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ImageFetcher

Fetches an image by performing an HTTP GET operation on the specified URL, and then returning the resulting data as the geometry of a raster feature.

If an error occurs while accessing the URL, or while converting the downloaded data into a raster, the translation will continue, and the feature will be output through the <Rejected> port.

Parameters

Image Request

Image URL

Enter the URL (for example, http://www.url.com) or select an attribute that contains a URL.

Image Type

Choose the image type. If the “<Auto-Detect from HTTP Headers>” option is chosen, the transformer will examine the ‘Content-Type’ header in the HTTP Response for a MIME type. If a known MIME type is found, the corresponding reader will be used to create the raster geometry.

HTTP Client Options

Save Cookies

If this parameter is set to Yes, any saved cookies that correspond to the URL being accessed will be sent with the request. In addition, any cookies contained in the response will be saved for use with subsequent HTTP requests.

Saved cookies will persist for the duration of the translation – they cannot be used in subsequent translations.

Saving cookies is useful when a web service keeps a "session". Then the following sequence of operations might be used:

An HTTPCaller transformer is used to log in to the web service and a session cookie is saved.
An ImageFetcher transformer is used to download an image from the web service, utilizing the saved session cookie.
A second HTTPCaller is used to log out of the web service, which invalidates the saved cookie.

Follow Redirects

If this parameter is set to Yes, the transformer will follow any URL redirects it encounters, making a second request to a new location.

Verify SSL Certificates

If this parameter is set to Yes, the transformer will verify SSL certificates. This is done in two stages:

Ensure that the certificate is for the host we are trying to connect to.
Ensure that the certificate is valid.

Connection Timeout Length

This parameter can be used to set a timeout on HTTP connection requests. If a connection to the server cannot be created within the given number of seconds, the request will fail, and the feature will be output through the <Rejected> port. The default connection timeout is 60 seconds. If 0 is entered, there will be no timeout, and the transformer will wait indefinitely for a successful connection.

Transfer Timeout Length

This parameter can be used to set a timeout on HTTP transfers. If data stops being transferred for more than the given number of seconds, the request will fail, and the feature will be output through the <Rejected> port. The default transfer timeout is 90 seconds. If 0 is entered, there will be no timeout, and the transformer will wait indefinitely for data to resume being transferred.

Response Headers and Status

List Attribute for Response Headers

This parameter is optional. If it is set to a list attribute name, then HTTP headers returned by the server will be stored in the list attribute. The headers will be split into names and values. For example:

`_headers{0}.name' has value `X-XSS-Protection'

`_headers{0}.value' has value `1; mode=block'

`_headers{1}.name' has value `Date'

`_headers{1}.value' has value `Wed, 25 May 2011 17:20:20 GMT'

`_headers{2}.name' has value `Transfer-Encoding'

`_headers{2}.value' has value `chunked'

`_headers{3}.name' has value `Content-Type'

`_headers{3}.value' has value `text/html; charset=ISO-8859-1'

`_headers{4}.name' has value `Cache-Control'

`_headers{4}.value' has value `private, max-age=0'

Status Code Attribute

This parameter is optional. If it is set to an attribute name, then the HTTP response code returned by the server will be stored in the attribute.

Error Attribute

This parameter is optional. If an error occurs, the feature will be output through the <Rejected> output port, and the attribute named in this parameter will contain a brief error message.

Use Authentication

Check this box if the image is being retrieved from a server that requires user authentication.

Authentication Method

Specify the method for authenticating with the server:

Basic (HTTP Basic authentication): This is the default choice, and the only method in widespread use and supported virtually everywhere. This sends a username and password over the network in plain text, easily captured by others.
Digest (HTTP Digest authentication): Digest authentication is more secure over public networks than the Basic method.
NTLM (HTTP NTLM authentication): NTLM is a proprietary protocol invented and used by Microsoft. It uses a challenge-response and hash concept similar to Digest to prevent the password from being eavesdropped.
Named Web Connection: Allows you to authenticate using a stored named web service connection. For more information, see Using Named Web Service Connections in the FME Workbench help.

Named Web Connection

If Authentication Method is Named Web Connection, specify the named connection to use for authentication. To add a new named connection, select Add Named Web Connection from the dropdown menu.

HTTP Authentication Username, HTTP Authentication Password

If Authentication Method is Basic, Digest, or NTLM, specify the username and password for authenticating.

FME Licensing Level

FME Professional edition and above

Editing Transformer Parameters

Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click beside the applicable parameter. For more information, see Transformer Parameter Menu Options.

Transformer Categories

Rasters

Workflows

Technical History

Associated FME function or factory: HTTPFactory, QueryFactory

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