Request for comments: Impress application server

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Timur Shemsedinov

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Jun 30, 2013, 12:00:44 PM6/30/13
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Hello,
I am looking for your comments and opinions about Impress, it is multipurpose application server and web framework with multiple hosts and ports, routing, db access, clustering, proxying, compressing, memory caching, templating and much more. The main difference from others that Impress core is monolithic and its approach is to make all in one solution with high code coupling for obligatory things and leave not obligatory to be integrated by applied developers optionally. High coupling in core gives us advantages in performance and code simplicity. For example, why we should implement static files serving or memory caching as a plugin while no one application will omit that? There is a list of Impress core functionality:
  • url routing based on file system
  • can hosts multiple sites or applications on one server
    • serving multiple ports, network interfaces, hosts and protocols
    • soft configuration changes with zero downtime 
  • simple server-side templating
  • caching server-side executable JavaScript and templates in memory
  • folder monitoring for server-side executable JavaScript changes and template changes
  • built-in authentication and user groups
    • sessions and cookies (memory state or persistent sessions with MongoDB)
    • template personalization for user groups
    • access modifiers for each folder in access.js files 
  • simple way for json-based web services development
  • serving static files with gzipping, memory caching and filesystem watching
  • implemented SSE (Server-Sent Events) with channels and milticast
  • multiple cluster instantiation strategies:
    • single instance (one process, no master and workers)
    • instance specialization (multiple processes, one master and different workers for each server)
    • multiple instances (multiple processes, one master and identical workers with no sticky)
    • ip sticky (multiple processes, one master and workers with serving sticky by IP) 
  • reverse-proxy (routing request to external HTTP server with url-rewriting)
  • flexible configuration in json file
  • simple logging web requests
  • connection drivers for MongoDB and MySQL
  • nodemailer as a plugin for email sending

After installing by "npm install impress" you can take example application for testing it:

  1. Copy project template from examples into your project folder (it contains 3 files and folder "sites" where virtual hosts are)
  2. Edit config.js file in project folder (or leave it untouched if you want just to test Impress)
  3. If you want to store persistent sessions in MongoDB you need this DBMS installed and you need to run "node setup.js" before starting Impress
  4. Run Impress using command "node server.js"

Handler examples and file system url mapping:

1. Template example
Location: http://localhost
Base template: /sites/localhost/html.template
2. Override included "left.template"
Location: http://localhost/override
Overriden template: /sites/localhost/override/left.template
Base template: /sites/localhost/html.template
Handler: /sites/localhost/request.js
3. JSON api method example
Location: http://localhost/api/examples/methodName.json
Handler: /sites/localhost/api/examples/methodName.json/get.js
4. Start anonymous session
Location: http://localhost/api/auth/anonymousSession.json
Handler: /sites/localhost/api/auth/anonymousSession.json/get.js
5. POST request handler
Location: POST http://localhost/api/auth/regvalidation.json
Handler: /sites/localhost/api/auth/regvalidation.json/post.js
6. MongoDB access example
Location: http://localhost/api/examples/getUsers.json
Handler: /sites/localhost/api/examples/getUsers.json/get.js

Filesystem routing is project a forming feature of Impress, here is

Following "server.js" is stating file. Run it using command line "node server" for debud or "nohup node server" for production.

require('impress');
impress.init(function() {
    // Place here other initialization code
    // to be executed after Impress initialization
});

File "access.js" is something line ".htaccess", you can easily define access restrictions for each folder, placing "access.js" in it.
If folder not contains "access.js" it will inherit from parent folder and so on. Example:

module.exports = {
    guests: true, // allow requests from not logged users
    logged: true, // allow requests from logged users
    http:   true, // allow requests using http protocol
    https:  true, // allow requests using https protocol (SSL)
    groups: []    // allow access for user groups listed in array
                  // or for all if array is empty or no groups field specified
}

File "request.js": place such file in folder to be executed on each request (GET, POST, PUT, etc.).
If folder not contains "request.js" it will inherit from parent folder and so on. Example:

module.exports = function(req, res, callback) {
    res.context.data = {
        title: "Page Title",
        users: [
            { name: "vasia", age: 22, emails: ["us...@gmail.com", "us...@gmail.com"] },
            { name: "dima", age: 32, emails: ["us...@gmail.com", "us...@gmail.com", "us...@gmail.com"] },
        ],
        session: JSON.stringify(impress.sessions[req.impress.session])
    };
    callback();
}

File "get.js": place such file in folder to be executed on GET request. For POST request "post.js", and so on.
If folder not contains "get.js" it will inherit from parent folder and so on. Example:

module.exports = function(req, res, callback) {
    db.polltool.query('select * from City', function(err, rows, fields) {
        if (err) throw err;
        res.context.data = { rows:rows, fields:fields };
        callback();
    });
}

File "html.template": place such file in folder as a main page template. Example:

<!DOCTYPE html>
<html>
<head>
    <title>@title@</title>
</head>
<body>
    <div> Field value: @field@ </div>
    <div> Include template: @[name]@ - this will include file "./name.template" </div>
    <div> This will iterate "res.context.data" from "request.js" example above:
        @[users]@
            <div>
                User name: @.name@<br/>
                User age: @.age@<br/>
                Email addresses:
                <ul>
                    @[emails]@
                        <li>@.value@</li>
                    @[/emails]@
                </ul>
            </div>
        @[/users]@
    </div>
</body>
</html>

Here are links:

Thank for your time and feedback,

Best regards,
~Timur Shemsedinov

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