Web Applications Software Engineering 2017 Alessio Gambi - Saarland - PowerPoint PPT Presentation

Qualities • “Basic” implementation - Limited scalability - Single point of failure - Limited Security

Performance Tactics • Control Resource Demand Increase the resource efficiency (caching) - Reduce overhead (pre-generate HTML from PHP) - • Manage Resources Schedule resources (load balancer) - https://www.digitalocean.com/community/tutorials/5-common-server-setups-for-your-web-application

Load Balancing deploy many replicated instances of the server on multiple machines

Caching + Load Balancing FrontEnd (Apache)

Caching + Load Balancing Squid Apache (Caching)

Caching + Load Balancing Squid Apache (Caching)

Caching + Load Balancing LoadBalancer Squid LoadBalancer Apache (Squid)

Caching + Load Balancing LoadBalancer Squid LoadBalancer Apache (Squid) Squid Apache Squid LoadBalancer Apache LoadBalancer Squid Apache

UI Page Static Submit Logic ArticleView Resources Skinning Localization ArticleEdit Parser Writes Reads Backend

UI Page Cache Cache Loader Submit Logic ArticleView Skinning Localization Static Cache Resources Cache ArticleEdit Parser Writes Reads Backend

Performance Tactics • Control Resource Demand Prioritize events (deferred article updates) - • Manage Resources Introduce concurrency (distributed database) - Schedule resources (load balancer) - Multiple copies of data and computations - https://www.digitalocean.com/community/tutorials/5-common-server-setups-for-your-web-application

Master/Slave split a large job into smaller independent partitions which can be processed in parallel

Distribution + Replication Database More reads than writes Near-live updates (no strict consistency requirements)

Distribution + Replication Load Balancer Writes Reads DB Master DB Slave More reads than writes Near-live updates (no strict consistency requirements)

Distribution + Replication Data Sharding Clear data separation (Article Name: A-B, C-D, etc..)

Distribution + Replication Load Balancer Writes Reads DB Master DB Slave

Distribution + Replication Partition Logic Load Balancer (Sharding, (Master) Relication Reads Writes DB Master DB Slave (Shard)

Visualization

UI Page Cache Cache Loader Submit Logic ArticleView Skinning Localization Static Cache Resources Cache ArticleEdit Parser Writes Reads Backend

UI Page Cached Cached Loader Submit Logic HTML File Skinning Localization Cache Static Resources ArticleView Cached Parser ArticleEdit Cache Job Queue Parser Writes Job Runner Reads Backend Writes Precompile/Recompile Regenerate/Invalidate

Security/Availability Tactics • Prevent Attacks • Challenge Tokens (CSRF) • Validation (User) and Sanitization (SQL Injection, XSS) • Resist Attacks • Maintain multiple copies of computations • Maintain multiple copies of data • Recover from Attacks • DB Versioning (Recovery from data loss)

UI Page Cache Cache Loader Submit Logic ArticleView Skinning Localization Static Cache Resources Cache ArticleEdit Parser Writes Reads Backend

UI Page Cache Cache Submit Logic Loader ArticleView Skinning Localization Static Resources Sanitizer Cache Pipeline Cache Parser ArticleEdit Reads Writes User Access Backend

UI Page Cache Cache Submit Logic Loader ArticleView Skinning Localization Static Resources Cache Cache Sanitizer Parser ArticleEdit Reads Writes Backend

Additional Qualities

Extensibility UI Page Cache Cache Submit Logic Loader ArticleView Skinning Localization Static Resources Cache Cache Sanitizer Parser ArticleEdit Reads Writes Backend

Extensibility UI Page Cache Cache Submit Logic Loader ArticleView Localization Skinning Static Resources Notify Cache Cache Sanitizer Notify Notify ArticleEdit Parser Notify Notify Reads Writes Register Callback External Hook Engine Backend Module