Some challenges in cloud computing for developers

- programming language,
- one of the main challenges to developing for the cloud is understanding how application service dependencies are handled. Application service dependencies include databases, message servers or other services deployed in a distributed environment. Traditionally this has been handled by mapping service references to the physical IPs during the deployment process, but the cloud introduces a new variable, and even the IP addresses are not known beforehand.
- Another issue with developing for the cloud is addressing horizontal scalability

Tools/skills for PaaS cloud model

Each cloud vendor technology provides the basic enterprise application building blocks you will need in order to build new skills or to deepen your current skills. They include message queues, databases, Web services and specific APIs to access specific cloud services. This collection of services is known as Platform as a Service or PaaS

The fastest way to skyrocket your skills to the cloud is to get some hands on experience with real tools. Google’s App Engine (GAE) is a super fast way to get started. Of course, this assumes you are a Java or Python developer. Microsoft .NET code jocks can start by looking at Microsoft Azure.

Some tools you use for development will have to change, especially if going to a PaaS cloud model. Vendor solutions have their own tools to streamline development on their platform. However, PaaS providers such as Google offer a plugin for the Eclipse development IDE. This plugin drastically simplifies development for the GAE. If you use Eclipse, no further tool skills are required.

5 ways to move your application to CLOUD

1. to rehost application on IaaS (infra as a service) it means redeploy the application on new infra/hardware
2. to refactor (run applications on a cloud provider's infrastructure) on PaaS(Platform as a service) using its language containers etc.
3. to  revise it on IaaS and PaaS ..it means to modify the existing code base then use refactor or rehost option as stated above
4. to rebuild on PaaS
5. to replace with software as  a service (SaaS)

Cloud computing and SOA difference

It is internet computing where shared servers provide software, resources, or data to computers and clients on demand like electricity. It is different than SOA (service oriented architecture) which are basically design/principles/approach to setup that type of IT computing environment. Some of the providers of cloud are - amazon, google, microsoft etc. Any CLOUD provides services in each of its following layers -


application layer - this is SaaS (software as a service) which delivers software without need of installation
platform layer - this is PaaS (platform as a service) which provides computing platform for deployment of application without buying any hardware or software
Infra layer - this is IaaS (infra as  service) which provides computer infra without buying any servers, data center, network equipments etc.


Some of the SOA concepts are - web services, SOAP, REST, CORBA, DCOM, RPC etc.

Pros - Cloud computing
- CAPEX reduced significantly
- Provides API to remote access 
- Location independence
- abstraction for consumer
- Reliability
- Scalability
- Security
- Maintainability easy
- Bill for usage

Cons - Cloud computing
- Privacy of data
- Compliance to standards like HIPAA, FISMA etc.
- Open standards
- More OPEX
- Availability for long