Skip to Content

Changes for page Multipart form-data

Last modified by Erik Bakker on 2024/06/17 11:39
From version 10.1
edited by Erik Bakker
on 2022/07/26 13:17
Change comment: There is no comment for this version
To version 23.1
edited by Erik Bakker
on 2024/01/19 08:20
Change comment: There is no comment for this version

Summary

Details

Page properties
Title
... ... @@ -1,1 +1,1 @@
1 -expert-securing-data-traffic-api-gw-security-external-idp
1 +Multipart form-data
Default language
... ... @@ -1,1 +1,0 @@
1 -en
Content
... ... @@ -1,5 +1,5 @@
1 1  {{container}}{{container layoutStyle="columns"}}(((
2 -In the crash course on the API Gateway we discussed the various options available to [[secure>>doc:Main.eMagiz Academy.Microlearnings.Crash Course.Crash Course API Gateway.crashcourse-api-gateway-security.WebHome||target="blank"]] your API Gateway properly. In this microlearning, we will expand our knowledge on that topic by looking at a special case of securing your API Gateway. That case is special as you use an external identity provider (IDP) to govern the roles and users that have rights on your API Gateway.
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  
... ... @@ -9,55 +9,73 @@
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 -By image transformation, we mean transforming the raw data that represents an image into another image format.
14 +Key aspects are:
15 15  
16 -* Read the help text 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 convert images in specific 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 help text 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}} This microlearning focuses on the image transformer component. Ensuring that the input is valid and the output fits the remainder of the process is highly dependent on the use case and will therefore not be discussed in this microlearning{{/warning}}
30 +{{info}}
31 +The following criteria apply when utilizing the boundary functionality within the multipart/form-data construction:
32 +* The value of the Boundary must begin with a double horizontal bar –, this is called a leading hyphen
33 +* The value of the Boundary must not contain more than 70 characters in addition to the leading hyphen.
34 +* The value of the Boundary must not contain characters that are disabled by the HTTP protocol or the URL, such as the colon: etc.
35 +* A boundary within the request body must always be preceeded by a CRLF line. This means that when the request body **ends** with a CRLF line an **additional** CRLF line is needed **before** the boundary doubling the CRLF lines in that part of the request body.{{/info}}
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 necessary component. For example, in the left panel, you can search for "Image." This will yield the following result.
37 +=== 3.1 Prepare the message ===
33 33  
34 -[[image:Main.Images.Microlearning.WebHome@expert-create-your-transformations-image-transformation-image-transformation-component.png]]
39 +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.
35 35  
36 -After dragging the component onto the canvas, you must define the channels first.
41 +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.
37 37  
38 -[[image:Main.Images.Microlearning.WebHome@expert-create-your-transformations-image-transformation-image-transformation-component-help.png]]
43 +On top of that, we need to define the contentType header.
39 39  
40 -Secondly, we must select the desired image format we want to transform. Finally, the field indicates all valid values you can choose. Please note that 'PNG' is the default selection.
45 +[[image:Main.Images.Microlearning.WebHome@expert-data-handling-multipart-form-data--content-type-header-config.png]]
41 41  
42 -[[image:Main.Images.Microlearning.WebHome@expert-create-your-transformations-image-transformation-image-transformation-component-image-options.png]]
47 +=== 3.2 Construct the message ===
43 43  
44 -Once you have done this, the component configuration is finished, and you can transform your input image to a desired output image format.
49 +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:
45 45  
46 -== 4. Assignment ==
51 +* Each part of the message needs to be separated by a boundary
52 +* The message needs to start with a boundary and finish with a boundary
53 +* Line breaks are needed to differentiate between the boundary and the text content
54 +* No line break is needed when the content is not text-based
47 47  
48 -Check whether the solution we discussed today can be found within your project.
49 -This assignment can be completed within the (Academy) project you created/used in the previous assignment.
56 +Given all this, you can write the following SpEL expression that will yield a desirable output:
50 50  
51 -== 5. Key takeaways ==
58 +{{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 52  
53 -* Read the help text of the component to understand which formats are supported
54 -* Ensure the input image is supplied in the correct format
55 -* Ensure you wrap the output image in something if you want to do additional transformations on the data further downstream
60 +Putting this in a standard transformation gives you the following solution in the flow.
56 56  
57 -== 6. Suggested Additional Readings ==
62 +[[image:Main.Images.Microlearning.WebHome@expert-data-handling-multipart-form-data--standard-transformer-config.png]]
58 58  
59 -If you are interested in this topic and want more information, please read the help text provided by eMagiz.
64 +=== 3.3 Calling the endpoint ===
60 60  
61 -== 7. Silent demonstration video ==
66 +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.
62 62  
63 -As this is more of theoretical microlearning, there is no video accompanying the microlearning.)))((({{toc/}}))){{/container}}{{/container}}
68 +== 4. Key takeaways ==
69 +
70 +* Make sure to define the boundary that separates the parts of the message
71 +* Make sure to define the content types of each part of the message
72 +* Make sure to define the content type that matches the specification for multipart/form-data
73 +* Construct the complete message according to the specification
74 +
75 +== 5. Suggested Additional Readings ==
76 +
77 +If you are interested in this topic, please read the help texts on the platform and read the following link:
78 +
79 +* [[Multipart form-data explained>>https://www.sobyte.net/post/2021-12/learn-about-http-multipart-form-data/||target="blank"]]
80 +
81 +)))((({{toc/}}))){{/container}}{{/container}}