Engineering and technology

Lua: getting started

Jovan Stosic February 15, 2017

Lua is a powerful and fast programming language that is easy to learn and use and to embed into your application. Lua is designed to be a lightweight embeddable scripting language and is used for all sorts of applications from games to web applications and image processing. See the about page for details and some reasons why you should choose Lua. See what Lua programs look and feel like in the live demo.

Source: Lua: getting started

App Inventor Tutorials and Examples: Manager Screen | Pura Vida Apps

Jovan Stosic February 14, 2017

The recommended method of switching screens in App InventorNote: Before starting to create another screen, first you should think about is it really necessary? See also Building apps with many screens and SteveJG’s post about advantages/disadvantages, because in only one screen you also can use vertical arrangements to simulate different screens, just set the arrangements to visible = true/false as needed…See also Martyn_HK’s example about how to use Tabs in App Inventor and another example from Cyd.Note from the Colored Dots tutorial:You can have many screens in an App Inventor app, but a screen always returns to the screen that opened it. On the other hand, you can get the effect of screens switching to arbitrary other screen by setting up a “manager screen” that is used for opening all the other screens. When a screen wants to switch, it returns to the manager with a value saying which screen to open next.This version demonstrates the use of a manager screen. If in a screen you want to go to another screen, you always go back to the manager screen telling him where you want to go. With this method, there only is one screen active in any moment. Additionally the back button will be catched with the Screen.BackPressed block.Note: if you only use the open another screen and never the close screen block, you will run out of memory after a while. Also reopening an already opened screen is a bad idea. For example if you open Screen1 twice, you also have to close your app twice!

Source: App Inventor Tutorials and Examples: Manager Screen | Pura Vida Apps

Creating new objects at runtime – Google Groups

Jovan Stosic February 13, 2017

Hi people!! I am loving the App Inventor, I have previously tried some droid dev using eclipse and the android SDK but I found it so hard to get to grips with. I am written a few apps and now am trying to write on that allows me to take pictures of my friends and assign their numbers to them… i want to be able to click my friends faces and call them from within the app but… is it possible to create new buttons at runtime? when i take a picture it should change the buttons image property to d

Source: Creating new objects at runtime – Google Groups

Representational state transfer

Jovan Stosic February 10, 2017

Representational state transfer (REST) or RESTful Web services are one way of providing interoperability between computer systems on the Internet. REST-compliant Web services allow requesting systems to access and manipulate textual representations of Web resources using a uniform and predefined set of stateless operations. Other forms of Web service exist, which expose their own arbitrary sets of operations such as WSDL and SOAP.[1] “Web resources” were first defined on the World Wide Web as documents or files identified by their URLs, but today they have a much more generic and abstract definition encompassing every thing or entity that can be identified, named, addressed or handled, in any way whatsoever, on the Web. In a RESTful Web service, requests made to a resource’s URI will elicit a response that may be in XML, HTML, JSON or some other defined format. The response may confirm that some alteration has been made to the stored resource, and it may provide hypertext links to other related resources or collections of resources. Using HTTP, as is most common, the kind of operations available include those predefined by the HTTP verbs GET, POST, PUT, DELETE and so on. By making use of a stateless protocol and standard operations, REST systems aim for fast performance, reliability, and the ability to grow, by re-using components that can be managed and updated without affecting the system as a whole, even while it is running.

The term representational state transfer was introduced and defined in 2000 by Roy Fielding in his doctoral dissertation.[2][3] Fielding used REST to design HTTP 1.1 and Uniform Resource Identifiers (URI).[4][5][6] The term is intended to evoke an image of how a well-designed Web application behaves: it is a network of Web resources (a virtual state-machine) where the user progresses through the application by selecting links, such as /user/tom, and operations such as GET or DELETE (state transitions), resulting in the next resource (representing the next state of the application) being transferred to the user for their use.

Source: Representational state transfer – Wikipedia

Ixia (company)

Jovan Stosic February 10, 2017

Ixia is a globally traded public company operating in around 25 countries. Ixia is headquartered in Calabasas, California and has approximately 1750 employees worldwide.

Ixia’s key customers include manufacturers of network equipment such as Cisco and Alcatel-Lucent,[1] service providers such as Verizon, NTT[2] and Deutsche Telekom,[3] and many enterprises and government agencies.

History[edit]

Ixia was founded by Errol Ginsberg and Joel Weissberger in 1997. Atul Bhatnagar[4] succeeded Ginsberg as President and CEO in 2007. On 19 March 2012 Ixia announced Victor Alston as President and Chief Executive Officer, with Ginsberg remaining Chairman of the Board and Chief Innovation Officer. On October 2013, Ixia announced Victor Alston’s resignation as Chief Executive Officer, and he was replaced by Ginsberg as acting CEO.[5] On August 21, 2014, the board named Bethany Mayer President and CEO. Mayer was also named to the board of directors. [6]

Historically an IP/Ethernet testing house, the acquisition of Catapult Communications in June 2009[7]established Ixia as a player in the wireless market. Ixia made a second significant acquisition in 2009, buying Agilent Technologies‘ N2X Data Networks Product Line for $44 million.[8] Ixia further expanded its testing capabilities by acquiring Wi-Fi testing company VeriWave, Inc. in July, 2011.[9] On 4 June 2012 Ixia announced the completion of the acquisition of Anue Systems, Inc., a leading developer of network visibility/tap aggregation solutions founded by Kevin Przybocki, Hemi Thaker, and Chip Webb. On August 24, 2012, the company announced another acquisition, BreakingPoint Systems,[10] a leading company in network security testing. Ixia continued its acquisitions by announcing the purchase of Net Optics[11] on October 29, 2013.

On January 30, 2017, Keysight Technologies Inc. agreed to buy Ixia for about $1.6 billion in all-cash, with the deal expected to close by October 2017.[12][13]

Tools and services[edit]

Ixia’s test and simulation platforms are used by network equipment manufacturers, service providers, enterprises, and government agencies to design and validate a wide range of wired, Wi-Fi, and 3G/4G networking equipment and networks.

Ixia Worldwide Headquarters, Calabasas, California

Ixia provides a wide range of testing, visibility and security solutions for enterprises and governments, service providers and network equipment manufacturers

Source: Ixia (company) – Wikipedia

Microsoft Silverlight

Jovan Stosic February 10, 2017

Microsoft Silverlight is a deprecated application framework for writing and running rich Internet applications, similar to Adobe Flash. A plugin for Silverlight is available for some browsers. While early versions of Silverlight focused on streaming media, later versions supported multimedia, graphics, and animation and gave developers support for CLI languages and development tools. Silverlight is also one of the two application development platforms for Windows Phone, but web pages that use Silverlight ca

Source: Microsoft Silverlight – Wikipedia

Where could I buy a valid SSL certificate? – Stack Overflow

Jovan Stosic February 10, 2017

I need to have a valid SSL certificate, by valid I mean not self signed. I don’t want my customers to have to deal with the ‘exception’.

How much does it cost? I’m bit lost because I checked on Verisign and it costs around ~1000$ while I can find others from 30$.

Any ideas? By the way I’m currently located in France, if that matters.

shareimprove this question

closed as off-topic by Artjom B., Dijkgraaf, CRABOLO, Shankar Damodaran, Krumia Jun 19 ’15 at 4:05

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • “Questions asking us to recommend or find a book, tool, software library, tutorial or other off-site resource are off-topic for Stack Overflow as they tend to attract opinionated answers and spam. Instead, describe the problem and what has been done so far to solve it.” – Artjom B., Dijkgraaf, CRABOLO, Shankar Damodaran, Krumia

If this question can be reworded to fit the rules in the help center, please edit the question.
64
This is an awesome question. While not exactly programming it’s very close to programming. – Jim ThioFeb 21 ’14 at 3:33
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@JimThio, Then vote for reopen. – Pacerier Apr 5 ’15 at 10:34
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@JimThio It’s nothing like programming, that’s a really odd thing to say. It’s relevant to some programmers, but that’s irrelevant on Stack Overflow. This question should definitely be on one of the other Stack Exchange sites instead, such as Webmasters or Server Fault. – Thor84no Oct 6 ’15 at 11:28
10
It’s ridiculous that this post was closed! This is one of the major pain points for programmers. – Hajjat Nov 24 ’15 at 15:04
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Could a moderator move this to webmasters.stackexchange.com ? – Adam Jun 1 ’16 at 10:40

3 Answers

up vote120down voteaccepted

The value of the certificate comes mostly from the trust of the internet users in the issuer of the certificate. To that end, Verisign is tough to beat. A certificate says to the client that you are who you say you are, and the issuer has verified that to be true.

You can get a free SSL certificate signed, for example, by StartSSL. This is an improvement on self-signed certificates, because your end-users would stop getting warning pop-ups informing them of a suspicious certificate on your end. However, the browser bar is not going to turn green when communicating with your site over https, so this solution is not ideal.

The cheapest SSL certificate that turns the bar green will cost you a few hundred dollars, and you would need to go through a process of proving the identity of your company to the issuer of the certificate by submitting relevant documents.

shareimprove this answer
1
I just got two certificates from StartSSL today. One shows the lockpad in Safari (the other doesn’t, oddly) and they both turn the bar green in Chrome. Has their trust level changed since this post? – wjl Apr 22 ’14 at 21:27
1
I loaded up a startssl cert and it worked with chrome, however, in firefox I was getting a “This site is not trusted” message. I realized that you need an intermediate certificate. When installing a startssl cert make sure you follow the steps here: startssl.com/?app=20 (for me I selected nginx) make sure you follow the part about the intermediate cert. Also you can double check cert problems here: sslshopper.com/ssl-checker.html, which helped me a lot. – Chase Roberts Nov 18 ’14 at 20:06
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StartSSL certs are MUCH better than self-signed certs because they don’t cause the browser to report security errors. – jcoffland Jan 27 ’15 at 3:25
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@dasblinkenlight from a usability standpoint it’s very important that the browser does not popup scary warnings. As to security value, StartCom’s CA certs are in the user’s browser which protects against man-in-the-middle attacks. Self-signed certs are totally open to such attacks. There are lots of vulnerabilities in the SSL infrastructure but certs from a CA that’s shipped with the browser are much more secure. – jcoffland Jan 27 ’15 at 7:39
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@dasblinkenlight, Establishing trust is not the core purpose of SSL cert. The core purpose is getting your traffic veritably encrypted by the domain name holder, such that MITMs, ISPs and whatnot can’t sniff your traffic. It has nothing to do with companies. Of course, for tar-and-mortar businesses that don’t live online, “establishing trust” is another thing SSL do. – Pacerier Apr 5 ’15 at 10:39

up vote98down vote

Let’s Encrypt is a free, automated, and open certificate authority made by the Internet Security Research Group (ISRG). It is sponsored by well-known organisations such as Mozilla, Cisco or Google Chrome. Most modern browsers are compatible.

Let’s Encrypt is in public beta since December 2015, which means everyone can get their certificates for free. The setup will be very easy, you just have to verify that you own the website. Some minutes later, you get your certificate.

There are many clients you can use to install a Let’s Encrypt certificate:

Let’s Encrypt uses the ACME protocol to verify that you control a given domain name and to issue you a certificate. To get a Let’s Encrypt certificate, you’ll need to choose a piece of ACME client software to use. – https://letsencrypt.org/docs/client-options/

Source: Where could I buy a valid SSL certificate? – Stack Overflow