Basic Usage

Each type of resource may specify its content type. It is important to specify the correct content type for the contents of the resource. When the WebDev module is installed, a new kind of project resource heading will apear in the Designer's project browser called "Web Dev". Right-clicking on this heading will allow the creation of three new types of project resources:

URL

Each resource will be directly accessible over HTTP and mounted beneath the/main/system/webdev path.

For example, if you created a Text Resource directly beneath the "Web Dev", it would be mounted at:

Notice that the project name and resource name are part of the path. If your resource is nested inside a folder, it will be part of the path too, for example:

Web dev resources may have periods in their name. This meas that if you upload an image file, you may include its extension directly in its name so that its path is more natural, for example, you might name an image resource "my_image.png" so that its URL is:

The Web Dev module respects the published vs. staging system of Ignition. If your project is set up to have separate staging and published verions, you may access your staging version resources via the URL:

Requests to the root of your project, i.e. will attempt to load a resource named "index.html". If no such resource exists, a 404 response code will be returned instead.

Python Resources

Python resources are the heart of the functionality of the Web Dev module. These resources are completely dynamic, and can handle all parts of the HTTP protocol, formulating any type of response.

Each time an incoming HTTP request arrives an a URL where a python resource is mounted, the corresponding python script will be run. Each python resource may have up to seven scripts, one for each HTTP method (GET, POST, HEAD, TRACE, etc.). In practice, most python resources will probably only implement one or two of these, usually doGet or doPost at a minimum.

Parameters

Each do* method receives the same two parameters: 'request' and 'session'.

Return Value

Each do* function on a python resource must generate some sort of HTTP response. This is done by returning a value from the function. The return value should always be a dictionary, in which the following keys are recognized. The keys are listed here in the order they are evaluated. For example, if you have both file and bytes, only file will take effect. The exception is the contentType key, which may be included with any of the other keys to override the default content type.

File: The value should be a string, which should be the path to a file on the server's filesystem. If no contentType is specified, then the system will attempt to probe the content type from the operating system using java.nio.Files.probeContentType. If thefile key is present, but the value points to a file that doesn't exist, an HTTP 404 will be returned.

Bytes: The value should be a byte array. The default content type is application/octet-stream, but you probably want to specify your own.

HTML: The value should be a string, which should be the source of an HTML document. Content type is assumed to be text/html.

JSON: The value is assumed to either be a string (which should be valid json) or to be a python object, which will then be encoded into a json string. Content type will beapplication/json

Response: If none of the other keys are present, the system will look for the key response which will be stringified and then returned with the content type text/plain.

If your implementation of the do* function returns a dictionary with none of the above keys, an HTTP 500 error will be returned. However, if you return None, no HTTP 500 error will be returned. In this case, it is assumed that you used therequest['servletResponse'] parameter to directly formulate your HTTP response.

Security Settings

Each python resource can configure its own optional security settings.