Skip to main content

libesphttpd and Micro API

libesphttpd is a HTTP server library for ESP8266. It has a fair documentation on Github and a demo. It supports common gateway interface (CGI) in C. It also has a tool to compile a collection of web pages into a binary blob which is to be flashed into ESP8266 separately from the web server codes. It can host static web files. In general, libesphttpd can be used to build a complete web server for ESP8266.

However, ESP8266 is too tiny for a full blown web server.

It is a standard practice to separate the development of web pages and a web server. In fact, due to the limited resources of the ESP8266, the web server should be kept to minimum by only exposing APIs. The web pages should be designed as the applications that run at the client side.

I wrote a micro-api framework using libesphttpd and esp-open-sdk.

Separation of concerns is important in web application development since it involves multiple stacks of tools. On the server side there will be embedded C-based tools. And on the client side there will be HTML, Javascript and CSS. The C codes for the server will have to be routinely compiled and flashed into the ESP8266 throughout the development. On the other hand, the web application development can be contained temporarily in localhost. HTML, Javascript and CSS are all scripts that do not need to be compiled. And they don't need to be flashed all the time throughout the development.

The web server is tiny. The memory is tiny. The database is as good as a flat file. Don't expect it to be an ordinary web server. The server's C codes have to be thoroughly optimized. Otherwise, the ESP8266 will be left with too little resources for it to do its embedded things.

Hence, micro API is the solution.

We can use various web frameworks on the client side. However, the total size of the files used must not reach the limit of the available flash memory in the ESP8266. Hence, we do have a development constraint on the client side. Fortunately, there are many thin front-end web frameworks for us to choose from and assemble.

Anyway, we are building the Internet of Things (IoTs). If we need a bigger web server then we should not be doing it on ESP8266.


Comments

Popular posts from this blog

Setting Up PyScripter for Quantum GIS

PyScripter is a general purpose Python Integrated Development Environment (IDE). Quantum GIS (QGIS) is a desktop GIS application that can be extended with Python plugins. Both are open source softwares. We intend to use PyScripter as an IDE to build QGIS Python plugin. We are using PyScripter 2.4.1.0 and QGIS 1.6.0 in Windows. PyScripter does not come with Python. On the other hand, QGIS is built in with Python. Thus, we will setup up PyScripter to use the build in Python in QGIS. We assume both PyScripter and QGIS are already installed. Preparing PyScripter batch file We assume that QGIS is installed in C:\OSGeo4W\ folder and PyScripter is installed in C:\Program Files\PyScripter\ . 1. Copy qgis.bat in C:\OSGeo4W\ bin to pyscripter.bat 2. Edit pyscripter.bat to remove the last line that read something like this start "Quantum GIS" /B "%OSGEO4W_ROOT%"\apps\qgis\bin\qgis.exe %* and replace it with this in one line Start "PyScripter" /B "C:\Progr

Sending Emails via SMTP

msmtp  requires a minimal setup for sending emails via SMTP compared to sendmail. Here is a configuration for you to send emails from a web host to an external SMTP server. Prior to doing that, you must check whether there is a clear communication channel between your web host and the SMTP server. You can use Telnet . Set up msmtp You are going to set msmtp as an MTA . Hence, you need to remove all other MTAs such as postfix and sendmail: $ sudo apt-get --purge autoremove postfix sendmail Install msmtp and related utilities: $ sudo apt-get install msmtp msmtp-mta mailutils Configure msmtp: $ sudo nano /etc/msmtprc # Set default values for all following accounts. defaults # Use the mail submission port 587 instead of the SMTP port 25. port 587 # Always use TLS. tls on # Set a list of trusted CAs for TLS. The default is to use system settings, but # you can select your own file. tls_trust_file /etc/ssl/certs/ca-certificates.crt # The SMTP server account mx host mail.mx.example

fatal: Couldn't find remote ref master

If you are using Github then  master is now known as main . Whatever you want to do with a master must now be referred to a main . If you search for this error message on the Internet then you will encounter with a lot of old discussions on how to set up your master properly which is probably not what you are looking for. The master  is your problem. Rename it to main . I wrote Git My Way about two years ago. Today I created another Github repository. I got this  "fatal: Couldn't find remote ref master"  error message when I wanted to sync the new repo for the first time with my notebook using the notes I wrote in the blog. All the discussions around the error message I found on the Internet were perplexing. Then I recalled that Github had renamed master to main  due to the master-slave connotation. We always have a master copy of a code, never a slave copy. Now suddenly a word context has been diminished for good. What is going to happen to the existing vast documen