[JSON] How to use jansson lib to generate JSON data in C

This exmple method will generate the result string below:

{ "command":"link_status",
  "result":["AAABBBCCC"] }

char* generate_json_data() { char *ret_strings = NULL; char *ret_string = "AAABBBCCC"; json_t *root = json_object(); json_t *result_json_arr = json_array(); json_object_set_new( root, "command", json_string( "link_status" ) ); json_object_set_new( root, "result", result_json_arr ); ... json_array_append( result_json_arr, json_string( ret_string ) ); free( ret_string ); ret_strings = json_dumps( root, 0 ); json_decref( root ); return ret_strings; }

For more example in details: 

#include <stdio.h> #include <jansson.h> void add_2array_to_json( json_t* obj, const char* name, const int* marr, size_t dim1, size_t dim2 ) { size_t i, j; json_t* jarr1 = json_array(); for( i=0; i<dim1; ++i ) { json_t* jarr2 = json_array(); for( j=0; j<dim2; ++j ) { int val = marr[ i*dim2 + j ]; json_t* jval = json_integer( val ); json_array_append_new( jarr2, jval ); } json_array_append_new( jarr1, jarr2 ); } json_object_set_new( obj, name, jarr1 ); return; } int main() { json_t* jdata; char* s; int arr1[2][3] = { {1,2,3}, {4,5,6} }; int arr2[4][4] = { {1,2,3,4}, {5,6,7,8}, {9,10,11,12}, {13,14,15,16} }; jdata = json_object(); add_2array_to_json( jdata, "arr1", &arr1[0][0], 2, 3 ); add_2array_to_json( jdata, "arr2", &arr2[0][0], 4, 4 ); s = json_dumps( jdata, 0 ); puts( s ); free( s ); json_decref( jdata ); return 0; } When run it outputs: {"arr1": [[1, 2, 3], [4, 5, 6]], "arr2": [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]}

Another example:

#include "jansson.h" ... json_error_t error; json_t *root = json_loads( reply->data.buffer, 0, &error ); if( root ) { json_t *jsonData = json_object_get( root, "data" ); if( json_is_array( jsonData ) ) { const uint length = json_array_size( jsonData ); for( uint i=0; i<length; ++i ) // Iterates over the sequence elements. { json_t *jsonObject = json_array_get( jsonData, i ); json_t *jsonID = json_object_get( jsonObject, "id" ); const char *jsonStringID = json_string_value( jsonID ); json_t *jsonName = json_object_get( jsonObject, "name" ); const char *jsonStringName = json_string_value( jsonName ); // We can now do something with our Name and ID } } json_decref( root ); }

[epoll] How to use epoll in socket program?

When we do socket program, the most popular way is of PPC/TPC mode ( Process Per Connection / Thread Per Connection ). But the mode has some drawbacks, for instance, it will consum too much memory and CPU for context switch when creating more than hundreds of connections. epoll is good solution to deal with that.

The following URL is a good explaintion about epoll.
How to use epoll? A complete example in C

And here is a complete examle of using epoll in socket program.

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <sys/wait.h>
#define SERVPORT 9527 /* Server Port Number */
#define BACKLOG 10 /* The Max of Client Number */

void setnonblocking(int sock)
{
    int opts;
    opts = fcntl(sock,F_GETFL);
    if(opts<0)
    {
        perror("fcntl(sock,GETFL)");
        exit(1);
    }
    opts = opts|O_NONBLOCK;
    if(fcntl(sock,F_SETFL,opts)<0)
    {
        perror("fcntl(sock,SETFL,opts)");
        exit(1);
    }  
}

void do_use_fd(int client_fd)
{
    const char str[] = "God bless you!\n";
    if (send(client_fd,  str,  sizeof(str),  0) == -1)
        perror("send");
    close(client_fd);
}

int main()
{
    int sockfd;
    struct sockaddr_in my_addr;
    struct sockaddr_in remote_addr;
    if ((sockfd = socket(AF_INET,  SOCK_STREAM,  0)) == -1) {
        perror("socket");
        exit(1);
    }
    my_addr.sin_family = AF_INET;
    my_addr.sin_port = htons(SERVPORT);
    my_addr.sin_addr.s_addr = INADDR_ANY;
    bzero(&(my_addr.sin_zero), 8);
    if (bind(sockfd,  (struct sockaddr *)&my_addr,  sizeof(struct sockaddr)) == -1) {
        perror("bind");
        exit(1);
    }
    printf("bind ok\n");
    if (listen(sockfd,  BACKLOG) == -1) {
        perror("listen");
        exit(1);
    }
    printf("listen ok\b");
    size_t sin_size = sizeof(struct sockaddr_in);

#define MAX_EVENTS 10
    struct epoll_event ev, events[MAX_EVENTS];
    int conn_sock, nfds, epollfd;

    epollfd = epoll_create(10);
    if (epollfd == -1) {
        perror("epoll_create");
        exit(EXIT_FAILURE);
    }
    printf("epoll_create\n");

    ev.events = EPOLLIN;
    ev.data.fd = sockfd;
    if (epoll_ctl(epollfd, EPOLL_CTL_ADD, sockfd, &ev) == -1) {
        perror("epoll_ctl: sockfd");
        exit(EXIT_FAILURE);
    }
    printf("epoll_ctl ok\n");

    for (;;) {
        printf("start epoll_wait\n");
        nfds = epoll_wait(epollfd, events, MAX_EVENTS, -1);
        if (nfds == -1) {
            perror("epoll_pwait");
            exit(EXIT_FAILURE);
        }
        printf("epoll_wait returns, nfds = %d\n", nfds);

        for (int n = 0; n < nfds; ++n) {
            if (events[n].data.fd == sockfd) {
                conn_sock = accept(sockfd,
                        (struct sockaddr *) &remote_addr, &sin_size);
                if (conn_sock == -1) {
                    perror("accept");
                    exit(EXIT_FAILURE);
                }
                setnonblocking(conn_sock);
                ev.events = EPOLLIN | EPOLLET;
                ev.data.fd = conn_sock;
                if (epoll_ctl(epollfd, EPOLL_CTL_ADD, conn_sock,
                            &ev) == -1) {
                    perror("epoll_ctl: conn_sock");
                    exit(EXIT_FAILURE);
                }
            } else {
                do_use_fd(events[n].data.fd);
            }
        }
    }
}

[Socket] How to use he function fcntl()

When server is running to accept() and no client connection request comes, what it happens? When the server stops waiting for the arrival of the connection request on accept(). Similarly, when the program is running to receive(), ifno data can be read, the program will also stop receiving statements. This situation is called blocking. 
If you want to only pay attention to check whether there are customers waiting for a connection server to accept connection, otherwise the program continues to do other things, through the Socket set for non-blocking way: non-blocking socket when no customers waiting for accept calls return immediately.
 
# include <unistd.h>
# include <fcntl.h>
....
sockfd = socket (AF_INET, SOCK_STREAM, 0);
fcntl (sockfd, F_SETFL, O_NONBLOCK);
....
 
Set socket to non-blocking mode, "polling" the Socket. When no data is waiting to be processed from a non-blocking Socket ( for read data ), the function will return immediately, and the return value is set to -1 and errno set of EWOULDBLOCK. 
But this "polling" causes the CPU is busy waiting mode, thereby reducing performance.


P.S:
There is another way to deal with non-blocking socket.
ioctl(sockfd, FIONBIO, 0); // 0 is about non-blocking mode

[Storage] Some articles of NoSQL and Object Storage ( S3 and Swift )

Severl months ago, I saw the first article "LINE Starage" and didn't pay too much attention on it. Recently Someone discussed storage with me and let me remember it. So I found it again ( took me a bunch of time to look for ) and also took some pretty nice related articles here as well.

LINE Storage: Storing billions of rows in Sharded-Redis and HBase per Month

http://tech.naver.jp/blog/?p=1420

NoSQL Data Modeling Techniques

http://highlyscalable.wordpress.com/2012/03/01/nosql-data-modeling-techniques/

Cassandra vs MongoDB vs CouchDB vs Redis vs Riak vs HBase vs Membase vs Neo4j comparison

http://kkovacs.eu/cassandra-vs-mongodb-vs-couchdb-vs-redis
 

Hadoop + S3

http://wiki.apache.org/hadoop/AmazonS3

Apache Hadoop over OpenStack Swift

http://bigdatacraft.com/archives/349

[Sqlite] A simple example of Sqlite in C

Here is a simple example of how to deal with Sqlite Database in C language.

#include <stdio.h> #include <sqlite3.h> static char *createsql = "CREATE TABLE Employee(" "ID INTEGER PRIMARY KEY," "Name VARCHAR(10)," "BadgeID VARCHAR(10));"; static char *insertsql = "INSERT INTO Employee VALUES(NULL, 'Danny', '12345');"; static char *querysql = "SELECT * FROM Employee;"; void main(void) { int rows, cols; sqlite3 *db; char *errMsg = NULL; char **result; /* Open database file */ if (sqlite3_open("my_example.db3", &db, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, NULL)) { return; } /* Build Table */ sqlite3_exec(db, createsql, 0, 0, &errMsg); /* Add a new record */ sqlite3_exec(db, insertsql, 0, 0, &errMsg); /* Get the last insert record's ID */ printf("%d\n", sqlite3_last_insert_rowid(db)); /* Get all records in database */ sqlite3_get_table(db , querysql, &result , &rows, &cols, &errMsg); /* List all the data */ for (i=0;i<rows;i++) { for (j=0;j<cols;j++) { printf("%s\t", result[i*cols+j]); } printf("\n"); } /* Free table */ sqlite3_free_table(result); /* Close database */ sqlite3_close(db); }

When Compiling, just add sqlite's flag  as follows:

gcc -lsqlite3 -o sqlite_exp sqlite_exp.c

[tun/tap] An introduction of TUN/TAP

http://www.kernel.org/pub/linux/kernel/people/marcelo/linux-2.4/Documentation/networking/tuntap.txt

TUN/TAP provides packet reception and transmission for user space programs. 
It can be viewed as a simple Point-to-Point or Ethernet device, which 
instead of receiving packets from a physical media, receives them from 
user space program and instead of sending packets via physical media 
writes them to the user space program. 

When a program opens /dev/net/tun, driver creates and registers corresponding
net device tunX or tapX. After a program closed above devices, driver will 
automatically delete tunX or tapX device and all routes corresponding to it.

And also, here is a web site about Universal TUN/TAP device driver Frequently Asked Question.

http://vtun.sourceforge.net/tun/faq.html

The description of Universal TUN/TAP device driver

https://www.kernel.org/doc/Documentation/networking/tuntap.txt

[SLB] Server Load Balancing with DSR

IPVS ( based on LVS) provides 3 kind of ways to do server load balancing:

1. Virtual Server via Network Address Translation（VS/NAT）
2. Virtual Server via IP Tunneling（VS/TUN）
3. Virtual Server via Direct Routing（VS/DR） 

Recently I find another way to do load balancing, and it is Direct Server Return
http://techiess.wordpress.com/2010/09/09/load-balancing-dsr-direct-server-return/
Using DSR, packet is returning directly from the server to client without going through L4 switch.

[Virtual Network] Midokura’s MidoNet

Recently I saw the article about Midokura MidoNet as follows:
http://blog.ioshints.info/2012/08/midokuras-midonet-layer-2-4-virtual.html
It is a layer 2-4 virtual network solution and catches my attention and lets me want to know more about.

Meanwhile, Midokura also provide Quantum Plugin for MidoNet to integrate into OpenStack.
https://github.com/midokura/midonet-openstack

On its web site, it provides a lot of features in virtual network solution and is pretty amazing. Due to MidoNet is not an open source project, so we are not able to see how it exactly achieves all of these things.
http://www.midokura.com/midonet/openstack/

MidoNet Key Features

• Fully virtualized Layer 2 through 7 networking
• VLAN-less VLANs – Virtual L2 Distributed Level Isolation and Switching with virtually no limitations
• Fully Distributed Architecture with no single points of failure
• Virtual L3 Distributed Routing
• Distributed Load Balancing and Firewall Services
• NAT
• VPN
• Access Control Lists (ACLs)
• Restful API
• Web Based Management Control Panel
• Monitoring and Metering of Networking Services
• Live Migration
• Rate Limiting
• Virtual Tap (Port Monitoring and Mirroring)

[OpenStack] Existing High Availability Options for Networking

 Existing High Availability Options for Networking

    OpenStack offical web site has document to explain the existing HA options for networking. I think most of important item is the option 1: multi-host networking mode. This mode avoids from single point of failure when Nova-Network component is down and also eliminate the potential network bottleneck in single-host networking mode.

For more in details, please see the this:
http://docs.openstack.org/trunk/openstack-compute/admin/content/existing-ha-networking-options.html

[Ubuntu] How to build local apt repositories

Reference : http://odzangba.wordpress.com/2006/10/13/how-to-build-local-apt-repositories/

Summary:

1. Edit your sources.list file 
2. Copy your debian packages to the folder where is the packages repository directory  (*.deb folder) 
3. Change into the packages repository directory  (cd ~/repository) 
4. Generate a Packages.gz file  (sudo dpkg-scanpackages . /dev/null | gzip -9c > Packages.gz) 
5. Install the build-essential package  (sudo apt-get install build-essentiall
6.  Update apt-get server packages list  (sudo apt-get update)

[SDN] HP's SDN solution

http://www.infoworld.com/d/networking/hp-aims-three-part-effort-network-virtualization-200048?source=IFWNLE_nlt_virtualization_2012-08-16

Summary:
HP provides 3 tools (softwares) to deal with network virtualization using SDN

• EVI (Ethernet Virtual Interconnect)
• EVI creates a tunnel through the Layer 3 network by encapsulating the packets traveling between the data centers. Rival Cisco already has software that can do this, called OTV (Overlay Transport Virtualization), but it charges extra for that software.

• MDC (Multitenant Device Context)

• It allows for segregating the resources of multiple tenants in a virtualized environment without buying separate switches. This secures the data and applications of one department or cloud service customer from other tenants.

• VSA

• StoreVirtual VSA, for virtualizing storage management. The software is based on VSA (virtual storage appliance) technology from LeftHand Networks, which HP acquired in 2008.

[Trema] The real case to test flow-based ECMP Routing Switch App

The following picture is a topology that used in testing my ECMP Routing Switch App.

After host3 send packets to host1, the app starts making path process and the related log as below. You will see this app picks up 2 paths ( "0xe5->0xe3->0xe4"  and  "0xe5->0xe2->0xe4" ) and choose one of them to setup flow entries.

[pickup_next_candidate] Find a candidate = 0xe5
[update_distance] node = 0xe3, distance = 1
[update_distance] node = 0xe2, distance = 1
[pickup_next_candidate] Find a candidate = 0xe3
[update_distance] node = 0xe1, distance = 2
[update_distance] node = 0xe4, distance = 2
[update_distance] node = 0xe2, distance = 1
[pickup_next_candidate] Find a candidate = 0xe2
[update_distance] node = 0xe1, distance = 2
[update_distance] node = 0xe4, distance = 2
[pickup_next_candidate] Find a candidate = 0xe1
[pickup_next_candidate] Find a candidate = 0xe4
[build_hop_list] build a hop = 0xe4
[build_hop_list] build a hop = 0xe3
[build_hop_list] build a hop = 0xe5
[resolve_path] find a hop list 0
[pickup_next_candidate] Find a candidate = 0xe5
[update_distance] node = 0xe2, distance = 1
[pickup_next_candidate] Find a candidate = 0xe2
[update_distance] node = 0xe1, distance = 2
[update_distance] node = 0xe4, distance = 2
[pickup_next_candidate] Find a candidate = 0xe1
[pickup_next_candidate] Find a candidate = 0xe4
[build_hop_list] build a hop = 0xe4
[build_hop_list] build a hop = 0xe2
[build_hop_list] build a hop = 0xe5
[resolve_path] find a hop list 1
[resolve_path] has 2 paths, pick up the key = 0 from hash_value = 2169503748

[Trema][Concept] How to do flow-based ECMP in Routing Switch App

  As we have known that Routing Switch App uses Dijkstra algorithm to pick up the lowest cost of the path. Only one path will be selected. If we want to do flow-based ECMP, how to do it? I have a simple way to slightly modify the Routing Switch App and then it can become "ECMP Routing Switch" App.

  Here is a topology as follows. If the source is PC1 and destination is PC2, we can know that the source switch is A and destination switch is B. I will base on this to explain my idea.

  First, we setup a number of multi-path , for instance, 8, and let the loop to do Dijkstra algorithm these times.
  Second, we need to add a new chosen flag to record nodes in the path that we have picked up, and get rid of the source and destination node. And also, when Dijkstra algorithm is running, we also need to add a condition to avoid from choosing the node whose chosen flag is true.

For instance, Path 1 is A->B->C->D. We need to add flag on B and C as true.
                        Path 2 is A->E->F->D. We need to add flag on E and F as true.

In this case, Dijkstra algorithm is not able to pick up the third path so that making paths is done.
I have implemented this in Routing Switch App and it works. I will post the real case in the next article.

[Trema] Provide a monitoring application to watch port and flow loading

I currently provide a initial version of monitoring application to watch port and flow loading information. Here are some items about the configuration and criteria for sending notification.

The configuration

• port_percentage_condition

• the threshold of port loading percentage

• port_setting_feature_rate

• the speed rate of port

• flow_bit_rate_conditon

• the threshold of flow loading

• flow_times_condition

• how many seconds will flow become big flow when being over the threshold of flow loading

The notification criteria of Port Loading

• Check port loading per 4 seconds

• Calculate the percentage of port loading

• port_bit_rate = avg_rx_bytes * 8
• port_loading_percentage = port_bit_rate * 100 / port_feature_rate

• If the port loading percentage is higer than port_percentage_condition, then it sends port loading notification

The notification criteria of Flow Loading

• Check port loading per 4 seconds

• Calculate the flow loading ( flow_bit_rate )

• flow_bit_rate = bytes_count * 8 / duration seconds

• If flow_bit_rate  is bigger than flow_bit_rate_condition, then flow_times adds 1.

• If flow_times is higher than flow_times_condition, for instance, 3, then it sends flow loading notification

[Introduction] ar and ranlib

ar and ranlib
ar this program can do the following actions to the archive (static library)
create, modify, and extract.Following is a list of several commonly used options explained:

• d: delete
• Remove files from the archive

• r: replace
• Insert archive files to be replaced

• u: update
• option 'r' is usually to replace all, but the option u only will be inserted over the files in the archive in

• v: verbose
• The implementation, as well as additional information

for example:
   > ar uv mylib.a first.o second.o

These directives is to establish two obj file into a mylib.a, and shows the implementation of the process information

ranlib generates an index to the contents of an archive and stores it in the archive. The index lists each symbol defined by a member of an archive that is a relocatable object file.

You can use nm-s or nm, - print-armap Include to list this index

To run this program is to increase the speed of linking to the library and allows routines in the library can call each other without having to worry about these routines in the archive of the placement order

[Cucumber] An brief introduction

http://cukes.info/
I just saw the "Cucumber" and was amazed by its power of scenario testing with human-readable syntax and sentences. It is so amazing...
If you guys want to do the job for testing, that is a good choice~

For more information in details, please also check it out:
http://andrewvos.com/2011/06/15/writing-better-cucumber-features/
http://grosser.it/2008/12/25/getting-started-with-cucumber-on-ubuntu/
http://jeannotsweblog.blogspot.tw/search?q=cucumber
http://holmwood.id.au/~lindsay/2009/11/09/behaviour-driven-infrastructure-through-cucumber/

How to install Cucumber
sudo apt-get install libxslt1-dev libxml2-dev racc
sudo apt-get install gem
sudo gem install gherkin
sudo gem install cucumber./script/generate cucumber
rake features

[How To] Add ZeroMQ in Trema App

If someone wants to add the mechanism of ZeroMQ to send message from Trema Application, for instance, Routing_Switch, there are several things that need to do and I have tested OK.

Example Trema App: Routing_Switch

1. Install ZeroMQ

• Please follow the instruction from the offical web site: http://www.zeromq.org/intro:get-the-software

2. Modify its Makefile: 

• add the include folder location of ZeroMQ :

• CFLAGS = $(shell $(TREMA)/trema-config --cflags) -I/home/liudanny/SourceCode/zeromq2-1/include -I../topology -g -std=gnu99 -D_GNU_SOURCE -fno-strict-aliasing -Werror -Wall -Wextra -Wformat=2 -Wcast-qual -Wcast-align -Wwrite-strings -Wconversion -Wfloat-equal -Wpointer-arith

• add library name of zeroMQ and link it:
• LDFLAGS = $(shell $(TREMA)/trema-config --libs) -lzmq -L../topology -ltopology

3. Write your ZeroMQ code in Routing_Switch.

[How to][Trema] Get Flow_Removed message in routing_switch app

I asked an question about how to get Flow_Removed message in routing_switch app. But, soon I realized that I asked a stupid one because the answer is also in OpenFlow Spec v1.0.0.
We should set a "OFPFF_SEND_FLOW_REM" flag into "Flow Mod" message when we want to set a flow. The following list is the discussion message log.

================================================================ 
Hi,


If you want to receive "Flow Removed" message, you have to set
"OFPFF_SEND_FLOW_REM" flag into "Flow Mod" message when you set the flow.


Currently "routing_switch" app does not set this flag, then switches does
not send "Flow Removed" message.

================================================================
Hi,
  I try to get "Flow_Removed" message in routing_switch app, but do not see any one coming in.
The following is what I have done in the app and could someone tell me how to fix or modify it?
Many thanks.


Add it in main():
  set_flow_removed_handler( handle_flow_removed, routing_switch );


Add a method for display:
void handle_flow_removed( uint64_t datapath_id, flow_removed message ) {
  routing_switch *routing_switch = message.user_data;
  info( "[handle_flow_removed] dpid = %#" PRIx64 ", match = %s",
          datapath_id, message.match );
}


Modify routing_switch.conf:
vswitch {
  datapath_id "0xe0"
}
vhost ("host1") {
  ip "192.168.0.1"
  netmask "255.255.0.0"
  mac "00:00:00:01:00:01"
}
vhost ("host2") {
  ip "192.168.0.2"
  netmask "255.255.0.0"
  mac "00:00:00:01:00:02"
}
link "0xe0", "host1"
link "0xe0", "host2"


run {
  path "../apps/topology/topology"
}
run {
  path "../apps/topology/topology_

discovery"
}
run {
  path "../apps/routing_switch/routing_switch"
}


event :port_status => "topology", :packet_in => "filter", :state_notify => "topology", :flow_removed => "routing_switch"
filter :lldp => "topology_discovery", :packet_in => "routing_switch"

[Shell Script][Example] Files Copying Operation with Warning When the Same File Exists

Because someone asks me to do him a favor for a sample of of file copying operation, I just use bash shell to do so. Here is an example to use shell script to copy files from source path to destination path, which will give a warning message and skip copying if there is a file that exists.

#!/bin/bash SRC_DIR="/home/liudanny/scripts" # put your source directory DST_DIR="/home/liudanny/Downloads" # put your destination directory for src_full_name in "$SRC_DIR"/* # loop all the files in source directory do fname=$(echo ${src_full_name}|sed 's#^.*/##') # get the file name echo "name:$fname" dst_full_name=`printf "%s/%s" $DST_DIR $fname` # generate the destination file name echo "dst_full_name:$dst_full_name" if [ -e $dst_full_name ]; # check if destination file exists then echo "File: $fname exists..." else echo "Do copying $fname ..." cp $src_full_name $dst_full_name # if not exists, then copy file fi done

[ARP] How to look up arp table (mac/ip mapping) in Linux

First, we can ping hostname(ip_addr) to add mac/ip mapping into arp table
or use arp command to do so:
> arp -s hostname(ip_addr) MAC_addr

Second, look up arp table:
> arp -n   (I recommend to use "-n" for avoiding DNS lookup. It is faster.)
        Address                  HWtype    HWaddress               Flags Mask            Iface
        10.3.207.245             ether      20:aa:4b:a3:4c:b7            C                     eth4

or there is another way:
> ip ne
        10.3.207.245 dev eth4 lladdr 20:aa:4b:a3:4c:b7 REACHABLE

[OpenFlow] Update and Setup TP-LINK TL-WR1043ND for OpenFlow

Currently the version of TP-LINK TL-WR1043ND which I can get in Taiwan is "(TW) ver:1.0" instead of ver:1.8 I want. But, fortunately, after asking the vendor about this issue, he responds that there is no difference in hardware between "(TW) ver:1.0"and ver:1.8 or ver:1.4. That is a good news to me though. The following items are my steps to  transform original TP-LINK TL-WR1043ND to OpenFlow-enabled switch. Most of information is from http://www.openflow.org/wk/index.php/Pantou_:_OpenFlow_1.0_for_OpenWRT

1. Update firmware on your device
Installing OpenWrt this web site has 4 methods for us to do updating. Because my TL-WR1043ND is brand new one, I choose the simplest of method 1: via orginal firmware.

• Download  image  (v1.8)
• Change your PC ip address to 192.168.1.2
• Connect to the switch with LAN port
• Browse http://192.168.1.1
• Choose function "update firmware" with the image bin file

2. Modify Configuration 

• Login  to 192.168.1.1 using telnet
• Setup your controller ip address (my controller ip is 192.168.1.244)
• vi  /etc/config/openflow

        config 'ofswitch'
                option 'dp' 'dp0'

                option 'dpid' '000000000011'

                option 'ofports' 'eth0.0 eth0.1 eth0.2 eth0.3 '
                option 'ofctl' 'tcp:192.168.1.244:6633'
                option 'mode'  'outofband'

• Setup your network configuration and setup this switch ip address (my switch ip is 192.168.1.11)
• vi /etc/config/network and paste the following lines

        config 'switch'
                option 'name' 'rtl8366rb'
                option 'reset' '1'
                option 'enable_vlan' '1'
                option 'enable_learning' '0'
               
        config 'switch_vlan'
                option 'device' 'rtl8366rb'
                option 'vlan' '1'
                option 'ports' '1 5t'
       
        config 'switch_vlan'
                option 'device' 'rtl8366rb'
                option 'vlan' '2'
                option 'ports' '2 5t'
       
        config 'switch_vlan'
                option 'device' 'rtl8366rb'
                option 'vlan' '3'
                option 'ports' '3 5t'
       
        config 'switch_vlan'
                option 'device' 'rtl8366rb'
                option 'vlan' '4'
                option 'ports' '4 5t'
       
        config 'switch_vlan'
                option 'device' 'rtl8366rb'
                option 'vlan' '5'
                option 'ports' '0 5t'
       
        config 'interface' 'loopback'
                option 'ifname' 'lo'
                option 'proto'  'static'
                option 'ipaddr' '127.0.0.1'
                option 'netmask' '255.0.0.0'
               
        config 'interface'
                option 'ifname' 'eth0.1'
                option 'proto' 'static'
       
        config 'interface'
                option 'ifname' 'eth0.2'
                option 'proto' 'static'
       
        config 'interface'
                option 'ifname' 'eth0.3'
                option 'proto' 'static'
       
        config 'interface'
                option 'ifname' 'eth0.4'
                option 'proto' 'static'
       
        config 'interface'
                option 'ifname' 'eth0.5'
                option 'proto' 'static'
                option 'ipaddr' '192.168.1.11'
                option 'netmask' '255.255.255.0' 

 3. Restart networking to enable your changes

• /etc/init.d/network restart

4. Verify (My case is for Trema Controller)

• Connect your Ethernet cable from LAN port to WAN port
• Start any kind of Trema app
• for instance : ./trema run ./objects/examples/learning_switch/learning_switch
• Show switch description
• TREMA_HOME=`pwd` ../apps/show_description/show_description
• And then we can get the information as follows:

        Manufacturer description: Stanford University
        Hardware description: Reference Userspace Switch
        Software description: 1.0.0
        Serial number: None
        Human readable description of datapath: OpenWrt pid=1933
        Datapath ID: 0x11
        Port no: 1(0x1)(Port up)
          Hardware address: 90:f6:52:89:c9:d0
          Port name: eth0.1
        Port no: 2(0x2)(Port up)
          Hardware address: 90:f6:52:89:c9:d0
          Port name: eth0.2
        Port no: 3(0x3)(Port up)
          Hardware address: 90:f6:52:89:c9:d0
          Port name: eth0.3
        Port no: 4(0x4)(Port up)
          Hardware address: 90:f6:52:89:c9:d0
          Port name: eth0.4