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Changes for page Multipart form-data

Last modified by Erik Bakker on 2024/06/17 11:39
From version 8.1
edited by Erik Bakker
on 2022/07/26 12:49
Change comment: There is no comment for this version
To version 21.1
edited by Erik Bakker
on 2023/01/23 13:12
Change comment: There is no comment for this version

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1 -Image Transformations
1 +Multipart form-data
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1 1  {{container}}{{container layoutStyle="columns"}}(((
2 -In most cases, you will transform XML messages to other XML messages, or you will transform JSON or EDI messages in another of these formats. However, sometimes you want to perform an image transformation. With this image transformation you can transform images in certain formats to another format (i.e. png). This can come in handy when you want to standardize the image format before using it further downstream in your business application(s).
2 +Sometimes when you call an external REST endpoint, they require you to send meta information and one or more "attachments" in one call to the REST endpoint. To make this possible, you need to send the information with the contentType called multipart/form-data. In this microlearning, we will discuss how you can configure a valid message within the eMagiz platform that allows you to send out messages with this contentType and have them accepted by the endpoint in question.
3 3  
4 4  Should you have any questions, please get in touch with [[academy@emagiz.com>>mailto:academy@emagiz.com]].
5 5  
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9 9  
10 10  == 2. Key concepts ==
11 11  
12 -This microlearning focuses on performing image transformations in eMagiz.
12 +This microlearning focuses on configuring a multipart/form-data message within eMagiz to ensure it is sent correctly to an endpoint.
13 13  
14 -With image transformation, we mean transforming the raw data that represents an image to another image format.
14 +Key aspects are:
15 15  
16 -* Read the helptext of the component to understand which formats are supported
17 -* Ensure the input image is supplied in the correct format
18 -* Ensure you wrap the output image in something if you want to do additional transformations on the data further downstream
16 +* Defining the boundary that separates the parts of the message
17 +* Defining the content types of each part of the message
18 +* Construction of the complete message according to the specification
19 19  
20 -== 3. Image Transformation ==
20 +== 3. Multipart form-data ==
21 21  
22 -In most cases, you will transform XML messages to other XML messages, or you will transform JSON or EDI messages in another of these formats. However, sometimes you want to perform an image transformation. With this image transformation you can transform images in certain formats to another format (i.e. png). This can come in handy when you want to standardize the image format before using it further downstream in your business application(s).
22 +Sometimes when you call an external REST endpoint, they require you to send meta information and one or more "attachments" in one call to the REST endpoint. To make this possible, you need to send the information with the contentType called multipart/form-data. In this microlearning, we will discuss how you can configure a valid message within the eMagiz platform that allows you to send out messages with this contentType and have them accepted by the endpoint in question.
23 23  
24 -Before we dive into the specifics of how to configure this let us first consider the following:
24 +Key aspects are:
25 25  
26 -* Read the helptext of the component to understand which formats are supported
27 -* Ensure the input image is supplied in the correct format
28 -* Ensure you wrap the output image in something if you want to do additional transformations on the data further downstream
26 +* Defining the boundary that separates the parts of the message
27 +* Defining the content types of each part of the message
28 +* Construction of the complete message according to the specification
29 29  
30 -{{warning}}The focus of this microlearning lies on the image transformer component. Ensuring that the input is useful and the output fits the remainder of the process is highly depending on the use case and will therefore not be discussed in this microlearning{{/warning}}
30 +=== 3.1 Prepare the message ===
31 31  
32 -When turning to the Create phase of eMagiz, we need to open the flow and enter "Start Editing" mode to add the component we need. For example, in the left panel, you can search for "Image". This will yield the following result.
32 +To construct the message, several steps are needed to make it work. Luckily, most of the steps necessary have to do with concepts we have already discussed in previous microlearnings. As you can imagine, based on what multipart/form-data entails, we need a way to both store the meta information and the file(s) we want to send to the external party. For example, put the metadata in one (or multiple) header(s) and use the file content as a payload. This you can achieve with a header enricher and standard transformer.
33 33  
34 -[[image:Main.Images.Microlearning.WebHome@expert-create-your-transformations-image-transformation-image-transformation-component.png]]
34 +Once the file content is your payload, you must ensure that the data is "raw." So when you have a base64 encoded string, you should decode it before sending it to the endpoint.
35 35  
36 +On top of that, we need to define the contentType header.
37 +
38 +[[image:Main.Images.Microlearning.WebHome@expert-data-handling-multipart-form-data--content-type-header-config.png]]
39 +
40 +=== 3.2 Construct the message ===
41 +
42 +After you have set the stage, you can use a standard transformer component to build your message correctly. To create it correctly, you need to take the following into account:
43 +
44 +* Each part of the message needs to be separated by a boundary
45 +* The message needs to start with a boundary and finish with a boundary
46 +* Line breaks are needed to differentiate between the boundary and the text content
47 +* No line break is needed when the content is not text-based
48 +
49 +Given all this, you can write the following SpEL expression that will yield a desirable output:
50 +
51 +{{code}}'${multi-part-form-data.data-handling.boundary}' + headers.metaInfo + T(com.emagiz.util.Newline).CRLF.characters + '${multi-part-form-data.data-handling.boundary}' + T(com.emagiz.util.Newline).CRLF.characters + 'Content-Disposition: form-data; name="file"; filename="' + headers.filename + '"' + T(com.emagiz.util.Newline).CRLF.characters + 'Content-Type: application/pdf' + T(com.emagiz.util.Newline).CRLF.characters + T(com.emagiz.util.Newline).CRLF.characters + payload + '${multi-part-form-data.data-handling.boundary}'{{/code}}
52 +
53 +Putting this in a standard transformation gives you the following solution in the flow.
54 +
55 +[[image:Main.Images.Microlearning.WebHome@expert-data-handling-multipart-form-data--standard-transformer-config.png]]
56 +
57 +=== 3.3 Calling the endpoint ===
58 +
59 +Now that we have constructed our message correctly, the last thing to do is call the endpoint in question. Since we have prepared our message and accurately defined our contentType calling the endpoint does not require any additional configurations compared to what you are already used to when dealing with REST endpoints.
60 +
36 36  == 4. Assignment ==
37 37  
38 -Check out which of the XPaths we have discussed today can be found within your project.
39 -This assignment can be completed within the (Academy) project you created/used in the previous assignment.
63 +Try to see whether you can construct the flow so that it outputs a valid multipart/form-data message.
64 +This assignment can be completed with the help of the (Academy) project you created/used in the previous assignment.
40 40  
41 41  == 5. Key takeaways ==
42 42  
43 -Some of the very complex XPath options are:
68 +* Make sure to define the boundary that separates the parts of the message
69 +* Make sure to define the content types of each part of the message
70 +* Make sure to define the content type that matches the specification for multipart/form-data
71 +* Construct the complete message according to the specification
44 44  
45 -* matches
46 -* replace
47 -* tokenize
48 -
49 49  == 6. Suggested Additional Readings ==
50 50  
51 -If you are interested in this topic and want more information on it, please read the help text provided by eMagiz and read more information on the following links:
75 +If you are interested in this topic, please read the help texts on the platform and read the following link:
52 52  
53 -* http://www.xsltfunctions.com/xsl/fn_matches.html
54 -* http://www.xsltfunctions.com/xsl/fn_replace.html
55 -* http://www.xsltfunctions.com/xsl/fn_tokenize.html
77 +* [[Multipart form-data explained>>https://www.sobyte.net/post/2021-12/learn-about-http-multipart-form-data/||target="blank"]]
56 56  
57 57  == 7. Silent demonstration video ==
58 58