice of RDBMS (such as MySQL, Oracle, SQL Server, or DB2) on an EC2 instance and manage it ourself. AWS customers hosting a database on Amazon EC2 have successfully used a variety of master/slave and replication models, including mirroring for read-only copies and log shipping for always-ready passive slaves.

Amazon EBS volumes automatically provide redundancy within the Availability Zone, which increases their availability over simple disks. If the performance of a single Amazon EBS volume is not sufficient for our databases needs, volumes can be striped to increase IOPS performance for our database. For demanding workloads we can also use EBS.

NoSQL solutions

-To support for relational databases, AWS also offers Amazon DynamoDB, a fully managed NoSQL database service that provides fast and predictable performance with seamless scalability. Using the AWS Management Console or the Amazon DynamoDB API, we can scale capacity up or down without downtime or performance degradation.

There are numerous options within the AWS cloud for storing, accessing, and backing up our web application data and assets. The Amazon Simple Storage Service (Amazon S3) provides a highly available and redundant object store. Amazon S3 is a great storage solution for somewhat static or slow-changing objects, such as images, videos, and other static media. Amazon S3 also supports edge caching and streaming of these assets by interacting with the Amazon CloudFront service. For attached file system like storage, EC2 instances can have Amazon Elastic Block Storage volumes attached, which can act like mountable disks for running EC2 instances. Amazon EBS is great for data that needs to be accessed as block storage and that requires persistence beyond the life of the running instance, such as database partitions and application logs.