Monday vhandit #2

Introduction to OpenLDAP directory service

"A directory is a specialized database specially designed for searching and browsing, in addition to supporting basic lookup and update functions"

A directory service can be local, providing a restricted context; or global, providing service to a much broader context. Curlie is a good example of a directory service.

LDAP (Lightweight Directory Access Protocol) is a protocol for accessing directory services, specifically X.500-based directory services.

OpenLDAP is an open-source implementation of LDAP.

Writing system software: code comments

I have read Clean Code (by Uncle Bob) and I thought that I should void comments since the code it explains its implementation itself. That is right but not always true. In this post, the author categorized the comments into 9 types. Only "trivial comments" and "backup comments" are the ones that should be avoided. I myself agree with "writing good comments is harder than writing good code".

How To Become A Hacker

This is an old post, but worth reading. Previously, I used to think that hackers are kind of bad people since they usually are known as someone trying to steal users' accounts, make a system down, etc. But, no! Hackers build stuff. Hackers are heroes to build the Internet and keep it safe for users. I am building myself to become a hacker as well.

And, Hacker News is my most favorite website for my daily updates.

Comments

Attribute 'for' of label component with id xxxx is not defined

I got the warning in the log file when I have used the tag <h:outputLabel> without attribute " for " in xhtml file. It was really polluting my server log files. The logged information actually makes sense anyway! We could find an answer as the following: "Having h:outputLabel without a "for" attribute is meaningless. If you are not attaching the label, you should be using h:outputText instead of h:outputLabel." However, these solutions are not possible just for my situation. Instead of using h:outputText for only displaying text, my team has used h:outputLabel too many places. We were nearly in our release time (next day) so it is quite risky and takes much efforts if we try to correct it. Because the style (with CSS) is already done with h:ouputLabel . The alternative by adding attribute " for " the existing h:outputLabel is not reasonable either. I really need to find another solution. Fortunately, I came across a way if I cha...

Styling Sort Icons Using Font Awesome for Primefaces' Data Table

So far, Primefaces has used image sprites for displaying the sort icons. This leads to a problem if we want to make a different style for these icons; for example, I would make the icon "arrow up" more blurry at the first time the table loading because I want to highlight the icon "arrow down". I found a way that I can replace these icons with Font Awesome icons. We will use "CSS Pseudo-classes" to achieve it. The hardest thing here is that we should handle displaying icons in different cases. There is a case both "arrow up" and "arrow down" showing and other case is only one of these icons is shown. .ui-sortable-column-icon.ui-icon.ui-icon-carat-2-n-s { background-image: none; margin-left: 5px; font-size: 1.1666em; position: relative; } .ui-sortable-column-icon.ui-icon.ui-icon-carat-2-n-s:not(.ui-icon-triangle-1-s)::before { content: "\f106"; font-family: "FontAwesome"; position: ...

Resolution for 2016

HCM full stack developer Meetup This is the topic of HMC full stack developers' meetup this time. We have shared our ideas and discussed about them. Most of discussions is focused on career path for developers in Vietnam and what next we will do in 2016. I have a problem with my career path in Vietnam. I seem to get lost my motivation because I don't like to become either a manager or a TA (such as Technical Assistant, Technical Analysis, Technical Architect). But, why only are there either manager or TA in Vietnam? How about a 60-years experiences developer? Salary is actually an issue. I admire several great developers in the world such as Jeff Atwood ( stackoverflow.com founder), John Sonmez ( simpleprogrammer.com fouder). They created very great and valuable stuffs for the community and they are free of finance - of course, I think. Why can't I follow that way? I would like to not only create cool stuffs but also get high salary. I love to becom...

Safari (older than 14.1.1) rejects TLS connections of TURN with Let's Encrypt certificates

Summary We could not make a video call successfully on Safari older than 14.1.1. The call kept disconnecting for some seconds. We got the following error in Nginx’s log SSL: error:14094418:SSL routines:ssl3_read_bytes:tlsv1 alert unknown ca:SSL alert number 48 Root cause The Safari didn’t trust our TLS certificates (certified by Let’s Encrypt) when establishing a TLS connection into our TURN server. It is a known issue that could be found at Bug 219274 - ICE does not resolve for `turns` relay candidates rooted in LetsEncrypt CA . The issue was just recently fixed (end of 2020), therefore old versions of Safari still meet the issues. Solution In our development environment, we replaced the untrusted certificate with a trusted one. We will warn our customers about this issue in our installation guide. Technical explained WebKit is a browser engine developed by Apple and primarily used in its Safari web browser, as well as all iOS web browsers. The WebRTC of WebKit relied on ...

Changing source code at run-time with Service Locator pattern

I have a service to get some data but the result can be different basing on where the implementation is. Technically, I have two or more concrete implementation of an interface and I am able to switch using these concrete classes at run-time. That means I have a place to configure it without re-deploying the application. In order to overcome this issue, I use Service Locator design pattern and here I only care about two advantages below: Encapsulating the specific implementation, we just declare the name and don't care about the implementation of the service. Changing the implementation at run-time. Client : an object that invokes the services via Service Locator Business services : services that is used by Client.

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