Suppose you're asked to create a Java applet that needs to communicate back to a web server i. What kind of restrictions? Suppose you're told that sockets, JDBC, and most every other cool communication technology was outlawed. What will you do?
I ran into this problem a short time ago when I decided to create a "to-do list" applet that would help me track various tasks I was working on.
Because I'm constantly moving from site to site, I decided to base this applet on our company's Internet server. Unfortunately, because our company's web server is hosted by a remote Internet Service Provider ISPI wasn't allowed to use sockets or RMI to communicate between the applet and the server.
Further, because we also don't have a database server out there, I had no direct access to a database. Very quickly I realized that I needed a way that my Java applet could read and write flat files on our Internet server. In this article, we'll demonstrate how to read flat text database files from a web server by looking at portions of my "To-Do List" code. We'll also show how to take the data we read and display it in an AWT List component. Then, we'll let the CGI program write the data to the Server filesystem.
Because many Internet users are still using older browsers, I follow this philosophy for most Internet applets I create Intranets are a different story. As a means of demonstrating the process of reading and writing files to an HTTP server, we'll first create a mini-version of the " ToDoList " applet.
The GUI for this applet is shown in Figure 1. The code for the GUI portion of the applet is shown in Listing 1. Don't worry if your X-Y coordinates aren't the same as those shown in Listing 1 - the actual values aren't too important for this example. Given the proper permissions, you can easily read files directly from the filesystem of an HTTP server.
In this section we'll show how to read a file from a web server just by specifying the URL of the desired file. I've created a method named getToDoList to perform the applet's read function. This method is called once when the applet is first started, and again each time the user clicks on the Refresh button.
The code for the getToDoList method is shown in Listing 2. First we create an object named url using the URL class. Note that for more robust applet's that you want to share with others, you'll want to use the getCodeBase method and a relative file path instead of the hard-coded path I'm using.
If you already know how they work and want to analyze them, read my post about log file analysis for SEO. If you know that, too, get a cup of coffee and take care of all those emails in your inbox. If you want to know the basics, you can read about the Common Log Format here.
The IP address of the client—the software that requested the file was— Again: Every request from every user agent is a line in the log file. Every request. Some technical teams cling to log files, citing security concerns.
Some site platforms hide log files so deep in their twisted innards finding them requires an electronic colonoscopy. But the log files are there. The site developer can zip them up and send them to you. Buy beers, bring chocolate, do whatever you need to do to make friends. Then ask. Log files are data lasagna. Screaming Frog Log File Analyser is my number one choice. Splunk is so powerful it terrifies me. Apache Log Viewer is free. It has a steeper learning curve than Screaming Frog, but, you know, free.
That kind of tracking requires cookies and a client-side analytics suite, like Google Analytics.Website statistics are based on server logs. A server log is a simple text file which records activity on the server.
There are several types of server log — website owners are especially interested in access logs which record hits and related information. Each line in the log file represents one request hit. If a visitor requests an HTML page which contains two images, three lines will be added to the log one for the page and two for the images.
The example above is known as a "raw log file" — it lists the information exactly as recorded by the server. Obviously this format is not particularly easy to read, and is all but useless for most people. Although some server admins have a use for raw log files, most webmasters need something much more human-friendly.
This is where log analysers come in. A log analyser is a software application which runs on either the server or a personal computer. It's job is to interpret log files and present the information in easy-to-read lists, graphs, etc. For more information see web statistics software.
Fetching data from the server
Note that raw log files can become incredibly large very quickly. Most servers have a system of automatically deleting old log files periodically. A good log analyser will be able to retain the basic statistical information in it's own database after the raw log files have been deleted.
Home : Internet : Stats : Logs. Server Log Files Website statistics are based on server logs. Access logs come in several different formats but they all tend to look something like this: Pages:  2.
I'm working on a monitoring project that logs some data to the SD card of the official Ethernet Shield as csv file, I want to show the logs contents on a web page that is produced by the arduinobut when I try to open the csv file for reading after the client is connected to the serverI get an error but when I try to open it on startup its working OK. Is it possible to switch ethernet SS pin while the client is connected and then switch it back after reading from SD card without losing the client connection??
If you can't open the file with SD. I'm sure the file exists because the same exact code is working OK on startup : and the file is only about 21 words. Code: [Select]. Quote from: billroy on Jan 08,pm. I used this as a test, and it worked good.
Quote from: SurferTim on Jan 08,pm.
What Arduino are you using? Maybe you are running out of SRAM. I'm using Arduino Uno Rev The art of getting good answers lies in asking good questions. Thanks you all. That should be pretty close to correct. I figured a bit over remaining as an estimate. If you are not out of memory, I don't know what to tell you. It should work.Another very common task in modern websites and applications is retrieving individual data items from the server to update sections of a webpage without having to load an entire new page.
This seemingly small detail has had a huge impact on the performance and behavior of sites, so in this article, we'll explain the concept and look at technologies that make it possible, such as XMLHttpRequest and the Fetch API. Originally page loading on the web was simple — you'd send a request for a website to a server, and as long as nothing went wrong, the assets that made the web page would be downloaded and displayed on your computer.
The trouble with this model is that whenever you want to update any part of the page, for example, to display a new set of products or load a new page, you've got to load the entire page again. This is extremely wasteful and results in a poor user experience, especially as pages get larger and more complex. This led to the creation of technologies that allow web pages to request small chunks of data such as HTMLXMLJSONor plain text and display them only when needed, helping to solve the problem described above.
These technologies allow web pages to directly handle making HTTP requests for specific resources available on a server and formatting the resulting data as needed before it is displayed. This is normally not the case these days you'd be more likely to use XMLHttpRequest or Fetch to request JSONbut the result is still the same, and the term "Ajax" is still often used to describe the technique. The Ajax model involves using a web API as a proxy to more intelligently request data rather than just having the browser reload the entire page.
Let's think about the significance of this:. To speed things up even further, some sites also store assets and data on the user's computer when they are first requested, meaning that on subsequent visits they use the local versions instead of downloading fresh copies when the page is first loaded. The content is only reloaded from the server when it has been updated. For these examples, we'll request data out of a few different text files and use them to populate a content area.
This series of files will act as our fake database; in a real application, we'd be more likely to use a server-side language like PHP, Python, or Node to request our data from a database. Here, however, we want to keep it simple and concentrate on the client-side part of this.ESP32 Arduino HTTP web server: Serve Image from SPIFFS file system
XMLHttpRequest which is frequently abbreviated to XHR is a fairly old technology now — it was invented by Microsoft in the late '90s, and has been standardized across browsers for quite a long time. To begin this example, make a local copy of ajax-start. In this example, we will load a different verse of the poem which you may well recognize via XHR when it's selected in the drop-down menu.
However, web servers tend to be case sensitive, and the file name doesn't have a space in it. To convert "Verse 1" to "verse1. This can be done with replacetoLowerCaseand simple string concatenation. Add the following lines inside your updateDisplay function:. You can call this object anything you like, but we'll call it request to keep things simple. Add the following below your previous lines:. Add this below your previous line:. Next, we'll set the type of response we are expecting — which is defined by the request's responseType property — as text.
This isn't strictly necessary here — XHR returns text by default — but it is a good idea to get into the habit of setting this in case you want to fetch other types of data in the future. Add this next:. Fetching a resource from the network is an asynchronous operation, meaning that you have to wait for that operation to complete e. XHR allows you to handle this using its onload event handler — this is run when the load event fires when the response has returned.I while back a need to be able to read a file off of a web server.
I found a couple ways to do so:. The latter ended up working the easiest to suit my needs. Send 'Check for any errors reported by the server If oHttp. Now, this function can easily be modified to open password protected page by simply modifying the Open method, since it has such optional parameters.
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I found a couple ways to do so: FTP into the webser assuming it is your web server and you have a valid login and download the file locally, then read it like you would any other file Use some browser automation IE to access the file and read it Use the MSXML library to read the file The latter ended up working the easiest to suit my needs.
This is how I read the config file. Finally this is my site structure in IIS server. Please note that three sub web site are hosted under main Web site. Notes: This error is not occurring always. Sometimes all web sites works fine without any issue. Also all three sub websites refer to same code base.
It seems that the path is wrong in the cache - System. You should try to clear the cache before using the new path. We have remove the cache values from the context and check. But still error occurs. This is how I clear the HttpContext cache. What problem are you trying to solve having the sub applications? Or could it be something such as having an application pointing to the virtual folder for another application which then points to a physical directory?
Only sub web sites site1,site2,site That's a very vague statement. How does this design enhance maintainability? Again what problem does this design solve? Are you trying to share a single web. Yes we are sharing single web. Not only web. This will help us to save time when we do manual deployments. The web. A common way to do this having a main application with virtual directories underneath.
VBA – Read a File From a Webserver or Internet Website
All virtual directories inherit from the root web. Frankly, I don't see the benefit of this design and it is causing errors. Okay, What if we create separate web site for each and every virtual application and point the to same physical location in file system.
Will it solve the issue? This sounds like the current design and I don't understand what problem the current design solves.