Amazon Web service (AWS) 2000
release based on IaaS Delivery model:
In this model cloud service
provider offer an infrastructure consisting of compute and storage servers interconnected by high speed network and supports, a set of services to access
theses resources. An application developer is responsible to install
application on a platform of his hoice and to manage the sources provided by
Amazon
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Cloud Watch
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AWS
Management Console
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S3
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EBS
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Simple DB
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EC2 instances on various OS
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SQS(Simple
queue Service)
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EC 2
instance
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Virtual
Private Cloud
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Auto
Scaling
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The diagram shows the Services offered by
AWS are accessible from the AWS Management Console.
Applications
running under a variety of operating system can be launched using EC2. Multiple
EC2 instances can communicate using SQS. Several storage services are
available, S3, SimpleDB, and EBS. The Cloud Watch supports performance
monitoring and the Auto Scaling supports elastic resource management. The
Virtual Private Cloud allows direct migration of parallel applications
Elastics compute cloud (EC2)
is a web service with the simple interface for launching instances of an
application under several operating systems. An instance is created from a
predefined Amazon Machine Image (AMI) digitally signed and stored in S3 or from
a user defined image. The image includes the operating system, the run time
environment, the libraries and the application desired by the user. AMI create
an exact copy of original image but without configuration dependent information
such as host name of MAC address. User can 1) launch an instance from an
existing AMI image and terminate an instance 2) start and stop an instance 3)
create a new image 4) add tags to identify an image 5) reboot an instance. EC2
is based on Xen Virtualization strategy. In each EC2 virtual machine or instance
functions as a virtual private server. An instance specifies the maximum amount
of resources available to an application, the interface for that instance, as
well as, cost per hour. A user can interact with EC2 using a set of SOAP
message and list of available AMI images, boot an instance from an image,
terminate an image, display the running instances of a user, display console
output and so on. The user has root access to each instance in the elastic and
secure computing environment of EC2. The instance can be placed in multiple
locations.
EC2 allows the import of virtual
machine images from the user environment to an instance through a facility
called VM import. It also automatically distributes the incoming application
traffic among multiple instances using elastic load balancing facility. EC2 associates an elastic IP address with an
account; this mechanism allow a user to mask the failure of an instance and
remap a public IP address to any instance of the account without the need to
interact with the software support.
Simple Storage System (S3)
is a storage service design to store large object. It supports minimal set of
function: write, read, delete. S3 allows application to handle an unlimited
number of object ranging in size from 1 byte to five terabyte. An object is
stored in a bucket and retrieved via unique developer assigned key. A bucket
can be stored in a region selected by the user. S3 maintains for each object;
the name, modification time, an access control list and up to 4 kilobyte of user
defined metadata. The object names are global.
Authentication mechanism ensures that data is kept secure and object can
be made public and write can be granted to other user.
S3 support PUT, GET and DELET
primitives to manipulate object but doesn’t’ support primitives to copy, to
rename, or to move an object from one bucket to another. Appending an object
requires a read followed by a write of the entire object. S3 computes (MD5) of every object written and
returned in a field called a ETag. A user is expected to compute the MD5 of an
object stored or written and compare this with the ETag; if the values do not
match, then the object was corrupted during transmission or storage.
The Amazon S3 SLA guarantees
reliability. S3 uses standards based REST and SOAP interfaces, the default
download protocol is HTTP, but Bittorrent protocol interface is also provide
to lower cost high scale distribution.
Elastic Block Store (EBS)
provides persistent block level storage volume for use with Amazon EC2
instances. A volume appears to an application as a raw, unformatted and
reliable physical disk. The size of the storage volume ranges from 1 Gigabyte to
1 Terabyte. The volumes are grouped
together in availability zones and are automatically replicated in each zone.
An EC2 instance may mount multiple volumes but a volume cannot be shared among
multiple instances. The EBS supports the creation of snapshots of the volume
attached to an instance and then uses them to restart an instance. The storage
strategy provided by EBS is evitable for databases application, file system,
and application using raw data devices.
Simple DB is non
relational data store that allows developer to store and query data item via
web services requests. It supports store and query function traditionally
provided only by relational databases. Simple DB create multiple geographically
distributed copies of each data item and support high performance web
application, at the same time it manages automatically the infrastructure
provisioning hardware and software maintenance and indexing of data item and
performance tuning.
Simple Queue Service (SQS) is
a hosted message query. SQS is a system for supporting automated workflows. It
allows multiple Amazon EC2 instances to coordinate their activities by
sending and receiving SQS message. Any computer connected to the internet can
add or read message without using any installed software or special firewall
configuration.
Application using SQS can run
independently and synchronously and do not need to be developed with same
technologies. A received message is ‘locked’ during processing. If processing
fails the lock expires and the message is available again. The time out for
locking can be changed dynamically via Change Message Visibility operation. Developer
can access SQS through standard based SOAP and query interfaces. Queries can be
shared with other AWS accounts. Query sharing can also be restricted by IP
address and time of day.
Cloud Watch is monitoring
infrastructure used by application developers, users and system administrator
to collect and track metrics important for optimizing the performance of
application and for increasing the efficiency of resource utilization. Without
installing software a user can monitor approximately a dozen pre selected
metrics and then view graphs and statistics for these metrics. Basic monitoring
is free, detailed monitoring is subjected to charges
Virtual private cloud (VPC)
provides a bridge between the existing IT infrastructure of an organization and
the AWS cloud; the existing infrastructure is connected via a virtual private
network (VPN) to a set of isolated AWS compute resources. VPC allows existing
management capabilities such as security services, firewall and intrusion
detection system to operate seamlessly within the cloud.
Auto scaling exploits
cloud elasticity and provides automatic scaling EC2 instances. The service
support grouping of instance, monitoring of instances in a group, and defining
triggers, pair of cloud watch alarms and policies, which allows the size of the
group to be scaled up or down.1
An auto scaling group consist of
a set of instances described in a statics faction by launch configuration. When
a group scales up new instance are started by using parameters of run instance
EC2 call provide by launch configuration. When the group scales down the
instance with older launch configuration are terminate first. The monitoring
function of auto scaling services carries out health checks to ensure the
specified policies. For example a user may specify a health check for elastic
load balancing and auto scaling will terminate an instance exhibiting a low
performance and start a new one. Trigger
uses cloud watch alarms to detect event and then initiate specific action; for
example a trigger cloud detect when the CPU utilization of the instances in the
group goes above 90% and then scales up the group by starting new instances.
AWS services:
1. Elastic
Map Reduce (EMR): a service supporting processing a large amount of data.
2. Simple
work flow (SWF) service: for work flow management, allows scheduling,
management of dependencies and co-ordination of multiple EC2 instances.
3. Elastic
Cache: A service enabling web application to retrieve data from a managed in
memory caching system rather than much slower disk based database
4. Dynamo
DB: a scalable and low latency fully managed no SQL database service.
5. Cloud
Front: a web service for content delivery.
6. Elastic
Load Balancer: Automatically distributes the incoming requests across multiple
instances of the application.
7. Elastic
Bean Stalk: uses/ interacts with the services of other AWS services and handle
automatically the deployment, capacity provisioning, load balancing, auto
scaling, and application monitoring function.
8. Cloud
formation: allows creation of stack describing the infrastructure of an
application
The AWS SLA allows the cloud
service provider to terminate service to any customer at any time for any
reason and contains a covenant not to sue Amazon or its affiliates for any
damage that might arise out of use of
AWS.
Users have several choices to
interact and manage AWS resources:
1. The
AWS management console available at http://aws.amazon.om/console/;
2. Command
link tools (aws.amazon.com/developer tools)
3. AWS
SDK libraries and tool kits for java , php, c++,object c
4. Raw
REST request
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Cloud
Interconnect
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NAT
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Internet
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S3
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EBS
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Simple DB
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AWS
Storage Services
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SQS
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Cloud Watch
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Elastic Cache
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Cloud Formation
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Elastic Bean Stalk
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Elastic Load Balance
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Cloud
Front
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AWS
Management Console
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Server Running AWS Service
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EC 2
Instances
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EC 2
Instances
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Compute
Servers
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The above diagram shows AWS
shows the configuration of an availability zone supporting AWS services.
Amazon offers
cloud services through a network of data centres on several continents. In each
region there are several availability zone interconnected by high speed
network. Region do not share resources and communicate through the internet.
An availability zone is data center consisting
of a large number of servers. A server may run multiple instances, started by
one or more user; an instance may run multiple virtual machine or instances,
started by one or more users. An instance may use storage service as well as
other services provided by AWS. Storage is automatically replicated within a
region. S3 buckets are replicated within an availability zone and between the
availability zones of a region, while EBS volumes are replicated only within
the same availability zone. An instance is a virtual server. The user chooses
the region and the availability zone where this virtual server should be placed
and also selects from a limited menu of instance type the one which provide the
resources, CPU cycles, main memory, secondary storage, communication and IP
bandwidth needed by the application. When launched, an instance is provide with
a DNS name, this name maps to a private IP address for internal communication
within the internal EC2 communication network and a public IP address for
communication outside the internal network of Amazon. Example for communication
with the user that launches the instance. NAT map external IP address to
internal ones. The public IP address assigned for lifetime of an instance and
it is returned to pool of available public IP address when the instance is
stopped or terminated. An instance can also request for a elastic IP address
which is static public IP address and need not be released when the instance is
stopped or terminated and must be released when no longer needed. EC2 instance
system offers several instances types: Standard instance, High memory instance,
High CPU instance, Cluster computing.
