In the meantime, I have partially solved the problem, except for the sorting part and thought of sharing it with you, expecting your valueable comments and suggestions.
I chose to make an "external" sort and pasted the result directly in the main tex file, since it seems the easiest of the options. I thought of using the datatool bundle, but the sorting just took me a few seconds using a simple text sorting outside TeX.
The data is collected from authors using a simple text file with the following structure:
\AUTHOR{}{} %% <--- {LastName}{FirstName}
\EMAIL{}
\AFFILIATION{}
\TITLE{}
\ABSTRACT{}
The main file reads these files and produces the contents of the Abstract Book, as in the following minimal example (where we read three files), where the macros are defined in the external abstractbook.sty file:
\documentclass[a4paper,12pt]{article}
\usepackage{abstractsbook}
\begin{document}
%% ++++++++++ Process submitted files ++++++++++++++++++
\begin{processfiles}
%% ---------------------------------------
\processfile{FirstAuthor}
\processfile{SecondAuthor}
\processfile{ThirdAuthor}
%% First sorted alphabetically outside TeX
\end{processfiles}
\parindent 0pt
%% +++++++++++++++++++ List of Talks ++++++++++++++++++
\listoftalks
%% +++++++++++++++++++ Abstracts ++++++++++++++++++++++
\abstracts
%% +++++++++++++++++++ Index of participants +++++++++++
\listofparticipants
%% +++++++++++++++++++++++++++++++++++++++++++++++++++++
\end{document}
The abstractbook.sty file defines all the above macros.
When processing files, \processfile{NameOfFile} reads the contents of NameOfFile.tex from the same folder with the main tex file. Each \processfile{...} increases a local counter (counting the number of read files) and defines the following macros:
\author-<x>-LastName
\author-<x>-FirstName
\affiliation-<x>
\email-<x>
\title-<x>
\abstract-<x>
where <x> is the current value of the counter.
When typesetting the document, we just cycle through all the values of the counter and display the required info.
See a minimal example below for the abstractbook.sty. I hope it is (not so hard) readable:
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{abstractsbook}
%% ++++++++++++++++++++++++++++++++++++++++++++++++++++
\RequirePackage{ifthen}
%% ----- some shortcuts ------
\let\ea=\expandafter
\let\cs=\csname
\let\ecs=\endcsname
%% ++++++++++++++++++++++++++++++++++++++++++++++++++++
\newenvironment{processfiles}
{\newcount\numabs % <--- TeX local counter that counts
% the number of abstracts
\numabs=0\relax
\newcounter{numabs} % <--- LaTeX global counter
}
{\setcounter{numabs}{\the\numabs}
% < --- saving the final (local) value of \numabs
} % for global later use
\long\def\processfile #1{%
\advance\numabs by 1\relax
\input{#1.tex}
}%
\long\def\AUTHOR #1#2{%
\ea\long\ea\gdef\cs author-\the\numabs-LastName\ecs{#1}%
\ea\long\ea\gdef\cs author-\the\numabs-FirstName\ecs{#2}%
}
\long\def\AFFILIATION #1{%
\ea\long\ea\gdef\cs affiliation-\the\numabs\ecs{#1}
}
\long\def\EMAIL #1{%
\ea\long\ea\gdef\cs email-\the\numabs\ecs{#1}
}
%%
\long\def\TITLE #1{%
\ea\long\ea\gdef\cs title-\the\numabs\ecs{#1}
}
%%
\long\def\ABSTRACT #1{%
\ea\long\ea\gdef\cs abstract-\the\numabs\ecs{#1}
}
% ++++++++++++++ List of Talks ++++++++++++++++++++++++++++++++++++++++++++++
\def\heading #1{\cleardoublepage{\LARGE\scshape #1}\par\hrulefill\vskip 6ex}
\long\def\listoftalks
{
\heading{List of Talks}
\newcount\@i
\@i=1\relax
\whiledo{\the\@i<\numexpr \thenumabs+1\relax}
{\begin{minipage}{\textwidth}
\vskip 1.5ex
\leftskip 0em
\textsc{\cs author-\the\@i-FirstName\ecs}~\MakeUppercase{\cs author-\the\@i-LastName\ecs}
\par\leftskip 2.5em
\textit{\cs title-\the\@i\ecs}\dotfill\pageref{marker-\the\@i}
\end{minipage}
\advance \@i by 1\relax
}%
}
% ++++++++++++++ List of Participants +++++++++++++++++++++++++++++++++++++
\long\def\listofparticipants
{\heading{List of Participants}
\newcount\@i
\@i=1\relax
\whiledo{\the\@i<\numexpr \thenumabs+1\relax}
{\begin{minipage}{\textwidth}
\textbf{\MakeUppercase{\cs author-\the\@i-LastName\ecs}},~\textbf{\cs author-\the\@i-FirstName\ecs}
\vskip 1ex
\textit{\cs affiliation-\the\@i\ecs}
\vskip 0.25ex
\texttt{\cs email-\the\@i\ecs}
\end{minipage}
\vskip 4ex
\advance \@i by 1\relax
}%
}
% +++++++++++++++ Abstracts of Talks +++++++++++++++++++++++++++++++++++++++++
\long\def\abstracts
{\heading{Abstracts of Talks}
\newcount\@i
\@i=1\relax
\whiledo{\the\@i<\numexpr \thenumabs+1\relax}
{%
\begin{minipage}{\textwidth}
\label{marker-\the\@i} % <--- used for later referencing of the page
\begin{center}
\textsc{\Large \cs title-\the\@i\ecs}
\vskip 1.5ex
\textbf{\Large \cs author-\the\@i-FirstName\ecs~\cs author-\the\@i-LastName\ecs}
\vskip 1ex
\normalsize{\cs affiliation-\the\@i\ecs}
\end{center}
\vskip 2.5ex
\cs abstract-\the\@i\ecs
\end{minipage}
\vskip 8ex
\vfill
\advance \@i by 1\relax
}%
}
Consider also the minimal examples of the abstract files below:
FirstAuthor.tex
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\AUTHOR{First}{Author}% <--- {LastName}{FirstName}
%%
\EMAIL{first.author@firstuniv.edu}
%%
\AFFILIATION{First University}
%%
\TITLE{The first title}
%%
\ABSTRACT{This is the abstract of the first talk.
And some math: $1+1=2$.
}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
SecondAuthor.tex
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\AUTHOR{Second}{Author}% <--- {LastName}{FirstName}
%%
\EMAIL{second.author@seconduniv.edu}
%%
\AFFILIATION{Second University}
%%
\TITLE{The second title}
%%
\ABSTRACT{This is the abstract of the second talk.
And some math:
\[
E=m\mathrm{c}^2.
\]}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ThirdAuthor.tex
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\AUTHOR{Third}{Author}% <--- {LastName}{FirstName}
%%
\EMAIL{third.author@thirduniv.edu}
%%
\AFFILIATION{Third University}
%%
\TITLE{The third title}
%%
\ABSTRACT{This is the abstract of the second talk.
And some math:
\[
\mathrm{e}^{i\pi}+1=0.
\]}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
The result of this minimal example is the following file:
