ballerina/mime package
Package Overview
This package provides functions to transmit and receive messages that have multiple parts, such as an attachment. The communication of such messages follow the MIME (Multipurpose Internet Mail Extensions) specification as specified in the RFC 2045 standard.
MIME Specific terms
The following terms are MIME specific and are extracted from the MIME specification.
Entity
This refers to the header fields and the content of a message, or a part of the body in a multipart entity.
Body Part
This refers to an entity that is inside a multipart entity.
Body
This is the body of an entity, which can be a body of a message or the body of a multipart entity.
Header Fields
Content-Type, Content-Transfer-Encoding, Content-ID, Content-Description, and Content-Disposition are some MIME header fields. These headers exist along with the other headers in the Entity
.
Content-Type: image/jpeg
Content-Disposition: attachment; filename=genome.jpeg;
Content-Description: a complete map of the human genome
Modify and retrieve the data in an Entity
The package provides functions to set and get an entity body from different kinds of message types. For example, XML, text, JSON, blob, and body parts. Headers can be modified through functions such as addHeader()
, setHeader()
, `removeHeader(), etc.
Samples
Handle multipart request
The sample service given below handles a multipart request. It gets the message from each part of the body, converts the messages to a string
, and sends a response.
import ballerina/http;
import ballerina/io;
import ballerina/mime;
endpoint http:Listener mockEP {
port:9090
};
@http:ServiceConfig {basePath:"/test"}
service<http:Service> test bind mockEP {
@http:ResourceConfig {
methods:["POST"],
path:"/multipleparts"
}
// The resource that handles multipart requests.
multipartResource(endpoint client, http:Request request) {
http:Response response = new;
// Get the body parts from the request.
match request.getBodyParts() {
// If there is an error while getting the body parts, set the response code as 500 and set the error message as the response message.
mime:EntityError err => {
response.statusCode = 500;
response.setStringPayload(err.message);
}
// If the body parts were returned, iterate through each body part and handle the content.
mime:Entity[] bodyParts => {
string content = "";
int i = 0;
while (i < lengthof bodyParts) {
mime:Entity part = bodyParts[i];
content = content + " -- " + handleContent(part);
i = i + 1;
}
response.setStringPayload(content);
}
}
_ = client -> respond(response);
}
}
// The function that handles the content based on the body part type.
function handleContent(mime:Entity bodyPart) returns (string) {
// Getting the base type of the specific body part.
string baseType = bodyPart.contentType.getBaseType();
// If the base type is ‘application/xml’ or ‘text/xml’, get the XML content from body part.
if (mime:APPLICATION_XML == baseType || mime:TEXT_XML == baseType) {
var payload = bodyPart.getXml();
match payload {
mime:EntityError err => return "Error in getting xml payload";
xml xmlContent => return xmlContent.getTextValue();
}
} else if (mime:APPLICATION_JSON == baseType) {
// If the base type is ‘application/json’, get the JSON content from body part.
var payload = bodyPart.getJson();
match payload {
mime:EntityError err => return "Error in getting json payload";
json jsonContent => {
return jsonContent.toString();
}
}
}
return "";
}
The sample request that is sent to the above service and the response that is printed on the console are shown below.
curl -v -F "request={\"param1\": \"value1\"};type=application/json" -F "language=ballerina;type=text/plain" -F "upload=@/home/megala/encode.txt;type=application/octet-stream" http://localhost:9090/test/multipleparts -H "Expect:"
* Trying 127.0.0.1...
* Connected to localhost (127.0.0.1) port 9090 (#0)
> POST /test/multipleparts HTTP/1.1
> Host: localhost:9090
> User-Agent: curl/7.47.0
> Accept: */*
> Content-Length: 521
> Content-Type: multipart/form-data; boundary=------------------------bf3f6dafe84260f2
>
< HTTP/1.1 200 OK
< content-type: text/plain
< content-length: 77
< server: ballerina/0.970.0-beta1-SNAPSHOT
< date: Wed, 18 Apr 2018 22:20:48 +0530
<
-- {"param1":"value1"} -- ballerina -- VGhpcyBpcyBhIGJhbGxlcmluYSBzYW1wbGU=
Create a multipart response
The sample given below creates a multipart response. It includes ‘application/json’ and ‘text/xml’ type content.
// Create a new body part.
mime:Entity bodyPart1 = new;
// Set the content type as ‘application/json’.
bodyPart1.contentType = mime:getMediaType(mime:APPLICATION_JSON);
// Finally, set the JSON content.
bodyPart1.setJson({"bodyPart":"jsonPart"});
// Create body part using an XML file.
mime:Entity bodyPart2 = new;
mime:MediaType textXml = mime:getMediaType(mime:TEXT_XML);
bodyPart2.contentType = textXml;
file:Path fileHandler = new("ballerina/mime/file.xml");
bodyPart2.setFileAsEntityBody(fileHandler);
//Create an array to hold all the body parts.
mime:Entity[] bodyParts = [bodyPart1, bodyPart2];
// Set the body parts to the outbound response.
http:Response outResponse = new;
// Set the content type as ‘multipart/mixed’ and set the body parts.
outResponse.setBodyParts(bodyParts, mime:MULTIPART_MIXED);
Primitives Summary
Type | Description |
---|
Type Definitions
Type | Values | Description |
---|
Annotations
Name | Attachement Points | Data Type | Description |
---|
Objects Summary
Object | Description |
---|---|
Base64DecodeError |
|
Base64EncodeError |
|
EntityError |
|
Endpoints Summary
Endpoint | Description |
---|
Functions Summary
Return Type | Function and Description |
---|---|
blob | Base64DecodeError | base64DecodeBlob(blob valueToBeDecoded)
|
ioByteChannel | Base64DecodeError | base64DecodeByteChannel(ByteChannel valueToBeDecoded)
|
string | Base64DecodeError | base64DecodeString(string valueToBeDecoded)
|
blob | Base64EncodeError | base64EncodeBlob(blob valueToBeEncoded)
|
ioByteChannel | Base64EncodeError | base64EncodeByteChannel(ByteChannel valueToBeEncoded)
|
string | Base64EncodeError | base64EncodeString(string valueToBeEncoded)
|
ContentDisposition | getContentDispositionObject(string contentDisposition)
|
MediaType | error | getMediaType(string contentType)
|
Global Variables
Name | Data Type | Description |
---|---|---|
APPLICATION_FORM_URLENCODED | string |
|
APPLICATION_JSON | string |
|
APPLICATION_OCTET_STREAM | string |
|
APPLICATION_PDF | string |
|
APPLICATION_SVG_XML | string |
|
APPLICATION_XHTML_XML | string |
|
APPLICATION_XML | string |
|
BOUNDARY | string |
|
CHARSET | string |
|
CONTENT_DISPOSITION | string |
|
CONTENT_ID | string |
|
CONTENT_LENGTH | string |
|
CONTENT_TYPE | string |
|
DEFAULT_CHARSET | string |
|
IMAGE_GIF | string |
|
IMAGE_JPEG | string |
|
IMAGE_PNG | string |
|
MULTIPART_ALTERNATIVE | string |
|
MULTIPART_FORM_DATA | string |
|
MULTIPART_MIXED | string |
|
MULTIPART_PARALLEL | string |
|
MULTIPART_RELATED | string |
|
START | string |
|
TEXT_HTML | string |
|
TEXT_PLAIN | string |
|
TEXT_XML | string |
|
TYPE | string |
|
public object Base64DecodeError
Represent errors related to mime base64 decoder.
Field Name | Data Type | Default Value | Description |
---|---|---|---|
message | string | The error message |
|
cause | error | The cause of the error |
public object Base64EncodeError
Represent errors related to mime base64 encoder.
Field Name | Data Type | Default Value | Description |
---|---|---|---|
message | string | The error message |
|
cause | error | The cause of the error |
public object EntityError
Represent all entity related errors.
Field Name | Data Type | Default Value | Description |
---|---|---|---|
message | string | The error message |
|
cause | error | The error which caused the entity error |
public function base64DecodeBlob(blob valueToBeDecoded) returns (blob | Base64DecodeError)
Decode a given blob with Base64 encoding scheme.
Parameter Name | Data Type | Default Value | Description |
---|---|---|---|
valueToBeDecoded | blob | Content that needs to be decoded |
Return Type | Description | ||
---|---|---|---|
blob | Base64DecodeError | Return a decoded blob |
public function base64DecodeByteChannel(ByteChannel valueToBeDecoded) returns (ioByteChannel | Base64DecodeError)
Decode a given ByteChannel with Base64 encoding scheme.
Parameter Name | Data Type | Default Value | Description |
---|---|---|---|
valueToBeDecoded | ByteChannel | Content that needs to be decoded |
Return Type | Description | ||
---|---|---|---|
ioByteChannel | Base64DecodeError | Return a decoded ByteChannel |
public function base64DecodeString(string valueToBeDecoded) returns (string | Base64DecodeError)
Decode a given string with Base64 encoding scheme.
Parameter Name | Data Type | Default Value | Description |
---|---|---|---|
valueToBeDecoded | string | Content that needs to be decoded |
Return Type | Description | ||
---|---|---|---|
string | Base64DecodeError | Return a decoded string |
public function base64EncodeBlob(blob valueToBeEncoded) returns (blob | Base64EncodeError)
Encode a given blob with Base64 encoding scheme.
Parameter Name | Data Type | Default Value | Description |
---|---|---|---|
valueToBeEncoded | blob | Content that needs to be encoded |
Return Type | Description | ||
---|---|---|---|
blob | Base64EncodeError | Return an encoded blob |
public function base64EncodeByteChannel(ByteChannel valueToBeEncoded) returns (ioByteChannel | Base64EncodeError)
Encode a given ByteChannel with Base64 encoding scheme.
Parameter Name | Data Type | Default Value | Description |
---|---|---|---|
valueToBeEncoded | ByteChannel | Content that needs to be encoded |
Return Type | Description | ||
---|---|---|---|
ioByteChannel | Base64EncodeError | Return an encoded ByteChannel |
public function base64EncodeString(string valueToBeEncoded) returns (string | Base64EncodeError)
Encode a given string with Base64 encoding scheme.
Parameter Name | Data Type | Default Value | Description |
---|---|---|---|
valueToBeEncoded | string | Content that needs to be encoded |
Return Type | Description | ||
---|---|---|---|
string | Base64EncodeError | Return an encoded string |
public function getContentDispositionObject(string contentDisposition) returns (ContentDisposition)
Given the Content-Disposition as a string, get the ContentDisposition struct object with it.
Parameter Name | Data Type | Default Value | Description |
---|---|---|---|
contentDisposition | string | content disposition string |
Return Type | Description | ||
---|---|---|---|
ContentDisposition | Return ContentDisposition object |
public function getMediaType(string contentType) returns (MediaType | error)
Given the Content-Type in string, get the MediaType object populated with it.
Parameter Name | Data Type | Default Value | Description |
---|---|---|---|
contentType | string | Content-Type in string |
Return Type | Description | ||
---|---|---|---|
MediaType | error | Return MediaType struct or an error in case of error |
public type ContentDisposition object
Represent values in Content-Disposition header.
Field Name | Data Type | Default Value | Description |
---|---|---|---|
fileName | string | Default filename for storing the bodypart, if the receiving agent wishes to store it in an external file |
|
disposition | string | Indicates how the body part should be presented (inline, attachment or as form-data) |
|
name | string | Represent the field name in case of 'multipart/form-data' |
|
parameters | map<string> | A set of parameters, specified in attribute=value notation |
-
<ContentDisposition> toString() returns (string)
Convert the ContentDisposition type to a string suitable for use as the value of a corresponding MIME header.
Return Type Description string Return the ContentDisposition object's content as a string
public type Entity object
Represent the headers and body of a message. This can be used to represent both the entity of a top level message
and an entity(body part) inside of a multipart entity.
-
<Entity> setContentType(string mediaType)
Set the content-type to entity.
Parameter Name Data Type Default Value Description mediaType string content-type that needs to be set to entity
-
<Entity> getContentType() returns (string)
Get the content-type of entity.
Return Type Description string Return content-type as a string
-
<Entity> setContentId(string contentId)
Set the content-id of the entity.
Parameter Name Data Type Default Value Description contentId string content-id that needs to be set to entity
-
<Entity> getContentId() returns (string)
Get the content-id of entity.
Return Type Description string Return content-id as a string
-
<Entity> setContentLength(int contentLength)
Set the content-length of the entity.
Parameter Name Data Type Default Value Description contentLength int content-length that needs to be set to entity
-
<Entity> getContentLength() returns (int | error)
Get the content-length of entity.
Return Type Description int | error Return content-length as an int
-
<Entity> setContentDisposition(ContentDisposition contentDisposition)
Set the content-disposition of the entity.
Parameter Name Data Type Default Value Description contentDisposition ContentDisposition content-disposition that needs to be set to entity
-
<Entity> getContentDisposition() returns (ContentDisposition)
Get the content-disposition of entity.
Return Type Description ContentDisposition Return ContentDisposition object
-
<Entity> setBody(string | xml | json | blob | ioByteChannel | Entity[] entityBody)
Set the entity body with a given content.
Parameter Name Data Type Default Value Description entityBody string | xml | json | blob | ioByteChannel | Entity[] -
<Entity> setFileAsEntityBody(string filePath)
Set the entity body with a given file handler.
Parameter Name Data Type Default Value Description filePath string Represent a file
-
<Entity> setJson(json jsonContent)
Set the entity body with the given json content.
Parameter Name Data Type Default Value Description jsonContent json Json content that needs to be set to entity
-
<Entity> getJson() returns (json | EntityError)
Given an entity, get the entity body in json form.
Return Type Description json | EntityError Return json data
-
<Entity> setXml(xml xmlContent)
Set the entity body with the given xml content
Parameter Name Data Type Default Value Description xmlContent xml Xml content that needs to be set to entity
-
<Entity> getXml() returns (xml | EntityError)
Given an entity, get the entity body in xml form.
Return Type Description xml | EntityError Return xml data
-
<Entity> setText(string textContent)
Set the entity body with the given text content.
Parameter Name Data Type Default Value Description textContent string Text content that needs to be set to entity
-
<Entity> getText() returns (string | EntityError)
Given an entity, get the entity body in text form.
Return Type Description string | EntityError Return text data
-
<Entity> setBlob(blob blobContent)
Set the entity body with the given blob content.
Parameter Name Data Type Default Value Description blobContent blob Blob content that needs to be set to entity
-
<Entity> getBlob() returns (blob | EntityError)
Given an entity, get the entity body as a blob. If the entity size is considerably large consider using getEntityWrapper() method instead.
Return Type Description blob | EntityError Return a blob
-
<Entity> setByteChannel(ByteChannel byteChannel)
Set the entity body with the given byte channel content.
Parameter Name Data Type Default Value Description byteChannel ByteChannel Byte channel that needs to be set to entity
-
<Entity> getByteChannel() returns (ioByteChannel | EntityError)
Given an entity, get the entity body as a byte channel.
Return Type Description ioByteChannel | EntityError Return a byte channel
-
<Entity> getBodyParts() returns (Entity[] | EntityError)
Given an entity, get its body parts.
Return Type Description Entity[] | EntityError Return an array of entities which represent its body parts
-
<Entity> getBodyPartsAsChannel() returns (ByteChannel)
Given an entity, get the body parts as a byte channel.
Return Type Description ByteChannel Return body parts as a byte channel
-
<Entity> setBodyParts(Entity[] bodyParts)
Set body parts to entity.
Parameter Name Data Type Default Value Description bodyParts Entity[] Represent the body parts that needs to be set to the entity
-
<Entity> getHeader(string headerName) returns (string)
Get the header value associated with the given header name.
Parameter Name Data Type Default Value Description headerName string Represent header name
Return Type Description string Return header value associated with the given header name. If multiple header values are present, then the first value will be returned
-
<Entity> getHeaders(string headerName) returns (string[])
Get all the header values associated with the given header name.
Parameter Name Data Type Default Value Description headerName string Represent the header name
Return Type Description string[] Return all the header values associated with the given header name as a string of arrays
-
<Entity> getHeaderNames() returns (string[])
Get all header names.
Return Type Description string[] Return all header names as an array of strings
-
<Entity> addHeader(string headerName, string headerValue)
Add the given header value against the given header.
Parameter Name Data Type Default Value Description headerName string Represent the header name
headerValue string Represent the header value to be added
-
<Entity> setHeader(string headerName, string headerValue)
Set the given header value against the given header. If a header already exist, its value will be replaced with the given header value.
Parameter Name Data Type Default Value Description headerName string Represent the header name
headerValue string Represent the header value
-
<Entity> removeHeader(string headerName)
Remove the given header from the entity.
Parameter Name Data Type Default Value Description headerName string Represent the header name
-
<Entity> removeAllHeaders()
Remove all headers associated with the entity.
-
<Entity> hasHeader(string headerName) returns (boolean)
Check the header existence.
Parameter Name Data Type Default Value Description headerName string Return Type Description boolean
public type MediaType object
Describes the nature of the data in the body of a MIME entity.
Field Name | Data Type | Default Value | Description |
---|---|---|---|
primaryType | string | Declares the general type of data |
|
subType | string | A specific format of the primary type data |
|
suffix | string | Identify the semantics of a specific media type |
|
parameters | map<string> | A set of parameters, specified in an attribute=value notation |
-
<MediaType> getBaseType() returns (string)
Get ���primaryType/subtype+suffix��� combination in string format.
Return Type Description string Return base type from MediaType struct
-
<MediaType> toString() returns (string)
Convert the media type to a string suitable for use as the value of a corresponding HTTP header.
Return Type Description string Return the Content-Type with parameters as a string