i'm trying to follow this tutorial to start with 4d server web.
http://doc.4d.com/4Dv16/4D/16/Serveur-Web.200-3246839.fe.html
i've disabled the default homepage index.html (and even deleted the actual file in the WebFolder folder) and then added these few lines on the On Web Connection method
C_TEXT($1)
Case of
:($1="/")
WEB SEND FILE("new_index.html")
End case
but still i get the 4d default page when i go to localhost:8080/
i then found out the method isn't even called unless i add something to the url (like localhost:8080/something)
If you have index.html listed in the database settings as the default home page then it will load that page (and sometimes it will create it if it does not exist).
Furthermore, using an html extension will not run any dynamic code, to invoke code you must either use an shtml extension or the file must not exist (OWA/OWC is triggered when the file is not found).
This tech tip still applies and gives a good rundown of in what situations the On Web Connection (and On Web Authentication) methods run:
Tech Tip: How to skip over HTTP and redirect to HTTPS: Part 2 (The Web decoy folder)
Quote:
The On Web Authentication database method is (by default) only called in the following situations:
when 4D receives a URL beginning with 4DACTION/
when 4D receives a URL beginning with 4DMETHOD/
when 4D receives a URL beginning with 4DCGI/
when 4D receives a URL requesting a static page that does not exist
when 4D processes a 4DSCRIPT tag in a semi-dynamic page
when 4D processes a 4DLOOP tag based on a method in a semi-dynamic page.
Note: The On Web Authentication database method expects a Boolean value to be returned in $0; True = request accepted, False = request rejected. The default value if $0 is not returned is True which means all requests are accepted.
The On Web Connection database method is (by default) called in the following cases:
When connecting a browser to a 4D Web server operating in contextual mode. The database method is called with the /... URL.
When 4D receives the /4DMETHOD URL. The Web server switches to contextual mode and the database method is called with the /4DMETHOD/MethodName URL in $1.
When 4D receives the /4DCGI URL. The database method is called with the /4DCGI/ URL in $1.
When a Web page is called with a URL of type / that is not found. The database method is called with the URL as $1.
When a Web page is called with a URL of type / and no home page has been defined by default. The database method is called with the URL as $1.
So (by default) if the web visitor is requesting a page, and that page exists in the webfolder at the location specified in the URL, that page will be automatically sent back to the customer without any special processing. This is fine in most situations but the developer can gain much greater control over the requests by implementing a web decoy folder.
So, If you want the / url to run your code you could use either of these approaches:
use an index.shtml (notice the s in shtml)
delete the entry in the database settings (so the default page field in the is empty)
When modifying the Web Configuration options in 4D, the User Settings will take precedence over the Database Settings.
if User Settings are enabled, make sure to check both User Settings and Database Settings.
The user settings are accessible under the following menu options:
or
Related
I served a react page under 127.0.0.1/react/ sub directary with my gateway. It can be viewed by explorer with 127.0.0.1/react/. But if I input 127.0.0.1/react it returns my vue page served under 127.0.0.1 which failed to match any routes.
There is another example https://www.curseforge.com/minecraft/mc-mods.
https://www.curseforge.com/minecraft/mc-mods is okay while https://www.curseforge.com/minecraft/mc-mods/ returns 404 not found. What's the difference?
Ordinary users might treat them as same url, they would expect both of them can access the page. So how should I make them both accessable?
The server can return whatever it wants for any path, and doesn't need to follow any particular standard conventions. However, most servers do follow some norms:
/react/ usually ends up fetching the index file (usually index.html unless configured otherwise) from the react folder under the web root. This is returned to the client transparent... the client isn't redirected.
/react This is a request for a file named react under the main root. However, in the absence of such file, and the presence of a folder, it's common to redirect the client to /react/.
How you do this depends entirely on your server configuration. You didn't tell us the server, so we can't point you in the right direction.
We have a web application which is used to manage a list of main records in a database via a Spring Boot Web server talking to a back-end Java Server.
We also have a JavaFX standalone application which is used to graphically manipulate sub-records of these main web records, using a similar connection to the back-end Java Server.
We want to be able to launch this JavaFX application by clicking on a link next to each of the main records in the web interface. We would like to do this as seemlessly as possible.
At the moment the only way I can think that we can do this, is to use the Browser's 'Applications' set up to associate a particular MIME file type with the standalone JavaFX application, and somehow pass the UID of the record we click on as the 'file' being 'downloaded'.
Trouble is I'm not really sure what I should be googling for, to find out about this download process. For instance, does the browser pass the 'file' in a MIME message that is passed to the application, or does it save the 'file' in a temporary directory and then call the application with the temporary file path?
Has anyone done this sort of thing before, that could give us some pointers?
I don't have a turnkey solution but I think what you are looking for is a custom URI scheme (like the Magnet URI scheme magnet:, mailto:, or tel:).
Here is an article about launching applications using custom browser protocols and here is how to register an application to a URI Scheme on Windows.
You will have to modify the Windows Registry to link your custom protocol to an application, it looks like:
HKEY_CLASSES_ROOT
alert
(Default) = "URL:Alert Protocol"
URL Protocol = ""
DefaultIcon
(Default) = "alert.exe,1"
shell
open
command
(Default) = "C:\Program Files\Alert\alert.exe" "%1"
I'm currently creating pdf documents server side with wkhtmlpdf and nodejs. The client side sends the html to be rendered (which may include img tags with a source). When the user is previewing the html in the browser the images they uploaded to their account show fine because the user is authenticated via the browser and the node route can simply look up the image based on the user id (saved to session) and image id (passed in each image request).
The issue is when the images are attempting to be rendered in wkhtmltopdf webkit the renderer is not authenticated when it makes the request for images via node's exec of wkhtmltopdf in a separate process. A request to something like GET /user/images/<imageId> will fail due to the session not being set when the request is made inside the headless wkhtmltopdf renderer.
Is there a way to pass authentication via some wkhtmltopdf option or possibly a different way of authentication for images? The only restriction is not making images public.
I asked a similar question a while back that might help you:
Generate PDF Behind Authentication Wall
WKHTMLTOPDF has --cookie-jar which should get you what you need. Note that it didn't for me, and I wound up answering my own question with an alternate solution. In a nutshell, I wound up accessing the page via CURL - much more flexible - then writing a temporary that I converted to PDF, then deleted the temporary file.
A little round-a-bout, but it got the job done.
To implement authentication I allowed a cookie id flag ( with connect the key defaults to connect.sid ) as a query option in my image routes. The only "gotcha" is since images are requested from the server's perspective, you must ensure all your image paths are absolute domain paths rather than relative to your application ( unless those two are the same of course).
Steps for Expressjs:
Setup the id flag middleware which checks for say sid in the query via req.query (eg ?id=abc123 where abc123 is the req.cookies['connect.sid'], or req.signedCookies['connect.sid'] if your using a secret as you probably should )You may need to ensure the query middleware is setup first.
Ensure the req.headers contains this session id key and value prior to the cookie parser so the session is properly setup (eg if a cookie exists append a new one or if one does add it as the first req.headers.cookie = 'connect.sid=abc123;')
Ensure all image paths contain the full url (eg https://www.yourdomain.com/images/imageId?id=abc123)
Some extra tid bits: The image source replacement should probably happen at the server level to ensure the user does not copy/paste the image url with the session id and say email it to a friend which obviously leaves the door open for account hijacking.
I'm workin' on a web project where performance is a very important issue.
EDIT:
The situation:
I wanna add some details about the user's workflow:
The user visits the welcome page of my website http://example.org/ .
He clicks a link in order to visit the page http://example.org/mypage
onclick-Handler of the link's executed.
The handler loads data usin' XHR.
The handler creates http://example.org/mypage dynamically.
The handler saves mypage locally usin' FileSystem API at filesystem:http://example.org/mypage. EDIT: ( filesystem:http://example.org/mypage is a local ressource stored in the FileSystem at the client side)
The handler extends the history and changes the URL of the location bar usin' History API from http://example.org/ (URL of the welcome page) to http://example.org/mypage (the page which the user wants to see) .
The user vists another page in the meantime.
Later on, the user types http://example.org/mypage directly into the location bar.
The browser shows/loads filesystem:http://example.org/mypage (which is the locally stored version of http://example.org/mypage) instead of http://example.org/mypage. That means: The browser doesn't create a new request, it uses the local stored copy of http://example.org/mypage .
How can I get the browser to use the locally stored version of the page instead of creating a new request? EDIT: - That's what I want to do in #10 of the list above.
EDIT:
My Question:
A client-side has already created/generated http://example.org/mypage in #2 to #7 of the list above. I don't need to create that page some other time. That's why I don't want the browser to create a request for http://example.org/mypage.
That's what I wanna do:
If filesystem:http://example.org/mypage has already been created (respectively if the user has already visited http://example.org/mypage):
Use filesystem:http://example.org/mypage instead of http://example.org/mypage.
Otherwise:
Send a request for http://example.org/mypage
Tries to solve:
I can't use the Fallback section of the manifest file to do something like: EDIT: (aside from the orgin)
FALLBACK:
http://example.org/mypage filesystem:http://example.org/mypage
In order to get the browser to use the local version stored in the FileSystem because Fallback directives are just used if the user is offline, otherwise they are ignored. EDIT: But I want to use filesystem:http://example.org/mypage instead of http://example.org/mypage, even if the user's online.
I know that I can use the Expire field in the response header of a server-generated page in order to not create a new request and to use the cached version.
But what if I create an page dynamically on the client side using JS and XHRs. EDIT: (I described that case in The situation) When create a page at the client side there's no way to get the client to cache that page. That's why I "cache" the page manually usin' FileSystem API to store it on the client side.
In order to improve the performance I'm trying to store any page which the user has already visited locally. When the user visits a page again then I show him the old, locally stored version of the page and my script creates an XHR to find out if the page changed in the meantime.
But how can I get the browser to use the local version of the page?
I can save the generated page locally on the client side using the FileSystem API and I can choose an URL for the generated page to display it at the browser's location bar using the History API.
When the user now visits another site and then presses the back button I can catch the onPopState event by an event handler.
And that event handler can load the dynamically created file using the FileSystem API.
But what should I do if the user doesn't use the back button and if he types the URL, which I have registered using the History API, directly into the location bar?
Then the browser wouldn't use the locally stored version of the page, the browser would create a request to load the page from the server.
Don't put dynamic data in the application cache. If you want to put dynamic data in your pages then get it from the server with AJAX, store the data in Local Storage, and populate the page with the data from storage through JavaScript (you can hook into the History API for this).
By the way, this won't work because fallback entries have to be on the same domain:
FALLBACK:
http://example.org/mypage filesystem:http://example.org/mypage
Once your page is in the Application Cache (ie. it is locally stored) the browser will always use the version from the Application Cache until the manifest is updated or the user deletes the cache. It doesn't really matter what expiry headers you put on the page, except if you put a long expiry and you frequently update the manifest then it's likely the Application Cache will be populated from the browser cache rather than refreshed from the server. This is why the stuff you put in the Application Cache should be static files. Get your dynamic stuff with AJAX.
You might use URLs that encode the actual link within your hierarchy, e.g. "mypage", in the anchor part of the URL, i.e. http://example.com/#mypage. Then you can use window.location.hash to obtain the string after the # and do whatever magic you want. Just make sure your root (or whatever you want in front of the #) is in AppCache.
I'm thinking about this question for a long time. It is a big question, since it almost covers all corners related to web developing.
In my understanding, the process should be like:
enter the url to the address bar
a request will be sent to the DNS server based on your network configuration
DNS will route you to the real IP of the domain name
a request(with complete Http header) will be sent to the server(with 3's IP to identify)'s 80 port(suppose we don't specify another port)
server will search the listening ports and forward the request to the app which is listening to 80 port(let's say nginx here) or to another server(then 3's server will be like a load balancer)
nginx will try to match the url to its configuration and serve as an static page directly, or invoke the corresponding script intepreter(e.g PHP/Python) or other app to get the dynamic content(with DB query, or other logics)
a html will be sent back to browser with a complete Http response header
browser will parse the DOM of html using its parser
external resources(JS/CSS/images/flash/videos..) will be requested in sequence(or not?)
for JS, it will be executed by JS engine
for CSS, it will be rendered by CSS engine and HTML's display will be adjusted based on the CSS(also in sequence or not?)
if there's an iframe in the DOM, then a separate same process will be executed from step 1-12
The above is my understanding, but I don't know whether it's correct or not? How much precise? Did I miss something?
If it's correct(or almost correct), I hope:
Make the step's description more precise in your words, or write your steps if there is a big change
Make a deep explanation for each step which you are most familiar with.
One answer per step. Others can make supplement in each answer's comment.
And I hope this thread can help all web developers to have a better understanding about what we do everyday.
And I will update this question based on the answers.
Thanks.
As you say this is a broad question where it's possible to go into great detail on a number of topics. There's nothing wrong with the sequence you described, but you're leaving out a lot of detail. To mention a few:
The DNS layer can help direct clients to different servers based on geographical location to help with load balancing and latency minimization, and one server can respond to requests from many different DNS names.
A browser can make different types of requests (GET, POST, HEAD, etc), and usually includes several different headers including cookies, browser capabilities, language preferences, etc.
Most browsers usually maintain a cache in order to avoid downloading stuff many times, and use various techniques to determine whether the cached version of a file is valid.
In modern webpages there's often complex interaction between many different kinds of files (HTML, CSS, images, JavaScript, video, Flash, ...), and web developers often need detailed knowledge of differences among browsers in order to keep their pages working for everyone
Each of these topics, and many more, could be discussed at length. Perhaps it's more practical to ask more specific questions about the topics you're interested in?
You type maps.google.com(Uniform Resource Locator) into the address bar of your browser and press enter.
Every URL has a unique IP address associated with it. The mapping is stored in Name Servers and this procedure is called Domain Name System.
The browser checks its cache to find the IP Address for the URL.
If it doesn't find it, it checks its OS to find the IP address (gethostname);
It then Checks the router's cache.
It then checks the ISP's cache. If it is not available there the ISP makes a recursive request to different name servers.
It Checks the com name server (we have many name servers such as 'in', 'mil', 'us' etc) and it will redirect to google.com
google.com name server will find the matching IP address for maps.google.com in its’ DNS records and return it to your DNS recursor which will send it back to your browser.
Browser initiates a TCP connection with the server.It uses a three way handshake
Client machine sends a SYN packet to the server over the internet asking if it is open for new connections.
If the server has open ports that can accept and initiate new connections, it’ll respond with an ACKnowledgment of the SYN packet using a SYN/ACK packet.
The client will receive the SYN/ACK packet from the server and will acknowledge it by sending an ACK packet.
Then a TCP connection is established for data transmission!
The browser will send a GET request asking for maps.google.com web page. If you’re entering credentials or submitting a form this could be a POST request.
The server sends the response.
Once the server supplies the resources (HTML, CSS, JS, images, etc.) to the browser it undergoes the below process:
Parsing - HTML, CSS, JS
Rendering - Construct DOM Tree → Render Tree → Layout of Render Tree → Painting the render tree
The rendering engine starts getting the contents of the requested document from the networking layer. This will usually be done in 8kB chunks.
A DOM tree is built out of the broken response.
New requests are made to the server for each new resource that is found in the HTML source (typically images, style sheets, and JavaScript files).
At this stage the browser marks the document as interactive and starts parsing scripts that are in "deferred" mode: those that should be executed after the document is parsed. The document state is set to "complete" and a "load" event is fired.
Each CSS file is parsed into a StyleSheet object, where each object contains CSS rules with selectors and objects corresponding CSS grammar. The tree built is called CSSCOM.
On top of DOM and CSSOM, a rendering tree is created, which is a set of objects to be rendered. Each of the rendering objects contains its corresponding DOM object (or a text block) plus the calculated styles. In other words, the render tree describes the visual representation of a DOM.
After the construction of the render tree it goes through a "layout" process. This means giving each node the exact coordinates where it should appear on the screen.
The next stage is painting–the render tree will be traversed and each node will be painted using the UI backend layer.
Repaint: When changing element styles which don't affect the element's position on a page (such as background-color, border-color, visibility), the browser just repaints the element again with the new styles applied (that means a "repaint" or "restyle" is happening).
Reflow: When the changes affect document contents or structure, or element position, a reflow (or relayout) happens.
i was also searching for the same thing and found this awesome detailed answer being built collaboratively at github
I can describe one point here -
Determining which file/resource to execute, which language interpreter to load.
Pardon me if I am wrong in using interpreter here. There may be other mistakes in my answer, I will try to correct them later and include proper technical terms for things.
When the web server (e.g. apache) has received the URI it checks if there is any existing rewrite rule matching it. In that case the rewritten URI is taken. In either case, if there is no file name to end the URI, the default file is loaded, which is generally index.html or index.php etc. According to the extension of the file name, the appropriate apache module for server-side programming language support is loaded, e.g. mod_php for PHP, mod_python in case of python. The appropriate server side language interpreter (considering interpreted languages like PHP) then prepares the final HTML or output in some other form for the web server which finally sends it as the HTTP response.
I hope above image help you to understand whole process.
Full article is here