Rest API Benchmark comparison between Ada and Java Read more

by Java 2 Ada

Arcadius Ahouansou from Menelic.com made an interesting benchmark to compare several Java Web servers: Java REST API Benchmark: Tomcat vs Jetty vs Grizzly vs Undertow, Round 3. His benchmark is not as broad as the TechEmpower Benchmark but it has the merit to be simple to understand and it can be executed very easily by everyone. I decided to make a similar benchmark for Ada Web servers with the same REST API so that it would be possible to compare Ada and Java implementations.

The goal is to benchmark the following servers and have an idea of how they compare with each others:

The first three are implemented in Ada and the last one in Java.

REST Server Implementation

The implementation is different for each server but they all implement the same REST GET operation accessible from the /api base URL. They return the same JSON content:

{"greeting":"Hello World!"}

Below is an extract of the server implementation for each server.

AWS Rest API Server

function Get_Api (Request : in AWS.Status.Data) return AWS.Response.Data is
begin
   return AWS.Response.Build ("application/json", "{""greeting"":""Hello World!""}");
end Get_Api;

ASF Rest API Server

procedure Get (Req    : in out ASF.Rest.Request'Class;
               Reply  : in out ASF.Rest.Response'Class;
               Stream : in out ASF.Rest.Output_Stream'Class) is
begin
   Stream.Start_Document;
   Stream.Write_Entity ("greeting", "Hello World!");
   Stream.End_Document;
end Get;

EWS Rest API Server

function Get (Request : EWS.HTTP.Request_P) return EWS.Dynamic.Dynamic_Response'Class is
   Result : EWS.Dynamic.Dynamic_Response (Request);
begin
   EWS.Dynamic.Set_Content_Type (Result, To => EWS.Types.JSON);
   EWS.Dynamic.Set_Content (Result, "{""greeting"":""Hello World!""}");
   return Result;
end Get;

Java Rest API Server

@Produces(APPLICATION_JSON_UTF8_VALUE)
@Path("/api")
@Component
public class ApiResource {
  public static final String RESPONSE = "{\"greeting\":\"Hello World!\"}";
  
  @GET
  public Response test() {
      return ok(RESPONSE).build();
  }
}

Benchmark Strategy and Results

The Ada and Java servers are started on the same host (one at a time), a Linux Ubuntu 14.04 64-bit powered by an Intel i7-33770S CPU @3.10Ghz with 8-cores. The benchmark is made by using Siege executed on a second computer running Linux Ubuntu 15.04 64-bit powered by an Intel i7-4720HQ CPU @2.60Ghz with 8-cores. Client and server hosts are connected through a Gigabit Ethernet link.

Siege makes an intensive use of network connections which results in exhaustion of TCP/IP port to connect to the server. This is due to the TCP TIME_WAIT that prevents the TCP/IP port from being re-used for future connections. To avoid such exhaustion, the network stack is tuned on both the server and the client hosts with the sysctl commands:

sudo sysctl -w net.ipv4.tcp_tw_recycle=1
sudo sysctl -w net.ipv4.tcp_tw_reuse=1

The benchmark tests are executed by running the run-load-test.sh script and then making GNUplot graphs using plot-perf.gpi script. The benchmark gives the number of REST requests which are made per second for different level of concurrency.

  • The Embedded Web Server targets embedded platforms and it uses only one task to serve requests. Despite this simple configuration, it gets some honorable results as it reaches 8000 requests per second.
  • The Ada Server Faces provides an Ada implementation of Java Server Faces. It uses the Ada Web Server. The benchmark shows a small overhead (arround 4%).
  • The Ada Web Server is the fastest server in this configuration. As for the Ada Server Faces it is configured to only have 8 tasks that serve requests. Increasing the number of tasks does not bring better performance.
  • The Java Grizzly server is the faster Java server reported by Arcadius's benchmark. It uses 62 threads. It appears to serve 7% less requests than the Ada Web Server.

ada-rest-api-benchmark.png

On the memory side, the process Resident Set Size (RSS) is measured once the benchmark test ends and graphed below. The Java Grizzly server uses arround 580 Mb, followed by Ada Server Faces that uses 5.6Mb, Ada Web Server 3.6Mb and the EWS only 1 Mb.

ada-rest-api-memory.png

Conclusion and References

The Ada Web Server has comparable performance with the Java Grizzly server (it is even a little bit faster). But as far a memory is concerned, Ada has a serious advantage since it cuts the memory size by a factor of 100. Ada has other advantages that make it an alternative choice for web development (safety, security, realtime capabilities, ...).

Sources of the benchmarks are available in the following two GitHub repositories:


Atlas 1.0.0 the Ada Web Application demonstrator available as Docker image Read more

by Java 2 Ada

Atlas is a small application intended to show various features provided by the Ada Web Application framework. The application features:

  • A small blogging system,
  • A question and answer area,
  • A complete wiki system,
  • A document and image storage space,
  • Authentication with Google+ or Facebook.

atlas-mashup.png

Atlas is now available as a Docker image so that you can easily try it.

What is Docker ?

Docker is a container platform that allows to run applications on the host but within an isolated environment. The container has its own libraries, its own network, its own root file system but it shares the same running Linux kernel as the host. Docker is based on Linux containers which provides kernel namespaces and cgroups. Docker provides a lot of abstractions that simplifies the creation, startup and management of containers.

To learn more about Docker, you may have a look at the Get started with Docker documentation.

Using the Atlas Docker image

The Atlas Docker image is available at the Docker Hub cloud-based registry service. This registry allows you to get and synchronize your local Docker images easily by pulling them from the cloud.

Assuming that you have installed Docker, you can pull the Atlas Docker image by using the following command:

  sudo docker pull ciceron/atlas

Beware that the Docker image is a 64-bit image so it runs only on Linux x86_64 hosts. Once you have obtained the image, you can create the container and start it as follows:

  sudo docker run --name atlas -p 8080:8080 ciceron/atlas

and then point your browser to http://localhost:8080/atlas/index.html The -p 8080:8080 option tells Docker to expose the TCP/IP port 8080 from the container to the host so that you can access the web application.

The application will first display some installation page that allows you to choose the database, configure the mail server and the Google and Facebook connexions (most of the default values should be correct).

To stop and cleanup the docker container, you can use the following commands:

  sudo docker stop atlas
  sudo docker rm atlas

Learning more about Ada Web Application

You may read the following tutorials to lean more about the technical details about setting up and building an Ada Web Application:


Ada with a side of JSON Read more

by Thomas Løcke Rambling

So, you've got Ada and you need to handle some JSON data, but you're not quite sure if there are tools available, or if you're going to have to come up with a homegrown solution. Well, as luck will have it, you need look no further than to the excellent GNATColl library from libre.adacore.com:

The GNAT Component Collection is a suite of reusable software components and utilities. It has been used by AdaCore in developing the GNAT tool set, the GPS Integrated Development Environment, and GNAT Tracker, its web-based customer support interface.

There's a lot of really nice stuff in GNATColl, but today I'll focus on the very new and shiny JSON features. Actually, at the time of writing, the GNATColl JSON facilities are so new that they haven't even made it into the GNATColl manual yet, but that's not really a problem, since they are so very easy to grasp.

But before we can get cracking on the actual Ada code, we need to install GNATColl. My personal preference is to go with the latest development snapshot:



Obviously you should take a look at the configure options, so you don't end up trying to compile features you don't want/need. Also it's worth noting that if you want to be sure of success, then it's probably best to use the GNAT GPL compiler from AdaCore. Once you've made it work with that, you can start experimenting with the FSF GCC compiler. I've compiled GNATColl with GCC 4.6.2, so I can at least attest to the fact that GNATColl compiled with that specific version at the time of writing.

So, now that we have GNATColl available, lets get down and dirty with some JSON.

Step one is to initialize an empty JSON_Value variable:



Running that should give you this output:

Yes, Penguin is a JSON object

The Create_Object call is where the magic is at. This gives us an empty JSON object, to which we can add values using the Set_Field procedure. The Kind function returns the kind of JSON_Value we're dealing with. There are 7 kinds:



It should be obvious what kinds of data the different types contain.

So, currently we've got an empty Penguin JSON object, next step is naming the cute little fellow. Add this to the JSON_Fun program:



And voila! We've got a penguin named Linux. Amazing stuff eh? In the above snippet we encounter two key subprograms in the GNATCOLL.JSON package: Set_Field and Get. The former adds data to a JSON_Value object, while the latter retrieves data. There are Set_Field and Get subprograms for all the available JSON_Value_Type's.

Moving on, lets give our penguin some parents. As we all know, Linux got a lot of parents, but we'll settle on adding three of those to a JSON_Array:



Woah! Lots of new stuff going on here. Lets take it from the top. First we declare a new JSON_Array object: Parents. We then append JSON_Value objects to Parents using the Append procedure, which takes a JSON_Array as its first parameter and a JSON_Value as its second. If you've programmed for more than 2 weeks, you should already have guessed that the value of the second parameter is appended to the JSON_Array given as the first parameter. There's an alternative method: Using the "&" function. It's slower, but to some the code is more readable:



I personally like the Append approach, but you can use whatever floats your boat. Naturally you can append both JSON_Value's and JSON_Array's.

Next we have the Create function. There's a series of Create functions in the GNATCOLL.JSON package, each returning a JSON_Value containing the data given in its sole parameter. In our case we give Create a String, so it returns a JSON_Value where the JSON_Value_Type is JSON_String_Type.

The Length (Parents) call returns the amount (Natural) of items in the Parents array, and in the loop we make use of that number to set the range. It would've been nice to not have to define the lower bound of the range with an actual number. I would've much preferred something like Parents'Range, but hey, you can't have it all.

In the loop we stumble on a less than pretty construction:



Gaggle! Lots of Get'ing going on there. But before you tear your hair out in frustration, lets take a look at the specification for the two Get functions used here:



Aha! Suddenly everything makes sense again. One could argue that readability could've been improved slighty, had the innermost call been named differently, but since that's not the case, we're just going to have to live with Get'ing twice.

Finally we output the JSON we've created:



Executing the program results in this:

Yes, Penguin is a JSON object
Our Penguin is named Linux
Linux got 3 parents.
They are:
Linus Torvalds
Alan Cox
Greg Kroah-Hartman
{"parents":["Linus Torvalds", "Alan Cox", "Greg Kroah-Hartman"], "name":"Linux"}

Amazing! Now, just as there's a Write function for turning a JSON object into a String, there's also a Read function to turn a JSON String into a JSON_Value object:



We Read the JSON String generated by the Write (Penguin) call into our newly declared Pingu object. The Filename parameter gives a file to where error messages are written, in case the given JSON String is mangled in some way. The two Set_Field calls overwrite the name and parents fields with new values (another famous penguin!), and finally we output the new JSON String, adding this to the previous output:

{"parents":"Otmar Gutmann", "name":"Pingu"}

Neat eh?

Using the Map_JSON_Object procedure it is also possible to iterate a JSON_Value object:



So as you can see, you can do most everything with the tools available in GNATCOLL.JSON - there is though one thing I feel is missing: Facilities to delete fields in a JSON_Value object, but I'm sure these will come as the package matures.

For the sake of completeness, here's the full listing of our penguin example:



I hope you've enjoyed reading this short introduction to the GNATCOLL.JSON package. Ada and JSON is a pretty good match, so if you don't need or want all the complexities of XML, then give JSON a chance. The tools are available and they are pretty good.

Consolidated RM available in EMACS info format Read more

by AdaIC

The consolidated Ada Reference manual is now available in EMACS info format, through the efforts of Stephen Leake. Find out more at his site — http://stephe-leake.org/ada/arm.html. The consolidated Ada 2012 Reference manual includes the original third edition (Ada 2012) and the corrections from Technical Corrigendum 1.

Tracking down a Program_Error Read more

by Forward in Code

A StackOverflow question about a Storage_Error exception when trying to implement a FastCGI example in Ada prompted me to investigate.

Read more »

GDB vs macOS Sierra Read more

by Forward in Code

We probably feel downhearted if we need to use the debugger to find out what's wrong with our Ada code.

Under those circumstances, we feel even more frustrated if the debugger doesn't work!

This is exactly what has happened with gdb and increased security in macOS Sierra.

Read more »

Two Compilers for FreeBSD ARM64 Read more

by DragonLace

Last week, a new cross-compiler based on GnatDroid was introduced into the FreeBSD Ports Collection. The host machine for this compiler is x86 FreeBSD or DragonFly while the target is aarch64--freebsd (FreeBSD/ARM64).

See Freshports GnatCross AArch64

This cross compiler was then used to bootstrap a native FSF GCC 6.3.1 with Ada frontend on FreeBSD/ARM64 (based on the 64-bit ARMv8 architecture). It passes every test in the GCC testsuite thanks to FreeBSD-specific signal frame unwinder I wrote that will be pushed to upstream to the GNU GCC project.

See Freshports GCC6-AUX

The existing GCC6-AUX port was updated to support aarch64, increasing the number of platforms to four:

  • FreeBSD i386
  • FreeBSD x86-64
  • FreeBSD aarch64
  • DragonFly x86-64

In related pkgsrc news, lang/gcc5-aux was upgraded from vesion 5.1 to 5.4 and lang/gcc6-aux (version 6.2) was introduced at the end of 2016. They support FreeBSD, DragonFly, and SunOS, but are limited to x86 architecture.


Ahven status update, January 2017 Read more

by Tero Koskinen

Even though I didn't manage to make any Ahven releases in year 2016 and the build job for Ahven as been failing for 6 months or so, I haven't completely abandoned it.

I added some performance tests and converted from Bounded_String usage to Unbounded_Strings. This helped with memory consumption for simple tests.

One of my long term plans had been to create functional tests for Ahven. Currently, Ahven is tested only by its own unit tests and that isn't enough.

My first option was to use cram for this functional tests, but recently I have started to think if the tests should be done using Robot Framework.

I also played a little with Gource and visualized Ahven's full Mercurial commit history (20MB video).

And made Ahven's homepage accessible via https.


Retrospective 2016 Read more

by Gautier de Montmollin

  • Ada PDF Writer. First release in 2016. Link here.
  • AZip 2.0. First release with standard Deflate compression format and a recompression tool for squeezing Zip archives smaller, with an automatic algorithm picking depending on data types. Link here.
  • Excel Writer. Internationalization and zoom factor added. Link here.
  • GID (Generic Image Decoder). Maintenance release. Added a chart reverse-engineering tool. Link here.
  • GLOBE_3D. Added multi-texturing (specular textures added for shiny effects). Uses GID for decoding textures (broad choice of image formats). Added Wavefront object format importer. Link here.
  • Mathpaqs. Maintenance release. The Copula package can use a vector of pseudo-random generators instead of a single generator. Link here.
  • Zip-Ada. Added a "true" - and original - Deflate algorithm which scans the LZ-compressed data stream for setting up compression blocks, but without losing too much time doing so (Taillaule algorithm). Added an original LZMA algorithm which uses floating-point calculations for probability estimates of encoding variants. On some data formats (such as raw camera image data or mobile device data) this algorithm outpaces all existing LZMA-based compressions on the SqueezeChart benchmark! Link to Zip-Ada here.
Oh, perhaps it's worthwhile to remind it: all of this software is fully in Ada. With the exception of AZip, it builds "out-of-the box" on at least two independent Ada toolsets: AdaCore GNAT, and PTC ObjectAda.

Simple UDP Echo Server on STM32F746 Read more

by Java 2 Ada

Writing a simple UDP server in Ada for a STM32F746 ARM controller is now easy with the use of the Ada Embedded Network stack. The article describes through a simple UDP echo server the different steps for the implementation of an UDP server.

Overview

The Echo server listens to the UDP port 7 on the Ethernet network and it sends back the received packet to the sender: this is the RFC 862 Echo protocol. Our application follows that RFC but it also maintains a list of the last 10 messages that have been received. The list is then displayed on the STM32 display so that we get a visual feedback of the received messages.

The Echo server uses the DHCP client to get and IPv4 address and the default gateway. We will see how that DHCP client is integrated in the application.

The application has two tasks. The main task loops to manage the refresh of the STM32 display and also to perform some network housekeeping such as the DHCP client management and ARP table management. The second task is responsible for waiting Ethernet packets, analyzing them to handle ARP, ICMP and UDP packets.

Through this article, you will see:

  1. How the STM32 board and network stack are initialized,
  2. How the board gets an IPv4 address using DHCP,
  3. How to implement the UDP echo server,
  4. How to build and test the echo server.

Initialization

STM32 Board Initialization

First of all, the STM32 board must be initialized. There is no random generator available in the Ada Ravenscar profile and we need one for the DHCP protocol for the XID generation. The STM32 provides a hardware random generator that we are going to use. The Initialize_RNG must be called once during the startup and before any network operation is called.

We will use the display to list the messages that we have received. The Display instance must be initialized and the layer configured.

with HAL.Bitmap;
with STM32.RNG.Interrupts;
with STM32.Board;
...
   STM32.RNG.Interrupts.Initialize_RNG;
   STM32.Board.Display.Initialize;
   STM32.Board.Display.Initialize_Layer (1, HAL.Bitmap.ARGB_1555);
Network stack initialization

The network stack will need some memory to receive and send network packets. As described in Using the Ada Embedded Network STM32 Ethernet Driver, we allocate the memory by using the SDRAM.Reserve function and the Add_Region procedure to configure the network buffers that will be available.

An instance of the STM32 Ethernet driver must be declared in a package. The instance must be aliased because the network stack will need to get an access to it.

with Interfaces;
with Net.Buffers;
with Net.Interfaces.STM32;
with STM32.SDRAM;
...
   NET_BUFFER_SIZE : constant Interfaces.Unsigned_32 := Net.Buffers.NET_ALLOC_SIZE * 256;
   Ifnet : aliased Net.Interfaces.STM32.STM32_Ifnet;

The Ethernet driver is initialized by calling the Initialize procedure. By doing so, the Ethernet receive and transmit rings are configured and we are ready to receive and transmit packets. On its side the Ethernet driver will also reserve some memory by using the Reserve and Add_Region operations. The buffers allocated will be used for the Ethernet receive ring.

   Net.Buffers.Add_Region (STM32.SDRAM.Reserve (Amount => NET_BUFFER_SIZE), NET_BUFFER_SIZE);
   Ifnet.Initialize;

The Ethernet driver configures the MII transceiver and enables interrupts for the receive and transmit rings.

Getting the IPv4 address with DHCP

At this stage, the network stack is almost ready but it does not have any IPv4 address. We are going to use the DHCP protocol to automatically get an IPv4 address, get the default gateway and other network configuration such as the DNS server. The DHCP client uses a UDP socket on port 68 to send and receive DHCP messages. Such DHCP client is provided by the Net.DHCP package and we need to declare an instance of it. The DHCP client is based on the UDP socket support that we are going to use for the echo server. The DHCP client instance must be declared aliased because the UDP socket layer need to get an access to it to propagate the DHCP packets that are received.

with Net.DHCP;
...
   Dhcp : aliased Net.DHCP.Client;

The DHCP client instance must be initialized and the Ethernet driver interface must be passed as parameter to correctly configure and bind the UDP socket. After the Initialize procedure is called, the DHCP state machine is ready to enter into action. We don't have an IPv4 address after the procedure returns.

   Dhcp.Initialize (Ifnet'Access);

The DHCP client is using an asynchronous implementation to maintain the client state according to RFC 2131. For this it has two important operations that are called by tasks in different contexts. First the Process procedure is responsible for sending requests to the DHCP server and to manage the timeouts used for the retransmissions, renewal and lease expiration. The Process procedure sends the DHCPDISCOVER and DHCPREQUEST messages. On the other hand, the Receive procedure is called by the network stack to handle the DHCP packets sent by the DHCP server. The Receive procedure gets the DHCPOFFER and DHCPACK messages.

Getting an IPv4 address with the DHCP protocol can take some time and must be repeated continuously due to the DHCP lease expiration. This is why the DHCP client must not be stopped and should continue forever.

Refer to the DHCP documentation to learn more about this process.

UDP Echo Server

Logger protected type

The echo server will record the message that are received. The message is inserted in the list by the receive task and it is read by the main task. We use the an Ada protected type to protect the list from concurrent accesses.

Each message is represented by the Message record which has an identifier that is unique and incremented each time a message is received. To avoid dynamic memory allocation the list of message is fixed and is represented by the Message_List array. The list itself is managed by the Logger protected type.

type Message is record
   Id      : Natural := 0;
   Content : String (1 .. 80) := (others => ' ');
end record;
type Message_List is array (1 .. 10) of Message;

protected type Logger is
   procedure Echo (Content : in Message);
   function Get return Message_List;
private
   Id   : Natural := 0;
   List : Message_List;
end Logger;

The Logger protected type provides the Echo procedure to insert a message to the list and the Get function to retrieve the list of messages.

Server Declaration

The UDP Echo Server uses the UDP socket support provided by the Net.Sockets.UDP package. The UDP package defines the Socket abstract type which represents the UDP endpoint. The Socket type is abstract because it defines the Receive procedure that must be implemented. The Receive procedure will be called by the network stack when a UDP packet for the socket is received.

The declaration of our echo server is the following:

with Net.Buffers;
with Net.Sockets;
...
   type Echo_Server is new Net.Sockets.UDP.Socket with record
      Count    : Natural := 0;
      Messages : Logger;
   end record;

It holds a counter of message as well as the messages in the Logger protected type.

The echo server must implement the Receive procedure:

overriding
procedure Receive (Endpoint : in out Echo_Server;
                   From     : in Net.Sockets.Sockaddr_In;
                   Packet   : in out Net.Buffers.Buffer_Type);

The network stack will call the Receive procedure each time a UDP packet for the socket is received. The From parameter will contain the IPv4 address and UDP port of the client that sent the UDP packet. The Packet parameter contains the received UDP packet.

Server Implementation

Implementing the server is very easy because we only have to implement the Receive procedure (we will leave the Logger protected type implementation as an exercise to the reader).

First we use the Get_Data_Size function to get the size of our packet. The function is able to return different sizes to take into account one or several protocol headers. We want to know the size of our UDP packet, excluding the UDP header. We tell Get_Data_Size we want to get the UDP_PACKET size. This size represents the size of the echo message sent by the client.

   Msg    : Message;
   Size   : constant Net.Uint16 := Packet.Get_Data_Size (Net.Buffers.UDP_PACKET);
   Len    : constant Natural
        := (if Size > Msg.Content'Length then Msg.Content'Length else Natural (Size));

Having the size we truncate it so that we get a string that fits in our message. We then use the Get_String procedure to retrieve the echo message in a string. This procedure gets from the packet a number of characters that corresponds to the string length passed as parameter.

   Packet.Get_String (Msg.Content (1 .. Len));

The Buffer_Type provides other Get operations to extract data from the packet. It maintains a position in the buffer that tells the Get operation the location to read in the packet and each Get updates the position according to what was actually read. There are also several Put operations intended to be used to write and build the packet before sending it. We are not going to use them because the echo server has to return the original packet as is. Instead, we have to tell what is the size of the packet that we are going to send. This is done by the Set_Data_Size procedure:

   Packet.Set_Data_Size (Size);

Here we want to give the orignal size so that we return the full packet.

Now we can use the Send procedure to send the packet back to the client. We use the client IPv4 address and UDP port represented by From as the destination address. The Send procedure returns a status that tells whether the packet was successfully sent or queued.

Status : Net.Error_Code;
...
   Endpoint.Send (To => From, Packet => Packet, Status => Status);
Server Initialization

Now that the Echo_Server type is implemented, we have to make a global instance of it and bind it to the UDP port 7 that corresponds to the UDP echo protocol. The port number must be defined in network byte order (as in Unix Socket API) and this is why it is converted using the To_Network function. We don't know our IPv4 address and by using 0 we tell the UDP stack to use the IPv4 address that is configured on the Ethernet interface.

Server : aliased Echo_Server;
...
   Server.Bind (Ifnet'Access, (Port => Net.Headers.To_Network (7),
                               Addr => (others => 0)));

Main loop and receive task

As explained in the overview, we need several tasks to handle the display, network housekeeping and reception of Ethernet packets. To make it simple the display, ARP table management and DHCP client management will be handled by the main task. The reception of Ethernet packet will be handled by a second task. It is possible to use a specific task for the ARP management and another one for the DHCP but there is no real benefit in doing so for our simple echo server.

The main loop repeats calls to the ARP Timeout procedure and the DHCP Process procedure. The Process procedure returns a delay that we are supposed to wait but we are not going to use it for this example. The main loop simply looks as follows:

Dhcp_Timeout : Ada.Real_Time.Time_Span;
...
   loop
      Net.Protos.Arp.Timeout (Ifnet);
      Dhcp.Process (Dhcp_Timeout);
      ...
      delay until Ada.Real_Time.Clock + Ada.Real_Time.Milliseconds (500);
   end loop;

The receive task was described in the previous article Using the Ada Embedded Network STM32 Ethernet Driver. The task is declared at package level as follows:

   task Controller with
     Storage_Size => (16 * 1024),
     Priority => System.Default_Priority;

And the implementation loops to receive packets from the Ethernet driver and calls either the ARP Receive procedure, the ICMP Receive procedure or the UDP Input procedure. The complete implementation can be found in the receive.adb file.

Building and testing the server

To build the UDP echo server and have it run on the STM32 board is a three step process:

  1. First, you will use the arm-eabi-gnatmake command with the echo GNAT project. After successful build, you will get the echo ELF binary image in obj/stm32f746disco/echo.
  2. Then, the ELF image must be converted to binary by extracting the ELF sections that must be put on the flash. This is done by running the arm-eabi-objcopy command.
  3. Finaly, the binary image produced by arm-eabi-objcopy must be put on the flash using the st-util utility. You may have to press the reset button on the board so that the st-util is able to take control of the board; then release the reset button to let st-util the flash the image.

To help in this process, you can use the Makefile and simply run the following make targets:

make echo
make flash-echo

Once the echo application is running, it displays some banner with the information of the DHCP state machine. Once the IPv4 address is obtained, it is displayed with the gateway and the DNS. Take that IPv4 address and use the following command to send message and have them written on the display:

echo -n 'Hello! Ada is great!' | socat - UDP:192.168.1.156:7

(replace 192.168.1.156 with the IPv4 address displayed on the board).

ada-enet-hello.png

The above message was printed with the following script:

#!/bin/sh
IP=$1
FILE=$2
while IFS='' read -r line ; do
  echo -n "$line" | socat - UDP:$IP:7
done < $FILE

and a text file generated with the UNIX System V banner utility.

References

Sources of the article are available in Github https://github.com/stcarrez/ada-enet and you may browse the following files and documentation:


GID release #06 - with Recurve, a chart data recovery tool Read more

by Gautier de Montmollin

GID means Generic Image Decoder, a free, open-source library that can be found here.

The latest release features a couple of new application examples, among them a tool called Recurve for retrieving data from an image with plotted curves. Typically you come across a chart on a web site and would like to get the corresponding data, for reworking them in Excel - perhaps you want to spot specific values, or compare two curves that were not originally on the same chart, or use the data for further calculation. Sometimes the data is not available from the web site - and even less if the chart is from a PDF or a scanned newspaper page.

Fortunately, Recurve will do the painful job of retrieving the data points for you. It will detect gridlines and filter them out, then track the curves by matching their respective colours.

An example here:
Mortgage rates in Switzerland - 2004 to now. Chart is from the Comparis web site


GLOBE_3D Release 2016-07-05 - "Blender edition" Read more

by Gautier de Montmollin

GLOBE_3D is a GL Object Based 3D engine realized with the Ada programming language.
URL: http://globe3d.sf.net

Latest additions:
  • Use of Generic Image Decoder (GID) in GL.IO; now most image formats are supported for textures and other bitmaps to be used with GLOBE_3D (or any GL app)
  • New Wavefront format (.obj / .mtl) importer
  • Doom 3 / Quake 4 map importer more complete
  • Unified GNAT project file (.gpr), allowing to selected the target Operating System (Windows, Linux, Mac) and compilation mode (fast, debug, small) for demos, tools, etc.
  • Project file for ObjectAda 9.1+ updated
The first two points facilitate the import of 3D models from software such as Blender.
Here is an example:
Click to enlarge
Coincidentally, the Wavefront file format so simple that you can also write 3D models "by hand" in that format. An example made in an Excel sheet is provided along with the importer, in the ./tools/wavefront directory.

Click to enlarge
Enjoy!

GLOBE_3D: most image formats now available for textures Read more

by Gautier de Montmollin

The texture loader in GL.IO was around 15 years old and supported only the Targa (.tga) format for textures, plus a few sub-formats of Windows bitmaps (.bmp).
In order to make things easy when dealing with various models, e.g. those imported from Blender, the old code for reading images has been wiped out and the loader is using now GID for the job, supporting JPEG or PNG in addition. For instance the Blender model below is using the JPEG format for textures.

Futuristic Combat Jet (hi poly version) by Dennis Haupt (DennisH2010)

The following Blender model has a single PNG texture projected on a complicated surface called a Mandelbulb (never heard of before!) :

Mandelbulb 3D Panorama 3 by DennisH2010


GLOBE_3D is a GL Object Based 3D engine realized with the Ada programming language.

URL: http://globe3d.sf.net/


AVR-Ada 1.2.2 RPMs for Fedora 25 Read more

by Tero Koskinen on AVR/Ada

Sparkfun DIY Arduino with ftdi cable

I have been slacking with Fedora AVR-Ada rpm binaries, but finally I found some time to make new binary rpms. These binaries are for Fedora 25 (x86_64), which will be released later in this month. I generated them on Fedora 25 (Server) Beta, but they should work on the released Fedora 25 version also.

Like always, create file /etc/yum.repos.d/fedora-adalanguage.repo with contents:

[fedora-adalanguage]
name=Tero's Fedora RPM repository for Ada packages
baseurl=http://fedora.ada-language.com/repo/$releasever/$basearch
enabled=1

And run:

sudo dnf install avr-ada --nogpgcheck

Notes:

  • The used GCC version is 4.9.2.
  • Instead of using normal .spec files + rpmbuild, I build the binaries with my custom build script and fpm (for installation, you need only dnf).
  • The installation happens to /opt/avr-ada-122
  • The RPMs are unofficial in every possible way and they are not endorsed by Fedora or AVR-Ada projects.

Zip-Ada v.52 - featuring LZMA compression Read more

by Gautier de Montmollin

In case you missed it, there is a new version of Zip-Ada @ http://unzip-ada.sf.net .

Actually, these are two successive versions: v.51 with a basic LZMA encoder, v.52 with a more advanced one.
The shift from v.50 to v.51 ensured 52 steps up in the Squeeze Chart benchmark, although the LZ part remained identical and the new "MA" part is a simple, straightforward encoder which comes in replacement of our sophisticated Taillaule algorithm for the Deflate format. This shows just how much the LZMA format is superior to Deflate.
Then, from v.51 to v.52, there were 45 more steps upward. This is due to a combination of a better-suited LZ algorithm, and a refinement of the "MA" algorithm - details below.

* Changes in '51', 27-Aug-2016:
  - LZMA.Encoding has been added; it is a standalone compressor,
      see lzma_enc.adb for an example of use.
  - Zip.Compress provides now LZMA_1, LZMA_2 methods. In other words, you
      can use the LZMA compression with Zip.Create.
  - Zip.Compress has also a "Preselection" method that selects
      a compression method depending on hints like the uncompressed size.
  - Zip.Compress.Deflate: Deflate_1 .. Deflate_3 compression is
      slightly better.

The LZMA format, new in Zip-Ada on the encoding side, is especially good for compressing database data - be it in binary or text forms. Don't be surprised if the resulting archive represent only a few percents of the original data...
The new piece of code, LZMA.Encoding, has been written from scratch. This simple version, fully functional, holds in only 399 lines, after going through J-P. Rosen's Normalize tool.
It can be interesting for those who are curious about how the "MA" part of that compression algorithm is working.
The code can be browsed here.

* Changes in '52', 08-Oct-2016:
  - UnZip.Streams: all procedures have an additional (optional)
      Ignore_Directory parameter.
  - Zip.Compress has the following new methods with improved compression:
      LZMA_3, Preselection_1 (replaces Preselection), Preselection_2.
      Preselection methods use now entry name extension and size for
      improving compression, while remaining 1-pass methods.

For those interested about what's happening "under the hood", LZMA.Encoding now computes (with floating-point numbers, something unusual in compression code!) an estimation of the predicted probabilities of some alternative encodings, and chooses the most probable one - it gives an immediate better local compression. Sometimes the repetition of such a repeated short-run improvement has a long-run positive effect, but sometimes not - that's where it's beginning to be fun...


MPU9250, continued Read more

by Forward in Code

This is a note on building support for the MPU92509-axis chip in the AdaPilotproject (the AdaRacerhardware). It continues this report.

Read more »

AZip 2.0 Read more

by Gautier de Montmollin

The version 2.0 of AZip is out!

    URL: http://azip.sf.net/

AZip is a Zip archive manager.

The latest addition is an archive recompression tool.

AZip's recompression tool's results - click to enlarge
Some features: 

    - Multi-document (should be familiar to MS Office users)
    - Flat view / Tree view
    - Simple to use (at least I hope so ;-) )
    - Useful tools:
        - Text search function through an archive, without having to extract files
        - Archive updater
        - Integrity check
        - Archive recompression (new), using an algorithm-picking approach for improving a zip archive's compression.
    - Encryption
    - Methods supported: Reduce, Shrink, Implode, Deflate, Deflate64, BZip2, LZMA
    - Free, open-source
    - Portable (no installation needed, no DLL, no configuration file)

"Under the hood" features:

    - AZip is from A to Z in Ada :-)
    - Uses the highly portable Zip-Ada library
    - Portablity to various platforms: currently it's fully implemented with GWindows (for Windows), and there is a GtkAda draft, but anyway the key parts of the UI and user persistence are generic, platform-independent

Enjoy!

Software Serial for Adafruit Trinket (TX only) Read more

by Tero Koskinen on AVR/Ada

Trinket on breadboard

Some AVR devices, like attiny85 (on Adafruit Trinket, for example), do not have hardware UART. However, it would be still nice to have serial output from them.

I wrote a simple Soft_Serial package, which can use any GPIO pin as TX UART pin.

package Soft_Serial is
   Serial_Pin : Boolean renames AVR.MCU.PORTB_Bits (2);
   Serial_Pin_DD : Boolean renames AVR.MCU.DDRB_Bits (2);

   procedure Init;
   procedure Write_Byte(B : Interfaces.Unsigned_8);
   procedure Write (S : AVR.Strings.AVR_String);
end Soft_Serial;

The interesting bits in the implementation are:

MCU_FREQ : constant := 16_000_000;

procedure Wait_A_Little is new AVR.Wait.Generic_Wait_USecs
     (Crystal_Hertz => MCU_FREQ,
      Micro_Seconds => 102);

procedure Write_Byte(B : Interfaces.Unsigned_8) is
   Data : Interfaces.Unsigned_8 := B;
   Mask : Interfaces.Unsigned_8 := 1;
begin
   Serial_Pin := False;
   Wait_A_Little;
   for I in Interfaces.Unsigned_8 range 0 .. 7 loop
      if (Data and Mask) = Mask then
         Serial_Pin := True;
      else
         Serial_Pin := False;
      end if;
      Wait_A_Little;
      Mask := Mask * 2;
   end loop;
   Serial_Pin := True;
   Wait_A_Little;
end Write_Byte;

Basically, the Write_Byte procedure will put the GPIO pin up or down with certain intervals.

The Wait_A_Little procedure has magic number 102, which gives us UART speed 9600bps. (9600bps means one bit about every 104 microseconds, the difference comes from the inaccurate internal oscillator.)

The procedure uses 8N1 format, meaning that the start bit (pin low) is sent first, then the data byte as 8 bits, and finally one stop bit (pin high).

The example code can be found from Bitbucket as usual.


The application is damaged and can't be opened Read more

by Forward in Code

I downloaded a new version of eclipseArduino(Arduino development within Eclipse). After unpacking and moving to /Applications, I get the message

"eclipseArduino" is damaged and can't be opened. You should move it to the Trash.

Huh.

After a lot of poking around, I found this:

  1. Open Gatekeeper settings located in System Preferences > Security & Privacy.
  2. Set Allow applications downloaded from: to Anywhereand confirm by pressing Allow From Anywhere.
  3. Run the application.
  4. Once the application has been successfully launched, it no longer goes through Gatekeeper; so, restore Gatekeeper settings to the default option Mac App Store and identified developers after successfully launching the application.

Invensense MPU9250 via SPI Read more

by Forward in Code

This is a note on building support for the MPU92509-axis chip in the AdaPilotproject (the AdaRacerhardware; the prototype board I have is subtly different from the one shown).

9-axis means it can measure each of acceleration, gyro and magnetic field values in 3 axes, which is very useful if your drone needs to know about its own motion.

Read more »