The requirement is to retrieve address from Google Geocoding by passing postal code.When passing postal code through HttpRequest, it should return the response in JSON.But I am not going to write how I call it in this entry.I will save it for future.*cough*
So I will write on how to generate signature...
Note on this limitation between free API and paid one.
- 2,500 requests per 24 hour period.
- 10 requests per second.
- 100,000 requests per 24 hour period.
- 10 requests per second.
See!!This is free...you can play around with it.
https://maps.googleapis.com/maps/api/geocode/json?components=postal_code:97510
It means , we required to have client and signature.
Google will give us client and private key.But it does not mean that we are on now.We need generate the signature using private key given.Each time when we request for postal code, we need to generate signature.
Example, postal code different so signature also can be different.
https://maps.googleapis.com/maps/api/geocode/json?components=postal_code:11900&client=gme-acme&signature=signature1
https://maps.googleapis.com/maps/api/geocode/json?components=postal_code:11800&client=gme-acme&signature=signature2
Actually it sound like a lot of job to generate signature.It is not fun because only Phyton and Java examples that available.I need to generate signature before calling the webservice.Calling out itself have limitation in Salesforce.*sigh*
But I after done some research, do experiment ,asking around ...at last I managed to generate the signature in Apex class.One of the forum that inspired me is here . But it seem that I need to play around with replace method before execute urlEncode.
Anyway, here the code.Note for this we need to use hmacSHA1 algorithm.
You can go ahead and run in Apex Execute Anonymous, but make sure that you have the client and private key.Hope it will help you.I could not guarantee it is error free, but it works for me.Let me know if you have better solution.
*Because this is for corporate use, go ahead and ask Google support.
Anyway, here the code.Note for this we need to use hmacSHA1 algorithm.
You can go ahead and run in Apex Execute Anonymous, but make sure that you have the client and private key.Hope it will help you.I could not guarantee it is error free, but it works for me.Let me know if you have better solution.
*Because this is for corporate use, go ahead and ask Google support.
//replace the number with any postal code to test String baseUrl = 'https://maps.googleapis.com/maps/api/geocode/json?components=postal_code:97005&client=gme-acme'; URL url = new URL(baseURL); String path =url.getPath(); String query=url.getQuery(); String input=path+'?'+query; String privateKey='whateverkeythatyougot'; Blob decodePK = EncodingUtil.base64Decode(privateKey); String algorithmName = 'hmacSHA1'; Blob hmacData = Crypto.generateMac(algorithmName, Blob.valueOf(input), decodePK); String encodePK =EncodingUtil.base64Encode(hmacData); //please make sure to replace. encodePK = encodePK.replace('+', '-'); encodePK = encodePK.replace('/', '_'); String signature =EncodingUtil.urlEncode(encodePK, 'UTF-8'); signature = signature.replace('+', '-'); signature = signature.replace('/', '_'); baseUrl +='&signature='+signature; //this is the final URL that can be pasted to browser system.debug('@unid baseURL ='+ baseURL);
References:
Google Geocoding API
Digital Signature
Stack Overflow
Salesforce Crypto Class
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