Google App Engine (GAE) is a Platform as a Service (PaaS) offering by Google. It enables developers to build, deploy, and scale web applications without managing the underlying infrastructure.
Google has the world’s largest search engine and operates hundreds of data centers globally with more than 460,000 servers. These are used for massive-scale cloud applications with high availability (HA). GAE is built upon this powerful infrastructure and supports various cloud and web applications.
Google Cloud Infrastructure
Google pioneered cloud development by leveraging its massive data centers, which power services like:
- Gmail
- Google Docs
- Google Earth
It achieved breakthroughs with technologies such as:
- Google File System (GFS) – for storing large-scale data
- MapReduce – for processing large data sets
- BigTable – for structured data storage
- Chubby – for distributed locking services
GAE was launched in 2008 to support scalable (elastic) web apps. It allows third-party developers to run their apps directly on Google’s cloud infrastructure across many data centers.
GAE Architecture
GAE architecture consists of the following core components:
- GFS – For large-scale data storage.
- MapReduce – For large-scale data processing.
- BigTable – A distributed structured storage system.
- Chubby – A distributed locking service.
- These technologies power cloud services internally. Applications run on Google-managed data centers with thousands of servers organized into clusters.
- Users interact through web interfaces, and third-party developers build apps using GAE which runs in the same environment as Google’s own applications.
- GAE abstracts server management, enabling developers to focus only on coding, not infrastructure.
- GAE provides a frontend application framework similar to ASP, J2EE, JSP, and supports Python and Java programming environments.
Functional Modules of GAE
GAE consists of the following five functional modules:
- Datastore:
- Object-oriented, distributed, and structured data storage.
- Built using BigTable technology.
- Provides secure data management and query support.
- Application Runtime Environment:
- Scalable execution environment for web apps.
- Supports Python and Java for application development.
- Software Development Kit (SDK):
- Used for local development and testing.
- Allows developers to run and test applications locally before uploading to GAE.
- Administration Console:
- Provides tools to manage application lifecycle and deployment.
- Does not deal with physical resource management.
- GAE Web Service Infrastructure:
- Special APIs for storage and network resource management.
- Offers features like user authentication (via Gmail accounts) and email services.
GAE is free for Gmail users within a quota. If usage exceeds limits, users are instructed on how to pay for the services.
GAE: Language and Platform Support
- GAE supports applications written in Python, Java, and Ruby.
- It is a PaaS platform only, unlike Amazon which provides both IaaS + PaaS.
- Developers use supported tools/languages but do not control or manage the underlying infrastructure.
- This is similar to Microsoft Azure, which supports .NET applications.
GAE Applications
Google App Engine supports several well-known applications:
Examples:
- Google Search
- Gmail
- Google Docs
- Google Earth
All of these apps run on Google’s internal cloud infrastructure managed within large-scale data centers.
GAE supports third-party developers to:
- Build and run web apps on the Google infrastructure.
- Store application-specific data.
- Use backend persistent storage with support for queries, sorting, and transactions similar to traditional DBMS.
Bonus GAE Feature:
- Web apps can use Gmail accounts for authentication and email services.
- This eliminates the need for custom user management modules.