User's Guide
Reference Manual
Release Notes
PDF
Top

inets
Reference Manual
Version 5.8

Expand All
Contract All

Table of Contents

# mod_esi

### MODULE

mod_esi

### MODULE SUMMARY

Erlang Server Interface

### DESCRIPTION

This module defines the Erlang Server Interface (ESI) API. It is a more efficient way of writing erlang scripts for your Inets web server than writing them as common CGI scripts.

### EXPORTS

deliver(SessionID, Data) -> ok | {error, Reason}

Types:

SessionID = term()
Data = string() | io_list() | binary()
Reason = term()

This function is only intended to be used from functions called by the Erl Scheme interface to deliver parts of the content to the user.

Sends data from a Erl Scheme script back to the client.

Note

Note that if any HTTP-header fields should be added by the script they must be in the first call to deliver/2 and the data in the call must be a string. Calls after the headers are complete may contain binary data to reduce copying overhead. Do not assume anything about the data type of SessionID, the SessionID must be the value given as input to the esi call back function that you implemented.

### ESI Callback Functions

### EXPORTS

Module:Function(SessionID, Env, Input)-> _

Types:

SessionID = term()
Env = [EnvironmentDirectives] ++ ParsedHeader
EnvironmentDirectives = {Key,Value}
Key = query_string | content_length | server_software | gateway_interface | server_protocol | server_port | request_method | remote_addr | script_name
Input = string()

The Module must be found in the code path and export Function with an arity of three. An erlScriptAlias must also be set up in the configuration file for the Web server.

If the HTTP request is a 'post' request and a body is sent then content_length will be the length of the posted data. If 'get' is used query_string will be the data after ? in the url.

ParsedHeader is the HTTP request as a key value tuple list. The keys in parsed header will be the in lower case.

SessionID is a identifier the server uses when deliver/2 is called; do not assume anything about the datatype.

Use this callback function to dynamically generate dynamic web content. When a part of the page is generated send the data back to the client through deliver/2. Note that the first chunk of data sent to the client must at least contain all HTTP header fields that the response will generate. If the first chunk does not contain the End of HTTP header, that is "\r\n\r\n", the server will assume that no HTTP header fields will be generated.

Module:Function(Env, Input)-> Response

Types:

Env = [EnvironmentDirectives] ++ ParsedHeader
EnvironmentDirectives = {Key,Value}
Key = query_string | content_length | server_software | gateway_interface | server_protocol | server_port | request_method | remote_addr | script_name.
Input = string()
Response = string()

This callback format consumes a lot of memory since the whole response must be generated before it is sent to the user. This function is deprecated and only kept for backwards compatibility. For new development Module:Function/3 should be used.