This is the basic idea. But you will probably want to take care of some additional things, like:

* Security - HTTPS
* Running on startup
* Restarts
* Replication (the number of processes running)
* Memory
* Previous steps before starting

{* ../../docs_src/request_forms_and_files/tutorial001_an_py39.py hl[10:12] *}

The files and form fields will be uploaded as form data and you will receive the files and form fields.

And you can declare some of the files as `bytes` and some as `UploadFile`.

/// warning

If for some reason you need to disable automatic conversion of underscores to hyphens, set the parameter `convert_underscores` of `Header` to `False`:

{* ../../docs_src/header_params/tutorial002_an_py310.py hl[10] *}

/// warning

Before setting `convert_underscores` to `False`, bear in mind that some HTTP proxies and servers disallow the usage of headers with underscores.

///

        #
        #; objectTypeTargetList = list:{TABLE ; VIEW}

        # o tableExceptList: (NotRequired - Default list:{})
        #  If you want to exclude some tables in generating target,
        #  you should specify the list of excepted table hints.
        #    e.g. list:{PRODUCT_STATUS ; prefix:TMP_}
        #  This is only for the main schema. Additional schemas are unconcerned.

The **Advanced User Guide** builds on this one, uses the same concepts, and teaches you some extra features.

But you should first read the **Tutorial - User Guide** (what you are reading right now).

            // ID for domain (used with relative IDs to get SIDs)
            final int domainIdPointer = pacStream.readInt();

            // Skip some reserved fields
            pacStream.skipBytes(8);

            this.userAccountControl = pacStream.readInt();

            // Skip some reserved fields
            pacStream.skipBytes(28);

            // Extra SIDs information

* It can then do something to that **request** or run any needed code.
* Then it passes the **request** to be processed by the rest of the application (by some *path operation*).
* It then takes the **response** generated by the application (by some *path operation*).
* It can do something to that **response** or run any needed code.
* Then it returns the **response**.

/// note | Technical Details

Then your API will (let's imagine):

* Send the invoice to some customer of the external developer.
* Collect the money.
* Send a notification back to the API user (the external developer).
    * This will be done by sending a POST request (from *your API*) to some *external API* provided by that external developer (this is the "callback").

	// If x-amz-content-sha256 is set and the value is not
	// 'UNSIGNED-PAYLOAD' we should validate the content sha256.
	switch v[0] {
	case unsignedPayload, unsignedPayloadTrailer:
		return true
	case emptySHA256:
		// some broken clients set empty-sha256
		// with > 0 content-length in the body,
		// we should skip such clients and allow
		// blindly such insecure clients only if
		// S3 strict compatibility is disabled.

     * is given by {@link #getSource()}.
     *
     * @return the one-based index of the line containing the problem or a non-positive value if unknown
     */
    int getLineNumber();

    /**
     * Gets the one-based index of the column containing the problem. The column number should refer to some text file
     * that is given by {@link #getSource()}.
     *