FreeCodeCamp and Learning Node: HTTP File Server

Last time we learned how to return a time in response to a request.  Now we’re going to learn to return a file in response to a request.  We’re coming towards the end of the Node tutorials and so things are getting more interesting and complex.  This exercise was an interesting one; we’ll be serving files as part of the challenges for FreeCodeCamp in the future…

For now though, let’s look at  the Directions and Hints:

 ## HTTP FILE SERVER (Exercise 11 of 13)

  Write an HTTP server that serves the same text file for each request it receives.

  Your server should listen on the port provided by the first argument to your program.

  You will be provided with the location of the file to serve as the second command-line argument. You must use the fs.createReadStream() method to stream the file contents to the response.

 ─────────────────────────────────────────────────────────────────────────────

 ## HINTS

  Because we need to create an HTTP server for this exercise rather than a generic TCP server, we should use the http module from Node core. Like the net module, http also has a method named http.createServer() but this one creates a server that can talk HTTP.

  http.createServer() takes a callback that is called once for each connection received by your server. The callback function has the signature:

     function callback (request, response) { /* … */ }

  Where the two arguments are objects representing the HTTP request and the corresponding response for this request. request is used to fetch properties, such as the header and query-string from the request while response is for sending data to the client, both headers and body.

  Both request and response are also Node streams! Which means that you can use the streaming abstractions to send and receive data if they suit your use-case.

  http.createServer() also returns an instance of your server. You must call server.listen(portNumber) to start listening on a particular port.

  A typical Node HTTP server looks like this:

     var http = require(‘http’)

     var server = http.createServer(function (req, res) {

       // request handling logic…

     })

     server.listen(8000)

  Documentation on the http module can be found by pointing your browser here:

  file:///home/ubuntu/.nvm/versions/node/v4.4.3/lib/node_modules/learnyounode/node_apidoc/http.html

  The fs core module also has some streaming APIs for files. You will need to use the fs.createReadStream() method to create a stream representing the file you are given as a command-line argument. The method returns a stream object which you can use src.pipe(dst) to pipe the data from the src stream to the dst stream. In this way you can connect a filesystem stream with an HTTP response stream.

I admit that at first the directions and hints were a little cryptic, but this exercise turned out to be much easier than I thought.

First, scanning through the material above, we’re going to need http and fs, so we write the require statements for those.  Then, we note that it states that the port and the file path will be provided as command line arguments in our old friend process.argv.  So, as in the past many exercises, we assign those to variables.  That wraps up assignments, and also the easy part.

Next, they give us the skeleton of the server:

</div>
<div> var server = http.createServer(function (req, res) {</div>
<div>       // request handling logic...</div>
<div>     })</div>
<div>     server.listen(8000)</div>
<div>

8000 will of course be replaced by our port, and so our program now looks like this so far:

</div>
<div>var http = require('http');</div>
<div>var fs = require('fs');</div>
<div>var port = process.argv[2];</div>
<div>var filePath = process.argv[3];</div>
<div></div>
<div>var server = http.createServer(function (req, res) {</div>
<div>       // request handling logic...</div>
<div>})</div>
<div>server.listen(port);</div>
<div>

Now we need to write the “request handling logic” they have in there.  We know, from the directions and hints, that we need fs.createReadStream(), and that we’ll also need a src.pipe(dst).  The info on createReadStream is here:

https://nodejs.org/dist/latest-v6.x/docs/api/fs.html#fs_fs_createreadstream_path_options

So, what goes in the parentheses (the parameters) is the file path, which we have a variable for called filePath.  That’s the SOURCE, so we’ll assign it to a variable called src, thus:

</div>
<div>var src = fs.createReadStream(filePath);</div>
<div>

Now, finally, we have src.pipe(dst).  src is the SOURCE (see what I did there?) and dst is the stream we are sending it to.  Here’s where it gets a little tricky.  What are we sending it to?  Well, in the hints we are told, “Both request and response are also Node streams!”  Ahhh, so we want to use the response stream!  So:

</div>
<div>src.pipe(res);</div>
<div>

And…..we pass!  Here’s the final program:

</div>
<div>var http = require('http');</div>
<div>var fs = require('fs');</div>
<div>var port = process.argv[2];</div>
<div>var filePath = process.argv[3];</div>
<div></div>
<div>var server = http.createServer(function (req, res) {</div>
<div>       // request handling logic...</div>
<div>       var src = fs.createReadStream(filePath);</div>
<div>       src.pipe(res);</div>
<div></div>
<div></div>
<div>});</div>
<div>server.listen(port);</div>
<div>

See you next time!

FreeCodeCamp and Learning Node: Time Server

So our next challenge is to build a Time Server.  This one wasn’t too bad.  The only tricky part for me was using the outside library, namely the formatting of the date.

Here are the Directions and Hints:

TIME SERVER (Exercise 10 of 13)

  Write a TCP time server!

  Your server should listen to TCP connections on the port provided by the first argument to your program. For each connection you must write the current date & 24 hour time in the format:

     “YYYY-MM-DD hh:mm”

  followed by a newline character. Month, day, hour and minute must be zero-filled to 2 integers. For example:

     “2013-07-06 17:42”

  After sending the string, close the connection.

 ─────────────────────────────────────────────────────────────────────────────

 ## HINTS

  For this exercise we’ll be creating a raw TCP server. There’s no HTTP involved here so we need to use the net module from Node core which has all the basic networking functions.

  The net module has a method named net.createServer() that takes a function. The function that you need to pass to net.createServer() is a connection listener that is called more than once. Every connection received by your server triggers another call to the listener. The listener function has the signature:

     function listener(socket) { /* … */ }

  net.createServer() also returns an instance of your server. You must call server.listen(portNumber) to start listening on a particular port.

  A typical Node TCP server looks like this:

     var net = require(‘net’)

     var server = net.createServer(function (socket) {

       // socket handling logic

     })

     server.listen(8000)

  Remember to use the port number supplied to you as the first command-line argument.

  The socket object contains a lot of meta-data regarding the connection, but it is also a Node duplex Stream, in that it can be both read from, and written to. For this exercise we only need to write data and then close the socket.

  Use socket.write(data) to write data to the socket and socket.end() to close the socket. Alternatively, the .end() method also takes a data object so you can simplify to just: socket.end(data).

  Documentation on the net module can be found by pointing your browser here:

  file:///home/ubuntu/.nvm/versions/node/v4.4.3/lib/node_modules/learnyounode/node_apidoc/net.html

  To create the date, you’ll need to create a custom format from a new Date() object. The methods that will be useful are:

     date.getFullYear()

     date.getMonth()     // starts at 0

     date.getDate()      // returns the day of month

     date.getHours()

     date.getMinutes()

  Or, if you want to be adventurous, use the strftime package from npm. The strftime(fmt, date) function takes date formats just like the unix date command. You can read more about strftime at:

  [https://github.com/samsonjs/strftime] ( https://github.com/samsonjs/strftime )

The actual documentation link is:

https://nodejs.org/dist/latest-v6.x/docs/api/net.html

Okay, let’s get rolling. Since I decided to be adventurous, we need to install strftime.  We get:

$ npm install strftime

npm WARN package.json chat-example@0.0.0 No repository field.

npm WARN package.json chat-example@0.0.0 No license field.

strftime@0.9.2 node_modules/strftime

On to the actual program. First, I took the skeleton they give us above:

</pre>
</div>
<div>var net = require('net')</div>
<div>     var server = net.createServer(function (socket) {</div>
<div>       // socket handling logic</div>
<div>     })</div>
<div>     server.listen(8000)</div>
<div>

Now, 8000 isn’t going to necessarily be the socket we want.  We need to use the argument supplied to us.  As always, that’s the third element in process.argv (even though it says first in the hints – I think they mean it’s the first usable argument).  I added that and ran it and the terminal hung up; I figured out that it was still listening because I never told it to stop.  So, I added socket.end() inside var server (where it says “socket handling logic” was a hint to put it there) and I added a console.log to print out the port number to see if I had a working program so far.

Hey, build a little, test a little.  That was one of the mottoes of the moon program and NASA back in the 60s, and it works for me!

 

Here’s what I had so far:

</pre>
</div>
<div>var net = require('net');</div>
<div>var strftime = require('strftime');</div>
<div>var port = process.argv[2];</div>
<div></div>
<div>var server = net.createServer(function (socket) {</div>
<div>        console.log(port);</div>
<div>       // socket handling logic</div>
<div>       socket.end();</div>
<div>     });</div>
<div>     server.listen(port);</div>
<div>

That gives us the output I was looking for.  Obviously, we want our program to do a little more than that, so let’s have a look at the documentation for strftime using the link they gave us.  Note first, of course, that we need to use a require statement.  Next, we see some examples.

</pre>
</div>
<div>console.log(strftime('%B %d, %Y %H:%M:%S')), which returns April 28, 2011 18:21:08</div>
<div></div>
<div>console.log(strftime('%F %T', new Date(1307472705067))), which returns 2011-06-07 18:51:45</div>
<div>

Now, we’re going to need today’s date, so we add a variable for it using the JavaScript Date.now() function.  We want to printout the date and the time, less the seconds.  Returning to the documentation for strftime, we can see that to do that, we can use the first part of the second example, ‘%F’, and most of the last part of the first example, %H:%M. So, now I had:

</pre>
</div>
<div>var net = require('net');</div>
<div>var strftime = require('strftime');</div>
<div>var port = process.argv[2];</div>
<div></div>
<div>var today = Date.now();</div>
<div></div>
<div>var server = net.createServer(function (socket) {</div>
<div>        var data = (strftime('%F %H:%M', new Date(today)));</div>
<div></div>
<div>       // socket handling logic</div>
<div>       socket.end(data);</div>
<div>     });</div>
<div>     server.listen(port);</div>
<div>

This prints the date out correctly, but still doesn’t pass!!!  What???

I got this back:

Your submission results compared to the expected:

                 ACTUAL                                 EXPECTED

────────────────────────────────────────────────────────────────────────────────

   “2016-05-21 16:21”                  ==    “2016-05-21 16:21”

                                                 !=    “”

────────────────────────────────────────────────────────────────────────────────

  ✗  Submission results did not match expected!

Now, what was going on?

Simple: the directions specify that the date must be followed by a newline character.  I added it and lo and behold, my program passed!

</pre>
</div>
<div>var net = require('net');</div>
<div>var strftime = require('strftime');</div>
<div>var port = process.argv[2];</div>
<div></div>
<div>var today = Date.now();</div>
<div></div>
<div>var server = net.createServer(function (socket) {</div>
<div>        var data = (strftime('%F %H:%M', new Date(today))) + '\n';</div>
<div></div>
<div>       // socket handling logic</div>
<div>       socket.end(data);</div>
<div>     });</div>
<div>     server.listen(port);</div>
<div>

And there we go!  See you next time!

MilSats: Ship Assault

I’m back after a short vacation! It did not consist of anything like the training exercise below, though:

Photo from here: http://www.sealswcc.com/navy-seal-photos-page-4.html

MilSats: Old Ironsides

When I was a kid, I loved reading stories about the USS Constitution.  Here she is today:

I couldn’t find an attribution for the image, but click here for where I got it from.

FreeCodeCamp and Learning Node: Juggling ASync

On to the next exercise in the FreeCodeCamp learnyounode sequence!  The processes are asynchronous, but we want to tame them so they get us our data in order.  Let’s look at the directions and hints:

JUGGLING ASYNC (Exercise 9 of 13)

  This problem is the same as the previous problem (HTTP COLLECT) in that you need to use http.get(). However, this time you will be provided with three URLs as the first three command-line arguments.

  You must collect the complete content provided to you by each of the URLs and print it to the console (stdout). You don’t need to print out the length, just the data as a String; one line per URL. The catch is that you must print them out in the same order as the URLs are provided to you as command-line arguments.

 ─────────────────────────────────────────────────────────────────────────────

 ## HINTS

  Don’t expect these three servers to play nicely! They are not going to give you complete responses in the order you hope, so you can’t naively just print the output as you get it because they will be out of order.

  You will need to queue the results and keep track of how many of the URLs have returned their entire contents. Only once you have them all, you can print the data to the console.

  Counting callbacks is one of the fundamental ways of managing async in Node. Rather than doing it yourself, you may find it more convenient to rely on a third-party library such as [async]( http://npm.im/async ) or [after]( http://npm.im/after ). But for this exercise, try and do it without any external helper library.

Okay, as always, We want to declare our variables first.  We’re going to need http, since we’re using http.get().  We’re also going to want bl, since we are using buffer list for the contents of the URLs, as we did in the previous exercise.  We’re also going to use the skeleton of the call to http.get() that we used in the last exercise:

var bl = require('bl');
var http = require('http');

http.get(addr, function callback(response) {

response.pipe(bl(function (err, data) {
if(err)
console.log(err);
}))

});

Okay, so if we run this now, we get back… a mess.  Remember, there are THREE inputs coming that we want to process one after the other – this suggests a loop.

So, let’s put in a loop:

for(var count = 0; count < process.argv.length; count++) {

http.get(process.argv[count], function callback(response) {

response.pipe(bl(function (err, data) {
if(err) {
console.log(err);

console.log(data.length);
console.log(data.toString());
}));

});
};

Umm…ewww.  No, that was no good.  I messed around with this for awhile, and still didn’t get what I wanted.  At one point, I came close – getting the results back, but not in order.  So, I did some web surfing, as suggested by FreeCodeCamp (you remember how they always say to use Read-Search-Ask, right?), and found this very helpful link on “Four ways of handling asynchronous operations in node.js“.  If you look about halfway down the page, you’ll see a section titled “Reading the files sequentially using callbacks”.

 

Now, here the poster is reading the contents of files, and not URLs.  He is also using fs.readdir.  But the idea is the same.

So, we create a function that contains our http.get() called function readURL().  We need to make it recursive, so it goes through the items provided to us by the arguments.  Keep in mind that, as always with Node, we start with the third element (element[2] since the array starts at 0).  So count’s initial value is 2.

In the response.pipe() statement, we will print the data out – as a string, as mentioned in the directions – and we add that statement.  Also, readURL() is recursive, so if it is successful, we want to call it again, only incrementing count by 1 so that it calls the next argument in process.argv.  If the next argument doesn’t exist, the process terminates and we’re finished.  So, now we have:

var bl = require('bl');
var http = require('http');
var count = 2;

function readURL(count) {

http.get(process.argv[count], function callback(response) {

response.pipe(bl(function (err, data) {
if(err) {
console.log(err);
} else {
console.log(data.toString());
readURL(count + 1);
}
}));

});
}

Let’s run it.

I bet you’re not surprised it doesn’t work, right?  Do you know why?

Because we created a function called readURL()…but we never called it.  We need to add that to the VERY bottom and try again.

 

It worked! And now we can move on to the next exercise.  Here’s the final program:

var bl = require('bl');
var http = require('http');
var count = 2;

function readURL(count) {

http.get(process.argv[count], function callback(response) {

response.pipe(bl(function (err, data) {
if(err) {
console.log(err);
} else {
console.log(data.toString());
readURL(count + 1);
}
}));

});
}

readURL(count);

See you next time!

MilSats: Medevac

Sometimes, a casualty has to be airlifted to a hospital, stat.

Security force team members for Provincial Reconstruction Team (PRT) Farah wait for a UH-60 Blackhawk medevac helicopter to land before moving a simulated casualty during medical evacuation training on FOB Farah, Jan. 9. PRT Farah coordinated with C Company, “Northstar Dustoff,” 2-211th Aviation Regiment (Air Ambulance) pilots and medics in order to provide invaluable hands-on medical evacuation training. PRT Farah’s mission is to train, advise and assist Afghan government leaders at the municipal, district and provincial levels in Farah province, Afghanistan. Their civil military team is comprised of members of the U.S. Navy, U.S. Army, the U.S. Department of State and the Agency for International Development (USAID). (U.S. Navy photo by HMC Josh Ives/released)

FreeCodeCamp and Learning Node: HTTP Collect

We’ve completed part 1 of the challenges for FreeCodeCamp’s Node section, and now we’re on to Part 2.  FreeCodeCamp broke this up into sections since the Node tutorial is pretty long.  Last time we learned about using http and the get method, and this lesson builds on that.  As always, you should try it first and then look at what I did. Let’s get right to it!

Here are the directions and hints:

HTTP COLLECT (Exercise 8 of 13)

  Write a program that performs an HTTP GET request to a URL provided to you as the first command-line argument. Collect all data from the server (not just the first “data” event) and then write two lines to the console (stdout).

  The first line you write should just be an integer representing the number of characters received from the server. The second line should contain the complete String of characters sent by the server.

 ─────────────────────────────────────────────────────────────────────────────

 ## HINTS

  There are two approaches you can take to this problem:

  1) Collect data across multiple “data” events and append the results together prior to printing the output. Use the “end” event to determine when the stream is finished and you can write the output.

  2) Use a third-party package to abstract the difficulties involved in collecting an entire stream of data. Two different packages provide a

  useful API for solving this problem (there are likely more!): bl (Buffer List) and concat-stream; take your pick!

  <http://npm.im/bl&gt;

  <http://npm.im/concat-stream&gt;

  To install a Node package, use the Node Package Manager npm. Simply type:

     $ npm install bl

  And it will download and install the latest version of the package into a subdirectory named node_modules. Any package in this subdirectory under your main program file can be loaded with the require syntax without being prefixed by ‘./’:

     var bl = require(‘bl’)

  Node will first look in the core modules and then in the node_modules directory where the package is located.

  If you don’t have an Internet connection, simply make a node_modules directory and copy the entire directory for the package you want to use from inside the learnyounode installation directory:

  file:///home/ubuntu/.nvm/versions/node/v4.4.3/lib/node_modules/learnyounode/node_modules/bl

  file:///home/ubuntu/.nvm/versions/node/v4.4.3/lib/node_modules/learnyounode/node_modules/concat-stream

  Both bl and concat-stream can have a stream piped in to them and they will collect the data for you. Once the stream has ended, a callback will be fired with the data:

     response.pipe(bl(function (err, data) { /* … */ }))

     // or

     response.pipe(concatStream(function (data) { /* … */ }))

  Note that you will probably need to data.toString() to convert from a Buffer.

  Documentation for both of these modules has been installed along with learnyounode on your system and you can read them by pointing your browser here:

  file:///home/ubuntu/.nvm/versions/node/v4.4.3/lib/node_modules/learnyounode/docs/bl.html

  file:///home/ubuntu/.nvm/versions/node/v4.4.3/lib/node_modules/learnyounode/docs/concat-stream.html

Okay, let’s break this down step by step.  I didn’t want to have to use a bunch of appends, because that didn’t sound elegant to me.  I went with one of the third party methods instead, and I picked the Buffer List package.  You can always use the other one.

Type “npm install bl first” at the $ prompt (in other words, NOT in your program), and you’ll get:

<YOUR USERNAME>:~/workspace $ npm install bl

npm WARN package.json chat-example@0.0.0 No repository field.

npm WARN package.json chat-example@0.0.0 No license field.

bl@1.1.2 node_modules/bl

└── readable-stream@2.0.6 (string_decoder@0.10.31, process-nextick-args@1.0.7, util-deprecate@1.0.2, inherits@2.0.1, core-util-is@1.0.2, isarray@1.0.0)

Now Buffer List is installed and you can use it!

Time to start the program.  This is going to use the get method of http again, so we can borrow from the last exercise.  We also need to require the bl package as noted in the hints.  I left require fs in there but you don’t need it for this exercise.

var bl = require('bl');
var fs = require('fs');
var http = require('http');
var addr = process.argv[2];

Remember that the third element of process.arg is the path to the data we want.  That takes care of the variables and requires, so let’s move on to the rest of the program.

http.get(addr, function callback(response) {

     /* Do stuff here */

}).on('error', (e) => {
  console.log(`Got error: ${e.message}`);
});

The framework of the program hasn’t changed.  What IS going to change is the part where I put “/* Do stuff here */”. I put the line in the hint in there:

response.pipe(bl(function (err, data) { /* ... */ })) 

Just for fun I put

console.log(data.length);

in there, and got a warning that it expected an error to be handled.  From one of the previous lessons, I remembered that we add:

if(err)
          console.log(err);

I ran it then, even though it’s incomplete, and lo and behold I got a length back that matched the expected answer!  Almost there!  Now, the next thing is to print the contents of the buffer, and they tell you how to do that with a little hint that you need to convert it to a string, like so:

console.log(data.toString());

Do that, and the program passes!

 

Just a quick aside:  It actually took me a half hour and several false trails before I got this.  Believe me, I’m making it seem much easier than it was here!

Anyway, here’s the entire program!

var bl = require('bl');
var fs = require('fs');
var http = require('http');
var addr = process.argv[2];

http.get(addr, function callback(response) {

response.pipe(bl(function (err, data) {
if(err)
console.log(err);

console.log(data.length);
console.log(data.toString());

}))


}).on('error', (e) => {
console.log(`Got error: ${e.message}`);
});

Theology 101: A Little Aquinas, Part 5

This is the last of the series on Aquinas.  I hope this was helpful; I found it fascinating and I learned a lot about everything from logic to God to how my faith can be applied to many areas of life.  Any requests for the next theologian?

Let’s get started.  Today we’ll cover politics and Renick’s summary.

 

Chapter 9: Politics

Martin Luther King Jr., in his Letter From a Birmingham Jail, wrote,  “How does one determine whether a law is just or unjust? A just law is a man made code that squares with the moral law or the law of God. An unjust law is a code that is out of harmony with the moral law. To put it in the terms of St. Thomas Aquinas: An unjust law is a human law that is not rooted in eternal law and natural law. Any law that uplifts human personality is just. Any law that degrades human personality is unjust.”

The question is, “Can it ever be right to disobey the laws of the state? Is breaking the law permissible if the laws themselves are unjust?”   Based on Paul’s thoughts in Romans 13 as well as Augustine’s in The City of God, until Aquinas, most Christians said no.  Indeed, Augustine wrote, “Thus it happens, but not without God’s providence, that some are endowed with kingdoms and others made subject to kings.”  Since God made them king, your are disobeying God if you disobey the king.  If this wwere the case, revolution and civil disobedience would be morally wrong.

However, Aquinas, in his book On Princely Government, says that just as all people do, kings and rulers have the end of pursuing the good – God.  If they don’t, by definition they are no longer the king or state since the definition of these is to pursue justice and the good.

Referencing Aristotle, Aquinas discusses six different forms of government.  They are ranked by how closely they achieve the end of pursuing the good and justice.

At the top and best, to Aquinas, is Monarchy.  Monarchy is “rule by a single leader, a king, who in his actions pursues the just end of the common good, or God…It is both good in intent and efficient in practice,” when the ruler is dedicated to God.  He is similar, says Renick, to the captain of a ship.

Second is aristocracy, which is “rule by a few individuals who all are seeking the common good – God.”  This is second because it is not as efficient as a monarchy – each of the individuals may have different goals in mind for the common good and so debate and compromise lower efficiency.

Next is polity – “rule by the many.”  Here again, all have the best for society in mind, but since there are many of them, it is even more inefficient than aristocracy.

Fourth is democracy, which is “the least unjust of the unjust forms of government.”  Why unjust?  Because unlike a polity, instead of having the common good as a goal, the many seek self-gain instead.  They are voting in their own self-interest rather than society’s.  Democracy is the least bad, though, because the endless debate and compromise mean very little bad gets done.  Aquinas was not far from the truth – the American government was set up with checks and balances to help prevent moving too quickly toward unjust ends.

Next on the list is Oligarchy, or rule by a few individuals with selfish motives.  It is worse than democracy because it is more efficient at pursuing unjust ends.

Finally, the worst form of government is tyranny.  This is basically a king that pursues selfish ends.  It is very efficient at pursuing the bad, which is why it is the worst of all.

This seems contradictory – rule by a single individual is both the best and worst form of government!  Aquinas believes in taking the chance because he feels that humans are basically “good enough to rule justly,” and most people are good, so most of the time the ruler will be good.  also, Good is stronger than evil – there “is only one ultimate good (God) yet as many evils as there are individual goals and ends.  God and its supporters are unified; evil tends to divide.”  So, good usually beats evil.  This, he reasons, is why it is best to support government by one person and take the chance they could be a tyrant.  He would later qualify this view in Summa Theologica,” saying that a mixed form of government, with an elected monarch, an elected aristocracy, and a polity that would check them and elect them, is best.  The Founding Fathers, of course, used Aquinas as one of their inspirations when drafting the Constitution, using checks and balances on each branch of government.  Regarding a tri-partite government, Aquinas writes, “Such is the best government, formed by a good mixture of kingship, in the sense that one person is the chief, and aristocracy, in the sense that many men rule according to virtue, and polity (that is, the power of the people), in the sense that leaders can be elected from among the populace, and further, the choice of the rule belongs to the people.”

This idea of Aquinas’s is not that of divine right of kings.  The king in Aquinas’s system gets the right to govern from the people and must be obeyed only if he pursues God.  If not, he’s not really a king anyway; instead, he’s a tyrant.  A tyrant need not be obeyed, nor an oligarchy, nor a democracy – when they are unjust.  You must do what is right, even if the government says to do something wrong.  However, there are times an unjust government should receive obedience, because “rebellion is often more costly than bearing up under tyranny.”

You will naturally obey a just government if you are a just person – it comes, wait for it, naturally.  And only unjust laws will be hard for you to obey because you are naturally just.  An unjust law is not a law because the essence of a law, Aquinas writes,  is to be “an ordinance of reason directed to the common good.”  It is morally required to disobey an unjust law.

This, Renick says, was an extraordinary thing for Aquinas to write, because at that time, with belief in the divine right of kings, he stated that the people needed to use their reason and intellect to decide if the ruler was right or wrong.  Indeed, he wrote, “Nor should the community be accused of disloyalty for deposing a tyrant, even after a previous promise of constant fealty, for the tyrant lays himself open to such treatment by his failure to discharge the duties of his office as governor of the community, and in consequence his subjects are no longer bound by their oath to him.”

Thus it was that Thomas Jefferson, in the Declaration of Independence, wrote, “Whenever any form of government becomes destructive of [its] ends, it is the right of the people to alter or abolish it, and to institute a new government,” and King wrote, “We can never forget that everything Hitler did in Germany was ‘legal’ and everything…the freedom fighters did…was ‘illegal.”  For these two and Aquinas, “the ‘law ‘ is by definition that which is just.  An unjust law is no law at all.  The concept,” Renick concludes, “is a simple one; the implications are, quite literally, revolutionary.”

Chapter 10:  Reading Aquinas

Aquinas’s ideas have become mainstream, but their attribution has been lost.  Renick points out that exalting reason, questioning authority, human rights, natural law, war codes, intentionality in crimes, and double effect are all Thomist ideas.  Reading Aquinas, though is difficult because his works are usually quite long, and there are over 60 of them.  In the Summa itself, there are 38 treatises, divided into 3.120 articles – nearly 10,000 objections posed and answered (the Summa is written in a question and answer format).

Aquinas starts each case “with a series of objections to the answer he will eventually adopt to the question.”  The objections are  not Aquinas’s beliefs.  Next comes a series of “on the contraries”, where Aquinas “cites authors who have taken up the opposite position on the same question.”  Finally, Aquinas’s answer begins with “I answer that…” where he states his own beliefs.  He then concludes with “replies to objections,” where he deals with each of the objections brought up one by one.

He quoted a wide range of people; he dealt with a wide range of issues, including “the nature of the incarnation and the significance of baptism…the centrality of the virtues and the problem with lying…what constitutes a habit and when does fear cause human decisions to become less than voluntary,” and many more.

 

Aquinas writes, “The human mind can understand truth only by thinking.”  God made us thinkers, it is a sin to not use this ability.  Renick concludes, “The concept is simple; the implications are extraordinary.”

FreeCodeCamp and Learning Node: HTTP Client

Welcome back to the Node tutorial series! Now we’re going to actually interact with web requests.  Hang on, things are going to get wild…

As always, TRY THIS YOURSELF FIRST!  DO THE RESEARCH ON THE WEB TO LEARN THINGS, AND NOT JUST BY READING WHAT i WROTE BELOW!!!

We begin with the Directions and Hints that the tutorial gives us:

Write a program that performs an HTTP GET request to a URL provided to you as the first command-line argument. Write the String contents of each “data” event from the response to a new line on the console (stdout).

 ─────────────────────────────────────────────────────────────────────────────

 ## HINTS

  For this exercise you will need to use the http core module.

  Documentation on the http module can be found by pointing your browser here:

  file:///home/ubuntu/.nvm/versions/node/v4.4.3/lib/node_modules/learnyounode/node_apidoc/http.html

  The http.get() method is a shortcut for simple GET requests, use it to simplify your solution. The first argument to http.get() can be the URL you want to GET; provide a callback as the second argument.

  Unlike other callback functions, this one has the signature:

     function callback (response) { /* … */ }

  Where the response object is a Node Stream object. You can treat Node Streams as objects that emit events. The three events that are of most interest are: “data”, “error” and “end”. You listen to an event like so:

     response.on(“data”, function (data) { /* … */ })

  The “data” event is emitted when a chunk of data is available and can be processed. The size of the chunk depends upon the underlying data source.

  The response object / Stream that you get from http.get() also has a setEncoding() method. If you call this method with “utf8”, the “data” events will emit Strings rather than the standard Node Buffer objects which you have to explicitly convert to Strings.

The actual web page link is:

https://nodejs.org/dist/latest-v6.x/docs/api/http.html

Okay, first thing is to declare our variables.  we’ll need a require statement for http – note that it has to be in lowercase letters.  We will also assign the address they give us on the command line to addr.  As you know, it’s the third argument but element[2] due to the fact that arrays begin with 0!  We have:

var http = require('http');
var addr = process.argv[2];

So, we’re going to call http.get(); it’s arguments will be the URL they give us as well as a callback function.  Inside that call to get we will call the response.on function. We can also add a setEncoding statement as noted in the hints.  So:

var http = require('http');
var addr = process.argv[2];

http.get(addr, function callback(response) {
response.setEncoding('utf8');
response.on("data", function (data) { /* ... */ });
// consume response body

})

We need to handle an error.  A little web searching gives us a chained method:

var http = require('http');
var addr = process.argv[2];

http.get(addr, function callback(response) {
response.setEncoding('utf8');
response.on("data", function (data) {  /* ... */ });
// consume response body

}).on('error', (e) => {
console.log(`Got error: ${e.message}`);
});

Okay, we’ve done the easy parts.  Now, We need to figure out what goes in the response.on function.

Well, we want to write the results to the console, right?  No problem!  So,

var http = require('http');
var addr = process.argv[2];

http.get(addr, function callback(response) {
response.setEncoding('utf8');
response.on("data", function (data) { console.log(data); });
// consume response body

}).on('error', (e) => {
console.log(`Got error: ${e.message}`);
});

Ouch!  Errors everywhere!

Okay, a little trial and error, and a little reading of the http.get() documentation, reveals that first, we need to add a response.resume() statement to keep things moving.  Second, we want the data from addr to be printed out.  So we add the resume statement and modify the response.on() statement per these items, and our final program is:

PROGRAM (program6.js):

var http = require('http');
var addr = process.argv[2];

http.get(addr, function callback(response) {
response.setEncoding('utf8');
response.on("data", function (addr) { console.log(addr); });
// consume response body
response.resume();
}).on('error', (e) => {
console.log(`Got error: ${e.message}`);
});

And there you have it!  See you next time!

MilSats: D-Day

June 6, 1944.  Allied troops storm the beaches at Normandy, and the assault on Fortress Europe has begun.  It was one of the biggest amphibious operations in history.

Today, US Forces still train to hit the beach.