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Server- side Scripting

Server- side Scripting. Martin Kruli š. Web Server (Revision). Serving Static Pages. Apache configuration. HTTP Request GET / myweb /index.html. / var /www/ myweb /. `. Internet. Client. Web Server. HTTP Response HTTP/1.1 200 OK Content-Length : 1019 Content-Type: text/html ; ...

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Server- side Scripting

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  1. Server-sideScripting Martin Kruliš by Martin Kruliš (v1.0)

  2. Web Server (Revision) • Serving Static Pages Apache configuration HTTP Request GET /myweb/index.html ... /var/www/myweb/ ` Internet Client Web Server HTTP Response HTTP/1.1 200 OK Content-Length: 1019 Content-Type: text/html; ... <contents of index.html> index.html by Martin Kruliš (v1.0)

  3. Web Server (Revision) • Serving Dynamic Content HTTP Request GET /myweb/app.cgi ... /var/www/myweb/ ` Internet stdin app.cgi stdout Client Web Server HTTP Response HTTP/1.1 200 OK Content-Length: 2049 Content-Type: text/html; ... <contents generated by cgi> by Martin Kruliš (v1.0)

  4. CGI • Common Gateway Interface • One of the first standards for generating dynamic web content • NSCA specification from 1993 how to invoke command line applications • Current version CGI 1.1 (RFC 3875) from 2004 • Specifies only the interface • Application may be written in any language • Important information and headers are set as environ-ment variables, POST body is directed to std. input • Response is taken from the std. output Example 1 by Martin Kruliš (v1.0)

  5. FastCGI • CGI Issues • Starting a process takes some system time • Each process handles exactly one request • Unable to keep session/shared data in memory • Fast CGI Improvement • Fast CGI server runs independently on web server • Keeps the process pool, resources, … • Communicates with web server via socket/TCP • Multi-request processing may be achieved by multiplexing, or multiple connections (or both) by Martin Kruliš (v1.0)

  6. Web Server (Revision) • Integrating Scripting Modules HTTP Request GET /myweb/index.php ... /var/www/myweb/ ` mod_php Internet index.php Client Web Server HTTP Response HTTP/1.1 200 OK Content-Length: 1984 Content-Type: text/html; ... <contents generated by php> by Martin Kruliš (v1.0)

  7. PHP • PHP: Hypertext Preprocessor • Popular language originally designed for the web • The language has integrate API for handling requests • PHP script code can be directly interleaved with • Things like URL parameters, POSTed data, headers,or server settings are presented in global variables • HTML (or other type of generated content) • The script is embedded between <?php, ?> marks • The PHP interpret process the script and replace its body with its output in the document Example 2 by Martin Kruliš (v1.0)

  8. WSGI • Web Server Gateway Interface • Universal interface between web servers and web applications designed for the Python language • Interface is called WSGI middleware and it is implemented by both sides (server and application) • Specific new features • Routing requests to application objects (by URL) • Multiple applications may run in one process • Content post-processing (e.g., by XSLT) • Load balancing (remote processing, forwarding, …) • Similar APIs • Rack (Ruby), PSGI (Perl), JSGI (JavaScript) Example 3 by Martin Kruliš (v1.0)

  9. Server-side Scripting • Client-server Architectures • Strict separation of two application parts • Client - data presentation, user interface • Server – business logic, data storage • Both sides are connected via specific API (HTTP) • The communication latency and overhead influence the application design • Three-tier architecture • Server part is overloaded, so we separate the data storage and management into separate tier • Thick client • Functionality is slowly shifting to the client-side by Martin Kruliš (v1.0)

  10. Server-side Scripting • Specific Issues • Traditional web applications • Work in batches – client wants to perform a large task with each HTTP request • Download a page full of formatted data • Submit a form and generate a response • Difficult state management (HTTP is stateless) • Code replication and dependency injections • Modern web applications • Just a remote API for AJAX calls • Difficult to integrate AJAX API into existing applications, or create applications that work both ways by Martin Kruliš (v1.0)

  11. Web Design Patterns Application logic, processing requests, orchestrating other components, … • Model-View-Controller Controller Presenting data, rendering web pages, … Providing interface with the data storage, … View Model Invoking actions Dataflow Database by Martin Kruliš (v1.0)

  12. ASP.NET • ASP.NET • Microsoft solution built on .NET platform • Supports all .NET languages (C#, VB, …) • Successor to Microsoft’s Active Server Pages • Requires Microsoft IIS web server • Mono version (mod_mono and FastCGI) exists • WebForms • Basic building blocks for ASP.NET web pages • Similar HTML interleaving syntax as PHP • The idea is to design web pages in the same manner as desktop applications by Martin Kruliš (v1.0)

  13. ASP.NET Example 4 • ASP.NET • WebForms • Event-based model, events may be processed at server • The forms automatically serializes the whole state • Razor syntax • Block starts with @ and doesnot require explicit closing • MVC • Alternative type of ASP.NET applications • Default view engine is either Razor (.cshtml, .vbhtml), or Web Forms (.aspx) • Controllers are .NET classes, methods are actions • Routers select controller class and invoke an action by Martin Kruliš (v1.0)

  14. JSP • Java Server Pages • Java-based solution for dynamic web pages • Requires web server with servlet container • Apache Tomcat, Jetty, … • Supports both “simple” PHP-like approach and MVC • Uses <%, %> marks for scriptlet-HTML interleaving • MVC usually uses JavaBeans as the model and Java servlets as the controller • Java compilation • Compiler is integrated in the web server and compiles the page when first needed (or when changed) by Martin Kruliš (v1.0)

  15. Ruby on Rails • Ruby on Rails • Ruby scripting language + Rails web framework • Basic philosophy • DRY (Don’t Repeat Yourself) – avoid code duplication • Convention Over Configuration – our way is the “best” • Very strict style of application development • Improves efficiency, but ties your hands • Specific structure of the application • Reflects the MVC pattern • $> rails new myapp • Generates new application structure in ./myapp Example 5 by Martin Kruliš (v1.0)

  16. Ruby on Rails • Representational State Transfer (REST) • Architectural abstraction for distributed systems • The application is formed by resources • Resources are identified by URL http://myapp.com/galery/2013 http://myapp.com/galery/2013/photo/42 • Components of the application communicate over the network and exchange resource representations • Representation is typically HTML, XML, or JSON • The API is built over HTTP and hypertext driven • GET http://myapp.com/galery/2013 • DELETE http://myapp.com/galery/2013/photo/42 by Martin Kruliš (v1.0)

  17. Node.js • JavaScript Server-side Platform • Basically a Google V8 JavaScript engine compiled as CLI script interpreter • V8 is used in Chrome and it is the fastest JS interpreter • Contains many pre-built packages for server-side application development (sockets, HTTP, …) • HTTP server is embedded in the application, so the programmer may tune it for specific needs • Aims for fast developed single-language solutions • Using JS on client and server allows some code sharing Example 6 by Martin Kruliš (v1.0)

  18. Statistics by Martin Kruliš (v1.0)

  19. Discussion by Martin Kruliš (v1.0)

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