In odoo 8 it's possible to  print a report just by defining the text of the html/qweb report and the action that starts the printing (called report action).
With just two file (and by update of the __openerp__.py ) a new item appears in the "print" dropdown menu of the UI (user interface) of odoo allowing to download the report. 

To get a file filled with the content of a contract (in Sale) the files can be: 


[code]
<?xml version="1.0" encoding="utf-8"?>
<openerp>
   <data>
       <report
           id="report_contract_pdf"
           string="Quotation / Order"
           model="account.analytic.account"
           report_type="qweb-pdf"
           file="sale.report_saleorder___ciccio"  
           name="contract_pdf.report_contract"
       />
   </data>
</openerp>
[/code]

[code]
<?xml version="1.0" encoding="utf-8"?>

<openerp>

<data>

<template id="report_contract_document">

   <t t-call="report.external_layout">

       <div class="page">

          <h1>hola<h1>

       </div>

   </t>

</template>


<template id="report_contract">

   <t t-call="report.html_container">

       <t t-foreach="doc_ids" t-as="doc_id">

           <t t-raw="translate_doc(doc_id, doc_model, 'partner_id.lang', 'sale.report_contract_document')"/>

       </t>

   </t>

</template>

</data>

</openerp>
[/code]



My question goes with the attributes of the the report action file. 


Why can't I set any report_name in the report action?


Which is the difference between these attributes: "report_name", "file", and "attachment"?

These are my answers:
- report_name: is the name of your report (which will be the name of the PDF output), the download pdf file
- file: the html name ( to see the report ad an html page at the address for instance http://<server-address>/report/pdf/sale.report_saleorder/38?) it seams not
- attachment: python expression that defines the name (which one? the download file name? but this is the report_name...) of the report


Andrea